--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/go/gofrontend/types.cc	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,12038 @@
+// types.cc -- Go frontend types.
+
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "go-system.h"
+
+#include <ostream>
+
+#include "go-c.h"
+#include "gogo.h"
+#include "go-diagnostics.h"
+#include "go-encode-id.h"
+#include "operator.h"
+#include "expressions.h"
+#include "statements.h"
+#include "export.h"
+#include "import.h"
+#include "backend.h"
+#include "types.h"
+
+// Forward declarations so that we don't have to make types.h #include
+// backend.h.
+
+static void
+get_backend_struct_fields(Gogo* gogo, const Struct_field_list* fields,
+			  bool use_placeholder,
+			  std::vector<Backend::Btyped_identifier>* bfields);
+
+static void
+get_backend_slice_fields(Gogo* gogo, Array_type* type, bool use_placeholder,
+			 std::vector<Backend::Btyped_identifier>* bfields);
+
+static void
+get_backend_interface_fields(Gogo* gogo, Interface_type* type,
+			     bool use_placeholder,
+			     std::vector<Backend::Btyped_identifier>* bfields);
+
+// Class Type.
+
+Type::Type(Type_classification classification)
+  : classification_(classification), btype_(NULL), type_descriptor_var_(NULL),
+    gc_symbol_var_(NULL)
+{
+}
+
+Type::~Type()
+{
+}
+
+// Get the base type for a type--skip names and forward declarations.
+
+Type*
+Type::base()
+{
+  switch (this->classification_)
+    {
+    case TYPE_NAMED:
+      return this->named_type()->named_base();
+    case TYPE_FORWARD:
+      return this->forward_declaration_type()->real_type()->base();
+    default:
+      return this;
+    }
+}
+
+const Type*
+Type::base() const
+{
+  switch (this->classification_)
+    {
+    case TYPE_NAMED:
+      return this->named_type()->named_base();
+    case TYPE_FORWARD:
+      return this->forward_declaration_type()->real_type()->base();
+    default:
+      return this;
+    }
+}
+
+// Skip defined forward declarations.
+
+Type*
+Type::forwarded()
+{
+  Type* t = this;
+  Forward_declaration_type* ftype = t->forward_declaration_type();
+  while (ftype != NULL && ftype->is_defined())
+    {
+      t = ftype->real_type();
+      ftype = t->forward_declaration_type();
+    }
+  return t;
+}
+
+const Type*
+Type::forwarded() const
+{
+  const Type* t = this;
+  const Forward_declaration_type* ftype = t->forward_declaration_type();
+  while (ftype != NULL && ftype->is_defined())
+    {
+      t = ftype->real_type();
+      ftype = t->forward_declaration_type();
+    }
+  return t;
+}
+
+// If this is a named type, return it.  Otherwise, return NULL.
+
+Named_type*
+Type::named_type()
+{
+  return this->forwarded()->convert_no_base<Named_type, TYPE_NAMED>();
+}
+
+const Named_type*
+Type::named_type() const
+{
+  return this->forwarded()->convert_no_base<const Named_type, TYPE_NAMED>();
+}
+
+// Return true if this type is not defined.
+
+bool
+Type::is_undefined() const
+{
+  return this->forwarded()->forward_declaration_type() != NULL;
+}
+
+// Return true if this is a basic type: a type which is not composed
+// of other types, and is not void.
+
+bool
+Type::is_basic_type() const
+{
+  switch (this->classification_)
+    {
+    case TYPE_INTEGER:
+    case TYPE_FLOAT:
+    case TYPE_COMPLEX:
+    case TYPE_BOOLEAN:
+    case TYPE_STRING:
+    case TYPE_NIL:
+      return true;
+
+    case TYPE_ERROR:
+    case TYPE_VOID:
+    case TYPE_FUNCTION:
+    case TYPE_POINTER:
+    case TYPE_STRUCT:
+    case TYPE_ARRAY:
+    case TYPE_MAP:
+    case TYPE_CHANNEL:
+    case TYPE_INTERFACE:
+      return false;
+
+    case TYPE_NAMED:
+    case TYPE_FORWARD:
+      return this->base()->is_basic_type();
+
+    default:
+      go_unreachable();
+    }
+}
+
+// Return true if this is an abstract type.
+
+bool
+Type::is_abstract() const
+{
+  switch (this->classification())
+    {
+    case TYPE_INTEGER:
+      return this->integer_type()->is_abstract();
+    case TYPE_FLOAT:
+      return this->float_type()->is_abstract();
+    case TYPE_COMPLEX:
+      return this->complex_type()->is_abstract();
+    case TYPE_STRING:
+      return this->is_abstract_string_type();
+    case TYPE_BOOLEAN:
+      return this->is_abstract_boolean_type();
+    default:
+      return false;
+    }
+}
+
+// Return a non-abstract version of an abstract type.
+
+Type*
+Type::make_non_abstract_type()
+{
+  go_assert(this->is_abstract());
+  switch (this->classification())
+    {
+    case TYPE_INTEGER:
+      if (this->integer_type()->is_rune())
+	return Type::lookup_integer_type("int32");
+      else
+	return Type::lookup_integer_type("int");
+    case TYPE_FLOAT:
+      return Type::lookup_float_type("float64");
+    case TYPE_COMPLEX:
+      return Type::lookup_complex_type("complex128");
+    case TYPE_STRING:
+      return Type::lookup_string_type();
+    case TYPE_BOOLEAN:
+      return Type::lookup_bool_type();
+    default:
+      go_unreachable();
+    }
+}
+
+// Return true if this is an error type.  Don't give an error if we
+// try to dereference an undefined forwarding type, as this is called
+// in the parser when the type may legitimately be undefined.
+
+bool
+Type::is_error_type() const
+{
+  const Type* t = this->forwarded();
+  // Note that we return false for an undefined forward type.
+  switch (t->classification_)
+    {
+    case TYPE_ERROR:
+      return true;
+    case TYPE_NAMED:
+      return t->named_type()->is_named_error_type();
+    default:
+      return false;
+    }
+}
+
+// If this is a pointer type, return the type to which it points.
+// Otherwise, return NULL.
+
+Type*
+Type::points_to() const
+{
+  const Pointer_type* ptype = this->convert<const Pointer_type,
+					    TYPE_POINTER>();
+  return ptype == NULL ? NULL : ptype->points_to();
+}
+
+// Return whether this is a slice type.
+
+bool
+Type::is_slice_type() const
+{
+  return this->array_type() != NULL && this->array_type()->length() == NULL;
+}
+
+// Return whether this is the predeclared constant nil being used as a
+// type.
+
+bool
+Type::is_nil_constant_as_type() const
+{
+  const Type* t = this->forwarded();
+  if (t->forward_declaration_type() != NULL)
+    {
+      const Named_object* no = t->forward_declaration_type()->named_object();
+      if (no->is_unknown())
+	no = no->unknown_value()->real_named_object();
+      if (no != NULL
+	  && no->is_const()
+	  && no->const_value()->expr()->is_nil_expression())
+	return true;
+    }
+  return false;
+}
+
+// Traverse a type.
+
+int
+Type::traverse(Type* type, Traverse* traverse)
+{
+  go_assert((traverse->traverse_mask() & Traverse::traverse_types) != 0
+	     || (traverse->traverse_mask()
+		 & Traverse::traverse_expressions) != 0);
+  if (traverse->remember_type(type))
+    {
+      // We have already traversed this type.
+      return TRAVERSE_CONTINUE;
+    }
+  if ((traverse->traverse_mask() & Traverse::traverse_types) != 0)
+    {
+      int t = traverse->type(type);
+      if (t == TRAVERSE_EXIT)
+	return TRAVERSE_EXIT;
+      else if (t == TRAVERSE_SKIP_COMPONENTS)
+	return TRAVERSE_CONTINUE;
+    }
+  // An array type has an expression which we need to traverse if
+  // traverse_expressions is set.
+  if (type->do_traverse(traverse) == TRAVERSE_EXIT)
+    return TRAVERSE_EXIT;
+  return TRAVERSE_CONTINUE;
+}
+
+// Default implementation for do_traverse for child class.
+
+int
+Type::do_traverse(Traverse*)
+{
+  return TRAVERSE_CONTINUE;
+}
+
+// Return whether two types are identical.  If ERRORS_ARE_IDENTICAL,
+// then return true for all erroneous types; this is used to avoid
+// cascading errors.  If REASON is not NULL, optionally set *REASON to
+// the reason the types are not identical.
+
+bool
+Type::are_identical(const Type* t1, const Type* t2, bool errors_are_identical,
+		    std::string* reason)
+{
+  return Type::are_identical_cmp_tags(t1, t2, COMPARE_TAGS,
+				      errors_are_identical, reason);
+}
+
+// Like are_identical, but with a CMP_TAGS parameter.
+
+bool
+Type::are_identical_cmp_tags(const Type* t1, const Type* t2, Cmp_tags cmp_tags,
+			     bool errors_are_identical, std::string* reason)
+{
+  if (t1 == NULL || t2 == NULL)
+    {
+      // Something is wrong.
+      return errors_are_identical ? true : t1 == t2;
+    }
+
+  // Skip defined forward declarations.
+  t1 = t1->forwarded();
+  t2 = t2->forwarded();
+
+  // Ignore aliases for purposes of type identity.
+  while (t1->named_type() != NULL && t1->named_type()->is_alias())
+    t1 = t1->named_type()->real_type()->forwarded();
+  while (t2->named_type() != NULL && t2->named_type()->is_alias())
+    t2 = t2->named_type()->real_type()->forwarded();
+
+  if (t1 == t2)
+    return true;
+
+  // An undefined forward declaration is an error.
+  if (t1->forward_declaration_type() != NULL
+      || t2->forward_declaration_type() != NULL)
+    return errors_are_identical;
+
+  // Avoid cascading errors with error types.
+  if (t1->is_error_type() || t2->is_error_type())
+    {
+      if (errors_are_identical)
+	return true;
+      return t1->is_error_type() && t2->is_error_type();
+    }
+
+  // Get a good reason for the sink type.  Note that the sink type on
+  // the left hand side of an assignment is handled in are_assignable.
+  if (t1->is_sink_type() || t2->is_sink_type())
+    {
+      if (reason != NULL)
+	*reason = "invalid use of _";
+      return false;
+    }
+
+  // A named type is only identical to itself.
+  if (t1->named_type() != NULL || t2->named_type() != NULL)
+    return false;
+
+  // Check type shapes.
+  if (t1->classification() != t2->classification())
+    return false;
+
+  switch (t1->classification())
+    {
+    case TYPE_VOID:
+    case TYPE_BOOLEAN:
+    case TYPE_STRING:
+    case TYPE_NIL:
+      // These types are always identical.
+      return true;
+
+    case TYPE_INTEGER:
+      return t1->integer_type()->is_identical(t2->integer_type());
+
+    case TYPE_FLOAT:
+      return t1->float_type()->is_identical(t2->float_type());
+
+    case TYPE_COMPLEX:
+      return t1->complex_type()->is_identical(t2->complex_type());
+
+    case TYPE_FUNCTION:
+      return t1->function_type()->is_identical(t2->function_type(),
+					       false,
+					       cmp_tags,
+					       errors_are_identical,
+					       reason);
+
+    case TYPE_POINTER:
+      return Type::are_identical_cmp_tags(t1->points_to(), t2->points_to(),
+					  cmp_tags, errors_are_identical,
+					  reason);
+
+    case TYPE_STRUCT:
+      return t1->struct_type()->is_identical(t2->struct_type(), cmp_tags,
+					     errors_are_identical);
+
+    case TYPE_ARRAY:
+      return t1->array_type()->is_identical(t2->array_type(), cmp_tags,
+					    errors_are_identical);
+
+    case TYPE_MAP:
+      return t1->map_type()->is_identical(t2->map_type(), cmp_tags,
+					  errors_are_identical);
+
+    case TYPE_CHANNEL:
+      return t1->channel_type()->is_identical(t2->channel_type(), cmp_tags,
+					      errors_are_identical);
+
+    case TYPE_INTERFACE:
+      return t1->interface_type()->is_identical(t2->interface_type(), cmp_tags,
+						errors_are_identical);
+
+    case TYPE_CALL_MULTIPLE_RESULT:
+      if (reason != NULL)
+	*reason = "invalid use of multiple-value function call";
+      return false;
+
+    default:
+      go_unreachable();
+    }
+}
+
+// Return true if it's OK to have a binary operation with types LHS
+// and RHS.  This is not used for shifts or comparisons.
+
+bool
+Type::are_compatible_for_binop(const Type* lhs, const Type* rhs)
+{
+  if (Type::are_identical(lhs, rhs, true, NULL))
+    return true;
+
+  // A constant of abstract bool type may be mixed with any bool type.
+  if ((rhs->is_abstract_boolean_type() && lhs->is_boolean_type())
+      || (lhs->is_abstract_boolean_type() && rhs->is_boolean_type()))
+    return true;
+
+  // A constant of abstract string type may be mixed with any string
+  // type.
+  if ((rhs->is_abstract_string_type() && lhs->is_string_type())
+      || (lhs->is_abstract_string_type() && rhs->is_string_type()))
+    return true;
+
+  lhs = lhs->base();
+  rhs = rhs->base();
+
+  // A constant of abstract integer, float, or complex type may be
+  // mixed with an integer, float, or complex type.
+  if ((rhs->is_abstract()
+       && (rhs->integer_type() != NULL
+	   || rhs->float_type() != NULL
+	   || rhs->complex_type() != NULL)
+       && (lhs->integer_type() != NULL
+	   || lhs->float_type() != NULL
+	   || lhs->complex_type() != NULL))
+      || (lhs->is_abstract()
+	  && (lhs->integer_type() != NULL
+	      || lhs->float_type() != NULL
+	      || lhs->complex_type() != NULL)
+	  && (rhs->integer_type() != NULL
+	      || rhs->float_type() != NULL
+	      || rhs->complex_type() != NULL)))
+    return true;
+
+  // The nil type may be compared to a pointer, an interface type, a
+  // slice type, a channel type, a map type, or a function type.
+  if (lhs->is_nil_type()
+      && (rhs->points_to() != NULL
+	  || rhs->interface_type() != NULL
+	  || rhs->is_slice_type()
+	  || rhs->map_type() != NULL
+	  || rhs->channel_type() != NULL
+	  || rhs->function_type() != NULL))
+    return true;
+  if (rhs->is_nil_type()
+      && (lhs->points_to() != NULL
+	  || lhs->interface_type() != NULL
+	  || lhs->is_slice_type()
+	  || lhs->map_type() != NULL
+	  || lhs->channel_type() != NULL
+	  || lhs->function_type() != NULL))
+    return true;
+
+  return false;
+}
+
+// Return true if a value with type T1 may be compared with a value of
+// type T2.  IS_EQUALITY_OP is true for == or !=, false for <, etc.
+
+bool
+Type::are_compatible_for_comparison(bool is_equality_op, const Type *t1,
+				    const Type *t2, std::string *reason)
+{
+  if (t1 != t2
+      && !Type::are_assignable(t1, t2, NULL)
+      && !Type::are_assignable(t2, t1, NULL))
+    {
+      if (reason != NULL)
+	*reason = "incompatible types in binary expression";
+      return false;
+    }
+
+  if (!is_equality_op)
+    {
+      if (t1->integer_type() == NULL
+	  && t1->float_type() == NULL
+	  && !t1->is_string_type())
+	{
+	  if (reason != NULL)
+	    *reason = _("invalid comparison of non-ordered type");
+	  return false;
+	}
+    }
+  else if (t1->is_slice_type()
+	   || t1->map_type() != NULL
+	   || t1->function_type() != NULL
+	   || t2->is_slice_type()
+	   || t2->map_type() != NULL
+	   || t2->function_type() != NULL)
+    {
+      if (!t1->is_nil_type() && !t2->is_nil_type())
+	{
+	  if (reason != NULL)
+	    {
+	      if (t1->is_slice_type() || t2->is_slice_type())
+		*reason = _("slice can only be compared to nil");
+	      else if (t1->map_type() != NULL || t2->map_type() != NULL)
+		*reason = _("map can only be compared to nil");
+	      else
+		*reason = _("func can only be compared to nil");
+
+	      // Match 6g error messages.
+	      if (t1->interface_type() != NULL || t2->interface_type() != NULL)
+		{
+		  char buf[200];
+		  snprintf(buf, sizeof buf, _("invalid operation (%s)"),
+			   reason->c_str());
+		  *reason = buf;
+		}
+	    }
+	  return false;
+	}
+    }
+  else
+    {
+      if (!t1->is_boolean_type()
+	  && t1->integer_type() == NULL
+	  && t1->float_type() == NULL
+	  && t1->complex_type() == NULL
+	  && !t1->is_string_type()
+	  && t1->points_to() == NULL
+	  && t1->channel_type() == NULL
+	  && t1->interface_type() == NULL
+	  && t1->struct_type() == NULL
+	  && t1->array_type() == NULL
+	  && !t1->is_nil_type())
+	{
+	  if (reason != NULL)
+	    *reason = _("invalid comparison of non-comparable type");
+	  return false;
+	}
+
+      if (t1->named_type() != NULL)
+	return t1->named_type()->named_type_is_comparable(reason);
+      else if (t2->named_type() != NULL)
+	return t2->named_type()->named_type_is_comparable(reason);
+      else if (t1->struct_type() != NULL)
+	{
+	  if (t1->struct_type()->is_struct_incomparable())
+	    {
+	      if (reason != NULL)
+		*reason = _("invalid comparison of generated struct");
+	      return false;
+	    }
+	  const Struct_field_list* fields = t1->struct_type()->fields();
+	  for (Struct_field_list::const_iterator p = fields->begin();
+	       p != fields->end();
+	       ++p)
+	    {
+	      if (!p->type()->is_comparable())
+		{
+		  if (reason != NULL)
+		    *reason = _("invalid comparison of non-comparable struct");
+		  return false;
+		}
+	    }
+	}
+      else if (t1->array_type() != NULL)
+	{
+	  if (t1->array_type()->is_array_incomparable())
+	    {
+	      if (reason != NULL)
+		*reason = _("invalid comparison of generated array");
+	      return false;
+	    }
+	  if (t1->array_type()->length()->is_nil_expression()
+	      || !t1->array_type()->element_type()->is_comparable())
+	    {
+	      if (reason != NULL)
+		*reason = _("invalid comparison of non-comparable array");
+	      return false;
+	    }
+	}
+    }
+
+  return true;
+}
+
+// Return true if a value with type RHS may be assigned to a variable
+// with type LHS.  If REASON is not NULL, set *REASON to the reason
+// the types are not assignable.
+
+bool
+Type::are_assignable(const Type* lhs, const Type* rhs, std::string* reason)
+{
+  // Do some checks first.  Make sure the types are defined.
+  if (rhs != NULL && !rhs->is_undefined())
+    {
+      if (rhs->is_void_type())
+	{
+	  if (reason != NULL)
+	    *reason = "non-value used as value";
+	  return false;
+	}
+      if (rhs->is_call_multiple_result_type())
+	{
+	  if (reason != NULL)
+	    reason->assign(_("multiple-value function call in "
+			     "single-value context"));
+	  return false;
+	}
+    }
+
+  // Any value may be assigned to the blank identifier.
+  if (lhs != NULL
+      && !lhs->is_undefined()
+      && lhs->is_sink_type())
+    return true;
+
+  // Identical types are assignable.
+  if (Type::are_identical(lhs, rhs, true, reason))
+    return true;
+
+  // The types are assignable if they have identical underlying types
+  // and either LHS or RHS is not a named type.
+  if (((lhs->named_type() != NULL && rhs->named_type() == NULL)
+       || (rhs->named_type() != NULL && lhs->named_type() == NULL))
+      && Type::are_identical(lhs->base(), rhs->base(), true, reason))
+    return true;
+
+  // The types are assignable if LHS is an interface type and RHS
+  // implements the required methods.
+  const Interface_type* lhs_interface_type = lhs->interface_type();
+  if (lhs_interface_type != NULL)
+    {
+      if (lhs_interface_type->implements_interface(rhs, reason))
+	return true;
+      const Interface_type* rhs_interface_type = rhs->interface_type();
+      if (rhs_interface_type != NULL
+	  && lhs_interface_type->is_compatible_for_assign(rhs_interface_type,
+							  reason))
+	return true;
+    }
+
+  // The type are assignable if RHS is a bidirectional channel type,
+  // LHS is a channel type, they have identical element types, and
+  // either LHS or RHS is not a named type.
+  if (lhs->channel_type() != NULL
+      && rhs->channel_type() != NULL
+      && rhs->channel_type()->may_send()
+      && rhs->channel_type()->may_receive()
+      && (lhs->named_type() == NULL || rhs->named_type() == NULL)
+      && Type::are_identical(lhs->channel_type()->element_type(),
+			     rhs->channel_type()->element_type(),
+			     true,
+			     reason))
+    return true;
+
+  // The nil type may be assigned to a pointer, function, slice, map,
+  // channel, or interface type.
+  if (rhs->is_nil_type()
+      && (lhs->points_to() != NULL
+	  || lhs->function_type() != NULL
+	  || lhs->is_slice_type()
+	  || lhs->map_type() != NULL
+	  || lhs->channel_type() != NULL
+	  || lhs->interface_type() != NULL))
+    return true;
+
+  // An untyped numeric constant may be assigned to a numeric type if
+  // it is representable in that type.
+  if ((rhs->is_abstract()
+       && (rhs->integer_type() != NULL
+	   || rhs->float_type() != NULL
+	   || rhs->complex_type() != NULL))
+      && (lhs->integer_type() != NULL
+	  || lhs->float_type() != NULL
+	  || lhs->complex_type() != NULL))
+    return true;
+
+  // Give some better error messages.
+  if (reason != NULL && reason->empty())
+    {
+      if (rhs->interface_type() != NULL)
+	reason->assign(_("need explicit conversion"));
+      else if (lhs->named_type() != NULL && rhs->named_type() != NULL)
+	{
+	  size_t len = (lhs->named_type()->name().length()
+			+ rhs->named_type()->name().length()
+			+ 100);
+	  char* buf = new char[len];
+	  snprintf(buf, len, _("cannot use type %s as type %s"),
+		   rhs->named_type()->message_name().c_str(),
+		   lhs->named_type()->message_name().c_str());
+	  reason->assign(buf);
+	  delete[] buf;
+	}
+    }
+
+  return false;
+}
+
+// Return true if a value with type RHS may be converted to type LHS.
+// If REASON is not NULL, set *REASON to the reason the types are not
+// convertible.
+
+bool
+Type::are_convertible(const Type* lhs, const Type* rhs, std::string* reason)
+{
+  // The types are convertible if they are assignable.
+  if (Type::are_assignable(lhs, rhs, reason))
+    return true;
+
+  // A pointer to a regular type may not be converted to a pointer to
+  // a type that may not live in the heap, except when converting from
+  // unsafe.Pointer.
+  if (lhs->points_to() != NULL
+      && rhs->points_to() != NULL
+      && !lhs->points_to()->in_heap()
+      && rhs->points_to()->in_heap()
+      && !rhs->is_unsafe_pointer_type())
+    {
+      if (reason != NULL)
+	reason->assign(_("conversion from normal type to notinheap type"));
+      return false;
+    }
+
+  // The types are convertible if they have identical underlying
+  // types, ignoring struct field tags.
+  if ((lhs->named_type() != NULL || rhs->named_type() != NULL)
+      && Type::are_identical_cmp_tags(lhs->base(), rhs->base(), IGNORE_TAGS,
+				      true, reason))
+    return true;
+
+  // The types are convertible if they are both unnamed pointer types
+  // and their pointer base types have identical underlying types,
+  // ignoring struct field tags.
+  if (lhs->named_type() == NULL
+      && rhs->named_type() == NULL
+      && lhs->points_to() != NULL
+      && rhs->points_to() != NULL
+      && (lhs->points_to()->named_type() != NULL
+	  || rhs->points_to()->named_type() != NULL)
+      && Type::are_identical_cmp_tags(lhs->points_to()->base(),
+				      rhs->points_to()->base(),
+				      IGNORE_TAGS,
+				      true,
+				      reason))
+    return true;
+
+  // Integer and floating point types are convertible to each other.
+  if ((lhs->integer_type() != NULL || lhs->float_type() != NULL)
+      && (rhs->integer_type() != NULL || rhs->float_type() != NULL))
+    return true;
+
+  // Complex types are convertible to each other.
+  if (lhs->complex_type() != NULL && rhs->complex_type() != NULL)
+    return true;
+
+  // An integer, or []byte, or []rune, may be converted to a string.
+  if (lhs->is_string_type())
+    {
+      if (rhs->integer_type() != NULL)
+	return true;
+      if (rhs->is_slice_type())
+	{
+	  const Type* e = rhs->array_type()->element_type()->forwarded();
+	  if (e->integer_type() != NULL
+	      && (e->integer_type()->is_byte()
+		  || e->integer_type()->is_rune()))
+	    return true;
+	}
+    }
+
+  // A string may be converted to []byte or []rune.
+  if (rhs->is_string_type() && lhs->is_slice_type())
+    {
+      const Type* e = lhs->array_type()->element_type()->forwarded();
+      if (e->integer_type() != NULL
+	  && (e->integer_type()->is_byte() || e->integer_type()->is_rune()))
+	return true;
+    }
+
+  // An unsafe.Pointer type may be converted to any pointer type or to
+  // a type whose underlying type is uintptr, and vice-versa.
+  if (lhs->is_unsafe_pointer_type()
+      && (rhs->points_to() != NULL
+	  || (rhs->integer_type() != NULL
+	      && rhs->integer_type() == Type::lookup_integer_type("uintptr")->real_type())))
+    return true;
+  if (rhs->is_unsafe_pointer_type()
+      && (lhs->points_to() != NULL
+	  || (lhs->integer_type() != NULL
+	      && lhs->integer_type() == Type::lookup_integer_type("uintptr")->real_type())))
+    return true;
+
+  // Give a better error message.
+  if (reason != NULL)
+    {
+      if (reason->empty())
+	*reason = "invalid type conversion";
+      else
+	{
+	  std::string s = "invalid type conversion (";
+	  s += *reason;
+	  s += ')';
+	  *reason = s;
+	}
+    }
+
+  return false;
+}
+
+// Return a hash code for the type to be used for method lookup.
+
+unsigned int
+Type::hash_for_method(Gogo* gogo) const
+{
+  if (this->named_type() != NULL && this->named_type()->is_alias())
+    return this->named_type()->real_type()->hash_for_method(gogo);
+  unsigned int ret = 0;
+  if (this->classification_ != TYPE_FORWARD)
+    ret += this->classification_;
+  return ret + this->do_hash_for_method(gogo);
+}
+
+// Default implementation of do_hash_for_method.  This is appropriate
+// for types with no subfields.
+
+unsigned int
+Type::do_hash_for_method(Gogo*) const
+{
+  return 0;
+}
+
+// Return a hash code for a string, given a starting hash.
+
+unsigned int
+Type::hash_string(const std::string& s, unsigned int h)
+{
+  const char* p = s.data();
+  size_t len = s.length();
+  for (; len > 0; --len)
+    {
+      h ^= *p++;
+      h*= 16777619;
+    }
+  return h;
+}
+
+// A hash table mapping unnamed types to the backend representation of
+// those types.
+
+Type::Type_btypes Type::type_btypes;
+
+// Return the backend representation for this type.
+
+Btype*
+Type::get_backend(Gogo* gogo)
+{
+  if (this->btype_ != NULL)
+    return this->btype_;
+
+  if (this->forward_declaration_type() != NULL
+      || this->named_type() != NULL)
+    return this->get_btype_without_hash(gogo);
+
+  if (this->is_error_type())
+    return gogo->backend()->error_type();
+
+  // To avoid confusing the backend, translate all identical Go types
+  // to the same backend representation.  We use a hash table to do
+  // that.  There is no need to use the hash table for named types, as
+  // named types are only identical to themselves.
+
+  std::pair<Type*, Type_btype_entry> val;
+  val.first = this;
+  val.second.btype = NULL;
+  val.second.is_placeholder = false;
+  std::pair<Type_btypes::iterator, bool> ins =
+    Type::type_btypes.insert(val);
+  if (!ins.second && ins.first->second.btype != NULL)
+    {
+      // Note that GOGO can be NULL here, but only when the GCC
+      // middle-end is asking for a frontend type.  That will only
+      // happen for simple types, which should never require
+      // placeholders.
+      if (!ins.first->second.is_placeholder)
+	this->btype_ = ins.first->second.btype;
+      else if (gogo->named_types_are_converted())
+	{
+	  this->finish_backend(gogo, ins.first->second.btype);
+	  ins.first->second.is_placeholder = false;
+	}
+
+      return ins.first->second.btype;
+    }
+
+  Btype* bt = this->get_btype_without_hash(gogo);
+
+  if (ins.first->second.btype == NULL)
+    {
+      ins.first->second.btype = bt;
+      ins.first->second.is_placeholder = false;
+    }
+  else
+    {
+      // We have already created a backend representation for this
+      // type.  This can happen when an unnamed type is defined using
+      // a named type which in turns uses an identical unnamed type.
+      // Use the representation we created earlier and ignore the one we just
+      // built.
+      if (this->btype_ == bt)
+	this->btype_ = ins.first->second.btype;
+      bt = ins.first->second.btype;
+    }
+
+  return bt;
+}
+
+// Return the backend representation for a type without looking in the
+// hash table for identical types.  This is used for named types,
+// since a named type is never identical to any other type.
+
+Btype*
+Type::get_btype_without_hash(Gogo* gogo)
+{
+  if (this->btype_ == NULL)
+    {
+      Btype* bt = this->do_get_backend(gogo);
+
+      // For a recursive function or pointer type, we will temporarily
+      // return a circular pointer type during the recursion.  We
+      // don't want to record that for a forwarding type, as it may
+      // confuse us later.
+      if (this->forward_declaration_type() != NULL
+	  && gogo->backend()->is_circular_pointer_type(bt))
+	return bt;
+
+      if (gogo == NULL || !gogo->named_types_are_converted())
+	return bt;
+
+      this->btype_ = bt;
+    }
+  return this->btype_;
+}
+
+// Get the backend representation of a type without forcing the
+// creation of the backend representation of all supporting types.
+// This will return a backend type that has the correct size but may
+// be incomplete.  E.g., a pointer will just be a placeholder pointer,
+// and will not contain the final representation of the type to which
+// it points.  This is used while converting all named types to the
+// backend representation, to avoid problems with indirect references
+// to types which are not yet complete.  When this is called, the
+// sizes of all direct references (e.g., a struct field) should be
+// known, but the sizes of indirect references (e.g., the type to
+// which a pointer points) may not.
+
+Btype*
+Type::get_backend_placeholder(Gogo* gogo)
+{
+  if (gogo->named_types_are_converted())
+    return this->get_backend(gogo);
+  if (this->btype_ != NULL)
+    return this->btype_;
+
+  Btype* bt;
+  switch (this->classification_)
+    {
+    case TYPE_ERROR:
+    case TYPE_VOID:
+    case TYPE_BOOLEAN:
+    case TYPE_INTEGER:
+    case TYPE_FLOAT:
+    case TYPE_COMPLEX:
+    case TYPE_STRING:
+    case TYPE_NIL:
+      // These are simple types that can just be created directly.
+      return this->get_backend(gogo);
+
+    case TYPE_MAP:
+    case TYPE_CHANNEL:
+      // All maps and channels have the same backend representation.
+      return this->get_backend(gogo);
+
+    case TYPE_NAMED:
+    case TYPE_FORWARD:
+      // Named types keep track of their own dependencies and manage
+      // their own placeholders.
+      return this->get_backend(gogo);
+
+    case TYPE_INTERFACE:
+      if (this->interface_type()->is_empty())
+	return Interface_type::get_backend_empty_interface_type(gogo);
+      break;
+
+    default:
+      break;
+    }
+
+  std::pair<Type*, Type_btype_entry> val;
+  val.first = this;
+  val.second.btype = NULL;
+  val.second.is_placeholder = false;
+  std::pair<Type_btypes::iterator, bool> ins =
+    Type::type_btypes.insert(val);
+  if (!ins.second && ins.first->second.btype != NULL)
+    return ins.first->second.btype;
+
+  switch (this->classification_)
+    {
+    case TYPE_FUNCTION:
+      {
+	// A Go function type is a pointer to a struct type.
+	Location loc = this->function_type()->location();
+	bt = gogo->backend()->placeholder_pointer_type("", loc, false);
+      }
+      break;
+
+    case TYPE_POINTER:
+      {
+	Location loc = Linemap::unknown_location();
+	bt = gogo->backend()->placeholder_pointer_type("", loc, false);
+	Pointer_type* pt = this->convert<Pointer_type, TYPE_POINTER>();
+	Type::placeholder_pointers.push_back(pt);
+      }
+      break;
+
+    case TYPE_STRUCT:
+      // We don't have to make the struct itself be a placeholder.  We
+      // are promised that we know the sizes of the struct fields.
+      // But we may have to use a placeholder for any particular
+      // struct field.
+      {
+	std::vector<Backend::Btyped_identifier> bfields;
+	get_backend_struct_fields(gogo, this->struct_type()->fields(),
+				  true, &bfields);
+	bt = gogo->backend()->struct_type(bfields);
+      }
+      break;
+
+    case TYPE_ARRAY:
+      if (this->is_slice_type())
+	{
+	  std::vector<Backend::Btyped_identifier> bfields;
+	  get_backend_slice_fields(gogo, this->array_type(), true, &bfields);
+	  bt = gogo->backend()->struct_type(bfields);
+	}
+      else
+	{
+	  Btype* element = this->array_type()->get_backend_element(gogo, true);
+	  Bexpression* len = this->array_type()->get_backend_length(gogo);
+	  bt = gogo->backend()->array_type(element, len);
+	}
+      break;
+	
+    case TYPE_INTERFACE:
+      {
+	go_assert(!this->interface_type()->is_empty());
+	std::vector<Backend::Btyped_identifier> bfields;
+	get_backend_interface_fields(gogo, this->interface_type(), true,
+				     &bfields);
+	bt = gogo->backend()->struct_type(bfields);
+      }
+      break;
+
+    case TYPE_SINK:
+    case TYPE_CALL_MULTIPLE_RESULT:
+      /* Note that various classifications were handled in the earlier
+	 switch.  */
+    default:
+      go_unreachable();
+    }
+
+  if (ins.first->second.btype == NULL)
+    {
+      ins.first->second.btype = bt;
+      ins.first->second.is_placeholder = true;
+    }
+  else
+    {
+      // A placeholder for this type got created along the way.  Use
+      // that one and ignore the one we just built.
+      bt = ins.first->second.btype;
+    }
+
+  return bt;
+}
+
+// Complete the backend representation.  This is called for a type
+// using a placeholder type.
+
+void
+Type::finish_backend(Gogo* gogo, Btype *placeholder)
+{
+  switch (this->classification_)
+    {
+    case TYPE_ERROR:
+    case TYPE_VOID:
+    case TYPE_BOOLEAN:
+    case TYPE_INTEGER:
+    case TYPE_FLOAT:
+    case TYPE_COMPLEX:
+    case TYPE_STRING:
+    case TYPE_NIL:
+      go_unreachable();
+
+    case TYPE_FUNCTION:
+      {
+	Btype* bt = this->do_get_backend(gogo);
+	if (!gogo->backend()->set_placeholder_pointer_type(placeholder, bt))
+	  go_assert(saw_errors());
+      }
+      break;
+
+    case TYPE_POINTER:
+      {
+	Btype* bt = this->do_get_backend(gogo);
+	if (!gogo->backend()->set_placeholder_pointer_type(placeholder, bt))
+	  go_assert(saw_errors());
+      }
+      break;
+
+    case TYPE_STRUCT:
+      // The struct type itself is done, but we have to make sure that
+      // all the field types are converted.
+      this->struct_type()->finish_backend_fields(gogo);
+      break;
+
+    case TYPE_ARRAY:
+      // The array type itself is done, but make sure the element type
+      // is converted.
+      this->array_type()->finish_backend_element(gogo);
+      break;
+	
+    case TYPE_MAP:
+    case TYPE_CHANNEL:
+      go_unreachable();
+
+    case TYPE_INTERFACE:
+      // The interface type itself is done, but make sure the method
+      // types are converted.
+      this->interface_type()->finish_backend_methods(gogo);
+      break;
+
+    case TYPE_NAMED:
+    case TYPE_FORWARD:
+      go_unreachable();
+
+    case TYPE_SINK:
+    case TYPE_CALL_MULTIPLE_RESULT:
+    default:
+      go_unreachable();
+    }
+
+  this->btype_ = placeholder;
+}
+
+// Return a pointer to the type descriptor for this type.
+
+Bexpression*
+Type::type_descriptor_pointer(Gogo* gogo, Location location)
+{
+  Type* t = this->forwarded();
+  while (t->named_type() != NULL && t->named_type()->is_alias())
+    t = t->named_type()->real_type()->forwarded();
+  if (t->type_descriptor_var_ == NULL)
+    {
+      t->make_type_descriptor_var(gogo);
+      go_assert(t->type_descriptor_var_ != NULL);
+    }
+  Bexpression* var_expr =
+      gogo->backend()->var_expression(t->type_descriptor_var_,
+                                      VE_rvalue, location);
+  Bexpression* var_addr =
+      gogo->backend()->address_expression(var_expr, location);
+  Type* td_type = Type::make_type_descriptor_type();
+  Btype* td_btype = td_type->get_backend(gogo);
+  Btype* ptd_btype = gogo->backend()->pointer_type(td_btype);
+  return gogo->backend()->convert_expression(ptd_btype, var_addr, location);
+}
+
+// A mapping from unnamed types to type descriptor variables.
+
+Type::Type_descriptor_vars Type::type_descriptor_vars;
+
+// Build the type descriptor for this type.
+
+void
+Type::make_type_descriptor_var(Gogo* gogo)
+{
+  go_assert(this->type_descriptor_var_ == NULL);
+
+  Named_type* nt = this->named_type();
+
+  // We can have multiple instances of unnamed types, but we only want
+  // to emit the type descriptor once.  We use a hash table.  This is
+  // not necessary for named types, as they are unique, and we store
+  // the type descriptor in the type itself.
+  Bvariable** phash = NULL;
+  if (nt == NULL)
+    {
+      Bvariable* bvnull = NULL;
+      std::pair<Type_descriptor_vars::iterator, bool> ins =
+	Type::type_descriptor_vars.insert(std::make_pair(this, bvnull));
+      if (!ins.second)
+	{
+	  // We've already built a type descriptor for this type.
+	  this->type_descriptor_var_ = ins.first->second;
+	  return;
+	}
+      phash = &ins.first->second;
+    }
+
+  // The type descriptor symbol for the unsafe.Pointer type is defined in
+  // libgo/go-unsafe-pointer.c, so we just return a reference to that
+  // symbol if necessary.
+  if (this->is_unsafe_pointer_type())
+    {
+      Location bloc = Linemap::predeclared_location();
+
+      Type* td_type = Type::make_type_descriptor_type();
+      Btype* td_btype = td_type->get_backend(gogo);
+      std::string name = gogo->type_descriptor_name(this, nt);
+      std::string asm_name(go_selectively_encode_id(name));
+      this->type_descriptor_var_ =
+	  gogo->backend()->immutable_struct_reference(name, asm_name,
+						      td_btype,
+						      bloc);
+
+      if (phash != NULL)
+	*phash = this->type_descriptor_var_;
+      return;
+    }
+
+  std::string var_name = gogo->type_descriptor_name(this, nt);
+
+  // Build the contents of the type descriptor.
+  Expression* initializer = this->do_type_descriptor(gogo, NULL);
+
+  Btype* initializer_btype = initializer->type()->get_backend(gogo);
+
+  Location loc = nt == NULL ? Linemap::predeclared_location() : nt->location();
+
+  const Package* dummy;
+  if (this->type_descriptor_defined_elsewhere(nt, &dummy))
+    {
+      std::string asm_name(go_selectively_encode_id(var_name));
+      this->type_descriptor_var_ =
+	  gogo->backend()->immutable_struct_reference(var_name, asm_name,
+						      initializer_btype,
+						      loc);
+      if (phash != NULL)
+	*phash = this->type_descriptor_var_;
+      return;
+    }
+
+  // See if this type descriptor can appear in multiple packages.
+  bool is_common = false;
+  if (nt != NULL)
+    {
+      // We create the descriptor for a builtin type whenever we need
+      // it.
+      is_common = nt->is_builtin();
+    }
+  else
+    {
+      // This is an unnamed type.  The descriptor could be defined in
+      // any package where it is needed, and the linker will pick one
+      // descriptor to keep.
+      is_common = true;
+    }
+
+  // We are going to build the type descriptor in this package.  We
+  // must create the variable before we convert the initializer to the
+  // backend representation, because the initializer may refer to the
+  // type descriptor of this type.  By setting type_descriptor_var_ we
+  // ensure that type_descriptor_pointer will work if called while
+  // converting INITIALIZER.
+
+  std::string asm_name(go_selectively_encode_id(var_name));
+  this->type_descriptor_var_ =
+      gogo->backend()->immutable_struct(var_name, asm_name, false, is_common,
+				      initializer_btype, loc);
+  if (phash != NULL)
+    *phash = this->type_descriptor_var_;
+
+  Translate_context context(gogo, NULL, NULL, NULL);
+  context.set_is_const();
+  Bexpression* binitializer = initializer->get_backend(&context);
+
+  gogo->backend()->immutable_struct_set_init(this->type_descriptor_var_,
+					     var_name, false, is_common,
+					     initializer_btype, loc,
+					     binitializer);
+}
+
+// Return true if this type descriptor is defined in a different
+// package.  If this returns true it sets *PACKAGE to the package.
+
+bool
+Type::type_descriptor_defined_elsewhere(Named_type* nt,
+					const Package** package)
+{
+  if (nt != NULL)
+    {
+      if (nt->named_object()->package() != NULL)
+	{
+	  // This is a named type defined in a different package.  The
+	  // type descriptor should be defined in that package.
+	  *package = nt->named_object()->package();
+	  return true;
+	}
+    }
+  else
+    {
+      if (this->points_to() != NULL
+	  && this->points_to()->named_type() != NULL
+	  && this->points_to()->named_type()->named_object()->package() != NULL)
+	{
+	  // This is an unnamed pointer to a named type defined in a
+	  // different package.  The descriptor should be defined in
+	  // that package.
+	  *package = this->points_to()->named_type()->named_object()->package();
+	  return true;
+	}
+    }
+  return false;
+}
+
+// Return a composite literal for a type descriptor.
+
+Expression*
+Type::type_descriptor(Gogo* gogo, Type* type)
+{
+  return type->do_type_descriptor(gogo, NULL);
+}
+
+// Return a composite literal for a type descriptor with a name.
+
+Expression*
+Type::named_type_descriptor(Gogo* gogo, Type* type, Named_type* name)
+{
+  go_assert(name != NULL && type->named_type() != name);
+  return type->do_type_descriptor(gogo, name);
+}
+
+// Make a builtin struct type from a list of fields.  The fields are
+// pairs of a name and a type.
+
+Struct_type*
+Type::make_builtin_struct_type(int nfields, ...)
+{
+  va_list ap;
+  va_start(ap, nfields);
+
+  Location bloc = Linemap::predeclared_location();
+  Struct_field_list* sfl = new Struct_field_list();
+  for (int i = 0; i < nfields; i++)
+    {
+      const char* field_name = va_arg(ap, const char *);
+      Type* type = va_arg(ap, Type*);
+      sfl->push_back(Struct_field(Typed_identifier(field_name, type, bloc)));
+    }
+
+  va_end(ap);
+
+  Struct_type* ret = Type::make_struct_type(sfl, bloc);
+  ret->set_is_struct_incomparable();
+  return ret;
+}
+
+// A list of builtin named types.
+
+std::vector<Named_type*> Type::named_builtin_types;
+
+// Make a builtin named type.
+
+Named_type*
+Type::make_builtin_named_type(const char* name, Type* type)
+{
+  Location bloc = Linemap::predeclared_location();
+  Named_object* no = Named_object::make_type(name, NULL, type, bloc);
+  Named_type* ret = no->type_value();
+  Type::named_builtin_types.push_back(ret);
+  return ret;
+}
+
+// Convert the named builtin types.
+
+void
+Type::convert_builtin_named_types(Gogo* gogo)
+{
+  for (std::vector<Named_type*>::const_iterator p =
+	 Type::named_builtin_types.begin();
+       p != Type::named_builtin_types.end();
+       ++p)
+    {
+      bool r = (*p)->verify();
+      go_assert(r);
+      (*p)->convert(gogo);
+    }
+}
+
+// Return the type of a type descriptor.  We should really tie this to
+// runtime.Type rather than copying it.  This must match the struct "_type"
+// declared in libgo/go/runtime/type.go.
+
+Type*
+Type::make_type_descriptor_type()
+{
+  static Type* ret;
+  if (ret == NULL)
+    {
+      Location bloc = Linemap::predeclared_location();
+
+      Type* uint8_type = Type::lookup_integer_type("uint8");
+      Type* pointer_uint8_type = Type::make_pointer_type(uint8_type);
+      Type* uint32_type = Type::lookup_integer_type("uint32");
+      Type* uintptr_type = Type::lookup_integer_type("uintptr");
+      Type* string_type = Type::lookup_string_type();
+      Type* pointer_string_type = Type::make_pointer_type(string_type);
+
+      // This is an unnamed version of unsafe.Pointer.  Perhaps we
+      // should use the named version instead, although that would
+      // require us to create the unsafe package if it has not been
+      // imported.  It probably doesn't matter.
+      Type* void_type = Type::make_void_type();
+      Type* unsafe_pointer_type = Type::make_pointer_type(void_type);
+
+      Typed_identifier_list *params = new Typed_identifier_list();
+      params->push_back(Typed_identifier("key", unsafe_pointer_type, bloc));
+      params->push_back(Typed_identifier("seed", uintptr_type, bloc));
+
+      Typed_identifier_list* results = new Typed_identifier_list();
+      results->push_back(Typed_identifier("", uintptr_type, bloc));
+
+      Type* hash_fntype = Type::make_function_type(NULL, params, results,
+						   bloc);
+
+      params = new Typed_identifier_list();
+      params->push_back(Typed_identifier("key1", unsafe_pointer_type, bloc));
+      params->push_back(Typed_identifier("key2", unsafe_pointer_type, bloc));
+
+      results = new Typed_identifier_list();
+      results->push_back(Typed_identifier("", Type::lookup_bool_type(), bloc));
+
+      Type* equal_fntype = Type::make_function_type(NULL, params, results,
+						    bloc);
+
+      // Forward declaration for the type descriptor type.
+      Named_object* named_type_descriptor_type =
+	Named_object::make_type_declaration("_type", NULL, bloc);
+      Type* ft = Type::make_forward_declaration(named_type_descriptor_type);
+      Type* pointer_type_descriptor_type = Type::make_pointer_type(ft);
+
+      // The type of a method on a concrete type.
+      Struct_type* method_type =
+	Type::make_builtin_struct_type(5,
+				       "name", pointer_string_type,
+				       "pkgPath", pointer_string_type,
+				       "mtyp", pointer_type_descriptor_type,
+				       "typ", pointer_type_descriptor_type,
+				       "tfn", unsafe_pointer_type);
+      Named_type* named_method_type =
+	Type::make_builtin_named_type("method", method_type);
+
+      // Information for types with a name or methods.
+      Type* slice_named_method_type =
+	Type::make_array_type(named_method_type, NULL);
+      Struct_type* uncommon_type =
+	Type::make_builtin_struct_type(3,
+				       "name", pointer_string_type,
+				       "pkgPath", pointer_string_type,
+				       "methods", slice_named_method_type);
+      Named_type* named_uncommon_type =
+	Type::make_builtin_named_type("uncommonType", uncommon_type);
+
+      Type* pointer_uncommon_type =
+	Type::make_pointer_type(named_uncommon_type);
+
+      // The type descriptor type.
+
+      Struct_type* type_descriptor_type =
+	Type::make_builtin_struct_type(12,
+				       "size", uintptr_type,
+				       "ptrdata", uintptr_type,
+				       "hash", uint32_type,
+				       "kind", uint8_type,
+				       "align", uint8_type,
+				       "fieldAlign", uint8_type,
+				       "hashfn", hash_fntype,
+				       "equalfn", equal_fntype,
+				       "gcdata", pointer_uint8_type,
+				       "string", pointer_string_type,
+				       "", pointer_uncommon_type,
+				       "ptrToThis",
+				       pointer_type_descriptor_type);
+
+      Named_type* named = Type::make_builtin_named_type("_type",
+							type_descriptor_type);
+
+      named_type_descriptor_type->set_type_value(named);
+
+      ret = named;
+    }
+
+  return ret;
+}
+
+// Make the type of a pointer to a type descriptor as represented in
+// Go.
+
+Type*
+Type::make_type_descriptor_ptr_type()
+{
+  static Type* ret;
+  if (ret == NULL)
+    ret = Type::make_pointer_type(Type::make_type_descriptor_type());
+  return ret;
+}
+
+// Return the alignment required by the memequalN function.  N is a
+// type size: 16, 32, 64, or 128.  The memequalN functions are defined
+// in libgo/go/runtime/alg.go.
+
+int64_t
+Type::memequal_align(Gogo* gogo, int size)
+{
+  const char* tn;
+  switch (size)
+    {
+    case 16:
+      tn = "int16";
+      break;
+    case 32:
+      tn = "int32";
+      break;
+    case 64:
+      tn = "int64";
+      break;
+    case 128:
+      // The code uses [2]int64, which must have the same alignment as
+      // int64.
+      tn = "int64";
+      break;
+    default:
+      go_unreachable();
+    }
+
+  Type* t = Type::lookup_integer_type(tn);
+
+  int64_t ret;
+  if (!t->backend_type_align(gogo, &ret))
+    go_unreachable();
+  return ret;
+}
+
+// Return whether this type needs specially built type functions.
+// This returns true for types that are comparable and either can not
+// use an identity comparison, or are a non-standard size.
+
+bool
+Type::needs_specific_type_functions(Gogo* gogo)
+{
+  Named_type* nt = this->named_type();
+  if (nt != NULL && nt->is_alias())
+    return false;
+  if (!this->is_comparable())
+    return false;
+  if (!this->compare_is_identity(gogo))
+    return true;
+
+  // We create a few predeclared types for type descriptors; they are
+  // really just for the backend and don't need hash or equality
+  // functions.
+  if (nt != NULL && Linemap::is_predeclared_location(nt->location()))
+    return false;
+
+  int64_t size, align;
+  if (!this->backend_type_size(gogo, &size)
+      || !this->backend_type_align(gogo, &align))
+    {
+      go_assert(saw_errors());
+      return false;
+    }
+  // This switch matches the one in Type::type_functions.
+  switch (size)
+    {
+    case 0:
+    case 1:
+    case 2:
+      return align < Type::memequal_align(gogo, 16);
+    case 4:
+      return align < Type::memequal_align(gogo, 32);
+    case 8:
+      return align < Type::memequal_align(gogo, 64);
+    case 16:
+      return align < Type::memequal_align(gogo, 128);
+    default:
+      return true;
+    }
+}
+
+// Set *HASH_FN and *EQUAL_FN to the runtime functions which compute a
+// hash code for this type and which compare whether two values of
+// this type are equal.  If NAME is not NULL it is the name of this
+// type.  HASH_FNTYPE and EQUAL_FNTYPE are the types of these
+// functions, for convenience; they may be NULL.
+
+void
+Type::type_functions(Gogo* gogo, Named_type* name, Function_type* hash_fntype,
+		     Function_type* equal_fntype, Named_object** hash_fn,
+		     Named_object** equal_fn)
+{
+  // If this loop leaves NAME as NULL, then the type does not have a
+  // name after all.
+  while (name != NULL && name->is_alias())
+    name = name->real_type()->named_type();
+
+  if (!this->is_comparable())
+    {
+      *hash_fn = NULL;
+      *equal_fn = NULL;
+      return;
+    }
+
+  if (hash_fntype == NULL || equal_fntype == NULL)
+    {
+      Location bloc = Linemap::predeclared_location();
+
+      Type* uintptr_type = Type::lookup_integer_type("uintptr");
+      Type* void_type = Type::make_void_type();
+      Type* unsafe_pointer_type = Type::make_pointer_type(void_type);
+
+      if (hash_fntype == NULL)
+	{
+	  Typed_identifier_list* params = new Typed_identifier_list();
+	  params->push_back(Typed_identifier("key", unsafe_pointer_type,
+					     bloc));
+	  params->push_back(Typed_identifier("seed", uintptr_type, bloc));
+
+	  Typed_identifier_list* results = new Typed_identifier_list();
+	  results->push_back(Typed_identifier("", uintptr_type, bloc));
+
+	  hash_fntype = Type::make_function_type(NULL, params, results, bloc);
+	}
+      if (equal_fntype == NULL)
+	{
+	  Typed_identifier_list* params = new Typed_identifier_list();
+	  params->push_back(Typed_identifier("key1", unsafe_pointer_type,
+					     bloc));
+	  params->push_back(Typed_identifier("key2", unsafe_pointer_type,
+					     bloc));
+
+	  Typed_identifier_list* results = new Typed_identifier_list();
+	  results->push_back(Typed_identifier("", Type::lookup_bool_type(),
+					      bloc));
+
+	  equal_fntype = Type::make_function_type(NULL, params, results, bloc);
+	}
+    }
+
+  const char* hash_fnname;
+  const char* equal_fnname;
+  if (this->compare_is_identity(gogo))
+    {
+      int64_t size, align;
+      if (!this->backend_type_size(gogo, &size)
+	  || !this->backend_type_align(gogo, &align))
+	{
+	  go_assert(saw_errors());
+	  return;
+	}
+      bool build_functions = false;
+      // This switch matches the one in Type::needs_specific_type_functions.
+      // The alignment tests are because of the memequal functions,
+      // which assume that the values are aligned as required for an
+      // integer of that size.
+      switch (size)
+	{
+	case 0:
+	  hash_fnname = "runtime.memhash0";
+	  equal_fnname = "runtime.memequal0";
+	  break;
+	case 1:
+	  hash_fnname = "runtime.memhash8";
+	  equal_fnname = "runtime.memequal8";
+	  break;
+	case 2:
+	  if (align < Type::memequal_align(gogo, 16))
+	    build_functions = true;
+	  else
+	    {
+	      hash_fnname = "runtime.memhash16";
+	      equal_fnname = "runtime.memequal16";
+	    }
+	  break;
+	case 4:
+	  if (align < Type::memequal_align(gogo, 32))
+	    build_functions = true;
+	  else
+	    {
+	      hash_fnname = "runtime.memhash32";
+	      equal_fnname = "runtime.memequal32";
+	    }
+	  break;
+	case 8:
+	  if (align < Type::memequal_align(gogo, 64))
+	    build_functions = true;
+	  else
+	    {
+	      hash_fnname = "runtime.memhash64";
+	      equal_fnname = "runtime.memequal64";
+	    }
+	  break;
+	case 16:
+	  if (align < Type::memequal_align(gogo, 128))
+	    build_functions = true;
+	  else
+	    {
+	      hash_fnname = "runtime.memhash128";
+	      equal_fnname = "runtime.memequal128";
+	    }
+	  break;
+	default:
+	  build_functions = true;
+	  break;
+	}
+      if (build_functions)
+	{
+	  // We don't have a built-in function for a type of this size
+	  // and alignment.  Build a function to use that calls the
+	  // generic hash/equality functions for identity, passing the size.
+	  this->specific_type_functions(gogo, name, size, hash_fntype,
+					equal_fntype, hash_fn, equal_fn);
+	  return;
+	}
+    }
+  else
+    {
+      switch (this->base()->classification())
+	{
+	case Type::TYPE_ERROR:
+	case Type::TYPE_VOID:
+	case Type::TYPE_NIL:
+	case Type::TYPE_FUNCTION:
+	case Type::TYPE_MAP:
+	  // For these types is_comparable should have returned false.
+	  go_unreachable();
+
+	case Type::TYPE_BOOLEAN:
+	case Type::TYPE_INTEGER:
+	case Type::TYPE_POINTER:
+	case Type::TYPE_CHANNEL:
+	  // For these types compare_is_identity should have returned true.
+	  go_unreachable();
+
+	case Type::TYPE_FLOAT:
+	  switch (this->float_type()->bits())
+	    {
+	    case 32:
+	      hash_fnname = "runtime.f32hash";
+	      equal_fnname = "runtime.f32equal";
+	      break;
+	    case 64:
+	      hash_fnname = "runtime.f64hash";
+	      equal_fnname = "runtime.f64equal";
+	      break;
+	    default:
+	      go_unreachable();
+	    }
+	  break;
+
+	case Type::TYPE_COMPLEX:
+	  switch (this->complex_type()->bits())
+	    {
+	    case 64:
+	      hash_fnname = "runtime.c64hash";
+	      equal_fnname = "runtime.c64equal";
+	      break;
+	    case 128:
+	      hash_fnname = "runtime.c128hash";
+	      equal_fnname = "runtime.c128equal";
+	      break;
+	    default:
+	      go_unreachable();
+	    }
+	  break;
+
+	case Type::TYPE_STRING:
+	  hash_fnname = "runtime.strhash";
+	  equal_fnname = "runtime.strequal";
+	  break;
+
+	case Type::TYPE_STRUCT:
+	  {
+	    // This is a struct which can not be compared using a
+	    // simple identity function.  We need to build a function
+	    // for comparison.
+	    this->specific_type_functions(gogo, name, -1, hash_fntype,
+					  equal_fntype, hash_fn, equal_fn);
+	    return;
+	  }
+
+	case Type::TYPE_ARRAY:
+	  if (this->is_slice_type())
+	    {
+	      // Type::is_compatible_for_comparison should have
+	      // returned false.
+	      go_unreachable();
+	    }
+	  else
+	    {
+	      // This is an array which can not be compared using a
+	      // simple identity function.  We need to build a
+	      // function for comparison.
+	      this->specific_type_functions(gogo, name, -1, hash_fntype,
+					    equal_fntype, hash_fn, equal_fn);
+	      return;
+	    }
+	  break;
+
+	case Type::TYPE_INTERFACE:
+	  if (this->interface_type()->is_empty())
+	    {
+	      hash_fnname = "runtime.nilinterhash";
+	      equal_fnname = "runtime.nilinterequal";
+	    }
+	  else
+	    {
+	      hash_fnname = "runtime.interhash";
+	      equal_fnname = "runtime.interequal";
+	    }
+	  break;
+
+	case Type::TYPE_NAMED:
+	case Type::TYPE_FORWARD:
+	  go_unreachable();
+
+	default:
+	  go_unreachable();
+	}
+    }
+
+
+  Location bloc = Linemap::predeclared_location();
+  *hash_fn = Named_object::make_function_declaration(hash_fnname, NULL,
+						     hash_fntype, bloc);
+  (*hash_fn)->func_declaration_value()->set_asm_name(hash_fnname);
+  *equal_fn = Named_object::make_function_declaration(equal_fnname, NULL,
+						      equal_fntype, bloc);
+  (*equal_fn)->func_declaration_value()->set_asm_name(equal_fnname);
+}
+
+// A hash table mapping types to the specific hash functions.
+
+Type::Type_functions Type::type_functions_table;
+
+// Handle a type function which is specific to a type: if SIZE == -1,
+// this is a struct or array that can not use an identity comparison.
+// Otherwise, it is a type that uses an identity comparison but is not
+// one of the standard supported sizes.
+
+void
+Type::specific_type_functions(Gogo* gogo, Named_type* name, int64_t size,
+			      Function_type* hash_fntype,
+			      Function_type* equal_fntype,
+			      Named_object** hash_fn,
+			      Named_object** equal_fn)
+{
+  Hash_equal_fn fnull(NULL, NULL);
+  std::pair<Type*, Hash_equal_fn> val(name != NULL ? name : this, fnull);
+  std::pair<Type_functions::iterator, bool> ins =
+    Type::type_functions_table.insert(val);
+  if (!ins.second)
+    {
+      // We already have functions for this type
+      *hash_fn = ins.first->second.first;
+      *equal_fn = ins.first->second.second;
+      return;
+    }
+
+  std::string hash_name;
+  std::string equal_name;
+  gogo->specific_type_function_names(this, name, &hash_name, &equal_name);
+
+  Location bloc = Linemap::predeclared_location();
+
+  const Package* package = NULL;
+  bool is_defined_elsewhere =
+    this->type_descriptor_defined_elsewhere(name, &package);
+  if (is_defined_elsewhere)
+    {
+      *hash_fn = Named_object::make_function_declaration(hash_name, package,
+							 hash_fntype, bloc);
+      *equal_fn = Named_object::make_function_declaration(equal_name, package,
+							  equal_fntype, bloc);
+    }
+  else
+    {
+      *hash_fn = gogo->declare_package_function(hash_name, hash_fntype, bloc);
+      *equal_fn = gogo->declare_package_function(equal_name, equal_fntype,
+						 bloc);
+    }
+
+  ins.first->second.first = *hash_fn;
+  ins.first->second.second = *equal_fn;
+
+  if (!is_defined_elsewhere)
+    {
+      if (gogo->in_global_scope())
+	this->write_specific_type_functions(gogo, name, size, hash_name,
+					    hash_fntype, equal_name,
+					    equal_fntype);
+      else
+	gogo->queue_specific_type_function(this, name, size, hash_name,
+					   hash_fntype, equal_name,
+					   equal_fntype);
+    }
+}
+
+// Write the hash and equality functions for a type which needs to be
+// written specially.
+
+void
+Type::write_specific_type_functions(Gogo* gogo, Named_type* name, int64_t size,
+				    const std::string& hash_name,
+				    Function_type* hash_fntype,
+				    const std::string& equal_name,
+				    Function_type* equal_fntype)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  if (gogo->specific_type_functions_are_written())
+    {
+      go_assert(saw_errors());
+      return;
+    }
+
+  go_assert(this->is_comparable());
+
+  Named_object* hash_fn = gogo->start_function(hash_name, hash_fntype, false,
+					       bloc);
+  hash_fn->func_value()->set_is_type_specific_function();
+  gogo->start_block(bloc);
+
+  if (size != -1)
+    this->write_identity_hash(gogo, size);
+  else if (name != NULL && name->real_type()->named_type() != NULL)
+    this->write_named_hash(gogo, name, hash_fntype, equal_fntype);
+  else if (this->struct_type() != NULL)
+    this->struct_type()->write_hash_function(gogo, name, hash_fntype,
+					     equal_fntype);
+  else if (this->array_type() != NULL)
+    this->array_type()->write_hash_function(gogo, name, hash_fntype,
+					    equal_fntype);
+  else
+    go_unreachable();
+
+  Block* b = gogo->finish_block(bloc);
+  gogo->add_block(b, bloc);
+  gogo->lower_block(hash_fn, b);
+  gogo->finish_function(bloc);
+
+  Named_object *equal_fn = gogo->start_function(equal_name, equal_fntype,
+						false, bloc);
+  equal_fn->func_value()->set_is_type_specific_function();
+  gogo->start_block(bloc);
+
+  if (size != -1)
+    this->write_identity_equal(gogo, size);
+  else if (name != NULL && name->real_type()->named_type() != NULL)
+    this->write_named_equal(gogo, name);
+  else if (this->struct_type() != NULL)
+    this->struct_type()->write_equal_function(gogo, name);
+  else if (this->array_type() != NULL)
+    this->array_type()->write_equal_function(gogo, name);
+  else
+    go_unreachable();
+
+  b = gogo->finish_block(bloc);
+  gogo->add_block(b, bloc);
+  gogo->lower_block(equal_fn, b);
+  gogo->finish_function(bloc);
+
+  // Build the function descriptors for the type descriptor to refer to.
+  hash_fn->func_value()->descriptor(gogo, hash_fn);
+  equal_fn->func_value()->descriptor(gogo, equal_fn);
+}
+
+// Write a hash function for a type that can use an identity hash but
+// is not one of the standard supported sizes.  For example, this
+// would be used for the type [3]byte.  This builds a return statement
+// that returns a call to the memhash function, passing the key and
+// seed from the function arguments (already constructed before this
+// is called), and the constant size.
+
+void
+Type::write_identity_hash(Gogo* gogo, int64_t size)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  Type* unsafe_pointer_type = Type::make_pointer_type(Type::make_void_type());
+  Type* uintptr_type = Type::lookup_integer_type("uintptr");
+
+  Typed_identifier_list* params = new Typed_identifier_list();
+  params->push_back(Typed_identifier("key", unsafe_pointer_type, bloc));
+  params->push_back(Typed_identifier("seed", uintptr_type, bloc));
+  params->push_back(Typed_identifier("size", uintptr_type, bloc));
+
+  Typed_identifier_list* results = new Typed_identifier_list();
+  results->push_back(Typed_identifier("", uintptr_type, bloc));
+
+  Function_type* memhash_fntype = Type::make_function_type(NULL, params,
+							   results, bloc);
+
+  Named_object* memhash =
+    Named_object::make_function_declaration("runtime.memhash", NULL,
+					    memhash_fntype, bloc);
+  memhash->func_declaration_value()->set_asm_name("runtime.memhash");
+
+  Named_object* key_arg = gogo->lookup("key", NULL);
+  go_assert(key_arg != NULL);
+  Named_object* seed_arg = gogo->lookup("seed", NULL);
+  go_assert(seed_arg != NULL);
+
+  Expression* key_ref = Expression::make_var_reference(key_arg, bloc);
+  Expression* seed_ref = Expression::make_var_reference(seed_arg, bloc);
+  Expression* size_arg = Expression::make_integer_int64(size, uintptr_type,
+							bloc);
+  Expression_list* args = new Expression_list();
+  args->push_back(key_ref);
+  args->push_back(seed_ref);
+  args->push_back(size_arg);
+  Expression* func = Expression::make_func_reference(memhash, NULL, bloc);
+  Expression* call = Expression::make_call(func, args, false, bloc);
+
+  Expression_list* vals = new Expression_list();
+  vals->push_back(call);
+  Statement* s = Statement::make_return_statement(vals, bloc);
+  gogo->add_statement(s);
+}
+
+// Write an equality function for a type that can use an identity
+// equality comparison but is not one of the standard supported sizes.
+// For example, this would be used for the type [3]byte.  This builds
+// a return statement that returns a call to the memequal function,
+// passing the two keys from the function arguments (already
+// constructed before this is called), and the constant size.
+
+void
+Type::write_identity_equal(Gogo* gogo, int64_t size)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  Type* unsafe_pointer_type = Type::make_pointer_type(Type::make_void_type());
+  Type* uintptr_type = Type::lookup_integer_type("uintptr");
+
+  Typed_identifier_list* params = new Typed_identifier_list();
+  params->push_back(Typed_identifier("key1", unsafe_pointer_type, bloc));
+  params->push_back(Typed_identifier("key2", unsafe_pointer_type, bloc));
+  params->push_back(Typed_identifier("size", uintptr_type, bloc));
+
+  Typed_identifier_list* results = new Typed_identifier_list();
+  results->push_back(Typed_identifier("", Type::lookup_bool_type(), bloc));
+
+  Function_type* memequal_fntype = Type::make_function_type(NULL, params,
+							    results, bloc);
+
+  Named_object* memequal =
+    Named_object::make_function_declaration("runtime.memequal", NULL,
+					    memequal_fntype, bloc);
+  memequal->func_declaration_value()->set_asm_name("runtime.memequal");
+
+  Named_object* key1_arg = gogo->lookup("key1", NULL);
+  go_assert(key1_arg != NULL);
+  Named_object* key2_arg = gogo->lookup("key2", NULL);
+  go_assert(key2_arg != NULL);
+
+  Expression* key1_ref = Expression::make_var_reference(key1_arg, bloc);
+  Expression* key2_ref = Expression::make_var_reference(key2_arg, bloc);
+  Expression* size_arg = Expression::make_integer_int64(size, uintptr_type,
+							bloc);
+  Expression_list* args = new Expression_list();
+  args->push_back(key1_ref);
+  args->push_back(key2_ref);
+  args->push_back(size_arg);
+  Expression* func = Expression::make_func_reference(memequal, NULL, bloc);
+  Expression* call = Expression::make_call(func, args, false, bloc);
+
+  Expression_list* vals = new Expression_list();
+  vals->push_back(call);
+  Statement* s = Statement::make_return_statement(vals, bloc);
+  gogo->add_statement(s);
+}
+
+// Write a hash function that simply calls the hash function for a
+// named type.  This is used when one named type is defined as
+// another.  This ensures that this case works when the other named
+// type is defined in another package and relies on calling hash
+// functions defined only in that package.
+
+void
+Type::write_named_hash(Gogo* gogo, Named_type* name,
+		       Function_type* hash_fntype, Function_type* equal_fntype)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  Named_type* base_type = name->real_type()->named_type();
+  while (base_type->is_alias())
+    {
+      base_type = base_type->real_type()->named_type();
+      go_assert(base_type != NULL);
+    }
+  go_assert(base_type != NULL);
+
+  // The pointer to the type we are going to hash.  This is an
+  // unsafe.Pointer.
+  Named_object* key_arg = gogo->lookup("key", NULL);
+  go_assert(key_arg != NULL);
+
+  // The seed argument to the hash function.
+  Named_object* seed_arg = gogo->lookup("seed", NULL);
+  go_assert(seed_arg != NULL);
+
+  Named_object* hash_fn;
+  Named_object* equal_fn;
+  name->real_type()->type_functions(gogo, base_type, hash_fntype, equal_fntype,
+				    &hash_fn, &equal_fn);
+
+  // Call the hash function for the base type.
+  Expression* key_ref = Expression::make_var_reference(key_arg, bloc);
+  Expression* seed_ref = Expression::make_var_reference(seed_arg, bloc);
+  Expression_list* args = new Expression_list();
+  args->push_back(key_ref);
+  args->push_back(seed_ref);
+  Expression* func = Expression::make_func_reference(hash_fn, NULL, bloc);
+  Expression* call = Expression::make_call(func, args, false, bloc);
+
+  // Return the hash of the base type.
+  Expression_list* vals = new Expression_list();
+  vals->push_back(call);
+  Statement* s = Statement::make_return_statement(vals, bloc);
+  gogo->add_statement(s);
+}
+
+// Write an equality function that simply calls the equality function
+// for a named type.  This is used when one named type is defined as
+// another.  This ensures that this case works when the other named
+// type is defined in another package and relies on calling equality
+// functions defined only in that package.
+
+void
+Type::write_named_equal(Gogo* gogo, Named_type* name)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  // The pointers to the types we are going to compare.  These have
+  // type unsafe.Pointer.
+  Named_object* key1_arg = gogo->lookup("key1", NULL);
+  Named_object* key2_arg = gogo->lookup("key2", NULL);
+  go_assert(key1_arg != NULL && key2_arg != NULL);
+
+  Named_type* base_type = name->real_type()->named_type();
+  go_assert(base_type != NULL);
+
+  // Build temporaries with the base type.
+  Type* pt = Type::make_pointer_type(base_type);
+
+  Expression* ref = Expression::make_var_reference(key1_arg, bloc);
+  ref = Expression::make_cast(pt, ref, bloc);
+  Temporary_statement* p1 = Statement::make_temporary(pt, ref, bloc);
+  gogo->add_statement(p1);
+
+  ref = Expression::make_var_reference(key2_arg, bloc);
+  ref = Expression::make_cast(pt, ref, bloc);
+  Temporary_statement* p2 = Statement::make_temporary(pt, ref, bloc);
+  gogo->add_statement(p2);
+
+  // Compare the values for equality.
+  Expression* t1 = Expression::make_temporary_reference(p1, bloc);
+  t1 = Expression::make_unary(OPERATOR_MULT, t1, bloc);
+
+  Expression* t2 = Expression::make_temporary_reference(p2, bloc);
+  t2 = Expression::make_unary(OPERATOR_MULT, t2, bloc);
+
+  Expression* cond = Expression::make_binary(OPERATOR_EQEQ, t1, t2, bloc);
+
+  // Return the equality comparison.
+  Expression_list* vals = new Expression_list();
+  vals->push_back(cond);
+  Statement* s = Statement::make_return_statement(vals, bloc);
+  gogo->add_statement(s);
+}
+
+// Return a composite literal for the type descriptor for a plain type
+// of kind RUNTIME_TYPE_KIND named NAME.
+
+Expression*
+Type::type_descriptor_constructor(Gogo* gogo, int runtime_type_kind,
+				  Named_type* name, const Methods* methods,
+				  bool only_value_methods)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  Type* td_type = Type::make_type_descriptor_type();
+  const Struct_field_list* fields = td_type->struct_type()->fields();
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve(12);
+
+  if (!this->has_pointer())
+    runtime_type_kind |= RUNTIME_TYPE_KIND_NO_POINTERS;
+  if (this->points_to() != NULL)
+    runtime_type_kind |= RUNTIME_TYPE_KIND_DIRECT_IFACE;
+  int64_t ptrsize;
+  int64_t ptrdata;
+  if (this->needs_gcprog(gogo, &ptrsize, &ptrdata))
+    runtime_type_kind |= RUNTIME_TYPE_KIND_GC_PROG;
+
+  Struct_field_list::const_iterator p = fields->begin();
+  go_assert(p->is_field_name("size"));
+  Expression::Type_info type_info = Expression::TYPE_INFO_SIZE;
+  vals->push_back(Expression::make_type_info(this, type_info));
+
+  ++p;
+  go_assert(p->is_field_name("ptrdata"));
+  type_info = Expression::TYPE_INFO_DESCRIPTOR_PTRDATA;
+  vals->push_back(Expression::make_type_info(this, type_info));
+
+  ++p;
+  go_assert(p->is_field_name("hash"));
+  unsigned int h;
+  if (name != NULL)
+    h = name->hash_for_method(gogo);
+  else
+    h = this->hash_for_method(gogo);
+  vals->push_back(Expression::make_integer_ul(h, p->type(), bloc));
+
+  ++p;
+  go_assert(p->is_field_name("kind"));
+  vals->push_back(Expression::make_integer_ul(runtime_type_kind, p->type(),
+					      bloc));
+
+  ++p;
+  go_assert(p->is_field_name("align"));
+  type_info = Expression::TYPE_INFO_ALIGNMENT;
+  vals->push_back(Expression::make_type_info(this, type_info));
+
+  ++p;
+  go_assert(p->is_field_name("fieldAlign"));
+  type_info = Expression::TYPE_INFO_FIELD_ALIGNMENT;
+  vals->push_back(Expression::make_type_info(this, type_info));
+
+  ++p;
+  go_assert(p->is_field_name("hashfn"));
+  Function_type* hash_fntype = p->type()->function_type();
+
+  ++p;
+  go_assert(p->is_field_name("equalfn"));
+  Function_type* equal_fntype = p->type()->function_type();
+
+  Named_object* hash_fn;
+  Named_object* equal_fn;
+  this->type_functions(gogo, name, hash_fntype, equal_fntype, &hash_fn,
+		       &equal_fn);
+  if (hash_fn == NULL)
+    vals->push_back(Expression::make_cast(hash_fntype,
+					  Expression::make_nil(bloc),
+					  bloc));
+  else
+    vals->push_back(Expression::make_func_reference(hash_fn, NULL, bloc));
+  if (equal_fn == NULL)
+    vals->push_back(Expression::make_cast(equal_fntype,
+					  Expression::make_nil(bloc),
+					  bloc));
+  else
+    vals->push_back(Expression::make_func_reference(equal_fn, NULL, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("gcdata"));
+  vals->push_back(Expression::make_gc_symbol(this));
+
+  ++p;
+  go_assert(p->is_field_name("string"));
+  Expression* s = Expression::make_string((name != NULL
+					   ? name->reflection(gogo)
+					   : this->reflection(gogo)),
+					  bloc);
+  vals->push_back(Expression::make_unary(OPERATOR_AND, s, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("uncommonType"));
+  if (name == NULL && methods == NULL)
+    vals->push_back(Expression::make_nil(bloc));
+  else
+    {
+      if (methods == NULL)
+	methods = name->methods();
+      vals->push_back(this->uncommon_type_constructor(gogo,
+						      p->type()->deref(),
+						      name, methods,
+						      only_value_methods));
+    }
+
+  ++p;
+  go_assert(p->is_field_name("ptrToThis"));
+  if (name == NULL && methods == NULL)
+    vals->push_back(Expression::make_nil(bloc));
+  else
+    {
+      Type* pt;
+      if (name != NULL)
+	pt = Type::make_pointer_type(name);
+      else
+	pt = Type::make_pointer_type(this);
+      vals->push_back(Expression::make_type_descriptor(pt, bloc));
+    }
+
+  ++p;
+  go_assert(p == fields->end());
+
+  return Expression::make_struct_composite_literal(td_type, vals, bloc);
+}
+
+// The maximum length of a GC ptrmask bitmap.  This corresponds to the
+// length used by the gc toolchain, and also appears in
+// libgo/go/reflect/type.go.
+
+static const int64_t max_ptrmask_bytes = 2048;
+
+// Return a pointer to the Garbage Collection information for this type.
+
+Bexpression*
+Type::gc_symbol_pointer(Gogo* gogo)
+{
+  Type* t = this->forwarded();
+  while (t->named_type() != NULL && t->named_type()->is_alias())
+    t = t->named_type()->real_type()->forwarded();
+
+  if (!t->has_pointer())
+    return gogo->backend()->nil_pointer_expression();
+
+  if (t->gc_symbol_var_ == NULL)
+    {
+      t->make_gc_symbol_var(gogo);
+      go_assert(t->gc_symbol_var_ != NULL);
+    }
+  Location bloc = Linemap::predeclared_location();
+  Bexpression* var_expr =
+      gogo->backend()->var_expression(t->gc_symbol_var_, VE_rvalue, bloc);
+  Bexpression* addr_expr =
+      gogo->backend()->address_expression(var_expr, bloc);
+
+  Type* uint8_type = Type::lookup_integer_type("uint8");
+  Type* pointer_uint8_type = Type::make_pointer_type(uint8_type);
+  Btype* ubtype = pointer_uint8_type->get_backend(gogo);
+  return gogo->backend()->convert_expression(ubtype, addr_expr, bloc);
+}
+
+// A mapping from unnamed types to GC symbol variables.
+
+Type::GC_symbol_vars Type::gc_symbol_vars;
+
+// Build the GC symbol for this type.
+
+void
+Type::make_gc_symbol_var(Gogo* gogo)
+{
+  go_assert(this->gc_symbol_var_ == NULL);
+
+  Named_type* nt = this->named_type();
+
+  // We can have multiple instances of unnamed types and similar to type
+  // descriptors, we only want to the emit the GC data once, so we use a
+  // hash table.
+  Bvariable** phash = NULL;
+  if (nt == NULL)
+    {
+      Bvariable* bvnull = NULL;
+      std::pair<GC_symbol_vars::iterator, bool> ins =
+	Type::gc_symbol_vars.insert(std::make_pair(this, bvnull));
+      if (!ins.second)
+	{
+	  // We've already built a gc symbol for this type.
+	  this->gc_symbol_var_ = ins.first->second;
+	  return;
+	}
+      phash = &ins.first->second;
+    }
+
+  int64_t ptrsize;
+  int64_t ptrdata;
+  if (!this->needs_gcprog(gogo, &ptrsize, &ptrdata))
+    {
+      this->gc_symbol_var_ = this->gc_ptrmask_var(gogo, ptrsize, ptrdata);
+      if (phash != NULL)
+	*phash = this->gc_symbol_var_;
+      return;
+    }
+
+  std::string sym_name = gogo->gc_symbol_name(this);
+
+  // Build the contents of the gc symbol.
+  Expression* sym_init = this->gcprog_constructor(gogo, ptrsize, ptrdata);
+  Btype* sym_btype = sym_init->type()->get_backend(gogo);
+
+  // If the type descriptor for this type is defined somewhere else, so is the
+  // GC symbol.
+  const Package* dummy;
+  if (this->type_descriptor_defined_elsewhere(nt, &dummy))
+    {
+      std::string asm_name(go_selectively_encode_id(sym_name));
+      this->gc_symbol_var_ =
+          gogo->backend()->implicit_variable_reference(sym_name, asm_name,
+                                                       sym_btype);
+      if (phash != NULL)
+	*phash = this->gc_symbol_var_;
+      return;
+    }
+
+  // See if this gc symbol can appear in multiple packages.
+  bool is_common = false;
+  if (nt != NULL)
+    {
+      // We create the symbol for a builtin type whenever we need
+      // it.
+      is_common = nt->is_builtin();
+    }
+  else
+    {
+      // This is an unnamed type.  The descriptor could be defined in
+      // any package where it is needed, and the linker will pick one
+      // descriptor to keep.
+      is_common = true;
+    }
+
+  // Since we are building the GC symbol in this package, we must create the
+  // variable before converting the initializer to its backend representation
+  // because the initializer may refer to the GC symbol for this type.
+  std::string asm_name(go_selectively_encode_id(sym_name));
+  this->gc_symbol_var_ =
+      gogo->backend()->implicit_variable(sym_name, asm_name,
+					 sym_btype, false, true, is_common, 0);
+  if (phash != NULL)
+    *phash = this->gc_symbol_var_;
+
+  Translate_context context(gogo, NULL, NULL, NULL);
+  context.set_is_const();
+  Bexpression* sym_binit = sym_init->get_backend(&context);
+  gogo->backend()->implicit_variable_set_init(this->gc_symbol_var_, sym_name,
+					      sym_btype, false, true, is_common,
+					      sym_binit);
+}
+
+// Return whether this type needs a GC program, and set *PTRDATA to
+// the size of the pointer data in bytes and *PTRSIZE to the size of a
+// pointer.
+
+bool
+Type::needs_gcprog(Gogo* gogo, int64_t* ptrsize, int64_t* ptrdata)
+{
+  Type* voidptr = Type::make_pointer_type(Type::make_void_type());
+  if (!voidptr->backend_type_size(gogo, ptrsize))
+    go_unreachable();
+
+  if (!this->backend_type_ptrdata(gogo, ptrdata))
+    {
+      go_assert(saw_errors());
+      return false;
+    }
+
+  return *ptrdata / *ptrsize > max_ptrmask_bytes;
+}
+
+// A simple class used to build a GC ptrmask for a type.
+
+class Ptrmask
+{
+ public:
+  Ptrmask(size_t count)
+    : bits_((count + 7) / 8, 0)
+  {}
+
+  void
+  set_from(Gogo*, Type*, int64_t ptrsize, int64_t offset);
+
+  std::string
+  symname() const;
+
+  Expression*
+  constructor(Gogo* gogo) const;
+
+ private:
+  void
+  set(size_t index)
+  { this->bits_.at(index / 8) |= 1 << (index % 8); }
+
+  // The actual bits.
+  std::vector<unsigned char> bits_;
+};
+
+// Set bits in ptrmask starting from OFFSET based on TYPE.  OFFSET
+// counts in bytes.  PTRSIZE is the size of a pointer on the target
+// system.
+
+void
+Ptrmask::set_from(Gogo* gogo, Type* type, int64_t ptrsize, int64_t offset)
+{
+  switch (type->base()->classification())
+    {
+    default:
+    case Type::TYPE_NIL:
+    case Type::TYPE_CALL_MULTIPLE_RESULT:
+    case Type::TYPE_NAMED:
+    case Type::TYPE_FORWARD:
+      go_unreachable();
+
+    case Type::TYPE_ERROR:
+    case Type::TYPE_VOID:
+    case Type::TYPE_BOOLEAN:
+    case Type::TYPE_INTEGER:
+    case Type::TYPE_FLOAT:
+    case Type::TYPE_COMPLEX:
+    case Type::TYPE_SINK:
+      break;
+
+    case Type::TYPE_FUNCTION:
+    case Type::TYPE_POINTER:
+    case Type::TYPE_MAP:
+    case Type::TYPE_CHANNEL:
+      // These types are all a single pointer.
+      go_assert((offset % ptrsize) == 0);
+      this->set(offset / ptrsize);
+      break;
+
+    case Type::TYPE_STRING:
+      // A string starts with a single pointer.
+      go_assert((offset % ptrsize) == 0);
+      this->set(offset / ptrsize);
+      break;
+
+    case Type::TYPE_INTERFACE:
+      // An interface is two pointers.
+      go_assert((offset % ptrsize) == 0);
+      this->set(offset / ptrsize);
+      this->set((offset / ptrsize) + 1);
+      break;
+
+    case Type::TYPE_STRUCT:
+      {
+	if (!type->has_pointer())
+	  return;
+
+	const Struct_field_list* fields = type->struct_type()->fields();
+	int64_t soffset = 0;
+	for (Struct_field_list::const_iterator pf = fields->begin();
+	     pf != fields->end();
+	     ++pf)
+	  {
+	    int64_t field_align;
+	    if (!pf->type()->backend_type_field_align(gogo, &field_align))
+	      {
+		go_assert(saw_errors());
+		return;
+	      }
+	    soffset = (soffset + (field_align - 1)) &~ (field_align - 1);
+
+	    this->set_from(gogo, pf->type(), ptrsize, offset + soffset);
+
+	    int64_t field_size;
+	    if (!pf->type()->backend_type_size(gogo, &field_size))
+	      {
+		go_assert(saw_errors());
+		return;
+	      }
+	    soffset += field_size;
+	  }
+      }
+      break;
+
+    case Type::TYPE_ARRAY:
+      if (type->is_slice_type())
+	{
+	  // A slice starts with a single pointer.
+	  go_assert((offset % ptrsize) == 0);
+	  this->set(offset / ptrsize);
+	  break;
+	}
+      else
+	{
+	  if (!type->has_pointer())
+	    return;
+
+	  int64_t len;
+	  if (!type->array_type()->int_length(&len))
+	    {
+	      go_assert(saw_errors());
+	      return;
+	    }
+
+	  Type* element_type = type->array_type()->element_type();
+	  int64_t ele_size;
+	  if (!element_type->backend_type_size(gogo, &ele_size))
+	    {
+	      go_assert(saw_errors());
+	      return;
+	    }
+
+	  int64_t eoffset = 0;
+	  for (int64_t i = 0; i < len; i++, eoffset += ele_size)
+	    this->set_from(gogo, element_type, ptrsize, offset + eoffset);
+	  break;
+	}
+    }
+}
+
+// Return a symbol name for this ptrmask.  This is used to coalesce
+// identical ptrmasks, which are common.  The symbol name must use
+// only characters that are valid in symbols.  It's nice if it's
+// short.  We convert it to a base64 string.
+
+std::string
+Ptrmask::symname() const
+{
+  const char chars[65] =
+    "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_.";
+  go_assert(chars[64] == '\0');
+  std::string ret;
+  unsigned int b = 0;
+  int remaining = 0;
+  for (std::vector<unsigned char>::const_iterator p = this->bits_.begin();
+       p != this->bits_.end();
+       ++p)
+    {
+      b |= *p << remaining;
+      remaining += 8;
+      while (remaining >= 6)
+	{
+	  ret += chars[b & 0x3f];
+	  b >>= 6;
+	  remaining -= 6;
+	}
+    }
+  while (remaining > 0)
+    {
+      ret += chars[b & 0x3f];
+      b >>= 6;
+      remaining -= 6;
+    }
+  return ret;
+}
+
+// Return a constructor for this ptrmask.  This will be used to
+// initialize the runtime ptrmask value.
+
+Expression*
+Ptrmask::constructor(Gogo* gogo) const
+{
+  Location bloc = Linemap::predeclared_location();
+  Type* byte_type = gogo->lookup_global("byte")->type_value();
+  Expression* len = Expression::make_integer_ul(this->bits_.size(), NULL,
+						bloc);
+  Array_type* at = Type::make_array_type(byte_type, len);
+  Expression_list* vals = new Expression_list();
+  vals->reserve(this->bits_.size());
+  for (std::vector<unsigned char>::const_iterator p = this->bits_.begin();
+       p != this->bits_.end();
+       ++p)
+    vals->push_back(Expression::make_integer_ul(*p, byte_type, bloc));
+  return Expression::make_array_composite_literal(at, vals, bloc);
+}
+
+// The hash table mapping a ptrmask symbol name to the ptrmask variable.
+Type::GC_gcbits_vars Type::gc_gcbits_vars;
+
+// Return a ptrmask variable for a type.  For a type descriptor this
+// is only used for variables that are small enough to not need a
+// gcprog, but for a global variable this is used for a variable of
+// any size.  PTRDATA is the number of bytes of the type that contain
+// pointer data.  PTRSIZE is the size of a pointer on the target
+// system.
+
+Bvariable*
+Type::gc_ptrmask_var(Gogo* gogo, int64_t ptrsize, int64_t ptrdata)
+{
+  Ptrmask ptrmask(ptrdata / ptrsize);
+  if (ptrdata >= ptrsize)
+    ptrmask.set_from(gogo, this, ptrsize, 0);
+  else
+    {
+      // This can happen in error cases.  Just build an empty gcbits.
+      go_assert(saw_errors());
+    }
+
+  std::string sym_name = gogo->ptrmask_symbol_name(ptrmask.symname());
+  Bvariable* bvnull = NULL;
+  std::pair<GC_gcbits_vars::iterator, bool> ins =
+    Type::gc_gcbits_vars.insert(std::make_pair(sym_name, bvnull));
+  if (!ins.second)
+    {
+      // We've already built a GC symbol for this set of gcbits.
+      return ins.first->second;
+    }
+
+  Expression* val = ptrmask.constructor(gogo);
+  Translate_context context(gogo, NULL, NULL, NULL);
+  context.set_is_const();
+  Bexpression* bval = val->get_backend(&context);
+
+  std::string asm_name(go_selectively_encode_id(sym_name));
+  Btype *btype = val->type()->get_backend(gogo);
+  Bvariable* ret = gogo->backend()->implicit_variable(sym_name, asm_name,
+						      btype, false, true,
+						      true, 0);
+  gogo->backend()->implicit_variable_set_init(ret, sym_name, btype, false,
+					      true, true, bval);
+  ins.first->second = ret;
+  return ret;
+}
+
+// A GCProg is used to build a program for the garbage collector.
+// This is used for types with a lot of pointer data, to reduce the
+// size of the data in the compiled program.  The program is expanded
+// at runtime.  For the format, see runGCProg in libgo/go/runtime/mbitmap.go.
+
+class GCProg
+{
+ public:
+  GCProg()
+    : bytes_(), index_(0), nb_(0)
+  {}
+
+  // The number of bits described so far.
+  int64_t
+  bit_index() const
+  { return this->index_; }
+
+  void
+  set_from(Gogo*, Type*, int64_t ptrsize, int64_t offset);
+
+  void
+  end();
+
+  Expression*
+  constructor(Gogo* gogo) const;
+
+ private:
+  void
+  ptr(int64_t);
+
+  bool
+  should_repeat(int64_t, int64_t);
+
+  void
+  repeat(int64_t, int64_t);
+
+  void
+  zero_until(int64_t);
+
+  void
+  lit(unsigned char);
+
+  void
+  varint(int64_t);
+
+  void
+  flushlit();
+
+  // Add a byte to the program.
+  void
+  byte(unsigned char x)
+  { this->bytes_.push_back(x); }
+
+  // The maximum number of bytes of literal bits.
+  static const int max_literal = 127;
+
+  // The program.
+  std::vector<unsigned char> bytes_;
+  // The index of the last bit described.
+  int64_t index_;
+  // The current set of literal bits.
+  unsigned char b_[max_literal];
+  // The current number of literal bits.
+  int nb_;
+};
+
+// Set data in gcprog starting from OFFSET based on TYPE.  OFFSET
+// counts in bytes.  PTRSIZE is the size of a pointer on the target
+// system.
+
+void
+GCProg::set_from(Gogo* gogo, Type* type, int64_t ptrsize, int64_t offset)
+{
+  switch (type->base()->classification())
+    {
+    default:
+    case Type::TYPE_NIL:
+    case Type::TYPE_CALL_MULTIPLE_RESULT:
+    case Type::TYPE_NAMED:
+    case Type::TYPE_FORWARD:
+      go_unreachable();
+
+    case Type::TYPE_ERROR:
+    case Type::TYPE_VOID:
+    case Type::TYPE_BOOLEAN:
+    case Type::TYPE_INTEGER:
+    case Type::TYPE_FLOAT:
+    case Type::TYPE_COMPLEX:
+    case Type::TYPE_SINK:
+      break;
+
+    case Type::TYPE_FUNCTION:
+    case Type::TYPE_POINTER:
+    case Type::TYPE_MAP:
+    case Type::TYPE_CHANNEL:
+      // These types are all a single pointer.
+      go_assert((offset % ptrsize) == 0);
+      this->ptr(offset / ptrsize);
+      break;
+
+    case Type::TYPE_STRING:
+      // A string starts with a single pointer.
+      go_assert((offset % ptrsize) == 0);
+      this->ptr(offset / ptrsize);
+      break;
+
+    case Type::TYPE_INTERFACE:
+      // An interface is two pointers.
+      go_assert((offset % ptrsize) == 0);
+      this->ptr(offset / ptrsize);
+      this->ptr((offset / ptrsize) + 1);
+      break;
+
+    case Type::TYPE_STRUCT:
+      {
+	if (!type->has_pointer())
+	  return;
+
+	const Struct_field_list* fields = type->struct_type()->fields();
+	int64_t soffset = 0;
+	for (Struct_field_list::const_iterator pf = fields->begin();
+	     pf != fields->end();
+	     ++pf)
+	  {
+	    int64_t field_align;
+	    if (!pf->type()->backend_type_field_align(gogo, &field_align))
+	      {
+		go_assert(saw_errors());
+		return;
+	      }
+	    soffset = (soffset + (field_align - 1)) &~ (field_align - 1);
+
+	    this->set_from(gogo, pf->type(), ptrsize, offset + soffset);
+
+	    int64_t field_size;
+	    if (!pf->type()->backend_type_size(gogo, &field_size))
+	      {
+		go_assert(saw_errors());
+		return;
+	      }
+	    soffset += field_size;
+	  }
+      }
+      break;
+
+    case Type::TYPE_ARRAY:
+      if (type->is_slice_type())
+	{
+	  // A slice starts with a single pointer.
+	  go_assert((offset % ptrsize) == 0);
+	  this->ptr(offset / ptrsize);
+	  break;
+	}
+      else
+	{
+	  if (!type->has_pointer())
+	    return;
+
+	  int64_t len;
+	  if (!type->array_type()->int_length(&len))
+	    {
+	      go_assert(saw_errors());
+	      return;
+	    }
+
+	  Type* element_type = type->array_type()->element_type();
+
+	  // Flatten array of array to a big array by multiplying counts.
+	  while (element_type->array_type() != NULL
+		 && !element_type->is_slice_type())
+	    {
+	      int64_t ele_len;
+	      if (!element_type->array_type()->int_length(&ele_len))
+		{
+		  go_assert(saw_errors());
+		  return;
+		}
+
+	      len *= ele_len;
+	      element_type = element_type->array_type()->element_type();
+	    }
+
+	  int64_t ele_size;
+	  if (!element_type->backend_type_size(gogo, &ele_size))
+	    {
+	      go_assert(saw_errors());
+	      return;
+	    }
+
+	  go_assert(len > 0 && ele_size > 0);
+
+	  if (!this->should_repeat(ele_size / ptrsize, len))
+	    {
+	      // Cheaper to just emit the bits.
+	      int64_t eoffset = 0;
+	      for (int64_t i = 0; i < len; i++, eoffset += ele_size)
+		this->set_from(gogo, element_type, ptrsize, offset + eoffset);
+	    }
+	  else
+	    {
+	      go_assert((offset % ptrsize) == 0);
+	      go_assert((ele_size % ptrsize) == 0);
+	      this->set_from(gogo, element_type, ptrsize, offset);
+	      this->zero_until((offset + ele_size) / ptrsize);
+	      this->repeat(ele_size / ptrsize, len - 1);
+	    }
+
+	  break;
+	}
+    }
+}
+
+// Emit a 1 into the bit stream of a GC program at the given bit index.
+
+void
+GCProg::ptr(int64_t index)
+{
+  go_assert(index >= this->index_);
+  this->zero_until(index);
+  this->lit(1);
+}
+
+// Return whether it is worthwhile to use a repeat to describe c
+// elements of n bits each, compared to just emitting c copies of the
+// n-bit description.
+
+bool
+GCProg::should_repeat(int64_t n, int64_t c)
+{
+  // Repeat if there is more than 1 item and if the total data doesn't
+  // fit into four bytes.
+  return c > 1 && c * n > 4 * 8;
+}
+
+// Emit an instruction to repeat the description of the last n words c
+// times (including the initial description, so c + 1 times in total).
+
+void
+GCProg::repeat(int64_t n, int64_t c)
+{
+  if (n == 0 || c == 0)
+    return;
+  this->flushlit();
+  if (n < 128)
+    this->byte(0x80 | static_cast<unsigned char>(n & 0x7f));
+  else
+    {
+      this->byte(0x80);
+      this->varint(n);
+    }
+  this->varint(c);
+  this->index_ += n * c;
+}
+
+// Add zeros to the bit stream up to the given index.
+
+void
+GCProg::zero_until(int64_t index)
+{
+  go_assert(index >= this->index_);
+  int64_t skip = index - this->index_;
+  if (skip == 0)
+    return;
+  if (skip < 4 * 8)
+    {
+      for (int64_t i = 0; i < skip; ++i)
+	this->lit(0);
+      return;
+    }
+  this->lit(0);
+  this->flushlit();
+  this->repeat(1, skip - 1);
+}
+
+// Add a single literal bit to the program.
+
+void
+GCProg::lit(unsigned char x)
+{
+  if (this->nb_ == GCProg::max_literal)
+    this->flushlit();
+  this->b_[this->nb_] = x;
+  ++this->nb_;
+  ++this->index_;
+}
+
+// Emit the varint encoding of x.
+
+void
+GCProg::varint(int64_t x)
+{
+  go_assert(x >= 0);
+  while (x >= 0x80)
+    {
+      this->byte(0x80 | static_cast<unsigned char>(x & 0x7f));
+      x >>= 7;
+    }
+  this->byte(static_cast<unsigned char>(x & 0x7f));
+}
+
+// Flush any pending literal bits.
+
+void
+GCProg::flushlit()
+{
+  if (this->nb_ == 0)
+    return;
+  this->byte(static_cast<unsigned char>(this->nb_));
+  unsigned char bits = 0;
+  for (int i = 0; i < this->nb_; ++i)
+    {
+      bits |= this->b_[i] << (i % 8);
+      if ((i + 1) % 8 == 0)
+	{
+	  this->byte(bits);
+	  bits = 0;
+	}
+    }
+  if (this->nb_ % 8 != 0)
+    this->byte(bits);
+  this->nb_ = 0;
+}
+
+// Mark the end of a GC program.
+
+void
+GCProg::end()
+{
+  this->flushlit();
+  this->byte(0);
+}
+
+// Return an Expression for the bytes in a GC program.
+
+Expression*
+GCProg::constructor(Gogo* gogo) const
+{
+  Location bloc = Linemap::predeclared_location();
+
+  // The first four bytes are the length of the program in target byte
+  // order.  Build a struct whose first type is uint32 to make this
+  // work.
+
+  Type* uint32_type = Type::lookup_integer_type("uint32");
+
+  Type* byte_type = gogo->lookup_global("byte")->type_value();
+  Expression* len = Expression::make_integer_ul(this->bytes_.size(), NULL,
+						bloc);
+  Array_type* at = Type::make_array_type(byte_type, len);
+
+  Struct_type* st = Type::make_builtin_struct_type(2, "len", uint32_type,
+						   "bytes", at);
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve(this->bytes_.size());
+  for (std::vector<unsigned char>::const_iterator p = this->bytes_.begin();
+       p != this->bytes_.end();
+       ++p)
+    vals->push_back(Expression::make_integer_ul(*p, byte_type, bloc));
+  Expression* bytes = Expression::make_array_composite_literal(at, vals, bloc);
+
+  vals = new Expression_list();
+  vals->push_back(Expression::make_integer_ul(this->bytes_.size(), uint32_type,
+					      bloc));
+  vals->push_back(bytes);
+
+  return Expression::make_struct_composite_literal(st, vals, bloc);
+}
+
+// Return a composite literal for the garbage collection program for
+// this type.  This is only used for types that are too large to use a
+// ptrmask.
+
+Expression*
+Type::gcprog_constructor(Gogo* gogo, int64_t ptrsize, int64_t ptrdata)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  GCProg prog;
+  prog.set_from(gogo, this, ptrsize, 0);
+  int64_t offset = prog.bit_index() * ptrsize;
+  prog.end();
+
+  int64_t type_size;
+  if (!this->backend_type_size(gogo, &type_size))
+    {
+      go_assert(saw_errors());
+      return Expression::make_error(bloc);
+    }
+
+  go_assert(offset >= ptrdata && offset <= type_size);
+
+  return prog.constructor(gogo);
+}
+
+// Return a composite literal for the uncommon type information for
+// this type.  UNCOMMON_STRUCT_TYPE is the type of the uncommon type
+// struct.  If name is not NULL, it is the name of the type.  If
+// METHODS is not NULL, it is the list of methods.  ONLY_VALUE_METHODS
+// is true if only value methods should be included.  At least one of
+// NAME and METHODS must not be NULL.
+
+Expression*
+Type::uncommon_type_constructor(Gogo* gogo, Type* uncommon_type,
+				Named_type* name, const Methods* methods,
+				bool only_value_methods) const
+{
+  Location bloc = Linemap::predeclared_location();
+
+  const Struct_field_list* fields = uncommon_type->struct_type()->fields();
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve(3);
+
+  Struct_field_list::const_iterator p = fields->begin();
+  go_assert(p->is_field_name("name"));
+
+  ++p;
+  go_assert(p->is_field_name("pkgPath"));
+
+  if (name == NULL)
+    {
+      vals->push_back(Expression::make_nil(bloc));
+      vals->push_back(Expression::make_nil(bloc));
+    }
+  else
+    {
+      Named_object* no = name->named_object();
+      std::string n = Gogo::unpack_hidden_name(no->name());
+      Expression* s = Expression::make_string(n, bloc);
+      vals->push_back(Expression::make_unary(OPERATOR_AND, s, bloc));
+
+      if (name->is_builtin())
+	vals->push_back(Expression::make_nil(bloc));
+      else
+	{
+	  const Package* package = no->package();
+	  const std::string& pkgpath(package == NULL
+				     ? gogo->pkgpath()
+				     : package->pkgpath());
+	  s = Expression::make_string(pkgpath, bloc);
+	  vals->push_back(Expression::make_unary(OPERATOR_AND, s, bloc));
+	}
+    }
+
+  ++p;
+  go_assert(p->is_field_name("methods"));
+  vals->push_back(this->methods_constructor(gogo, p->type(), methods,
+					    only_value_methods));
+
+  ++p;
+  go_assert(p == fields->end());
+
+  Expression* r = Expression::make_struct_composite_literal(uncommon_type,
+							    vals, bloc);
+  return Expression::make_unary(OPERATOR_AND, r, bloc);
+}
+
+// Sort methods by name.
+
+class Sort_methods
+{
+ public:
+  bool
+  operator()(const std::pair<std::string, const Method*>& m1,
+	     const std::pair<std::string, const Method*>& m2) const
+  {
+    return (Gogo::unpack_hidden_name(m1.first)
+	    < Gogo::unpack_hidden_name(m2.first));
+  }
+};
+
+// Return a composite literal for the type method table for this type.
+// METHODS_TYPE is the type of the table, and is a slice type.
+// METHODS is the list of methods.  If ONLY_VALUE_METHODS is true,
+// then only value methods are used.
+
+Expression*
+Type::methods_constructor(Gogo* gogo, Type* methods_type,
+			  const Methods* methods,
+			  bool only_value_methods) const
+{
+  Location bloc = Linemap::predeclared_location();
+
+  std::vector<std::pair<std::string, const Method*> > smethods;
+  if (methods != NULL)
+    {
+      smethods.reserve(methods->count());
+      for (Methods::const_iterator p = methods->begin();
+	   p != methods->end();
+	   ++p)
+	{
+	  if (p->second->is_ambiguous())
+	    continue;
+	  if (only_value_methods && !p->second->is_value_method())
+	    continue;
+
+	  // This is where we implement the magic //go:nointerface
+	  // comment.  If we saw that comment, we don't add this
+	  // method to the type descriptor.
+	  if (p->second->nointerface())
+	    continue;
+
+	  smethods.push_back(std::make_pair(p->first, p->second));
+	}
+    }
+
+  if (smethods.empty())
+    return Expression::make_slice_composite_literal(methods_type, NULL, bloc);
+
+  std::sort(smethods.begin(), smethods.end(), Sort_methods());
+
+  Type* method_type = methods_type->array_type()->element_type();
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve(smethods.size());
+  for (std::vector<std::pair<std::string, const Method*> >::const_iterator p
+	 = smethods.begin();
+       p != smethods.end();
+       ++p)
+    vals->push_back(this->method_constructor(gogo, method_type, p->first,
+					     p->second, only_value_methods));
+
+  return Expression::make_slice_composite_literal(methods_type, vals, bloc);
+}
+
+// Return a composite literal for a single method.  METHOD_TYPE is the
+// type of the entry.  METHOD_NAME is the name of the method and M is
+// the method information.
+
+Expression*
+Type::method_constructor(Gogo*, Type* method_type,
+			 const std::string& method_name,
+			 const Method* m,
+			 bool only_value_methods) const
+{
+  Location bloc = Linemap::predeclared_location();
+
+  const Struct_field_list* fields = method_type->struct_type()->fields();
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve(5);
+
+  Struct_field_list::const_iterator p = fields->begin();
+  go_assert(p->is_field_name("name"));
+  const std::string n = Gogo::unpack_hidden_name(method_name);
+  Expression* s = Expression::make_string(n, bloc);
+  vals->push_back(Expression::make_unary(OPERATOR_AND, s, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("pkgPath"));
+  if (!Gogo::is_hidden_name(method_name))
+    vals->push_back(Expression::make_nil(bloc));
+  else
+    {
+      s = Expression::make_string(Gogo::hidden_name_pkgpath(method_name),
+				  bloc);
+      vals->push_back(Expression::make_unary(OPERATOR_AND, s, bloc));
+    }
+
+  Named_object* no = (m->needs_stub_method()
+		      ? m->stub_object()
+		      : m->named_object());
+
+  Function_type* mtype;
+  if (no->is_function())
+    mtype = no->func_value()->type();
+  else
+    mtype = no->func_declaration_value()->type();
+  go_assert(mtype->is_method());
+  Type* nonmethod_type = mtype->copy_without_receiver();
+
+  ++p;
+  go_assert(p->is_field_name("mtyp"));
+  vals->push_back(Expression::make_type_descriptor(nonmethod_type, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("typ"));
+  bool want_pointer_receiver = !only_value_methods && m->is_value_method();
+  nonmethod_type = mtype->copy_with_receiver_as_param(want_pointer_receiver);
+  vals->push_back(Expression::make_type_descriptor(nonmethod_type, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("tfn"));
+  vals->push_back(Expression::make_func_code_reference(no, bloc));
+
+  ++p;
+  go_assert(p == fields->end());
+
+  return Expression::make_struct_composite_literal(method_type, vals, bloc);
+}
+
+// Return a composite literal for the type descriptor of a plain type.
+// RUNTIME_TYPE_KIND is the value of the kind field.  If NAME is not
+// NULL, it is the name to use as well as the list of methods.
+
+Expression*
+Type::plain_type_descriptor(Gogo* gogo, int runtime_type_kind,
+			    Named_type* name)
+{
+  return this->type_descriptor_constructor(gogo, runtime_type_kind,
+					   name, NULL, true);
+}
+
+// Return the type reflection string for this type.
+
+std::string
+Type::reflection(Gogo* gogo) const
+{
+  std::string ret;
+
+  // The do_reflection virtual function should set RET to the
+  // reflection string.
+  this->do_reflection(gogo, &ret);
+
+  return ret;
+}
+
+// Return whether the backend size of the type is known.
+
+bool
+Type::is_backend_type_size_known(Gogo* gogo)
+{
+  switch (this->classification_)
+    {
+    case TYPE_ERROR:
+    case TYPE_VOID:
+    case TYPE_BOOLEAN:
+    case TYPE_INTEGER:
+    case TYPE_FLOAT:
+    case TYPE_COMPLEX:
+    case TYPE_STRING:
+    case TYPE_FUNCTION:
+    case TYPE_POINTER:
+    case TYPE_NIL:
+    case TYPE_MAP:
+    case TYPE_CHANNEL:
+    case TYPE_INTERFACE:
+      return true;
+
+    case TYPE_STRUCT:
+      {
+	const Struct_field_list* fields = this->struct_type()->fields();
+	for (Struct_field_list::const_iterator pf = fields->begin();
+	     pf != fields->end();
+	     ++pf)
+	  if (!pf->type()->is_backend_type_size_known(gogo))
+	    return false;
+	return true;
+      }
+
+    case TYPE_ARRAY:
+      {
+	const Array_type* at = this->array_type();
+	if (at->length() == NULL)
+	  return true;
+	else
+	  {
+	    Numeric_constant nc;
+	    if (!at->length()->numeric_constant_value(&nc))
+	      return false;
+	    mpz_t ival;
+	    if (!nc.to_int(&ival))
+	      return false;
+	    mpz_clear(ival);
+	    return at->element_type()->is_backend_type_size_known(gogo);
+	  }
+      }
+
+    case TYPE_NAMED:
+      this->named_type()->convert(gogo);
+      return this->named_type()->is_named_backend_type_size_known();
+
+    case TYPE_FORWARD:
+      {
+	Forward_declaration_type* fdt = this->forward_declaration_type();
+	return fdt->real_type()->is_backend_type_size_known(gogo);
+      }
+
+    case TYPE_SINK:
+    case TYPE_CALL_MULTIPLE_RESULT:
+      go_unreachable();
+
+    default:
+      go_unreachable();
+    }
+}
+
+// If the size of the type can be determined, set *PSIZE to the size
+// in bytes and return true.  Otherwise, return false.  This queries
+// the backend.
+
+bool
+Type::backend_type_size(Gogo* gogo, int64_t *psize)
+{
+  if (!this->is_backend_type_size_known(gogo))
+    return false;
+  if (this->is_error_type())
+    return false;
+  Btype* bt = this->get_backend_placeholder(gogo);
+  *psize = gogo->backend()->type_size(bt);
+  if (*psize == -1)
+    {
+      if (this->named_type() != NULL)
+	go_error_at(this->named_type()->location(),
+		 "type %s larger than address space",
+		 Gogo::message_name(this->named_type()->name()).c_str());
+      else
+	go_error_at(Linemap::unknown_location(),
+		    "type %s larger than address space",
+		    this->reflection(gogo).c_str());
+
+      // Make this an error type to avoid knock-on errors.
+      this->classification_ = TYPE_ERROR;
+      return false;
+    }
+  return true;
+}
+
+// If the alignment of the type can be determined, set *PALIGN to
+// the alignment in bytes and return true.  Otherwise, return false.
+
+bool
+Type::backend_type_align(Gogo* gogo, int64_t *palign)
+{
+  if (!this->is_backend_type_size_known(gogo))
+    return false;
+  Btype* bt = this->get_backend_placeholder(gogo);
+  *palign = gogo->backend()->type_alignment(bt);
+  return true;
+}
+
+// Like backend_type_align, but return the alignment when used as a
+// field.
+
+bool
+Type::backend_type_field_align(Gogo* gogo, int64_t *palign)
+{
+  if (!this->is_backend_type_size_known(gogo))
+    return false;
+  Btype* bt = this->get_backend_placeholder(gogo);
+  *palign = gogo->backend()->type_field_alignment(bt);
+  return true;
+}
+
+// Get the ptrdata value for a type.  This is the size of the prefix
+// of the type that contains all pointers.  Store the ptrdata in
+// *PPTRDATA and return whether we found it.
+
+bool
+Type::backend_type_ptrdata(Gogo* gogo, int64_t* pptrdata)
+{
+  *pptrdata = 0;
+
+  if (!this->has_pointer())
+    return true;
+
+  if (!this->is_backend_type_size_known(gogo))
+    return false;
+
+  switch (this->classification_)
+    {
+    case TYPE_ERROR:
+      return true;
+
+    case TYPE_FUNCTION:
+    case TYPE_POINTER:
+    case TYPE_MAP:
+    case TYPE_CHANNEL:
+      // These types are nothing but a pointer.
+      return this->backend_type_size(gogo, pptrdata);
+
+    case TYPE_INTERFACE:
+      // An interface is a struct of two pointers.
+      return this->backend_type_size(gogo, pptrdata);
+
+    case TYPE_STRING:
+      {
+	// A string is a struct whose first field is a pointer, and
+	// whose second field is not.
+	Type* uint8_type = Type::lookup_integer_type("uint8");
+	Type* ptr = Type::make_pointer_type(uint8_type);
+	return ptr->backend_type_size(gogo, pptrdata);
+      }
+
+    case TYPE_NAMED:
+    case TYPE_FORWARD:
+      return this->base()->backend_type_ptrdata(gogo, pptrdata);
+
+    case TYPE_STRUCT:
+      {
+	const Struct_field_list* fields = this->struct_type()->fields();
+	int64_t offset = 0;
+	const Struct_field *ptr = NULL;
+	int64_t ptr_offset = 0;
+	for (Struct_field_list::const_iterator pf = fields->begin();
+	     pf != fields->end();
+	     ++pf)
+	  {
+	    int64_t field_align;
+	    if (!pf->type()->backend_type_field_align(gogo, &field_align))
+	      return false;
+	    offset = (offset + (field_align - 1)) &~ (field_align - 1);
+
+	    if (pf->type()->has_pointer())
+	      {
+		ptr = &*pf;
+		ptr_offset = offset;
+	      }
+
+	    int64_t field_size;
+	    if (!pf->type()->backend_type_size(gogo, &field_size))
+	      return false;
+	    offset += field_size;
+	  }
+
+	if (ptr != NULL)
+	  {
+	    int64_t ptr_ptrdata;
+	    if (!ptr->type()->backend_type_ptrdata(gogo, &ptr_ptrdata))
+	      return false;
+	    *pptrdata = ptr_offset + ptr_ptrdata;
+	  }
+	return true;
+      }
+
+    case TYPE_ARRAY:
+      if (this->is_slice_type())
+	{
+	  // A slice is a struct whose first field is a pointer, and
+	  // whose remaining fields are not.
+	  Type* element_type = this->array_type()->element_type();
+	  Type* ptr = Type::make_pointer_type(element_type);
+	  return ptr->backend_type_size(gogo, pptrdata);
+	}
+      else
+	{
+	  Numeric_constant nc;
+	  if (!this->array_type()->length()->numeric_constant_value(&nc))
+	    return false;
+	  int64_t len;
+	  if (!nc.to_memory_size(&len))
+	    return false;
+
+	  Type* element_type = this->array_type()->element_type();
+	  int64_t ele_size;
+	  int64_t ele_ptrdata;
+	  if (!element_type->backend_type_size(gogo, &ele_size)
+	      || !element_type->backend_type_ptrdata(gogo, &ele_ptrdata))
+	    return false;
+	  go_assert(ele_size > 0 && ele_ptrdata > 0);
+
+	  *pptrdata = (len - 1) * ele_size + ele_ptrdata;
+	  return true;
+	}
+
+    default:
+    case TYPE_VOID:
+    case TYPE_BOOLEAN:
+    case TYPE_INTEGER:
+    case TYPE_FLOAT:
+    case TYPE_COMPLEX:
+    case TYPE_SINK:
+    case TYPE_NIL:
+    case TYPE_CALL_MULTIPLE_RESULT:
+      go_unreachable();
+    }
+}
+
+// Get the ptrdata value to store in a type descriptor.  This is
+// normally the same as backend_type_ptrdata, but for a type that is
+// large enough to use a gcprog we may need to store a different value
+// if it ends with an array.  If the gcprog uses a repeat descriptor
+// for the array, and if the array element ends with non-pointer data,
+// then the gcprog will produce a value that describes the complete
+// array where the backend ptrdata will omit the non-pointer elements
+// of the final array element.  This is a subtle difference but the
+// run time code checks it to verify that it has expanded a gcprog as
+// expected.
+
+bool
+Type::descriptor_ptrdata(Gogo* gogo, int64_t* pptrdata)
+{
+  int64_t backend_ptrdata;
+  if (!this->backend_type_ptrdata(gogo, &backend_ptrdata))
+    return false;
+
+  int64_t ptrsize;
+  if (!this->needs_gcprog(gogo, &ptrsize, &backend_ptrdata))
+    {
+      *pptrdata = backend_ptrdata;
+      return true;
+    }
+
+  GCProg prog;
+  prog.set_from(gogo, this, ptrsize, 0);
+  int64_t offset = prog.bit_index() * ptrsize;
+
+  go_assert(offset >= backend_ptrdata);
+  *pptrdata = offset;
+  return true;
+}
+
+// Default function to export a type.
+
+void
+Type::do_export(Export*) const
+{
+  go_unreachable();
+}
+
+// Import a type.
+
+Type*
+Type::import_type(Import* imp)
+{
+  if (imp->match_c_string("("))
+    return Function_type::do_import(imp);
+  else if (imp->match_c_string("*"))
+    return Pointer_type::do_import(imp);
+  else if (imp->match_c_string("struct "))
+    return Struct_type::do_import(imp);
+  else if (imp->match_c_string("["))
+    return Array_type::do_import(imp);
+  else if (imp->match_c_string("map "))
+    return Map_type::do_import(imp);
+  else if (imp->match_c_string("chan "))
+    return Channel_type::do_import(imp);
+  else if (imp->match_c_string("interface"))
+    return Interface_type::do_import(imp);
+  else
+    {
+      go_error_at(imp->location(), "import error: expected type");
+      return Type::make_error_type();
+    }
+}
+
+// Class Error_type.
+
+// Return the backend representation of an Error type.
+
+Btype*
+Error_type::do_get_backend(Gogo* gogo)
+{
+  return gogo->backend()->error_type();
+}
+
+// Return an expression for the type descriptor for an error type.
+
+
+Expression*
+Error_type::do_type_descriptor(Gogo*, Named_type*)
+{
+  return Expression::make_error(Linemap::predeclared_location());
+}
+
+// We should not be asked for the reflection string for an error type.
+
+void
+Error_type::do_reflection(Gogo*, std::string*) const
+{
+  go_assert(saw_errors());
+}
+
+Type*
+Type::make_error_type()
+{
+  static Error_type singleton_error_type;
+  return &singleton_error_type;
+}
+
+// Class Void_type.
+
+// Get the backend representation of a void type.
+
+Btype*
+Void_type::do_get_backend(Gogo* gogo)
+{
+  return gogo->backend()->void_type();
+}
+
+Type*
+Type::make_void_type()
+{
+  static Void_type singleton_void_type;
+  return &singleton_void_type;
+}
+
+// Class Boolean_type.
+
+// Return the backend representation of the boolean type.
+
+Btype*
+Boolean_type::do_get_backend(Gogo* gogo)
+{
+  return gogo->backend()->bool_type();
+}
+
+// Make the type descriptor.
+
+Expression*
+Boolean_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  if (name != NULL)
+    return this->plain_type_descriptor(gogo, RUNTIME_TYPE_KIND_BOOL, name);
+  else
+    {
+      Named_object* no = gogo->lookup_global("bool");
+      go_assert(no != NULL);
+      return Type::type_descriptor(gogo, no->type_value());
+    }
+}
+
+Type*
+Type::make_boolean_type()
+{
+  static Boolean_type boolean_type;
+  return &boolean_type;
+}
+
+// The named type "bool".
+
+static Named_type* named_bool_type;
+
+// Get the named type "bool".
+
+Named_type*
+Type::lookup_bool_type()
+{
+  return named_bool_type;
+}
+
+// Make the named type "bool".
+
+Named_type*
+Type::make_named_bool_type()
+{
+  Type* bool_type = Type::make_boolean_type();
+  Named_object* named_object =
+    Named_object::make_type("bool", NULL, bool_type,
+                            Linemap::predeclared_location());
+  Named_type* named_type = named_object->type_value();
+  named_bool_type = named_type;
+  return named_type;
+}
+
+// Class Integer_type.
+
+Integer_type::Named_integer_types Integer_type::named_integer_types;
+
+// Create a new integer type.  Non-abstract integer types always have
+// names.
+
+Named_type*
+Integer_type::create_integer_type(const char* name, bool is_unsigned,
+				  int bits, int runtime_type_kind)
+{
+  Integer_type* integer_type = new Integer_type(false, is_unsigned, bits,
+						runtime_type_kind);
+  std::string sname(name);
+  Named_object* named_object =
+    Named_object::make_type(sname, NULL, integer_type,
+                            Linemap::predeclared_location());
+  Named_type* named_type = named_object->type_value();
+  std::pair<Named_integer_types::iterator, bool> ins =
+    Integer_type::named_integer_types.insert(std::make_pair(sname, named_type));
+  go_assert(ins.second);
+  return named_type;
+}
+
+// Look up an existing integer type.
+
+Named_type*
+Integer_type::lookup_integer_type(const char* name)
+{
+  Named_integer_types::const_iterator p =
+    Integer_type::named_integer_types.find(name);
+  go_assert(p != Integer_type::named_integer_types.end());
+  return p->second;
+}
+
+// Create a new abstract integer type.
+
+Integer_type*
+Integer_type::create_abstract_integer_type()
+{
+  static Integer_type* abstract_type;
+  if (abstract_type == NULL)
+    {
+      Type* int_type = Type::lookup_integer_type("int");
+      abstract_type = new Integer_type(true, false,
+				       int_type->integer_type()->bits(),
+				       RUNTIME_TYPE_KIND_INT);
+    }
+  return abstract_type;
+}
+
+// Create a new abstract character type.
+
+Integer_type*
+Integer_type::create_abstract_character_type()
+{
+  static Integer_type* abstract_type;
+  if (abstract_type == NULL)
+    {
+      abstract_type = new Integer_type(true, false, 32,
+				       RUNTIME_TYPE_KIND_INT32);
+      abstract_type->set_is_rune();
+    }
+  return abstract_type;
+}
+
+// Integer type compatibility.
+
+bool
+Integer_type::is_identical(const Integer_type* t) const
+{
+  if (this->is_unsigned_ != t->is_unsigned_ || this->bits_ != t->bits_)
+    return false;
+  return this->is_abstract_ == t->is_abstract_;
+}
+
+// Hash code.
+
+unsigned int
+Integer_type::do_hash_for_method(Gogo*) const
+{
+  return ((this->bits_ << 4)
+	  + ((this->is_unsigned_ ? 1 : 0) << 8)
+	  + ((this->is_abstract_ ? 1 : 0) << 9));
+}
+
+// Convert an Integer_type to the backend representation.
+
+Btype*
+Integer_type::do_get_backend(Gogo* gogo)
+{
+  if (this->is_abstract_)
+    {
+      go_assert(saw_errors());
+      return gogo->backend()->error_type();
+    }
+  return gogo->backend()->integer_type(this->is_unsigned_, this->bits_);
+}
+
+// The type descriptor for an integer type.  Integer types are always
+// named.
+
+Expression*
+Integer_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  go_assert(name != NULL || saw_errors());
+  return this->plain_type_descriptor(gogo, this->runtime_type_kind_, name);
+}
+
+// We should not be asked for the reflection string of a basic type.
+
+void
+Integer_type::do_reflection(Gogo*, std::string*) const
+{
+  go_assert(saw_errors());
+}
+
+// Make an integer type.
+
+Named_type*
+Type::make_integer_type(const char* name, bool is_unsigned, int bits,
+			int runtime_type_kind)
+{
+  return Integer_type::create_integer_type(name, is_unsigned, bits,
+					   runtime_type_kind);
+}
+
+// Make an abstract integer type.
+
+Integer_type*
+Type::make_abstract_integer_type()
+{
+  return Integer_type::create_abstract_integer_type();
+}
+
+// Make an abstract character type.
+
+Integer_type*
+Type::make_abstract_character_type()
+{
+  return Integer_type::create_abstract_character_type();
+}
+
+// Look up an integer type.
+
+Named_type*
+Type::lookup_integer_type(const char* name)
+{
+  return Integer_type::lookup_integer_type(name);
+}
+
+// Class Float_type.
+
+Float_type::Named_float_types Float_type::named_float_types;
+
+// Create a new float type.  Non-abstract float types always have
+// names.
+
+Named_type*
+Float_type::create_float_type(const char* name, int bits,
+			      int runtime_type_kind)
+{
+  Float_type* float_type = new Float_type(false, bits, runtime_type_kind);
+  std::string sname(name);
+  Named_object* named_object =
+    Named_object::make_type(sname, NULL, float_type,
+                            Linemap::predeclared_location());
+  Named_type* named_type = named_object->type_value();
+  std::pair<Named_float_types::iterator, bool> ins =
+    Float_type::named_float_types.insert(std::make_pair(sname, named_type));
+  go_assert(ins.second);
+  return named_type;
+}
+
+// Look up an existing float type.
+
+Named_type*
+Float_type::lookup_float_type(const char* name)
+{
+  Named_float_types::const_iterator p =
+    Float_type::named_float_types.find(name);
+  go_assert(p != Float_type::named_float_types.end());
+  return p->second;
+}
+
+// Create a new abstract float type.
+
+Float_type*
+Float_type::create_abstract_float_type()
+{
+  static Float_type* abstract_type;
+  if (abstract_type == NULL)
+    abstract_type = new Float_type(true, 64, RUNTIME_TYPE_KIND_FLOAT64);
+  return abstract_type;
+}
+
+// Whether this type is identical with T.
+
+bool
+Float_type::is_identical(const Float_type* t) const
+{
+  if (this->bits_ != t->bits_)
+    return false;
+  return this->is_abstract_ == t->is_abstract_;
+}
+
+// Hash code.
+
+unsigned int
+Float_type::do_hash_for_method(Gogo*) const
+{
+  return (this->bits_ << 4) + ((this->is_abstract_ ? 1 : 0) << 8);
+}
+
+// Convert to the backend representation.
+
+Btype*
+Float_type::do_get_backend(Gogo* gogo)
+{
+  return gogo->backend()->float_type(this->bits_);
+}
+
+// The type descriptor for a float type.  Float types are always named.
+
+Expression*
+Float_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  go_assert(name != NULL || saw_errors());
+  return this->plain_type_descriptor(gogo, this->runtime_type_kind_, name);
+}
+
+// We should not be asked for the reflection string of a basic type.
+
+void
+Float_type::do_reflection(Gogo*, std::string*) const
+{
+  go_assert(saw_errors());
+}
+
+// Make a floating point type.
+
+Named_type*
+Type::make_float_type(const char* name, int bits, int runtime_type_kind)
+{
+  return Float_type::create_float_type(name, bits, runtime_type_kind);
+}
+
+// Make an abstract float type.
+
+Float_type*
+Type::make_abstract_float_type()
+{
+  return Float_type::create_abstract_float_type();
+}
+
+// Look up a float type.
+
+Named_type*
+Type::lookup_float_type(const char* name)
+{
+  return Float_type::lookup_float_type(name);
+}
+
+// Class Complex_type.
+
+Complex_type::Named_complex_types Complex_type::named_complex_types;
+
+// Create a new complex type.  Non-abstract complex types always have
+// names.
+
+Named_type*
+Complex_type::create_complex_type(const char* name, int bits,
+				  int runtime_type_kind)
+{
+  Complex_type* complex_type = new Complex_type(false, bits,
+						runtime_type_kind);
+  std::string sname(name);
+  Named_object* named_object =
+    Named_object::make_type(sname, NULL, complex_type,
+                            Linemap::predeclared_location());
+  Named_type* named_type = named_object->type_value();
+  std::pair<Named_complex_types::iterator, bool> ins =
+    Complex_type::named_complex_types.insert(std::make_pair(sname,
+							    named_type));
+  go_assert(ins.second);
+  return named_type;
+}
+
+// Look up an existing complex type.
+
+Named_type*
+Complex_type::lookup_complex_type(const char* name)
+{
+  Named_complex_types::const_iterator p =
+    Complex_type::named_complex_types.find(name);
+  go_assert(p != Complex_type::named_complex_types.end());
+  return p->second;
+}
+
+// Create a new abstract complex type.
+
+Complex_type*
+Complex_type::create_abstract_complex_type()
+{
+  static Complex_type* abstract_type;
+  if (abstract_type == NULL)
+    abstract_type = new Complex_type(true, 128, RUNTIME_TYPE_KIND_COMPLEX128);
+  return abstract_type;
+}
+
+// Whether this type is identical with T.
+
+bool
+Complex_type::is_identical(const Complex_type *t) const
+{
+  if (this->bits_ != t->bits_)
+    return false;
+  return this->is_abstract_ == t->is_abstract_;
+}
+
+// Hash code.
+
+unsigned int
+Complex_type::do_hash_for_method(Gogo*) const
+{
+  return (this->bits_ << 4) + ((this->is_abstract_ ? 1 : 0) << 8);
+}
+
+// Convert to the backend representation.
+
+Btype*
+Complex_type::do_get_backend(Gogo* gogo)
+{
+  return gogo->backend()->complex_type(this->bits_);
+}
+
+// The type descriptor for a complex type.  Complex types are always
+// named.
+
+Expression*
+Complex_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  go_assert(name != NULL || saw_errors());
+  return this->plain_type_descriptor(gogo, this->runtime_type_kind_, name);
+}
+
+// We should not be asked for the reflection string of a basic type.
+
+void
+Complex_type::do_reflection(Gogo*, std::string*) const
+{
+  go_assert(saw_errors());
+}
+
+// Make a complex type.
+
+Named_type*
+Type::make_complex_type(const char* name, int bits, int runtime_type_kind)
+{
+  return Complex_type::create_complex_type(name, bits, runtime_type_kind);
+}
+
+// Make an abstract complex type.
+
+Complex_type*
+Type::make_abstract_complex_type()
+{
+  return Complex_type::create_abstract_complex_type();
+}
+
+// Look up a complex type.
+
+Named_type*
+Type::lookup_complex_type(const char* name)
+{
+  return Complex_type::lookup_complex_type(name);
+}
+
+// Class String_type.
+
+// Convert String_type to the backend representation.  A string is a
+// struct with two fields: a pointer to the characters and a length.
+
+Btype*
+String_type::do_get_backend(Gogo* gogo)
+{
+  static Btype* backend_string_type;
+  if (backend_string_type == NULL)
+    {
+      std::vector<Backend::Btyped_identifier> fields(2);
+
+      Type* b = gogo->lookup_global("byte")->type_value();
+      Type* pb = Type::make_pointer_type(b);
+
+      // We aren't going to get back to this field to finish the
+      // backend representation, so force it to be finished now.
+      if (!gogo->named_types_are_converted())
+	{
+	  Btype* bt = pb->get_backend_placeholder(gogo);
+	  pb->finish_backend(gogo, bt);
+	}
+
+      fields[0].name = "__data";
+      fields[0].btype = pb->get_backend(gogo);
+      fields[0].location = Linemap::predeclared_location();
+
+      Type* int_type = Type::lookup_integer_type("int");
+      fields[1].name = "__length";
+      fields[1].btype = int_type->get_backend(gogo);
+      fields[1].location = fields[0].location;
+
+      backend_string_type = gogo->backend()->struct_type(fields);
+    }
+  return backend_string_type;
+}
+
+// The type descriptor for the string type.
+
+Expression*
+String_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  if (name != NULL)
+    return this->plain_type_descriptor(gogo, RUNTIME_TYPE_KIND_STRING, name);
+  else
+    {
+      Named_object* no = gogo->lookup_global("string");
+      go_assert(no != NULL);
+      return Type::type_descriptor(gogo, no->type_value());
+    }
+}
+
+// We should not be asked for the reflection string of a basic type.
+
+void
+String_type::do_reflection(Gogo*, std::string* ret) const
+{
+  ret->append("string");
+}
+
+// Make a string type.
+
+Type*
+Type::make_string_type()
+{
+  static String_type string_type;
+  return &string_type;
+}
+
+// The named type "string".
+
+static Named_type* named_string_type;
+
+// Get the named type "string".
+
+Named_type*
+Type::lookup_string_type()
+{
+  return named_string_type;
+}
+
+// Make the named type string.
+
+Named_type*
+Type::make_named_string_type()
+{
+  Type* string_type = Type::make_string_type();
+  Named_object* named_object =
+    Named_object::make_type("string", NULL, string_type,
+                            Linemap::predeclared_location());
+  Named_type* named_type = named_object->type_value();
+  named_string_type = named_type;
+  return named_type;
+}
+
+// The sink type.  This is the type of the blank identifier _.  Any
+// type may be assigned to it.
+
+class Sink_type : public Type
+{
+ public:
+  Sink_type()
+    : Type(TYPE_SINK)
+  { }
+
+ protected:
+  bool
+  do_compare_is_identity(Gogo*)
+  { return false; }
+
+  Btype*
+  do_get_backend(Gogo*)
+  { go_unreachable(); }
+
+  Expression*
+  do_type_descriptor(Gogo*, Named_type*)
+  { go_unreachable(); }
+
+  void
+  do_reflection(Gogo*, std::string*) const
+  { go_unreachable(); }
+
+  void
+  do_mangled_name(Gogo*, std::string*) const
+  { go_unreachable(); }
+};
+
+// Make the sink type.
+
+Type*
+Type::make_sink_type()
+{
+  static Sink_type sink_type;
+  return &sink_type;
+}
+
+// Class Function_type.
+
+// Traversal.
+
+int
+Function_type::do_traverse(Traverse* traverse)
+{
+  if (this->receiver_ != NULL
+      && Type::traverse(this->receiver_->type(), traverse) == TRAVERSE_EXIT)
+    return TRAVERSE_EXIT;
+  if (this->parameters_ != NULL
+      && this->parameters_->traverse(traverse) == TRAVERSE_EXIT)
+    return TRAVERSE_EXIT;
+  if (this->results_ != NULL
+      && this->results_->traverse(traverse) == TRAVERSE_EXIT)
+    return TRAVERSE_EXIT;
+  return TRAVERSE_CONTINUE;
+}
+
+// Returns whether T is a valid redeclaration of this type.  If this
+// returns false, and REASON is not NULL, *REASON may be set to a
+// brief explanation of why it returned false.
+
+bool
+Function_type::is_valid_redeclaration(const Function_type* t,
+				      std::string* reason) const
+{
+  if (!this->is_identical(t, false, COMPARE_TAGS, true, reason))
+    return false;
+
+  // A redeclaration of a function is required to use the same names
+  // for the receiver and parameters.
+  if (this->receiver() != NULL
+      && this->receiver()->name() != t->receiver()->name())
+    {
+      if (reason != NULL)
+	*reason = "receiver name changed";
+      return false;
+    }
+
+  const Typed_identifier_list* parms1 = this->parameters();
+  const Typed_identifier_list* parms2 = t->parameters();
+  if (parms1 != NULL)
+    {
+      Typed_identifier_list::const_iterator p1 = parms1->begin();
+      for (Typed_identifier_list::const_iterator p2 = parms2->begin();
+	   p2 != parms2->end();
+	   ++p2, ++p1)
+	{
+	  if (p1->name() != p2->name())
+	    {
+	      if (reason != NULL)
+		*reason = "parameter name changed";
+	      return false;
+	    }
+
+	  // This is called at parse time, so we may have unknown
+	  // types.
+	  Type* t1 = p1->type()->forwarded();
+	  Type* t2 = p2->type()->forwarded();
+	  if (t1 != t2
+	      && t1->forward_declaration_type() != NULL
+	      && (t2->forward_declaration_type() == NULL
+		  || (t1->forward_declaration_type()->named_object()
+		      != t2->forward_declaration_type()->named_object())))
+	    return false;
+	}
+    }
+
+  const Typed_identifier_list* results1 = this->results();
+  const Typed_identifier_list* results2 = t->results();
+  if (results1 != NULL)
+    {
+      Typed_identifier_list::const_iterator res1 = results1->begin();
+      for (Typed_identifier_list::const_iterator res2 = results2->begin();
+	   res2 != results2->end();
+	   ++res2, ++res1)
+	{
+	  if (res1->name() != res2->name())
+	    {
+	      if (reason != NULL)
+		*reason = "result name changed";
+	      return false;
+	    }
+
+	  // This is called at parse time, so we may have unknown
+	  // types.
+	  Type* t1 = res1->type()->forwarded();
+	  Type* t2 = res2->type()->forwarded();
+	  if (t1 != t2
+	      && t1->forward_declaration_type() != NULL
+	      && (t2->forward_declaration_type() == NULL
+		  || (t1->forward_declaration_type()->named_object()
+		      != t2->forward_declaration_type()->named_object())))
+	    return false;
+	}
+    }
+
+  return true;
+}
+
+// Check whether T is the same as this type.
+
+bool
+Function_type::is_identical(const Function_type* t, bool ignore_receiver,
+			    Cmp_tags cmp_tags, bool errors_are_identical,
+			    std::string* reason) const
+{
+  if (!ignore_receiver)
+    {
+      const Typed_identifier* r1 = this->receiver();
+      const Typed_identifier* r2 = t->receiver();
+      if ((r1 != NULL) != (r2 != NULL))
+	{
+	  if (reason != NULL)
+	    *reason = _("different receiver types");
+	  return false;
+	}
+      if (r1 != NULL)
+	{
+	  if (!Type::are_identical_cmp_tags(r1->type(), r2->type(), cmp_tags,
+					    errors_are_identical, reason))
+	    {
+	      if (reason != NULL && !reason->empty())
+		*reason = "receiver: " + *reason;
+	      return false;
+	    }
+	}
+    }
+
+  const Typed_identifier_list* parms1 = this->parameters();
+  const Typed_identifier_list* parms2 = t->parameters();
+  if ((parms1 != NULL) != (parms2 != NULL))
+    {
+      if (reason != NULL)
+	*reason = _("different number of parameters");
+      return false;
+    }
+  if (parms1 != NULL)
+    {
+      Typed_identifier_list::const_iterator p1 = parms1->begin();
+      for (Typed_identifier_list::const_iterator p2 = parms2->begin();
+	   p2 != parms2->end();
+	   ++p2, ++p1)
+	{
+	  if (p1 == parms1->end())
+	    {
+	      if (reason != NULL)
+		*reason = _("different number of parameters");
+	      return false;
+	    }
+
+	  if (!Type::are_identical_cmp_tags(p1->type(), p2->type(), cmp_tags,
+					    errors_are_identical, NULL))
+	    {
+	      if (reason != NULL)
+		*reason = _("different parameter types");
+	      return false;
+	    }
+	}
+      if (p1 != parms1->end())
+	{
+	  if (reason != NULL)
+	    *reason = _("different number of parameters");
+	return false;
+	}
+    }
+
+  if (this->is_varargs() != t->is_varargs())
+    {
+      if (reason != NULL)
+	*reason = _("different varargs");
+      return false;
+    }
+
+  const Typed_identifier_list* results1 = this->results();
+  const Typed_identifier_list* results2 = t->results();
+  if ((results1 != NULL) != (results2 != NULL))
+    {
+      if (reason != NULL)
+	*reason = _("different number of results");
+      return false;
+    }
+  if (results1 != NULL)
+    {
+      Typed_identifier_list::const_iterator res1 = results1->begin();
+      for (Typed_identifier_list::const_iterator res2 = results2->begin();
+	   res2 != results2->end();
+	   ++res2, ++res1)
+	{
+	  if (res1 == results1->end())
+	    {
+	      if (reason != NULL)
+		*reason = _("different number of results");
+	      return false;
+	    }
+
+	  if (!Type::are_identical_cmp_tags(res1->type(), res2->type(),
+					    cmp_tags, errors_are_identical,
+					    NULL))
+	    {
+	      if (reason != NULL)
+		*reason = _("different result types");
+	      return false;
+	    }
+	}
+      if (res1 != results1->end())
+	{
+	  if (reason != NULL)
+	    *reason = _("different number of results");
+	  return false;
+	}
+    }
+
+  return true;
+}
+
+// Hash code.
+
+unsigned int
+Function_type::do_hash_for_method(Gogo* gogo) const
+{
+  unsigned int ret = 0;
+  // We ignore the receiver type for hash codes, because we need to
+  // get the same hash code for a method in an interface and a method
+  // declared for a type.  The former will not have a receiver.
+  if (this->parameters_ != NULL)
+    {
+      int shift = 1;
+      for (Typed_identifier_list::const_iterator p = this->parameters_->begin();
+	   p != this->parameters_->end();
+	   ++p, ++shift)
+	ret += p->type()->hash_for_method(gogo) << shift;
+    }
+  if (this->results_ != NULL)
+    {
+      int shift = 2;
+      for (Typed_identifier_list::const_iterator p = this->results_->begin();
+	   p != this->results_->end();
+	   ++p, ++shift)
+	ret += p->type()->hash_for_method(gogo) << shift;
+    }
+  if (this->is_varargs_)
+    ret += 1;
+  ret <<= 4;
+  return ret;
+}
+
+// Hash result parameters.
+
+unsigned int
+Function_type::Results_hash::operator()(const Typed_identifier_list* t) const
+{
+  unsigned int hash = 0;
+  for (Typed_identifier_list::const_iterator p = t->begin();
+       p != t->end();
+       ++p)
+    {
+      hash <<= 2;
+      hash = Type::hash_string(p->name(), hash);
+      hash += p->type()->hash_for_method(NULL);
+    }
+  return hash;
+}
+
+// Compare result parameters so that can map identical result
+// parameters to a single struct type.
+
+bool
+Function_type::Results_equal::operator()(const Typed_identifier_list* a,
+					 const Typed_identifier_list* b) const
+{
+  if (a->size() != b->size())
+    return false;
+  Typed_identifier_list::const_iterator pa = a->begin();
+  for (Typed_identifier_list::const_iterator pb = b->begin();
+       pb != b->end();
+       ++pa, ++pb)
+    {
+      if (pa->name() != pb->name()
+	  || !Type::are_identical(pa->type(), pb->type(), true, NULL))
+	return false;
+    }
+  return true;
+}
+
+// Hash from results to a backend struct type.
+
+Function_type::Results_structs Function_type::results_structs;
+
+// Get the backend representation for a function type.
+
+Btype*
+Function_type::get_backend_fntype(Gogo* gogo)
+{
+  if (this->fnbtype_ == NULL)
+    {
+      Backend::Btyped_identifier breceiver;
+      if (this->receiver_ != NULL)
+        {
+          breceiver.name = Gogo::unpack_hidden_name(this->receiver_->name());
+
+          // We always pass the address of the receiver parameter, in
+          // order to make interface calls work with unknown types.
+          Type* rtype = this->receiver_->type();
+          if (rtype->points_to() == NULL)
+            rtype = Type::make_pointer_type(rtype);
+          breceiver.btype = rtype->get_backend(gogo);
+          breceiver.location = this->receiver_->location();
+        }
+
+      std::vector<Backend::Btyped_identifier> bparameters;
+      if (this->parameters_ != NULL)
+        {
+          bparameters.resize(this->parameters_->size());
+          size_t i = 0;
+          for (Typed_identifier_list::const_iterator p =
+                   this->parameters_->begin(); p != this->parameters_->end();
+               ++p, ++i)
+	    {
+              bparameters[i].name = Gogo::unpack_hidden_name(p->name());
+              bparameters[i].btype = p->type()->get_backend(gogo);
+              bparameters[i].location = p->location();
+            }
+          go_assert(i == bparameters.size());
+        }
+
+      std::vector<Backend::Btyped_identifier> bresults;
+      Btype* bresult_struct = NULL;
+      if (this->results_ != NULL)
+        {
+          bresults.resize(this->results_->size());
+          size_t i = 0;
+          for (Typed_identifier_list::const_iterator p =
+                   this->results_->begin();
+	       p != this->results_->end();
+               ++p, ++i)
+	    {
+              bresults[i].name = Gogo::unpack_hidden_name(p->name());
+              bresults[i].btype = p->type()->get_backend(gogo);
+              bresults[i].location = p->location();
+            }
+          go_assert(i == bresults.size());
+
+	  if (this->results_->size() > 1)
+	    {
+	      // Use the same results struct for all functions that
+	      // return the same set of results.  This is useful to
+	      // unify calls to interface methods with other calls.
+	      std::pair<Typed_identifier_list*, Btype*> val;
+	      val.first = this->results_;
+	      val.second = NULL;
+	      std::pair<Results_structs::iterator, bool> ins =
+		Function_type::results_structs.insert(val);
+	      if (ins.second)
+		{
+		  // Build a new struct type.
+		  Struct_field_list* sfl = new Struct_field_list;
+		  for (Typed_identifier_list::const_iterator p =
+			 this->results_->begin();
+		       p != this->results_->end();
+		       ++p)
+		    {
+		      Typed_identifier tid = *p;
+		      if (tid.name().empty())
+			tid = Typed_identifier("UNNAMED", tid.type(),
+					       tid.location());
+		      sfl->push_back(Struct_field(tid));
+		    }
+		  Struct_type* st = Type::make_struct_type(sfl,
+							   this->location());
+		  st->set_is_struct_incomparable();
+		  ins.first->second = st->get_backend(gogo);
+		}
+	      bresult_struct = ins.first->second;
+	    }
+        }
+
+      this->fnbtype_ = gogo->backend()->function_type(breceiver, bparameters,
+                                                      bresults, bresult_struct,
+                                                      this->location());
+
+    }
+
+  return this->fnbtype_;
+}
+
+// Get the backend representation for a Go function type.
+
+Btype*
+Function_type::do_get_backend(Gogo* gogo)
+{
+  // When we do anything with a function value other than call it, it
+  // is represented as a pointer to a struct whose first field is the
+  // actual function.  So that is what we return as the type of a Go
+  // function.
+
+  Location loc = this->location();
+  Btype* struct_type =
+    gogo->backend()->placeholder_struct_type("__go_descriptor", loc);
+  Btype* ptr_struct_type = gogo->backend()->pointer_type(struct_type);
+
+  std::vector<Backend::Btyped_identifier> fields(1);
+  fields[0].name = "code";
+  fields[0].btype = this->get_backend_fntype(gogo);
+  fields[0].location = loc;
+  if (!gogo->backend()->set_placeholder_struct_type(struct_type, fields))
+    return gogo->backend()->error_type();
+  return ptr_struct_type;
+}
+
+// The type of a function type descriptor.
+
+Type*
+Function_type::make_function_type_descriptor_type()
+{
+  static Type* ret;
+  if (ret == NULL)
+    {
+      Type* tdt = Type::make_type_descriptor_type();
+      Type* ptdt = Type::make_type_descriptor_ptr_type();
+
+      Type* bool_type = Type::lookup_bool_type();
+
+      Type* slice_type = Type::make_array_type(ptdt, NULL);
+
+      Struct_type* s = Type::make_builtin_struct_type(4,
+						      "", tdt,
+						      "dotdotdot", bool_type,
+						      "in", slice_type,
+						      "out", slice_type);
+
+      ret = Type::make_builtin_named_type("FuncType", s);
+    }
+
+  return ret;
+}
+
+// The type descriptor for a function type.
+
+Expression*
+Function_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  Type* ftdt = Function_type::make_function_type_descriptor_type();
+
+  const Struct_field_list* fields = ftdt->struct_type()->fields();
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve(4);
+
+  Struct_field_list::const_iterator p = fields->begin();
+  go_assert(p->is_field_name("_type"));
+  vals->push_back(this->type_descriptor_constructor(gogo,
+						    RUNTIME_TYPE_KIND_FUNC,
+						    name, NULL, true));
+
+  ++p;
+  go_assert(p->is_field_name("dotdotdot"));
+  vals->push_back(Expression::make_boolean(this->is_varargs(), bloc));
+
+  ++p;
+  go_assert(p->is_field_name("in"));
+  vals->push_back(this->type_descriptor_params(p->type(), this->receiver(),
+					       this->parameters()));
+
+  ++p;
+  go_assert(p->is_field_name("out"));
+  vals->push_back(this->type_descriptor_params(p->type(), NULL,
+					       this->results()));
+
+  ++p;
+  go_assert(p == fields->end());
+
+  return Expression::make_struct_composite_literal(ftdt, vals, bloc);
+}
+
+// Return a composite literal for the parameters or results of a type
+// descriptor.
+
+Expression*
+Function_type::type_descriptor_params(Type* params_type,
+				      const Typed_identifier* receiver,
+				      const Typed_identifier_list* params)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  if (receiver == NULL && params == NULL)
+    return Expression::make_slice_composite_literal(params_type, NULL, bloc);
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve((params == NULL ? 0 : params->size())
+		+ (receiver != NULL ? 1 : 0));
+
+  if (receiver != NULL)
+    vals->push_back(Expression::make_type_descriptor(receiver->type(), bloc));
+
+  if (params != NULL)
+    {
+      for (Typed_identifier_list::const_iterator p = params->begin();
+	   p != params->end();
+	   ++p)
+	vals->push_back(Expression::make_type_descriptor(p->type(), bloc));
+    }
+
+  return Expression::make_slice_composite_literal(params_type, vals, bloc);
+}
+
+// The reflection string.
+
+void
+Function_type::do_reflection(Gogo* gogo, std::string* ret) const
+{
+  // FIXME: Turn this off until we straighten out the type of the
+  // struct field used in a go statement which calls a method.
+  // go_assert(this->receiver_ == NULL);
+
+  ret->append("func");
+
+  if (this->receiver_ != NULL)
+    {
+      ret->push_back('(');
+      this->append_reflection(this->receiver_->type(), gogo, ret);
+      ret->push_back(')');
+    }
+
+  ret->push_back('(');
+  const Typed_identifier_list* params = this->parameters();
+  if (params != NULL)
+    {
+      bool is_varargs = this->is_varargs_;
+      for (Typed_identifier_list::const_iterator p = params->begin();
+	   p != params->end();
+	   ++p)
+	{
+	  if (p != params->begin())
+	    ret->append(", ");
+	  if (!is_varargs || p + 1 != params->end())
+	    this->append_reflection(p->type(), gogo, ret);
+	  else
+	    {
+	      ret->append("...");
+	      this->append_reflection(p->type()->array_type()->element_type(),
+				      gogo, ret);
+	    }
+	}
+    }
+  ret->push_back(')');
+
+  const Typed_identifier_list* results = this->results();
+  if (results != NULL && !results->empty())
+    {
+      if (results->size() == 1)
+	ret->push_back(' ');
+      else
+	ret->append(" (");
+      for (Typed_identifier_list::const_iterator p = results->begin();
+	   p != results->end();
+	   ++p)
+	{
+	  if (p != results->begin())
+	    ret->append(", ");
+	  this->append_reflection(p->type(), gogo, ret);
+	}
+      if (results->size() > 1)
+	ret->push_back(')');
+    }
+}
+
+// Export a function type.
+
+void
+Function_type::do_export(Export* exp) const
+{
+  // We don't write out the receiver.  The only function types which
+  // should have a receiver are the ones associated with explicitly
+  // defined methods.  For those the receiver type is written out by
+  // Function::export_func.
+
+  exp->write_c_string("(");
+  bool first = true;
+  if (this->parameters_ != NULL)
+    {
+      bool is_varargs = this->is_varargs_;
+      for (Typed_identifier_list::const_iterator p =
+	     this->parameters_->begin();
+	   p != this->parameters_->end();
+	   ++p)
+	{
+	  if (first)
+	    first = false;
+	  else
+	    exp->write_c_string(", ");
+	  exp->write_name(p->name());
+	  exp->write_c_string(" ");
+	  if (!is_varargs || p + 1 != this->parameters_->end())
+	    exp->write_type(p->type());
+	  else
+	    {
+	      exp->write_c_string("...");
+	      exp->write_type(p->type()->array_type()->element_type());
+	    }
+	}
+    }
+  exp->write_c_string(")");
+
+  const Typed_identifier_list* results = this->results_;
+  if (results != NULL)
+    {
+      exp->write_c_string(" ");
+      if (results->size() == 1 && results->begin()->name().empty())
+	exp->write_type(results->begin()->type());
+      else
+	{
+	  first = true;
+	  exp->write_c_string("(");
+	  for (Typed_identifier_list::const_iterator p = results->begin();
+	       p != results->end();
+	       ++p)
+	    {
+	      if (first)
+		first = false;
+	      else
+		exp->write_c_string(", ");
+	      exp->write_name(p->name());
+	      exp->write_c_string(" ");
+	      exp->write_type(p->type());
+	    }
+	  exp->write_c_string(")");
+	}
+    }
+}
+
+// Import a function type.
+
+Function_type*
+Function_type::do_import(Import* imp)
+{
+  imp->require_c_string("(");
+  Typed_identifier_list* parameters;
+  bool is_varargs = false;
+  if (imp->peek_char() == ')')
+    parameters = NULL;
+  else
+    {
+      parameters = new Typed_identifier_list();
+      while (true)
+	{
+	  std::string name = imp->read_name();
+	  imp->require_c_string(" ");
+
+	  if (imp->match_c_string("..."))
+	    {
+	      imp->advance(3);
+	      is_varargs = true;
+	    }
+
+	  Type* ptype = imp->read_type();
+	  if (is_varargs)
+	    ptype = Type::make_array_type(ptype, NULL);
+	  parameters->push_back(Typed_identifier(name, ptype,
+						 imp->location()));
+	  if (imp->peek_char() != ',')
+	    break;
+	  go_assert(!is_varargs);
+	  imp->require_c_string(", ");
+	}
+    }
+  imp->require_c_string(")");
+
+  Typed_identifier_list* results;
+  if (imp->peek_char() != ' ')
+    results = NULL;
+  else
+    {
+      imp->advance(1);
+      results = new Typed_identifier_list;
+      if (imp->peek_char() != '(')
+	{
+	  Type* rtype = imp->read_type();
+	  results->push_back(Typed_identifier("", rtype, imp->location()));
+	}
+      else
+	{
+	  imp->advance(1);
+	  while (true)
+	    {
+	      std::string name = imp->read_name();
+	      imp->require_c_string(" ");
+	      Type* rtype = imp->read_type();
+	      results->push_back(Typed_identifier(name, rtype,
+						  imp->location()));
+	      if (imp->peek_char() != ',')
+		break;
+	      imp->require_c_string(", ");
+	    }
+	  imp->require_c_string(")");
+	}
+    }
+
+  Function_type* ret = Type::make_function_type(NULL, parameters, results,
+						imp->location());
+  if (is_varargs)
+    ret->set_is_varargs();
+  return ret;
+}
+
+// Make a copy of a function type without a receiver.
+
+Function_type*
+Function_type::copy_without_receiver() const
+{
+  go_assert(this->is_method());
+  Function_type *ret = Type::make_function_type(NULL, this->parameters_,
+						this->results_,
+						this->location_);
+  if (this->is_varargs())
+    ret->set_is_varargs();
+  if (this->is_builtin())
+    ret->set_is_builtin();
+  return ret;
+}
+
+// Make a copy of a function type with a receiver.
+
+Function_type*
+Function_type::copy_with_receiver(Type* receiver_type) const
+{
+  go_assert(!this->is_method());
+  Typed_identifier* receiver = new Typed_identifier("", receiver_type,
+						    this->location_);
+  Function_type* ret = Type::make_function_type(receiver, this->parameters_,
+						this->results_,
+						this->location_);
+  if (this->is_varargs_)
+    ret->set_is_varargs();
+  return ret;
+}
+
+// Make a copy of a function type with the receiver as the first
+// parameter.
+
+Function_type*
+Function_type::copy_with_receiver_as_param(bool want_pointer_receiver) const
+{
+  go_assert(this->is_method());
+  Typed_identifier_list* new_params = new Typed_identifier_list();
+  Type* rtype = this->receiver_->type();
+  if (want_pointer_receiver)
+    rtype = Type::make_pointer_type(rtype);
+  Typed_identifier receiver(this->receiver_->name(), rtype,
+			    this->receiver_->location());
+  new_params->push_back(receiver);
+  const Typed_identifier_list* orig_params = this->parameters_;
+  if (orig_params != NULL && !orig_params->empty())
+    {
+      for (Typed_identifier_list::const_iterator p = orig_params->begin();
+	   p != orig_params->end();
+	   ++p)
+	new_params->push_back(*p);
+    }
+  return Type::make_function_type(NULL, new_params, this->results_,
+				  this->location_);
+}
+
+// Make a copy of a function type ignoring any receiver and adding a
+// closure parameter.
+
+Function_type*
+Function_type::copy_with_names() const
+{
+  Typed_identifier_list* new_params = new Typed_identifier_list();
+  const Typed_identifier_list* orig_params = this->parameters_;
+  if (orig_params != NULL && !orig_params->empty())
+    {
+      static int count;
+      char buf[50];
+      for (Typed_identifier_list::const_iterator p = orig_params->begin();
+	   p != orig_params->end();
+	   ++p)
+	{
+	  snprintf(buf, sizeof buf, "pt.%u", count);
+	  ++count;
+	  new_params->push_back(Typed_identifier(buf, p->type(),
+						 p->location()));
+	}
+    }
+
+  const Typed_identifier_list* orig_results = this->results_;
+  Typed_identifier_list* new_results;
+  if (orig_results == NULL || orig_results->empty())
+    new_results = NULL;
+  else
+    {
+      new_results = new Typed_identifier_list();
+      for (Typed_identifier_list::const_iterator p = orig_results->begin();
+	   p != orig_results->end();
+	   ++p)
+	new_results->push_back(Typed_identifier("", p->type(),
+						p->location()));
+    }
+
+  return Type::make_function_type(NULL, new_params, new_results,
+				  this->location());
+}
+
+// Make a function type.
+
+Function_type*
+Type::make_function_type(Typed_identifier* receiver,
+			 Typed_identifier_list* parameters,
+			 Typed_identifier_list* results,
+			 Location location)
+{
+  return new Function_type(receiver, parameters, results, location);
+}
+
+// Make a backend function type.
+
+Backend_function_type*
+Type::make_backend_function_type(Typed_identifier* receiver,
+                                 Typed_identifier_list* parameters,
+                                 Typed_identifier_list* results,
+                                 Location location)
+{
+  return new Backend_function_type(receiver, parameters, results, location);
+}
+
+// Class Pointer_type.
+
+// Traversal.
+
+int
+Pointer_type::do_traverse(Traverse* traverse)
+{
+  return Type::traverse(this->to_type_, traverse);
+}
+
+// Hash code.
+
+unsigned int
+Pointer_type::do_hash_for_method(Gogo* gogo) const
+{
+  return this->to_type_->hash_for_method(gogo) << 4;
+}
+
+// Get the backend representation for a pointer type.
+
+Btype*
+Pointer_type::do_get_backend(Gogo* gogo)
+{
+  Btype* to_btype = this->to_type_->get_backend(gogo);
+  return gogo->backend()->pointer_type(to_btype);
+}
+
+// The type of a pointer type descriptor.
+
+Type*
+Pointer_type::make_pointer_type_descriptor_type()
+{
+  static Type* ret;
+  if (ret == NULL)
+    {
+      Type* tdt = Type::make_type_descriptor_type();
+      Type* ptdt = Type::make_type_descriptor_ptr_type();
+
+      Struct_type* s = Type::make_builtin_struct_type(2,
+						      "", tdt,
+						      "elem", ptdt);
+
+      ret = Type::make_builtin_named_type("PtrType", s);
+    }
+
+  return ret;
+}
+
+// The type descriptor for a pointer type.
+
+Expression*
+Pointer_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  if (this->is_unsafe_pointer_type())
+    {
+      go_assert(name != NULL);
+      return this->plain_type_descriptor(gogo,
+					 RUNTIME_TYPE_KIND_UNSAFE_POINTER,
+					 name);
+    }
+  else
+    {
+      Location bloc = Linemap::predeclared_location();
+
+      const Methods* methods;
+      Type* deref = this->points_to();
+      if (deref->named_type() != NULL)
+	methods = deref->named_type()->methods();
+      else if (deref->struct_type() != NULL)
+	methods = deref->struct_type()->methods();
+      else
+	methods = NULL;
+
+      Type* ptr_tdt = Pointer_type::make_pointer_type_descriptor_type();
+
+      const Struct_field_list* fields = ptr_tdt->struct_type()->fields();
+
+      Expression_list* vals = new Expression_list();
+      vals->reserve(2);
+
+      Struct_field_list::const_iterator p = fields->begin();
+      go_assert(p->is_field_name("_type"));
+      vals->push_back(this->type_descriptor_constructor(gogo,
+							RUNTIME_TYPE_KIND_PTR,
+							name, methods, false));
+
+      ++p;
+      go_assert(p->is_field_name("elem"));
+      vals->push_back(Expression::make_type_descriptor(deref, bloc));
+
+      return Expression::make_struct_composite_literal(ptr_tdt, vals, bloc);
+    }
+}
+
+// Reflection string.
+
+void
+Pointer_type::do_reflection(Gogo* gogo, std::string* ret) const
+{
+  ret->push_back('*');
+  this->append_reflection(this->to_type_, gogo, ret);
+}
+
+// Export.
+
+void
+Pointer_type::do_export(Export* exp) const
+{
+  exp->write_c_string("*");
+  if (this->is_unsafe_pointer_type())
+    exp->write_c_string("any");
+  else
+    exp->write_type(this->to_type_);
+}
+
+// Import.
+
+Pointer_type*
+Pointer_type::do_import(Import* imp)
+{
+  imp->require_c_string("*");
+  if (imp->match_c_string("any"))
+    {
+      imp->advance(3);
+      return Type::make_pointer_type(Type::make_void_type());
+    }
+  Type* to = imp->read_type();
+  return Type::make_pointer_type(to);
+}
+
+// Cache of pointer types. Key is "to" type, value is pointer type
+// that points to key.
+
+Type::Pointer_type_table Type::pointer_types;
+
+// A list of placeholder pointer types.  We keep this so we can ensure
+// they are finalized.
+
+std::vector<Pointer_type*> Type::placeholder_pointers;
+
+// Make a pointer type.
+
+Pointer_type*
+Type::make_pointer_type(Type* to_type)
+{
+  Pointer_type_table::const_iterator p = pointer_types.find(to_type);
+  if (p != pointer_types.end())
+    return p->second;
+  Pointer_type* ret = new Pointer_type(to_type);
+  pointer_types[to_type] = ret;
+  return ret;
+}
+
+// This helper is invoked immediately after named types have been
+// converted, to clean up any unresolved pointer types remaining in
+// the pointer type cache.
+//
+// The motivation for this routine: occasionally the compiler creates
+// some specific pointer type as part of a lowering operation (ex:
+// pointer-to-void), then Type::backend_type_size() is invoked on the
+// type (which creates a Btype placeholder for it), that placeholder
+// passed somewhere along the line to the back end, but since there is
+// no reference to the type in user code, there is never a call to
+// Type::finish_backend for the type (hence the Btype remains as an
+// unresolved placeholder).  Calling this routine will clean up such
+// instances.
+
+void
+Type::finish_pointer_types(Gogo* gogo)
+{
+  // We don't use begin() and end() because it is possible to add new
+  // placeholder pointer types as we finalized existing ones.
+  for (size_t i = 0; i < Type::placeholder_pointers.size(); i++)
+    {
+      Pointer_type* pt = Type::placeholder_pointers[i];
+      Type_btypes::iterator tbti = Type::type_btypes.find(pt);
+      if (tbti != Type::type_btypes.end() && tbti->second.is_placeholder)
+        {
+          pt->finish_backend(gogo, tbti->second.btype);
+          tbti->second.is_placeholder = false;
+        }
+    }
+}
+
+// Class Nil_type.
+
+// Get the backend representation of a nil type.  FIXME: Is this ever
+// actually called?
+
+Btype*
+Nil_type::do_get_backend(Gogo* gogo)
+{
+  return gogo->backend()->pointer_type(gogo->backend()->void_type());
+}
+
+// Make the nil type.
+
+Type*
+Type::make_nil_type()
+{
+  static Nil_type singleton_nil_type;
+  return &singleton_nil_type;
+}
+
+// The type of a function call which returns multiple values.  This is
+// really a struct, but we don't want to confuse a function call which
+// returns a struct with a function call which returns multiple
+// values.
+
+class Call_multiple_result_type : public Type
+{
+ public:
+  Call_multiple_result_type(Call_expression* call)
+    : Type(TYPE_CALL_MULTIPLE_RESULT),
+      call_(call)
+  { }
+
+ protected:
+  bool
+  do_has_pointer() const
+  { return false; }
+
+  bool
+  do_compare_is_identity(Gogo*)
+  { return false; }
+
+  Btype*
+  do_get_backend(Gogo* gogo)
+  {
+    go_assert(saw_errors());
+    return gogo->backend()->error_type();
+  }
+
+  Expression*
+  do_type_descriptor(Gogo*, Named_type*)
+  {
+    go_assert(saw_errors());
+    return Expression::make_error(Linemap::unknown_location());
+  }
+
+  void
+  do_reflection(Gogo*, std::string*) const
+  { go_assert(saw_errors()); }
+
+  void
+  do_mangled_name(Gogo*, std::string*) const
+  { go_assert(saw_errors()); }
+
+ private:
+  // The expression being called.
+  Call_expression* call_;
+};
+
+// Make a call result type.
+
+Type*
+Type::make_call_multiple_result_type(Call_expression* call)
+{
+  return new Call_multiple_result_type(call);
+}
+
+// Class Struct_field.
+
+// Get the name of a field.
+
+const std::string&
+Struct_field::field_name() const
+{
+  const std::string& name(this->typed_identifier_.name());
+  if (!name.empty())
+    return name;
+  else
+    {
+      // This is called during parsing, before anything is lowered, so
+      // we have to be pretty careful to avoid dereferencing an
+      // unknown type name.
+      Type* t = this->typed_identifier_.type();
+      Type* dt = t;
+      if (t->classification() == Type::TYPE_POINTER)
+	{
+	  // Very ugly.
+	  Pointer_type* ptype = static_cast<Pointer_type*>(t);
+	  dt = ptype->points_to();
+	}
+      if (dt->forward_declaration_type() != NULL)
+	return dt->forward_declaration_type()->name();
+      else if (dt->named_type() != NULL)
+	{
+	  // Note that this can be an alias name.
+	  return dt->named_type()->name();
+	}
+      else if (t->is_error_type() || dt->is_error_type())
+	{
+	  static const std::string error_string = "*error*";
+	  return error_string;
+	}
+      else
+	{
+	  // Avoid crashing in the erroneous case where T is named but
+	  // DT is not.
+	  go_assert(t != dt);
+	  if (t->forward_declaration_type() != NULL)
+	    return t->forward_declaration_type()->name();
+	  else if (t->named_type() != NULL)
+	    return t->named_type()->name();
+	  else
+	    go_unreachable();
+	}
+    }
+}
+
+// Return whether this field is named NAME.
+
+bool
+Struct_field::is_field_name(const std::string& name) const
+{
+  const std::string& me(this->typed_identifier_.name());
+  if (!me.empty())
+    return me == name;
+  else
+    {
+      Type* t = this->typed_identifier_.type();
+      if (t->points_to() != NULL)
+	t = t->points_to();
+      Named_type* nt = t->named_type();
+      if (nt != NULL && nt->name() == name)
+	return true;
+
+      // This is a horrible hack caused by the fact that we don't pack
+      // the names of builtin types.  FIXME.
+      if (!this->is_imported_
+	  && nt != NULL
+	  && nt->is_builtin()
+	  && nt->name() == Gogo::unpack_hidden_name(name))
+	return true;
+
+      return false;
+    }
+}
+
+// Return whether this field is an unexported field named NAME.
+
+bool
+Struct_field::is_unexported_field_name(Gogo* gogo,
+				       const std::string& name) const
+{
+  const std::string& field_name(this->field_name());
+  if (Gogo::is_hidden_name(field_name)
+      && name == Gogo::unpack_hidden_name(field_name)
+      && gogo->pack_hidden_name(name, false) != field_name)
+    return true;
+
+  // Check for the name of a builtin type.  This is like the test in
+  // is_field_name, only there we return false if this->is_imported_,
+  // and here we return true.
+  if (this->is_imported_ && this->is_anonymous())
+    {
+      Type* t = this->typed_identifier_.type();
+      if (t->points_to() != NULL)
+	t = t->points_to();
+      Named_type* nt = t->named_type();
+      if (nt != NULL
+	  && nt->is_builtin()
+	  && nt->name() == Gogo::unpack_hidden_name(name))
+	return true;
+    }
+
+  return false;
+}
+
+// Return whether this field is an embedded built-in type.
+
+bool
+Struct_field::is_embedded_builtin(Gogo* gogo) const
+{
+  const std::string& name(this->field_name());
+  // We know that a field is an embedded type if it is anonymous.
+  // We can decide if it is a built-in type by checking to see if it is
+  // registered globally under the field's name.
+  // This allows us to distinguish between embedded built-in types and
+  // embedded types that are aliases to built-in types.
+  return (this->is_anonymous()
+          && !Gogo::is_hidden_name(name)
+          && gogo->lookup_global(name.c_str()) != NULL);
+}
+
+// Class Struct_type.
+
+// A hash table used to find identical unnamed structs so that they
+// share method tables.
+
+Struct_type::Identical_structs Struct_type::identical_structs;
+
+// A hash table used to merge method sets for identical unnamed
+// structs.
+
+Struct_type::Struct_method_tables Struct_type::struct_method_tables;
+
+// Traversal.
+
+int
+Struct_type::do_traverse(Traverse* traverse)
+{
+  Struct_field_list* fields = this->fields_;
+  if (fields != NULL)
+    {
+      for (Struct_field_list::iterator p = fields->begin();
+	   p != fields->end();
+	   ++p)
+	{
+	  if (Type::traverse(p->type(), traverse) == TRAVERSE_EXIT)
+	    return TRAVERSE_EXIT;
+	}
+    }
+  return TRAVERSE_CONTINUE;
+}
+
+// Verify that the struct type is complete and valid.
+
+bool
+Struct_type::do_verify()
+{
+  Struct_field_list* fields = this->fields_;
+  if (fields == NULL)
+    return true;
+  for (Struct_field_list::iterator p = fields->begin();
+       p != fields->end();
+       ++p)
+    {
+      Type* t = p->type();
+      if (p->is_anonymous())
+	{
+	  if ((t->named_type() != NULL && t->points_to() != NULL)
+              || (t->named_type() == NULL && t->points_to() != NULL
+                  && t->points_to()->points_to() != NULL))
+	    {
+	      go_error_at(p->location(), "embedded type may not be a pointer");
+	      p->set_type(Type::make_error_type());
+	    }
+	  else if (t->points_to() != NULL
+		   && t->points_to()->interface_type() != NULL)
+	    {
+	      go_error_at(p->location(),
+		       "embedded type may not be pointer to interface");
+	      p->set_type(Type::make_error_type());
+	    }
+	}
+    }
+  return true;
+}
+
+// Whether this contains a pointer.
+
+bool
+Struct_type::do_has_pointer() const
+{
+  const Struct_field_list* fields = this->fields();
+  if (fields == NULL)
+    return false;
+  for (Struct_field_list::const_iterator p = fields->begin();
+       p != fields->end();
+       ++p)
+    {
+      if (p->type()->has_pointer())
+	return true;
+    }
+  return false;
+}
+
+// Whether this type is identical to T.
+
+bool
+Struct_type::is_identical(const Struct_type* t, Cmp_tags cmp_tags,
+			  bool errors_are_identical) const
+{
+  if (this->is_struct_incomparable_ != t->is_struct_incomparable_)
+    return false;
+  const Struct_field_list* fields1 = this->fields();
+  const Struct_field_list* fields2 = t->fields();
+  if (fields1 == NULL || fields2 == NULL)
+    return fields1 == fields2;
+  Struct_field_list::const_iterator pf2 = fields2->begin();
+  for (Struct_field_list::const_iterator pf1 = fields1->begin();
+       pf1 != fields1->end();
+       ++pf1, ++pf2)
+    {
+      if (pf2 == fields2->end())
+	return false;
+      if (pf1->field_name() != pf2->field_name())
+	return false;
+      if (pf1->is_anonymous() != pf2->is_anonymous()
+	  || !Type::are_identical_cmp_tags(pf1->type(), pf2->type(), cmp_tags,
+					   errors_are_identical, NULL))
+	return false;
+      if (cmp_tags == COMPARE_TAGS)
+	{
+	  if (!pf1->has_tag())
+	    {
+	      if (pf2->has_tag())
+		return false;
+	    }
+	  else
+	    {
+	      if (!pf2->has_tag())
+		return false;
+	      if (pf1->tag() != pf2->tag())
+		return false;
+	    }
+	}
+    }
+  if (pf2 != fields2->end())
+    return false;
+  return true;
+}
+
+// Whether comparisons of this struct type are simple identity
+// comparisons.
+
+bool
+Struct_type::do_compare_is_identity(Gogo* gogo)
+{
+  const Struct_field_list* fields = this->fields_;
+  if (fields == NULL)
+    return true;
+  int64_t offset = 0;
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf)
+    {
+      if (Gogo::is_sink_name(pf->field_name()))
+	return false;
+
+      if (!pf->type()->compare_is_identity(gogo))
+	return false;
+
+      int64_t field_align;
+      if (!pf->type()->backend_type_align(gogo, &field_align))
+	return false;
+      if ((offset & (field_align - 1)) != 0)
+	{
+	  // This struct has padding.  We don't guarantee that that
+	  // padding is zero-initialized for a stack variable, so we
+	  // can't use memcmp to compare struct values.
+	  return false;
+	}
+
+      int64_t field_size;
+      if (!pf->type()->backend_type_size(gogo, &field_size))
+	return false;
+      offset += field_size;
+    }
+
+  int64_t struct_size;
+  if (!this->backend_type_size(gogo, &struct_size))
+    return false;
+  if (offset != struct_size)
+    {
+      // Trailing padding may not be zero when on the stack.
+      return false;
+    }
+
+  return true;
+}
+
+// Return whether this struct type is reflexive--whether a value of
+// this type is always equal to itself.
+
+bool
+Struct_type::do_is_reflexive()
+{
+  const Struct_field_list* fields = this->fields_;
+  if (fields == NULL)
+    return true;
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf)
+    {
+      if (!pf->type()->is_reflexive())
+	return false;
+    }
+  return true;
+}
+
+// Return whether this struct type needs a key update when used as a
+// map key.
+
+bool
+Struct_type::do_needs_key_update()
+{
+  const Struct_field_list* fields = this->fields_;
+  if (fields == NULL)
+    return false;
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf)
+    {
+      if (pf->type()->needs_key_update())
+	return true;
+    }
+  return false;
+}
+
+// Return whether this struct type is permitted to be in the heap.
+
+bool
+Struct_type::do_in_heap()
+{
+  const Struct_field_list* fields = this->fields_;
+  if (fields == NULL)
+    return true;
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf)
+    {
+      if (!pf->type()->in_heap())
+	return false;
+    }
+  return true;
+}
+
+// Build identity and hash functions for this struct.
+
+// Hash code.
+
+unsigned int
+Struct_type::do_hash_for_method(Gogo* gogo) const
+{
+  unsigned int ret = 0;
+  if (this->fields() != NULL)
+    {
+      for (Struct_field_list::const_iterator pf = this->fields()->begin();
+	   pf != this->fields()->end();
+	   ++pf)
+	ret = (ret << 1) + pf->type()->hash_for_method(gogo);
+    }
+  ret <<= 2;
+  if (this->is_struct_incomparable_)
+    ret <<= 1;
+  return ret;
+}
+
+// Find the local field NAME.
+
+const Struct_field*
+Struct_type::find_local_field(const std::string& name,
+			      unsigned int *pindex) const
+{
+  const Struct_field_list* fields = this->fields_;
+  if (fields == NULL)
+    return NULL;
+  unsigned int i = 0;
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf, ++i)
+    {
+      if (pf->is_field_name(name))
+	{
+	  if (pindex != NULL)
+	    *pindex = i;
+	  return &*pf;
+	}
+    }
+  return NULL;
+}
+
+// Return an expression for field NAME in STRUCT_EXPR, or NULL.
+
+Field_reference_expression*
+Struct_type::field_reference(Expression* struct_expr, const std::string& name,
+			     Location location) const
+{
+  unsigned int depth;
+  return this->field_reference_depth(struct_expr, name, location, NULL,
+				     &depth);
+}
+
+// Return an expression for a field, along with the depth at which it
+// was found.
+
+Field_reference_expression*
+Struct_type::field_reference_depth(Expression* struct_expr,
+				   const std::string& name,
+				   Location location,
+				   Saw_named_type* saw,
+				   unsigned int* depth) const
+{
+  const Struct_field_list* fields = this->fields_;
+  if (fields == NULL)
+    return NULL;
+
+  // Look for a field with this name.
+  unsigned int i = 0;
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf, ++i)
+    {
+      if (pf->is_field_name(name))
+	{
+	  *depth = 0;
+	  return Expression::make_field_reference(struct_expr, i, location);
+	}
+    }
+
+  // Look for an anonymous field which contains a field with this
+  // name.
+  unsigned int found_depth = 0;
+  Field_reference_expression* ret = NULL;
+  i = 0;
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf, ++i)
+    {
+      if (!pf->is_anonymous())
+	continue;
+
+      Struct_type* st = pf->type()->deref()->struct_type();
+      if (st == NULL)
+	continue;
+
+      Saw_named_type* hold_saw = saw;
+      Saw_named_type saw_here;
+      Named_type* nt = pf->type()->named_type();
+      if (nt == NULL)
+	nt = pf->type()->deref()->named_type();
+      if (nt != NULL)
+	{
+	  Saw_named_type* q;
+	  for (q = saw; q != NULL; q = q->next)
+	    {
+	      if (q->nt == nt)
+		{
+		  // If this is an error, it will be reported
+		  // elsewhere.
+		  break;
+		}
+	    }
+	  if (q != NULL)
+	    continue;
+	  saw_here.next = saw;
+	  saw_here.nt = nt;
+	  saw = &saw_here;
+	}
+
+      // Look for a reference using a NULL struct expression.  If we
+      // find one, fill in the struct expression with a reference to
+      // this field.
+      unsigned int subdepth;
+      Field_reference_expression* sub = st->field_reference_depth(NULL, name,
+								  location,
+								  saw,
+								  &subdepth);
+
+      saw = hold_saw;
+
+      if (sub == NULL)
+	continue;
+
+      if (ret == NULL || subdepth < found_depth)
+	{
+	  if (ret != NULL)
+	    delete ret;
+	  ret = sub;
+	  found_depth = subdepth;
+	  Expression* here = Expression::make_field_reference(struct_expr, i,
+							      location);
+	  if (pf->type()->points_to() != NULL)
+	    here = Expression::make_unary(OPERATOR_MULT, here, location);
+	  while (sub->expr() != NULL)
+	    {
+	      sub = sub->expr()->deref()->field_reference_expression();
+	      go_assert(sub != NULL);
+	    }
+	  sub->set_struct_expression(here);
+          sub->set_implicit(true);
+	}
+      else if (subdepth > found_depth)
+	delete sub;
+      else
+	{
+	  // We do not handle ambiguity here--it should be handled by
+	  // Type::bind_field_or_method.
+	  delete sub;
+	  found_depth = 0;
+	  ret = NULL;
+	}
+    }
+
+  if (ret != NULL)
+    *depth = found_depth + 1;
+
+  return ret;
+}
+
+// Return the total number of fields, including embedded fields.
+
+unsigned int
+Struct_type::total_field_count() const
+{
+  if (this->fields_ == NULL)
+    return 0;
+  unsigned int ret = 0;
+  for (Struct_field_list::const_iterator pf = this->fields_->begin();
+       pf != this->fields_->end();
+       ++pf)
+    {
+      if (!pf->is_anonymous() || pf->type()->struct_type() == NULL)
+	++ret;
+      else
+	ret += pf->type()->struct_type()->total_field_count();
+    }
+  return ret;
+}
+
+// Return whether NAME is an unexported field, for better error reporting.
+
+bool
+Struct_type::is_unexported_local_field(Gogo* gogo,
+				       const std::string& name) const
+{
+  const Struct_field_list* fields = this->fields_;
+  if (fields != NULL)
+    {
+      for (Struct_field_list::const_iterator pf = fields->begin();
+	   pf != fields->end();
+	   ++pf)
+	if (pf->is_unexported_field_name(gogo, name))
+	  return true;
+    }
+  return false;
+}
+
+// Finalize the methods of an unnamed struct.
+
+void
+Struct_type::finalize_methods(Gogo* gogo)
+{
+  if (this->all_methods_ != NULL)
+    return;
+
+  // It is possible to have multiple identical structs that have
+  // methods.  We want them to share method tables.  Otherwise we will
+  // emit identical methods more than once, which is bad since they
+  // will even have the same names.
+  std::pair<Identical_structs::iterator, bool> ins =
+    Struct_type::identical_structs.insert(std::make_pair(this, this));
+  if (!ins.second)
+    {
+      // An identical struct was already entered into the hash table.
+      // Note that finalize_methods is, fortunately, not recursive.
+      this->all_methods_ = ins.first->second->all_methods_;
+      return;
+    }
+
+  Type::finalize_methods(gogo, this, this->location_, &this->all_methods_);
+}
+
+// Return the method NAME, or NULL if there isn't one or if it is
+// ambiguous.  Set *IS_AMBIGUOUS if the method exists but is
+// ambiguous.
+
+Method*
+Struct_type::method_function(const std::string& name, bool* is_ambiguous) const
+{
+  return Type::method_function(this->all_methods_, name, is_ambiguous);
+}
+
+// Return a pointer to the interface method table for this type for
+// the interface INTERFACE.  IS_POINTER is true if this is for a
+// pointer to THIS.
+
+Expression*
+Struct_type::interface_method_table(Interface_type* interface,
+				    bool is_pointer)
+{
+  std::pair<Struct_type*, Struct_type::Struct_method_table_pair*>
+    val(this, NULL);
+  std::pair<Struct_type::Struct_method_tables::iterator, bool> ins =
+    Struct_type::struct_method_tables.insert(val);
+
+  Struct_method_table_pair* smtp;
+  if (!ins.second)
+    smtp = ins.first->second;
+  else
+    {
+      smtp = new Struct_method_table_pair();
+      smtp->first = NULL;
+      smtp->second = NULL;
+      ins.first->second = smtp;
+    }
+
+  return Type::interface_method_table(this, interface, is_pointer,
+				      &smtp->first, &smtp->second);
+}
+
+// Convert struct fields to the backend representation.  This is not
+// declared in types.h so that types.h doesn't have to #include
+// backend.h.
+
+static void
+get_backend_struct_fields(Gogo* gogo, const Struct_field_list* fields,
+			  bool use_placeholder,
+			  std::vector<Backend::Btyped_identifier>* bfields)
+{
+  bfields->resize(fields->size());
+  size_t i = 0;
+  for (Struct_field_list::const_iterator p = fields->begin();
+       p != fields->end();
+       ++p, ++i)
+    {
+      (*bfields)[i].name = Gogo::unpack_hidden_name(p->field_name());
+      (*bfields)[i].btype = (use_placeholder
+			     ? p->type()->get_backend_placeholder(gogo)
+			     : p->type()->get_backend(gogo));
+      (*bfields)[i].location = p->location();
+    }
+  go_assert(i == fields->size());
+}
+
+// Get the backend representation for a struct type.
+
+Btype*
+Struct_type::do_get_backend(Gogo* gogo)
+{
+  std::vector<Backend::Btyped_identifier> bfields;
+  get_backend_struct_fields(gogo, this->fields_, false, &bfields);
+  return gogo->backend()->struct_type(bfields);
+}
+
+// Finish the backend representation of the fields of a struct.
+
+void
+Struct_type::finish_backend_fields(Gogo* gogo)
+{
+  const Struct_field_list* fields = this->fields_;
+  if (fields != NULL)
+    {
+      for (Struct_field_list::const_iterator p = fields->begin();
+	   p != fields->end();
+	   ++p)
+	p->type()->get_backend(gogo);
+    }
+}
+
+// The type of a struct type descriptor.
+
+Type*
+Struct_type::make_struct_type_descriptor_type()
+{
+  static Type* ret;
+  if (ret == NULL)
+    {
+      Type* tdt = Type::make_type_descriptor_type();
+      Type* ptdt = Type::make_type_descriptor_ptr_type();
+
+      Type* uintptr_type = Type::lookup_integer_type("uintptr");
+      Type* string_type = Type::lookup_string_type();
+      Type* pointer_string_type = Type::make_pointer_type(string_type);
+
+      Struct_type* sf =
+	Type::make_builtin_struct_type(5,
+				       "name", pointer_string_type,
+				       "pkgPath", pointer_string_type,
+				       "typ", ptdt,
+				       "tag", pointer_string_type,
+				       "offsetAnon", uintptr_type);
+      Type* nsf = Type::make_builtin_named_type("structField", sf);
+
+      Type* slice_type = Type::make_array_type(nsf, NULL);
+
+      Struct_type* s = Type::make_builtin_struct_type(2,
+						      "", tdt,
+						      "fields", slice_type);
+
+      ret = Type::make_builtin_named_type("StructType", s);
+    }
+
+  return ret;
+}
+
+// Build a type descriptor for a struct type.
+
+Expression*
+Struct_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  Type* stdt = Struct_type::make_struct_type_descriptor_type();
+
+  const Struct_field_list* fields = stdt->struct_type()->fields();
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve(2);
+
+  const Methods* methods = this->methods();
+  // A named struct should not have methods--the methods should attach
+  // to the named type.
+  go_assert(methods == NULL || name == NULL);
+
+  Struct_field_list::const_iterator ps = fields->begin();
+  go_assert(ps->is_field_name("_type"));
+  vals->push_back(this->type_descriptor_constructor(gogo,
+						    RUNTIME_TYPE_KIND_STRUCT,
+						    name, methods, true));
+
+  ++ps;
+  go_assert(ps->is_field_name("fields"));
+
+  Expression_list* elements = new Expression_list();
+  elements->reserve(this->fields_->size());
+  Type* element_type = ps->type()->array_type()->element_type();
+  for (Struct_field_list::const_iterator pf = this->fields_->begin();
+       pf != this->fields_->end();
+       ++pf)
+    {
+      const Struct_field_list* f = element_type->struct_type()->fields();
+
+      Expression_list* fvals = new Expression_list();
+      fvals->reserve(5);
+
+      Struct_field_list::const_iterator q = f->begin();
+      go_assert(q->is_field_name("name"));
+      std::string n = Gogo::unpack_hidden_name(pf->field_name());
+      Expression* s = Expression::make_string(n, bloc);
+      fvals->push_back(Expression::make_unary(OPERATOR_AND, s, bloc));
+
+      ++q;
+      go_assert(q->is_field_name("pkgPath"));
+      bool is_embedded_builtin = pf->is_embedded_builtin(gogo);
+      if (!Gogo::is_hidden_name(pf->field_name()) && !is_embedded_builtin)
+        fvals->push_back(Expression::make_nil(bloc));
+      else
+	{
+	  std::string n;
+          if (is_embedded_builtin)
+            n = gogo->package_name();
+          else
+            n = Gogo::hidden_name_pkgpath(pf->field_name());
+	  Expression* s = Expression::make_string(n, bloc);
+	  fvals->push_back(Expression::make_unary(OPERATOR_AND, s, bloc));
+	}
+
+      ++q;
+      go_assert(q->is_field_name("typ"));
+      fvals->push_back(Expression::make_type_descriptor(pf->type(), bloc));
+
+      ++q;
+      go_assert(q->is_field_name("tag"));
+      if (!pf->has_tag())
+	fvals->push_back(Expression::make_nil(bloc));
+      else
+	{
+	  Expression* s = Expression::make_string(pf->tag(), bloc);
+	  fvals->push_back(Expression::make_unary(OPERATOR_AND, s, bloc));
+	}
+
+      ++q;
+      go_assert(q->is_field_name("offsetAnon"));
+      Type* uintptr_type = Type::lookup_integer_type("uintptr");
+      Expression* o = Expression::make_struct_field_offset(this, &*pf);
+      Expression* one = Expression::make_integer_ul(1, uintptr_type, bloc);
+      o = Expression::make_binary(OPERATOR_LSHIFT, o, one, bloc);
+      int av = pf->is_anonymous() ? 1 : 0;
+      Expression* anon = Expression::make_integer_ul(av, uintptr_type, bloc);
+      o = Expression::make_binary(OPERATOR_OR, o, anon, bloc);
+      fvals->push_back(o);
+
+      Expression* v = Expression::make_struct_composite_literal(element_type,
+								fvals, bloc);
+      elements->push_back(v);
+    }
+
+  vals->push_back(Expression::make_slice_composite_literal(ps->type(),
+							   elements, bloc));
+
+  return Expression::make_struct_composite_literal(stdt, vals, bloc);
+}
+
+// Write the hash function for a struct which can not use the identity
+// function.
+
+void
+Struct_type::write_hash_function(Gogo* gogo, Named_type*,
+				 Function_type* hash_fntype,
+				 Function_type* equal_fntype)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  // The pointer to the struct that we are going to hash.  This is an
+  // argument to the hash function we are implementing here.
+  Named_object* key_arg = gogo->lookup("key", NULL);
+  go_assert(key_arg != NULL);
+  Type* key_arg_type = key_arg->var_value()->type();
+
+  // The seed argument to the hash function.
+  Named_object* seed_arg = gogo->lookup("seed", NULL);
+  go_assert(seed_arg != NULL);
+
+  Type* uintptr_type = Type::lookup_integer_type("uintptr");
+
+  // Make a temporary to hold the return value, initialized to the seed.
+  Expression* ref = Expression::make_var_reference(seed_arg, bloc);
+  Temporary_statement* retval = Statement::make_temporary(uintptr_type, ref,
+							  bloc);
+  gogo->add_statement(retval);
+
+  // Make a temporary to hold the key as a uintptr.
+  ref = Expression::make_var_reference(key_arg, bloc);
+  ref = Expression::make_cast(uintptr_type, ref, bloc);
+  Temporary_statement* key = Statement::make_temporary(uintptr_type, ref,
+						       bloc);
+  gogo->add_statement(key);
+
+  // Loop over the struct fields.
+  const Struct_field_list* fields = this->fields_;
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf)
+    {
+      if (Gogo::is_sink_name(pf->field_name()))
+	continue;
+
+      // Get a pointer to the value of this field.
+      Expression* offset = Expression::make_struct_field_offset(this, &*pf);
+      ref = Expression::make_temporary_reference(key, bloc);
+      Expression* subkey = Expression::make_binary(OPERATOR_PLUS, ref, offset,
+						   bloc);
+      subkey = Expression::make_cast(key_arg_type, subkey, bloc);
+
+      // Get the hash function to use for the type of this field.
+      Named_object* hash_fn;
+      Named_object* equal_fn;
+      pf->type()->type_functions(gogo, pf->type()->named_type(), hash_fntype,
+				 equal_fntype, &hash_fn, &equal_fn);
+
+      // Call the hash function for the field, passing retval as the seed.
+      ref = Expression::make_temporary_reference(retval, bloc);
+      Expression_list* args = new Expression_list();
+      args->push_back(subkey);
+      args->push_back(ref);
+      Expression* func = Expression::make_func_reference(hash_fn, NULL, bloc);
+      Expression* call = Expression::make_call(func, args, false, bloc);
+
+      // Set retval to the result.
+      Temporary_reference_expression* tref =
+	Expression::make_temporary_reference(retval, bloc);
+      tref->set_is_lvalue();
+      Statement* s = Statement::make_assignment(tref, call, bloc);
+      gogo->add_statement(s);
+    }
+
+  // Return retval to the caller of the hash function.
+  Expression_list* vals = new Expression_list();
+  ref = Expression::make_temporary_reference(retval, bloc);
+  vals->push_back(ref);
+  Statement* s = Statement::make_return_statement(vals, bloc);
+  gogo->add_statement(s);
+}
+
+// Write the equality function for a struct which can not use the
+// identity function.
+
+void
+Struct_type::write_equal_function(Gogo* gogo, Named_type* name)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  // The pointers to the structs we are going to compare.
+  Named_object* key1_arg = gogo->lookup("key1", NULL);
+  Named_object* key2_arg = gogo->lookup("key2", NULL);
+  go_assert(key1_arg != NULL && key2_arg != NULL);
+
+  // Build temporaries with the right types.
+  Type* pt = Type::make_pointer_type(name != NULL
+				     ? static_cast<Type*>(name)
+				     : static_cast<Type*>(this));
+
+  Expression* ref = Expression::make_var_reference(key1_arg, bloc);
+  ref = Expression::make_unsafe_cast(pt, ref, bloc);
+  Temporary_statement* p1 = Statement::make_temporary(pt, ref, bloc);
+  gogo->add_statement(p1);
+
+  ref = Expression::make_var_reference(key2_arg, bloc);
+  ref = Expression::make_unsafe_cast(pt, ref, bloc);
+  Temporary_statement* p2 = Statement::make_temporary(pt, ref, bloc);
+  gogo->add_statement(p2);
+
+  const Struct_field_list* fields = this->fields_;
+  unsigned int field_index = 0;
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf, ++field_index)
+    {
+      if (Gogo::is_sink_name(pf->field_name()))
+	continue;
+
+      // Compare one field in both P1 and P2.
+      Expression* f1 = Expression::make_temporary_reference(p1, bloc);
+      f1 = Expression::make_unary(OPERATOR_MULT, f1, bloc);
+      f1 = Expression::make_field_reference(f1, field_index, bloc);
+
+      Expression* f2 = Expression::make_temporary_reference(p2, bloc);
+      f2 = Expression::make_unary(OPERATOR_MULT, f2, bloc);
+      f2 = Expression::make_field_reference(f2, field_index, bloc);
+
+      Expression* cond = Expression::make_binary(OPERATOR_NOTEQ, f1, f2, bloc);
+
+      // If the values are not equal, return false.
+      gogo->start_block(bloc);
+      Expression_list* vals = new Expression_list();
+      vals->push_back(Expression::make_boolean(false, bloc));
+      Statement* s = Statement::make_return_statement(vals, bloc);
+      gogo->add_statement(s);
+      Block* then_block = gogo->finish_block(bloc);
+
+      s = Statement::make_if_statement(cond, then_block, NULL, bloc);
+      gogo->add_statement(s);
+    }
+
+  // All the fields are equal, so return true.
+  Expression_list* vals = new Expression_list();
+  vals->push_back(Expression::make_boolean(true, bloc));
+  Statement* s = Statement::make_return_statement(vals, bloc);
+  gogo->add_statement(s);
+}
+
+// Reflection string.
+
+void
+Struct_type::do_reflection(Gogo* gogo, std::string* ret) const
+{
+  ret->append("struct {");
+
+  for (Struct_field_list::const_iterator p = this->fields_->begin();
+       p != this->fields_->end();
+       ++p)
+    {
+      if (p != this->fields_->begin())
+	ret->push_back(';');
+      ret->push_back(' ');
+      if (p->is_anonymous())
+	ret->push_back('?');
+      else
+	ret->append(Gogo::unpack_hidden_name(p->field_name()));
+      ret->push_back(' ');
+      if (p->is_anonymous()
+	  && p->type()->named_type() != NULL
+	  && p->type()->named_type()->is_alias())
+	p->type()->named_type()->append_reflection_type_name(gogo, true, ret);
+      else
+	this->append_reflection(p->type(), gogo, ret);
+
+      if (p->has_tag())
+	{
+	  const std::string& tag(p->tag());
+	  ret->append(" \"");
+	  for (std::string::const_iterator p = tag.begin();
+	       p != tag.end();
+	       ++p)
+	    {
+	      if (*p == '\0')
+		ret->append("\\x00");
+	      else if (*p == '\n')
+		ret->append("\\n");
+	      else if (*p == '\t')
+		ret->append("\\t");
+	      else if (*p == '"')
+		ret->append("\\\"");
+	      else if (*p == '\\')
+		ret->append("\\\\");
+	      else
+		ret->push_back(*p);
+	    }
+	  ret->push_back('"');
+	}
+    }
+
+  if (!this->fields_->empty())
+    ret->push_back(' ');
+
+  ret->push_back('}');
+}
+
+// If the offset of field INDEX in the backend implementation can be
+// determined, set *POFFSET to the offset in bytes and return true.
+// Otherwise, return false.
+
+bool
+Struct_type::backend_field_offset(Gogo* gogo, unsigned int index,
+				  int64_t* poffset)
+{
+  if (!this->is_backend_type_size_known(gogo))
+    return false;
+  Btype* bt = this->get_backend_placeholder(gogo);
+  *poffset = gogo->backend()->type_field_offset(bt, index);
+  return true;
+}
+
+// Export.
+
+void
+Struct_type::do_export(Export* exp) const
+{
+  exp->write_c_string("struct { ");
+  const Struct_field_list* fields = this->fields_;
+  go_assert(fields != NULL);
+  for (Struct_field_list::const_iterator p = fields->begin();
+       p != fields->end();
+       ++p)
+    {
+      if (p->is_anonymous())
+	exp->write_string("? ");
+      else
+	{
+	  exp->write_string(p->field_name());
+	  exp->write_c_string(" ");
+	}
+      exp->write_type(p->type());
+
+      if (p->has_tag())
+	{
+	  exp->write_c_string(" ");
+	  Expression* expr =
+            Expression::make_string(p->tag(), Linemap::predeclared_location());
+	  expr->export_expression(exp);
+	  delete expr;
+	}
+
+      exp->write_c_string("; ");
+    }
+  exp->write_c_string("}");
+}
+
+// Import.
+
+Struct_type*
+Struct_type::do_import(Import* imp)
+{
+  imp->require_c_string("struct { ");
+  Struct_field_list* fields = new Struct_field_list;
+  if (imp->peek_char() != '}')
+    {
+      while (true)
+	{
+	  std::string name;
+	  if (imp->match_c_string("? "))
+	    imp->advance(2);
+	  else
+	    {
+	      name = imp->read_identifier();
+	      imp->require_c_string(" ");
+	    }
+	  Type* ftype = imp->read_type();
+
+	  Struct_field sf(Typed_identifier(name, ftype, imp->location()));
+	  sf.set_is_imported();
+
+	  if (imp->peek_char() == ' ')
+	    {
+	      imp->advance(1);
+	      Expression* expr = Expression::import_expression(imp);
+	      String_expression* sexpr = expr->string_expression();
+	      go_assert(sexpr != NULL);
+	      sf.set_tag(sexpr->val());
+	      delete sexpr;
+	    }
+
+	  imp->require_c_string("; ");
+	  fields->push_back(sf);
+	  if (imp->peek_char() == '}')
+	    break;
+	}
+    }
+  imp->require_c_string("}");
+
+  return Type::make_struct_type(fields, imp->location());
+}
+
+// Whether we can write this struct type to a C header file.
+// We can't if any of the fields are structs defined in a different package.
+
+bool
+Struct_type::can_write_to_c_header(
+    std::vector<const Named_object*>* requires,
+    std::vector<const Named_object*>* declare) const
+{
+  const Struct_field_list* fields = this->fields_;
+  if (fields == NULL || fields->empty())
+    return false;
+  int sinks = 0;
+  for (Struct_field_list::const_iterator p = fields->begin();
+       p != fields->end();
+       ++p)
+    {
+      if (p->is_anonymous())
+	return false;
+      if (!this->can_write_type_to_c_header(p->type(), requires, declare))
+	return false;
+      if (Gogo::message_name(p->field_name()) == "_")
+	sinks++;
+    }
+  if (sinks > 1)
+    return false;
+  return true;
+}
+
+// Whether we can write the type T to a C header file.
+
+bool
+Struct_type::can_write_type_to_c_header(
+    const Type* t,
+    std::vector<const Named_object*>* requires,
+    std::vector<const Named_object*>* declare) const
+{
+  t = t->forwarded();
+  switch (t->classification())
+    {
+    case TYPE_ERROR:
+    case TYPE_FORWARD:
+      return false;
+
+    case TYPE_VOID:
+    case TYPE_BOOLEAN:
+    case TYPE_INTEGER:
+    case TYPE_FLOAT:
+    case TYPE_COMPLEX:
+    case TYPE_STRING:
+    case TYPE_FUNCTION:
+    case TYPE_MAP:
+    case TYPE_CHANNEL:
+    case TYPE_INTERFACE:
+      return true;
+
+    case TYPE_POINTER:
+      // Don't try to handle a pointer to an array.
+      if (t->points_to()->array_type() != NULL
+	  && !t->points_to()->is_slice_type())
+	return false;
+
+      if (t->points_to()->named_type() != NULL
+	  && t->points_to()->struct_type() != NULL)
+	declare->push_back(t->points_to()->named_type()->named_object());
+      return true;
+
+    case TYPE_STRUCT:
+      return t->struct_type()->can_write_to_c_header(requires, declare);
+
+    case TYPE_ARRAY:
+      if (t->is_slice_type())
+	return true;
+      return this->can_write_type_to_c_header(t->array_type()->element_type(),
+					      requires, declare);
+
+    case TYPE_NAMED:
+      {
+	const Named_object* no = t->named_type()->named_object();
+	if (no->package() != NULL)
+	  {
+	    if (t->is_unsafe_pointer_type())
+	      return true;
+	    return false;
+	  }
+	if (t->struct_type() != NULL)
+	  {
+	    requires->push_back(no);
+	    return t->struct_type()->can_write_to_c_header(requires, declare);
+	  }
+	return this->can_write_type_to_c_header(t->base(), requires, declare);
+      }
+
+    case TYPE_CALL_MULTIPLE_RESULT:
+    case TYPE_NIL:
+    case TYPE_SINK:
+    default:
+      go_unreachable();
+    }
+}
+
+// Write this struct to a C header file.
+
+void
+Struct_type::write_to_c_header(std::ostream& os) const
+{
+  const Struct_field_list* fields = this->fields_;
+  for (Struct_field_list::const_iterator p = fields->begin();
+       p != fields->end();
+       ++p)
+    {
+      os << '\t';
+      this->write_field_to_c_header(os, p->field_name(), p->type());
+      os << ';' << std::endl;
+    }
+}
+
+// Write the type of a struct field to a C header file.
+
+void
+Struct_type::write_field_to_c_header(std::ostream& os, const std::string& name,
+				     const Type *t) const
+{
+  bool print_name = true;
+  t = t->forwarded();
+  switch (t->classification())
+    {
+    case TYPE_VOID:
+      os << "void";
+      break;
+
+    case TYPE_BOOLEAN:
+      os << "_Bool";
+      break;
+
+    case TYPE_INTEGER:
+      {
+	const Integer_type* it = t->integer_type();
+	if (it->is_unsigned())
+	  os << 'u';
+	os << "int" << it->bits() << "_t";
+      }
+      break;
+
+    case TYPE_FLOAT:
+      switch (t->float_type()->bits())
+	{
+	case 32:
+	  os << "float";
+	  break;
+	case 64:
+	  os << "double";
+	  break;
+	default:
+	  go_unreachable();
+	}
+      break;
+
+    case TYPE_COMPLEX:
+      switch (t->complex_type()->bits())
+	{
+	case 64:
+	  os << "float _Complex";
+	  break;
+	case 128:
+	  os << "double _Complex";
+	  break;
+	default:
+	  go_unreachable();
+	}
+      break;
+
+    case TYPE_STRING:
+      os << "String";
+      break;
+
+    case TYPE_FUNCTION:
+      os << "FuncVal*";
+      break;
+
+    case TYPE_POINTER:
+      {
+	std::vector<const Named_object*> requires;
+	std::vector<const Named_object*> declare;
+	if (!this->can_write_type_to_c_header(t->points_to(), &requires,
+					      &declare))
+	  os << "void*";
+	else
+	  {
+	    this->write_field_to_c_header(os, "", t->points_to());
+	    os << '*';
+	  }
+      }
+      break;
+
+    case TYPE_MAP:
+      os << "Map*";
+      break;
+
+    case TYPE_CHANNEL:
+      os << "Chan*";
+      break;
+
+    case TYPE_INTERFACE:
+      if (t->interface_type()->is_empty())
+	os << "Eface";
+      else
+	os << "Iface";
+      break;
+
+    case TYPE_STRUCT:
+      os << "struct {" << std::endl;
+      t->struct_type()->write_to_c_header(os);
+      os << "\t}";
+      break;
+
+    case TYPE_ARRAY:
+      if (t->is_slice_type())
+	os << "Slice";
+      else
+	{
+	  const Type *ele = t;
+	  std::vector<const Type*> array_types;
+	  while (ele->array_type() != NULL && !ele->is_slice_type())
+	    {
+	      array_types.push_back(ele);
+	      ele = ele->array_type()->element_type();
+	    }
+	  this->write_field_to_c_header(os, "", ele);
+	  os << ' ' << Gogo::message_name(name);
+	  print_name = false;
+	  while (!array_types.empty())
+	    {
+	      ele = array_types.back();
+	      array_types.pop_back();
+	      os << '[';
+	      Numeric_constant nc;
+	      if (!ele->array_type()->length()->numeric_constant_value(&nc))
+		go_unreachable();
+	      mpz_t val;
+	      if (!nc.to_int(&val))
+		go_unreachable();
+	      char* s = mpz_get_str(NULL, 10, val);
+	      os << s;
+	      free(s);
+	      mpz_clear(val);
+	      os << ']';
+	    }
+	}
+      break;
+
+    case TYPE_NAMED:
+      {
+	const Named_object* no = t->named_type()->named_object();
+	if (t->struct_type() != NULL)
+	  os << "struct " << no->message_name();
+	else if (t->is_unsafe_pointer_type())
+	  os << "void*";
+	else if (t == Type::lookup_integer_type("uintptr"))
+	  os << "uintptr_t";
+	else
+	  {
+	    this->write_field_to_c_header(os, name, t->base());
+	    print_name = false;
+	  }
+      }
+      break;
+
+    case TYPE_ERROR:
+    case TYPE_FORWARD:
+    case TYPE_CALL_MULTIPLE_RESULT:
+    case TYPE_NIL:
+    case TYPE_SINK:
+    default:
+      go_unreachable();
+    }
+
+  if (print_name && !name.empty())
+    os << ' ' << Gogo::message_name(name);
+}
+
+// Make a struct type.
+
+Struct_type*
+Type::make_struct_type(Struct_field_list* fields,
+		       Location location)
+{
+  return new Struct_type(fields, location);
+}
+
+// Class Array_type.
+
+// Store the length of an array as an int64_t into *PLEN.  Return
+// false if the length can not be determined.  This will assert if
+// called for a slice.
+
+bool
+Array_type::int_length(int64_t* plen)
+{
+  go_assert(this->length_ != NULL);
+  Numeric_constant nc;
+  if (!this->length_->numeric_constant_value(&nc))
+    return false;
+  return nc.to_memory_size(plen);
+}
+
+// Whether two array types are identical.
+
+bool
+Array_type::is_identical(const Array_type* t, Cmp_tags cmp_tags,
+			 bool errors_are_identical) const
+{
+  if (!Type::are_identical_cmp_tags(this->element_type(), t->element_type(),
+				    cmp_tags, errors_are_identical, NULL))
+    return false;
+
+  if (this->is_array_incomparable_ != t->is_array_incomparable_)
+    return false;
+
+  Expression* l1 = this->length();
+  Expression* l2 = t->length();
+
+  // Slices of the same element type are identical.
+  if (l1 == NULL && l2 == NULL)
+    return true;
+
+  // Arrays of the same element type are identical if they have the
+  // same length.
+  if (l1 != NULL && l2 != NULL)
+    {
+      if (l1 == l2)
+	return true;
+
+      // Try to determine the lengths.  If we can't, assume the arrays
+      // are not identical.
+      bool ret = false;
+      Numeric_constant nc1, nc2;
+      if (l1->numeric_constant_value(&nc1)
+	  && l2->numeric_constant_value(&nc2))
+	{
+	  mpz_t v1;
+	  if (nc1.to_int(&v1))
+	    {
+	      mpz_t v2;
+	      if (nc2.to_int(&v2))
+		{
+		  ret = mpz_cmp(v1, v2) == 0;
+		  mpz_clear(v2);
+		}
+	      mpz_clear(v1);
+	    }
+	}
+      return ret;
+    }
+
+  // Otherwise the arrays are not identical.
+  return false;
+}
+
+// Traversal.
+
+int
+Array_type::do_traverse(Traverse* traverse)
+{
+  if (Type::traverse(this->element_type_, traverse) == TRAVERSE_EXIT)
+    return TRAVERSE_EXIT;
+  if (this->length_ != NULL
+      && Expression::traverse(&this->length_, traverse) == TRAVERSE_EXIT)
+    return TRAVERSE_EXIT;
+  return TRAVERSE_CONTINUE;
+}
+
+// Check that the length is valid.
+
+bool
+Array_type::verify_length()
+{
+  if (this->length_ == NULL)
+    return true;
+
+  Type_context context(Type::lookup_integer_type("int"), false);
+  this->length_->determine_type(&context);
+
+  if (!this->length_->is_constant())
+    {
+      go_error_at(this->length_->location(), "array bound is not constant");
+      return false;
+    }
+
+  Numeric_constant nc;
+  if (!this->length_->numeric_constant_value(&nc))
+    {
+      if (this->length_->type()->integer_type() != NULL
+	  || this->length_->type()->float_type() != NULL)
+	go_error_at(this->length_->location(), "array bound is not constant");
+      else
+	go_error_at(this->length_->location(), "array bound is not numeric");
+      return false;
+    }
+
+  Type* int_type = Type::lookup_integer_type("int");
+  unsigned int tbits = int_type->integer_type()->bits();
+  unsigned long val;
+  switch (nc.to_unsigned_long(&val))
+    {
+    case Numeric_constant::NC_UL_VALID:
+      if (sizeof(val) >= tbits / 8 && val >> (tbits - 1) != 0)
+	{
+	  go_error_at(this->length_->location(), "array bound overflows");
+	  return false;
+	}
+      break;
+    case Numeric_constant::NC_UL_NOTINT:
+      go_error_at(this->length_->location(), "array bound truncated to integer");
+      return false;
+    case Numeric_constant::NC_UL_NEGATIVE:
+      go_error_at(this->length_->location(), "negative array bound");
+      return false;
+    case Numeric_constant::NC_UL_BIG:
+      {
+	mpz_t val;
+	if (!nc.to_int(&val))
+	  go_unreachable();
+	unsigned int bits = mpz_sizeinbase(val, 2);
+	mpz_clear(val);
+	if (bits >= tbits)
+	  {
+	    go_error_at(this->length_->location(), "array bound overflows");
+	    return false;
+	  }
+      }
+      break;
+    default:
+      go_unreachable();
+    }
+
+  return true;
+}
+
+// Verify the type.
+
+bool
+Array_type::do_verify()
+{
+  if (this->element_type()->is_error_type())
+    return false;
+  if (!this->verify_length())
+    this->length_ = Expression::make_error(this->length_->location());
+  return true;
+}
+
+// Whether the type contains pointers.  This is always true for a
+// slice.  For an array it is true if the element type has pointers
+// and the length is greater than zero.
+
+bool
+Array_type::do_has_pointer() const
+{
+  if (this->length_ == NULL)
+    return true;
+  if (!this->element_type_->has_pointer())
+    return false;
+
+  Numeric_constant nc;
+  if (!this->length_->numeric_constant_value(&nc))
+    {
+      // Error reported elsewhere.
+      return false;
+    }
+
+  unsigned long val;
+  switch (nc.to_unsigned_long(&val))
+    {
+    case Numeric_constant::NC_UL_VALID:
+      return val > 0;
+    case Numeric_constant::NC_UL_BIG:
+      return true;
+    default:
+      // Error reported elsewhere.
+      return false;
+    }
+}
+
+// Whether we can use memcmp to compare this array.
+
+bool
+Array_type::do_compare_is_identity(Gogo* gogo)
+{
+  if (this->length_ == NULL)
+    return false;
+
+  // Check for [...], which indicates that this is not a real type.
+  if (this->length_->is_nil_expression())
+    return false;
+
+  if (!this->element_type_->compare_is_identity(gogo))
+    return false;
+
+  // If there is any padding, then we can't use memcmp.
+  int64_t size;
+  int64_t align;
+  if (!this->element_type_->backend_type_size(gogo, &size)
+      || !this->element_type_->backend_type_align(gogo, &align))
+    return false;
+  if ((size & (align - 1)) != 0)
+    return false;
+
+  return true;
+}
+
+// Array type hash code.
+
+unsigned int
+Array_type::do_hash_for_method(Gogo* gogo) const
+{
+  unsigned int ret;
+
+  // There is no very convenient way to get a hash code for the
+  // length.
+  ret = this->element_type_->hash_for_method(gogo) + 1;
+  if (this->is_array_incomparable_)
+    ret <<= 1;
+  return ret;
+}
+
+// Write the hash function for an array which can not use the identify
+// function.
+
+void
+Array_type::write_hash_function(Gogo* gogo, Named_type* name,
+				Function_type* hash_fntype,
+				Function_type* equal_fntype)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  // The pointer to the array that we are going to hash.  This is an
+  // argument to the hash function we are implementing here.
+  Named_object* key_arg = gogo->lookup("key", NULL);
+  go_assert(key_arg != NULL);
+  Type* key_arg_type = key_arg->var_value()->type();
+
+  // The seed argument to the hash function.
+  Named_object* seed_arg = gogo->lookup("seed", NULL);
+  go_assert(seed_arg != NULL);
+
+  Type* uintptr_type = Type::lookup_integer_type("uintptr");
+
+  // Make a temporary to hold the return value, initialized to the seed.
+  Expression* ref = Expression::make_var_reference(seed_arg, bloc);
+  Temporary_statement* retval = Statement::make_temporary(uintptr_type, ref,
+							  bloc);
+  gogo->add_statement(retval);
+
+  // Make a temporary to hold the key as a uintptr.
+  ref = Expression::make_var_reference(key_arg, bloc);
+  ref = Expression::make_cast(uintptr_type, ref, bloc);
+  Temporary_statement* key = Statement::make_temporary(uintptr_type, ref,
+						       bloc);
+  gogo->add_statement(key);
+
+  // Loop over the array elements.
+  // for i = range a
+  Type* int_type = Type::lookup_integer_type("int");
+  Temporary_statement* index = Statement::make_temporary(int_type, NULL, bloc);
+  gogo->add_statement(index);
+
+  Expression* iref = Expression::make_temporary_reference(index, bloc);
+  Expression* aref = Expression::make_var_reference(key_arg, bloc);
+  Type* pt = Type::make_pointer_type(name != NULL
+				     ? static_cast<Type*>(name)
+				     : static_cast<Type*>(this));
+  aref = Expression::make_cast(pt, aref, bloc);
+  For_range_statement* for_range = Statement::make_for_range_statement(iref,
+								       NULL,
+								       aref,
+								       bloc);
+
+  gogo->start_block(bloc);
+
+  // Get the hash function for the element type.
+  Named_object* hash_fn;
+  Named_object* equal_fn;
+  this->element_type_->type_functions(gogo, this->element_type_->named_type(),
+				      hash_fntype, equal_fntype, &hash_fn,
+				      &equal_fn);
+
+  // Get a pointer to this element in the loop.
+  Expression* subkey = Expression::make_temporary_reference(key, bloc);
+  subkey = Expression::make_cast(key_arg_type, subkey, bloc);
+
+  // Get the size of each element.
+  Expression* ele_size = Expression::make_type_info(this->element_type_,
+						    Expression::TYPE_INFO_SIZE);
+
+  // Get the hash of this element, passing retval as the seed.
+  ref = Expression::make_temporary_reference(retval, bloc);
+  Expression_list* args = new Expression_list();
+  args->push_back(subkey);
+  args->push_back(ref);
+  Expression* func = Expression::make_func_reference(hash_fn, NULL, bloc);
+  Expression* call = Expression::make_call(func, args, false, bloc);
+
+  // Set retval to the result.
+  Temporary_reference_expression* tref =
+    Expression::make_temporary_reference(retval, bloc);
+  tref->set_is_lvalue();
+  Statement* s = Statement::make_assignment(tref, call, bloc);
+  gogo->add_statement(s);
+
+  // Increase the element pointer.
+  tref = Expression::make_temporary_reference(key, bloc);
+  tref->set_is_lvalue();
+  s = Statement::make_assignment_operation(OPERATOR_PLUSEQ, tref, ele_size,
+					   bloc);
+  Block* statements = gogo->finish_block(bloc);
+
+  for_range->add_statements(statements);
+  gogo->add_statement(for_range);
+
+  // Return retval to the caller of the hash function.
+  Expression_list* vals = new Expression_list();
+  ref = Expression::make_temporary_reference(retval, bloc);
+  vals->push_back(ref);
+  s = Statement::make_return_statement(vals, bloc);
+  gogo->add_statement(s);
+}
+
+// Write the equality function for an array which can not use the
+// identity function.
+
+void
+Array_type::write_equal_function(Gogo* gogo, Named_type* name)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  // The pointers to the arrays we are going to compare.
+  Named_object* key1_arg = gogo->lookup("key1", NULL);
+  Named_object* key2_arg = gogo->lookup("key2", NULL);
+  go_assert(key1_arg != NULL && key2_arg != NULL);
+
+  // Build temporaries for the keys with the right types.
+  Type* pt = Type::make_pointer_type(name != NULL
+				     ? static_cast<Type*>(name)
+				     : static_cast<Type*>(this));
+
+  Expression* ref = Expression::make_var_reference(key1_arg, bloc);
+  ref = Expression::make_unsafe_cast(pt, ref, bloc);
+  Temporary_statement* p1 = Statement::make_temporary(pt, ref, bloc);
+  gogo->add_statement(p1);
+
+  ref = Expression::make_var_reference(key2_arg, bloc);
+  ref = Expression::make_unsafe_cast(pt, ref, bloc);
+  Temporary_statement* p2 = Statement::make_temporary(pt, ref, bloc);
+  gogo->add_statement(p2);
+
+  // Loop over the array elements.
+  // for i = range a
+  Type* int_type = Type::lookup_integer_type("int");
+  Temporary_statement* index = Statement::make_temporary(int_type, NULL, bloc);
+  gogo->add_statement(index);
+
+  Expression* iref = Expression::make_temporary_reference(index, bloc);
+  Expression* aref = Expression::make_temporary_reference(p1, bloc);
+  For_range_statement* for_range = Statement::make_for_range_statement(iref,
+								       NULL,
+								       aref,
+								       bloc);
+
+  gogo->start_block(bloc);
+
+  // Compare element in P1 and P2.
+  Expression* e1 = Expression::make_temporary_reference(p1, bloc);
+  e1 = Expression::make_unary(OPERATOR_MULT, e1, bloc);
+  ref = Expression::make_temporary_reference(index, bloc);
+  e1 = Expression::make_array_index(e1, ref, NULL, NULL, bloc);
+
+  Expression* e2 = Expression::make_temporary_reference(p2, bloc);
+  e2 = Expression::make_unary(OPERATOR_MULT, e2, bloc);
+  ref = Expression::make_temporary_reference(index, bloc);
+  e2 = Expression::make_array_index(e2, ref, NULL, NULL, bloc);
+
+  Expression* cond = Expression::make_binary(OPERATOR_NOTEQ, e1, e2, bloc);
+
+  // If the elements are not equal, return false.
+  gogo->start_block(bloc);
+  Expression_list* vals = new Expression_list();
+  vals->push_back(Expression::make_boolean(false, bloc));
+  Statement* s = Statement::make_return_statement(vals, bloc);
+  gogo->add_statement(s);
+  Block* then_block = gogo->finish_block(bloc);
+
+  s = Statement::make_if_statement(cond, then_block, NULL, bloc);
+  gogo->add_statement(s);
+
+  Block* statements = gogo->finish_block(bloc);
+
+  for_range->add_statements(statements);
+  gogo->add_statement(for_range);
+
+  // All the elements are equal, so return true.
+  vals = new Expression_list();
+  vals->push_back(Expression::make_boolean(true, bloc));
+  s = Statement::make_return_statement(vals, bloc);
+  gogo->add_statement(s);
+}
+
+// Get the backend representation of the fields of a slice.  This is
+// not declared in types.h so that types.h doesn't have to #include
+// backend.h.
+//
+// We use int for the count and capacity fields.  This matches 6g.
+// The language more or less assumes that we can't allocate space of a
+// size which does not fit in int.
+
+static void
+get_backend_slice_fields(Gogo* gogo, Array_type* type, bool use_placeholder,
+			 std::vector<Backend::Btyped_identifier>* bfields)
+{
+  bfields->resize(3);
+
+  Type* pet = Type::make_pointer_type(type->element_type());
+  Btype* pbet = (use_placeholder
+		 ? pet->get_backend_placeholder(gogo)
+		 : pet->get_backend(gogo));
+  Location ploc = Linemap::predeclared_location();
+
+  Backend::Btyped_identifier* p = &(*bfields)[0];
+  p->name = "__values";
+  p->btype = pbet;
+  p->location = ploc;
+
+  Type* int_type = Type::lookup_integer_type("int");
+
+  p = &(*bfields)[1];
+  p->name = "__count";
+  p->btype = int_type->get_backend(gogo);
+  p->location = ploc;
+
+  p = &(*bfields)[2];
+  p->name = "__capacity";
+  p->btype = int_type->get_backend(gogo);
+  p->location = ploc;
+}
+
+// Get the backend representation for the type of this array.  A fixed array is
+// simply represented as ARRAY_TYPE with the appropriate index--i.e., it is
+// just like an array in C.  An open array is a struct with three
+// fields: a data pointer, the length, and the capacity.
+
+Btype*
+Array_type::do_get_backend(Gogo* gogo)
+{
+  if (this->length_ == NULL)
+    {
+      std::vector<Backend::Btyped_identifier> bfields;
+      get_backend_slice_fields(gogo, this, false, &bfields);
+      return gogo->backend()->struct_type(bfields);
+    }
+  else
+    {
+      Btype* element = this->get_backend_element(gogo, false);
+      Bexpression* len = this->get_backend_length(gogo);
+      return gogo->backend()->array_type(element, len);
+    }
+}
+
+// Return the backend representation of the element type.
+
+Btype*
+Array_type::get_backend_element(Gogo* gogo, bool use_placeholder)
+{
+  if (use_placeholder)
+    return this->element_type_->get_backend_placeholder(gogo);
+  else
+    return this->element_type_->get_backend(gogo);
+}
+
+// Return the backend representation of the length. The length may be
+// computed using a function call, so we must only evaluate it once.
+
+Bexpression*
+Array_type::get_backend_length(Gogo* gogo)
+{
+  go_assert(this->length_ != NULL);
+  if (this->blength_ == NULL)
+    {
+      if (this->length_->is_error_expression())
+        {
+          this->blength_ = gogo->backend()->error_expression();
+          return this->blength_;
+        }
+      Numeric_constant nc;
+      mpz_t val;
+      if (this->length_->numeric_constant_value(&nc) && nc.to_int(&val))
+	{
+	  if (mpz_sgn(val) < 0)
+	    {
+	      this->blength_ = gogo->backend()->error_expression();
+	      return this->blength_;
+	    }
+	  Type* t = nc.type();
+	  if (t == NULL)
+	    t = Type::lookup_integer_type("int");
+	  else if (t->is_abstract())
+	    t = t->make_non_abstract_type();
+          Btype* btype = t->get_backend(gogo);
+          this->blength_ =
+	    gogo->backend()->integer_constant_expression(btype, val);
+	  mpz_clear(val);
+	}
+      else
+	{
+	  // Make up a translation context for the array length
+	  // expression.  FIXME: This won't work in general.
+	  Translate_context context(gogo, NULL, NULL, NULL);
+	  this->blength_ = this->length_->get_backend(&context);
+
+	  Btype* ibtype = Type::lookup_integer_type("int")->get_backend(gogo);
+	  this->blength_ =
+	    gogo->backend()->convert_expression(ibtype, this->blength_,
+						this->length_->location());
+	}
+    }
+  return this->blength_;
+}
+
+// Finish backend representation of the array.
+
+void
+Array_type::finish_backend_element(Gogo* gogo)
+{
+  Type* et = this->array_type()->element_type();
+  et->get_backend(gogo);
+  if (this->is_slice_type())
+    {
+      // This relies on the fact that we always use the same
+      // structure for a pointer to any given type.
+      Type* pet = Type::make_pointer_type(et);
+      pet->get_backend(gogo);
+    }
+}
+
+// Return an expression for a pointer to the values in ARRAY.
+
+Expression*
+Array_type::get_value_pointer(Gogo*, Expression* array, bool is_lvalue) const
+{
+  if (this->length() != NULL)
+    {
+      // Fixed array.
+      go_assert(array->type()->array_type() != NULL);
+      Type* etype = array->type()->array_type()->element_type();
+      array = Expression::make_unary(OPERATOR_AND, array, array->location());
+      return Expression::make_cast(Type::make_pointer_type(etype), array,
+                                   array->location());
+    }
+
+  // Slice.
+
+  if (is_lvalue)
+    {
+      Temporary_reference_expression* tref =
+          array->temporary_reference_expression();
+      Var_expression* ve = array->var_expression();
+      if (tref != NULL)
+        {
+          tref = tref->copy()->temporary_reference_expression();
+          tref->set_is_lvalue();
+          array = tref;
+        }
+      else if (ve != NULL)
+        {
+          ve = new Var_expression(ve->named_object(), ve->location());
+          ve->set_in_lvalue_pos();
+          array = ve;
+        }
+    }
+
+  return Expression::make_slice_info(array,
+                                     Expression::SLICE_INFO_VALUE_POINTER,
+                                     array->location());
+}
+
+// Return an expression for the length of the array ARRAY which has this
+// type.
+
+Expression*
+Array_type::get_length(Gogo*, Expression* array) const
+{
+  if (this->length_ != NULL)
+    return this->length_;
+
+  // This is a slice.  We need to read the length field.
+  return Expression::make_slice_info(array, Expression::SLICE_INFO_LENGTH,
+                                     array->location());
+}
+
+// Return an expression for the capacity of the array ARRAY which has this
+// type.
+
+Expression*
+Array_type::get_capacity(Gogo*, Expression* array) const
+{
+  if (this->length_ != NULL)
+    return this->length_;
+
+  // This is a slice.  We need to read the capacity field.
+  return Expression::make_slice_info(array, Expression::SLICE_INFO_CAPACITY,
+                                     array->location());
+}
+
+// Export.
+
+void
+Array_type::do_export(Export* exp) const
+{
+  exp->write_c_string("[");
+  if (this->length_ != NULL)
+    this->length_->export_expression(exp);
+  exp->write_c_string("] ");
+  exp->write_type(this->element_type_);
+}
+
+// Import.
+
+Array_type*
+Array_type::do_import(Import* imp)
+{
+  imp->require_c_string("[");
+  Expression* length;
+  if (imp->peek_char() == ']')
+    length = NULL;
+  else
+    length = Expression::import_expression(imp);
+  imp->require_c_string("] ");
+  Type* element_type = imp->read_type();
+  return Type::make_array_type(element_type, length);
+}
+
+// The type of an array type descriptor.
+
+Type*
+Array_type::make_array_type_descriptor_type()
+{
+  static Type* ret;
+  if (ret == NULL)
+    {
+      Type* tdt = Type::make_type_descriptor_type();
+      Type* ptdt = Type::make_type_descriptor_ptr_type();
+
+      Type* uintptr_type = Type::lookup_integer_type("uintptr");
+
+      Struct_type* sf =
+	Type::make_builtin_struct_type(4,
+				       "", tdt,
+				       "elem", ptdt,
+				       "slice", ptdt,
+				       "len", uintptr_type);
+
+      ret = Type::make_builtin_named_type("ArrayType", sf);
+    }
+
+  return ret;
+}
+
+// The type of an slice type descriptor.
+
+Type*
+Array_type::make_slice_type_descriptor_type()
+{
+  static Type* ret;
+  if (ret == NULL)
+    {
+      Type* tdt = Type::make_type_descriptor_type();
+      Type* ptdt = Type::make_type_descriptor_ptr_type();
+
+      Struct_type* sf =
+	Type::make_builtin_struct_type(2,
+				       "", tdt,
+				       "elem", ptdt);
+
+      ret = Type::make_builtin_named_type("SliceType", sf);
+    }
+
+  return ret;
+}
+
+// Build a type descriptor for an array/slice type.
+
+Expression*
+Array_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  if (this->length_ != NULL)
+    return this->array_type_descriptor(gogo, name);
+  else
+    return this->slice_type_descriptor(gogo, name);
+}
+
+// Build a type descriptor for an array type.
+
+Expression*
+Array_type::array_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  Type* atdt = Array_type::make_array_type_descriptor_type();
+
+  const Struct_field_list* fields = atdt->struct_type()->fields();
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve(3);
+
+  Struct_field_list::const_iterator p = fields->begin();
+  go_assert(p->is_field_name("_type"));
+  vals->push_back(this->type_descriptor_constructor(gogo,
+						    RUNTIME_TYPE_KIND_ARRAY,
+						    name, NULL, true));
+
+  ++p;
+  go_assert(p->is_field_name("elem"));
+  vals->push_back(Expression::make_type_descriptor(this->element_type_, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("slice"));
+  Type* slice_type = Type::make_array_type(this->element_type_, NULL);
+  vals->push_back(Expression::make_type_descriptor(slice_type, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("len"));
+  vals->push_back(Expression::make_cast(p->type(), this->length_, bloc));
+
+  ++p;
+  go_assert(p == fields->end());
+
+  return Expression::make_struct_composite_literal(atdt, vals, bloc);
+}
+
+// Build a type descriptor for a slice type.
+
+Expression*
+Array_type::slice_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  Type* stdt = Array_type::make_slice_type_descriptor_type();
+
+  const Struct_field_list* fields = stdt->struct_type()->fields();
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve(2);
+
+  Struct_field_list::const_iterator p = fields->begin();
+  go_assert(p->is_field_name("_type"));
+  vals->push_back(this->type_descriptor_constructor(gogo,
+						    RUNTIME_TYPE_KIND_SLICE,
+						    name, NULL, true));
+
+  ++p;
+  go_assert(p->is_field_name("elem"));
+  vals->push_back(Expression::make_type_descriptor(this->element_type_, bloc));
+
+  ++p;
+  go_assert(p == fields->end());
+
+  return Expression::make_struct_composite_literal(stdt, vals, bloc);
+}
+
+// Reflection string.
+
+void
+Array_type::do_reflection(Gogo* gogo, std::string* ret) const
+{
+  ret->push_back('[');
+  if (this->length_ != NULL)
+    {
+      Numeric_constant nc;
+      if (!this->length_->numeric_constant_value(&nc))
+	{
+	  go_assert(saw_errors());
+	  return;
+	}
+      mpz_t val;
+      if (!nc.to_int(&val))
+	{
+	  go_assert(saw_errors());
+	  return;
+	}
+      char* s = mpz_get_str(NULL, 10, val);
+      ret->append(s);
+      free(s);
+      mpz_clear(val);
+    }
+  ret->push_back(']');
+
+  this->append_reflection(this->element_type_, gogo, ret);
+}
+
+// Make an array type.
+
+Array_type*
+Type::make_array_type(Type* element_type, Expression* length)
+{
+  return new Array_type(element_type, length);
+}
+
+// Class Map_type.
+
+Named_object* Map_type::zero_value;
+int64_t Map_type::zero_value_size;
+int64_t Map_type::zero_value_align;
+
+// If this map requires the "fat" functions, return the pointer to
+// pass as the zero value to those functions.  Otherwise, in the
+// normal case, return NULL.  The map requires the "fat" functions if
+// the value size is larger than max_zero_size bytes.  max_zero_size
+// must match maxZero in libgo/go/runtime/hashmap.go.
+
+Expression*
+Map_type::fat_zero_value(Gogo* gogo)
+{
+  int64_t valsize;
+  if (!this->val_type_->backend_type_size(gogo, &valsize))
+    {
+      go_assert(saw_errors());
+      return NULL;
+    }
+  if (valsize <= Map_type::max_zero_size)
+    return NULL;
+
+  if (Map_type::zero_value_size < valsize)
+    Map_type::zero_value_size = valsize;
+
+  int64_t valalign;
+  if (!this->val_type_->backend_type_align(gogo, &valalign))
+    {
+      go_assert(saw_errors());
+      return NULL;
+    }
+
+  if (Map_type::zero_value_align < valalign)
+    Map_type::zero_value_align = valalign;
+
+  Location bloc = Linemap::predeclared_location();
+
+  if (Map_type::zero_value == NULL)
+    {
+      // The final type will be set in backend_zero_value.
+      Type* uint8_type = Type::lookup_integer_type("uint8");
+      Expression* size = Expression::make_integer_ul(0, NULL, bloc);
+      Array_type* array_type = Type::make_array_type(uint8_type, size);
+      array_type->set_is_array_incomparable();
+      Variable* var = new Variable(array_type, NULL, true, false, false, bloc);
+      std::string name = gogo->map_zero_value_name();
+      Map_type::zero_value = Named_object::make_variable(name, NULL, var);
+    }
+
+  Expression* z = Expression::make_var_reference(Map_type::zero_value, bloc);
+  z = Expression::make_unary(OPERATOR_AND, z, bloc);
+  Type* unsafe_ptr_type = Type::make_pointer_type(Type::make_void_type());
+  z = Expression::make_cast(unsafe_ptr_type, z, bloc);
+  return z;
+}
+
+// Return whether VAR is the map zero value.
+
+bool
+Map_type::is_zero_value(Variable* var)
+{
+  return (Map_type::zero_value != NULL
+	  && Map_type::zero_value->var_value() == var);
+}
+
+// Return the backend representation for the zero value.
+
+Bvariable*
+Map_type::backend_zero_value(Gogo* gogo)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  go_assert(Map_type::zero_value != NULL);
+
+  Type* uint8_type = Type::lookup_integer_type("uint8");
+  Btype* buint8_type = uint8_type->get_backend(gogo);
+
+  Type* int_type = Type::lookup_integer_type("int");
+
+  Expression* e = Expression::make_integer_int64(Map_type::zero_value_size,
+						 int_type, bloc);
+  Translate_context context(gogo, NULL, NULL, NULL);
+  Bexpression* blength = e->get_backend(&context);
+
+  Btype* barray_type = gogo->backend()->array_type(buint8_type, blength);
+
+  std::string zname = Map_type::zero_value->name();
+  std::string asm_name(go_selectively_encode_id(zname));
+  Bvariable* zvar =
+      gogo->backend()->implicit_variable(zname, asm_name,
+                                         barray_type, false, true, true,
+				       Map_type::zero_value_align);
+  gogo->backend()->implicit_variable_set_init(zvar, zname, barray_type,
+					      false, true, true, NULL);
+  return zvar;
+}
+
+// Traversal.
+
+int
+Map_type::do_traverse(Traverse* traverse)
+{
+  if (Type::traverse(this->key_type_, traverse) == TRAVERSE_EXIT
+      || Type::traverse(this->val_type_, traverse) == TRAVERSE_EXIT)
+    return TRAVERSE_EXIT;
+  return TRAVERSE_CONTINUE;
+}
+
+// Check that the map type is OK.
+
+bool
+Map_type::do_verify()
+{
+  // The runtime support uses "map[void]void".
+  if (!this->key_type_->is_comparable() && !this->key_type_->is_void_type())
+    go_error_at(this->location_, "invalid map key type");
+  if (!this->key_type_->in_heap())
+    go_error_at(this->location_, "go:notinheap map key not allowed");
+  if (!this->val_type_->in_heap())
+    go_error_at(this->location_, "go:notinheap map value not allowed");
+  return true;
+}
+
+// Whether two map types are identical.
+
+bool
+Map_type::is_identical(const Map_type* t, Cmp_tags cmp_tags,
+		       bool errors_are_identical) const
+{
+  return (Type::are_identical_cmp_tags(this->key_type(), t->key_type(),
+				       cmp_tags, errors_are_identical, NULL)
+	  && Type::are_identical_cmp_tags(this->val_type(), t->val_type(),
+					  cmp_tags, errors_are_identical,
+					  NULL));
+}
+
+// Hash code.
+
+unsigned int
+Map_type::do_hash_for_method(Gogo* gogo) const
+{
+  return (this->key_type_->hash_for_method(gogo)
+	  + this->val_type_->hash_for_method(gogo)
+	  + 2);
+}
+
+// Get the backend representation for a map type.  A map type is
+// represented as a pointer to a struct.  The struct is hmap in
+// runtime/hashmap.go.
+
+Btype*
+Map_type::do_get_backend(Gogo* gogo)
+{
+  static Btype* backend_map_type;
+  if (backend_map_type == NULL)
+    {
+      std::vector<Backend::Btyped_identifier> bfields(9);
+
+      Location bloc = Linemap::predeclared_location();
+
+      Type* int_type = Type::lookup_integer_type("int");
+      bfields[0].name = "count";
+      bfields[0].btype = int_type->get_backend(gogo);
+      bfields[0].location = bloc;
+
+      Type* uint8_type = Type::lookup_integer_type("uint8");
+      bfields[1].name = "flags";
+      bfields[1].btype = uint8_type->get_backend(gogo);
+      bfields[1].location = bloc;
+
+      bfields[2].name = "B";
+      bfields[2].btype = bfields[1].btype;
+      bfields[2].location = bloc;
+
+      Type* uint16_type = Type::lookup_integer_type("uint16");
+      bfields[3].name = "noverflow";
+      bfields[3].btype = uint16_type->get_backend(gogo);
+      bfields[3].location = bloc;
+
+      Type* uint32_type = Type::lookup_integer_type("uint32");
+      bfields[4].name = "hash0";
+      bfields[4].btype = uint32_type->get_backend(gogo);
+      bfields[4].location = bloc;
+
+      Btype* bvt = gogo->backend()->void_type();
+      Btype* bpvt = gogo->backend()->pointer_type(bvt);
+      bfields[5].name = "buckets";
+      bfields[5].btype = bpvt;
+      bfields[5].location = bloc;
+
+      bfields[6].name = "oldbuckets";
+      bfields[6].btype = bpvt;
+      bfields[6].location = bloc;
+
+      Type* uintptr_type = Type::lookup_integer_type("uintptr");
+      bfields[7].name = "nevacuate";
+      bfields[7].btype = uintptr_type->get_backend(gogo);
+      bfields[7].location = bloc;
+
+      bfields[8].name = "overflow";
+      bfields[8].btype = bpvt;
+      bfields[8].location = bloc;
+
+      Btype *bt = gogo->backend()->struct_type(bfields);
+      bt = gogo->backend()->named_type("runtime.hmap", bt, bloc);
+      backend_map_type = gogo->backend()->pointer_type(bt);
+    }
+  return backend_map_type;
+}
+
+// The type of a map type descriptor.
+
+Type*
+Map_type::make_map_type_descriptor_type()
+{
+  static Type* ret;
+  if (ret == NULL)
+    {
+      Type* tdt = Type::make_type_descriptor_type();
+      Type* ptdt = Type::make_type_descriptor_ptr_type();
+      Type* uint8_type = Type::lookup_integer_type("uint8");
+      Type* uint16_type = Type::lookup_integer_type("uint16");
+      Type* bool_type = Type::lookup_bool_type();
+
+      Struct_type* sf =
+	Type::make_builtin_struct_type(12,
+				       "", tdt,
+				       "key", ptdt,
+				       "elem", ptdt,
+				       "bucket", ptdt,
+				       "hmap", ptdt,
+				       "keysize", uint8_type,
+				       "indirectkey", bool_type,
+				       "valuesize", uint8_type,
+				       "indirectvalue", bool_type,
+				       "bucketsize", uint16_type,
+				       "reflexivekey", bool_type,
+				       "needkeyupdate", bool_type);
+
+      ret = Type::make_builtin_named_type("MapType", sf);
+    }
+
+  return ret;
+}
+
+// Build a type descriptor for a map type.
+
+Expression*
+Map_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  Type* mtdt = Map_type::make_map_type_descriptor_type();
+  Type* uint8_type = Type::lookup_integer_type("uint8");
+  Type* uint16_type = Type::lookup_integer_type("uint16");
+
+  int64_t keysize;
+  if (!this->key_type_->backend_type_size(gogo, &keysize))
+    {
+      go_error_at(this->location_, "error determining map key type size");
+      return Expression::make_error(this->location_);
+    }
+
+  int64_t valsize;
+  if (!this->val_type_->backend_type_size(gogo, &valsize))
+    {
+      go_error_at(this->location_, "error determining map value type size");
+      return Expression::make_error(this->location_);
+    }
+
+  int64_t ptrsize;
+  if (!Type::make_pointer_type(uint8_type)->backend_type_size(gogo, &ptrsize))
+    {
+      go_assert(saw_errors());
+      return Expression::make_error(this->location_);
+    }
+
+  Type* bucket_type = this->bucket_type(gogo, keysize, valsize);
+  if (bucket_type == NULL)
+    {
+      go_assert(saw_errors());
+      return Expression::make_error(this->location_);
+    }
+
+  int64_t bucketsize;
+  if (!bucket_type->backend_type_size(gogo, &bucketsize))
+    {
+      go_assert(saw_errors());
+      return Expression::make_error(this->location_);
+    }
+
+  const Struct_field_list* fields = mtdt->struct_type()->fields();
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve(12);
+
+  Struct_field_list::const_iterator p = fields->begin();
+  go_assert(p->is_field_name("_type"));
+  vals->push_back(this->type_descriptor_constructor(gogo,
+						    RUNTIME_TYPE_KIND_MAP,
+						    name, NULL, true));
+
+  ++p;
+  go_assert(p->is_field_name("key"));
+  vals->push_back(Expression::make_type_descriptor(this->key_type_, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("elem"));
+  vals->push_back(Expression::make_type_descriptor(this->val_type_, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("bucket"));
+  vals->push_back(Expression::make_type_descriptor(bucket_type, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("hmap"));
+  Type* hmap_type = this->hmap_type(bucket_type);
+  vals->push_back(Expression::make_type_descriptor(hmap_type, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("keysize"));
+  if (keysize > Map_type::max_key_size)
+    vals->push_back(Expression::make_integer_int64(ptrsize, uint8_type, bloc));
+  else
+    vals->push_back(Expression::make_integer_int64(keysize, uint8_type, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("indirectkey"));
+  vals->push_back(Expression::make_boolean(keysize > Map_type::max_key_size,
+					   bloc));
+
+  ++p;
+  go_assert(p->is_field_name("valuesize"));
+  if (valsize > Map_type::max_val_size)
+    vals->push_back(Expression::make_integer_int64(ptrsize, uint8_type, bloc));
+  else
+    vals->push_back(Expression::make_integer_int64(valsize, uint8_type, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("indirectvalue"));
+  vals->push_back(Expression::make_boolean(valsize > Map_type::max_val_size,
+					   bloc));
+
+  ++p;
+  go_assert(p->is_field_name("bucketsize"));
+  vals->push_back(Expression::make_integer_int64(bucketsize, uint16_type,
+						 bloc));
+
+  ++p;
+  go_assert(p->is_field_name("reflexivekey"));
+  vals->push_back(Expression::make_boolean(this->key_type_->is_reflexive(),
+					   bloc));
+
+  ++p;
+  go_assert(p->is_field_name("needkeyupdate"));
+  vals->push_back(Expression::make_boolean(this->key_type_->needs_key_update(),
+					   bloc));
+
+  ++p;
+  go_assert(p == fields->end());
+
+  return Expression::make_struct_composite_literal(mtdt, vals, bloc);
+}
+
+// Return the bucket type to use for a map type.  This must correspond
+// to libgo/go/runtime/hashmap.go.
+
+Type*
+Map_type::bucket_type(Gogo* gogo, int64_t keysize, int64_t valsize)
+{
+  if (this->bucket_type_ != NULL)
+    return this->bucket_type_;
+
+  Type* key_type = this->key_type_;
+  if (keysize > Map_type::max_key_size)
+    key_type = Type::make_pointer_type(key_type);
+
+  Type* val_type = this->val_type_;
+  if (valsize > Map_type::max_val_size)
+    val_type = Type::make_pointer_type(val_type);
+
+  Expression* bucket_size = Expression::make_integer_ul(Map_type::bucket_size,
+							NULL, this->location_);
+
+  Type* uint8_type = Type::lookup_integer_type("uint8");
+  Array_type* topbits_type = Type::make_array_type(uint8_type, bucket_size);
+  topbits_type->set_is_array_incomparable();
+  Array_type* keys_type = Type::make_array_type(key_type, bucket_size);
+  keys_type->set_is_array_incomparable();
+  Array_type* values_type = Type::make_array_type(val_type, bucket_size);
+  values_type->set_is_array_incomparable();
+
+  // If keys and values have no pointers, the map implementation can
+  // keep a list of overflow pointers on the side so that buckets can
+  // be marked as having no pointers.  Arrange for the bucket to have
+  // no pointers by changing the type of the overflow field to uintptr
+  // in this case.  See comment on the hmap.overflow field in
+  // libgo/go/runtime/hashmap.go.
+  Type* overflow_type;
+  if (!key_type->has_pointer() && !val_type->has_pointer())
+    overflow_type = Type::lookup_integer_type("uintptr");
+  else
+    {
+      // This should really be a pointer to the bucket type itself,
+      // but that would require us to construct a Named_type for it to
+      // give it a way to refer to itself.  Since nothing really cares
+      // (except perhaps for someone using a debugger) just use an
+      // unsafe pointer.
+      overflow_type = Type::make_pointer_type(Type::make_void_type());
+    }
+
+  // Make sure the overflow pointer is the last memory in the struct,
+  // because the runtime assumes it can use size-ptrSize as the offset
+  // of the overflow pointer.  We double-check that property below
+  // once the offsets and size are computed.
+
+  int64_t topbits_field_size, topbits_field_align;
+  int64_t keys_field_size, keys_field_align;
+  int64_t values_field_size, values_field_align;
+  int64_t overflow_field_size, overflow_field_align;
+  if (!topbits_type->backend_type_size(gogo, &topbits_field_size)
+      || !topbits_type->backend_type_field_align(gogo, &topbits_field_align)
+      || !keys_type->backend_type_size(gogo, &keys_field_size)
+      || !keys_type->backend_type_field_align(gogo, &keys_field_align)
+      || !values_type->backend_type_size(gogo, &values_field_size)
+      || !values_type->backend_type_field_align(gogo, &values_field_align)
+      || !overflow_type->backend_type_size(gogo, &overflow_field_size)
+      || !overflow_type->backend_type_field_align(gogo, &overflow_field_align))
+    {
+      go_assert(saw_errors());
+      return NULL;
+    }
+
+  Struct_type* ret;
+  int64_t max_align = std::max(std::max(topbits_field_align, keys_field_align),
+			       values_field_align);
+  if (max_align <= overflow_field_align)
+    ret =  make_builtin_struct_type(4,
+				    "topbits", topbits_type,
+				    "keys", keys_type,
+				    "values", values_type,
+				    "overflow", overflow_type);
+  else
+    {
+      size_t off = topbits_field_size;
+      off = ((off + keys_field_align - 1)
+	     &~ static_cast<size_t>(keys_field_align - 1));
+      off += keys_field_size;
+      off = ((off + values_field_align - 1)
+	     &~ static_cast<size_t>(values_field_align - 1));
+      off += values_field_size;
+
+      int64_t padded_overflow_field_size =
+	((overflow_field_size + max_align - 1)
+	 &~ static_cast<size_t>(max_align - 1));
+
+      size_t ovoff = off;
+      ovoff = ((ovoff + max_align - 1)
+	       &~ static_cast<size_t>(max_align - 1));
+      size_t pad = (ovoff - off
+		    + padded_overflow_field_size - overflow_field_size);
+
+      Expression* pad_expr = Expression::make_integer_ul(pad, NULL,
+							 this->location_);
+      Array_type* pad_type = Type::make_array_type(uint8_type, pad_expr);
+      pad_type->set_is_array_incomparable();
+
+      ret = make_builtin_struct_type(5,
+				     "topbits", topbits_type,
+				     "keys", keys_type,
+				     "values", values_type,
+				     "pad", pad_type,
+				     "overflow", overflow_type);
+    }
+
+  // Verify that the overflow field is just before the end of the
+  // bucket type.
+
+  Btype* btype = ret->get_backend(gogo);
+  int64_t offset = gogo->backend()->type_field_offset(btype,
+						      ret->field_count() - 1);
+  int64_t size;
+  if (!ret->backend_type_size(gogo, &size))
+    {
+      go_assert(saw_errors());
+      return NULL;
+    }
+
+  int64_t ptr_size;
+  if (!Type::make_pointer_type(uint8_type)->backend_type_size(gogo, &ptr_size))
+    {
+      go_assert(saw_errors());
+      return NULL;
+    }
+
+  go_assert(offset + ptr_size == size);
+
+  ret->set_is_struct_incomparable();
+
+  this->bucket_type_ = ret;
+  return ret;
+}
+
+// Return the hashmap type for a map type.
+
+Type*
+Map_type::hmap_type(Type* bucket_type)
+{
+  if (this->hmap_type_ != NULL)
+    return this->hmap_type_;
+
+  Type* int_type = Type::lookup_integer_type("int");
+  Type* uint8_type = Type::lookup_integer_type("uint8");
+  Type* uint32_type = Type::lookup_integer_type("uint32");
+  Type* uintptr_type = Type::lookup_integer_type("uintptr");
+  Type* void_ptr_type = Type::make_pointer_type(Type::make_void_type());
+
+  Type* ptr_bucket_type = Type::make_pointer_type(bucket_type);
+
+  Struct_type* ret = make_builtin_struct_type(8,
+					      "count", int_type,
+					      "flags", uint8_type,
+					      "B", uint8_type,
+					      "hash0", uint32_type,
+					      "buckets", ptr_bucket_type,
+					      "oldbuckets", ptr_bucket_type,
+					      "nevacuate", uintptr_type,
+					      "overflow", void_ptr_type);
+  ret->set_is_struct_incomparable();
+  this->hmap_type_ = ret;
+  return ret;
+}
+
+// Return the iterator type for a map type.  This is the type of the
+// value used when doing a range over a map.
+
+Type*
+Map_type::hiter_type(Gogo* gogo)
+{
+  if (this->hiter_type_ != NULL)
+    return this->hiter_type_;
+
+  int64_t keysize, valsize;
+  if (!this->key_type_->backend_type_size(gogo, &keysize)
+      || !this->val_type_->backend_type_size(gogo, &valsize))
+    {
+      go_assert(saw_errors());
+      return NULL;
+    }
+
+  Type* key_ptr_type = Type::make_pointer_type(this->key_type_);
+  Type* val_ptr_type = Type::make_pointer_type(this->val_type_);
+  Type* uint8_type = Type::lookup_integer_type("uint8");
+  Type* uint8_ptr_type = Type::make_pointer_type(uint8_type);
+  Type* uintptr_type = Type::lookup_integer_type("uintptr");
+  Type* bucket_type = this->bucket_type(gogo, keysize, valsize);
+  Type* bucket_ptr_type = Type::make_pointer_type(bucket_type);
+  Type* hmap_type = this->hmap_type(bucket_type);
+  Type* hmap_ptr_type = Type::make_pointer_type(hmap_type);
+  Type* void_ptr_type = Type::make_pointer_type(Type::make_void_type());
+
+  Struct_type* ret = make_builtin_struct_type(12,
+					      "key", key_ptr_type,
+					      "val", val_ptr_type,
+					      "t", uint8_ptr_type,
+					      "h", hmap_ptr_type,
+					      "buckets", bucket_ptr_type,
+					      "bptr", bucket_ptr_type,
+					      "overflow0", void_ptr_type,
+					      "overflow1", void_ptr_type,
+					      "startBucket", uintptr_type,
+					      "stuff", uintptr_type,
+					      "bucket", uintptr_type,
+					      "checkBucket", uintptr_type);
+  ret->set_is_struct_incomparable();
+  this->hiter_type_ = ret;
+  return ret;
+}
+
+// Reflection string for a map.
+
+void
+Map_type::do_reflection(Gogo* gogo, std::string* ret) const
+{
+  ret->append("map[");
+  this->append_reflection(this->key_type_, gogo, ret);
+  ret->append("]");
+  this->append_reflection(this->val_type_, gogo, ret);
+}
+
+// Export a map type.
+
+void
+Map_type::do_export(Export* exp) const
+{
+  exp->write_c_string("map [");
+  exp->write_type(this->key_type_);
+  exp->write_c_string("] ");
+  exp->write_type(this->val_type_);
+}
+
+// Import a map type.
+
+Map_type*
+Map_type::do_import(Import* imp)
+{
+  imp->require_c_string("map [");
+  Type* key_type = imp->read_type();
+  imp->require_c_string("] ");
+  Type* val_type = imp->read_type();
+  return Type::make_map_type(key_type, val_type, imp->location());
+}
+
+// Make a map type.
+
+Map_type*
+Type::make_map_type(Type* key_type, Type* val_type, Location location)
+{
+  return new Map_type(key_type, val_type, location);
+}
+
+// Class Channel_type.
+
+// Verify.
+
+bool
+Channel_type::do_verify()
+{
+  // We have no location for this error, but this is not something the
+  // ordinary user will see.
+  if (!this->element_type_->in_heap())
+    go_error_at(Linemap::unknown_location(),
+		"chan of go:notinheap type not allowed");
+  return true;
+}
+
+// Hash code.
+
+unsigned int
+Channel_type::do_hash_for_method(Gogo* gogo) const
+{
+  unsigned int ret = 0;
+  if (this->may_send_)
+    ret += 1;
+  if (this->may_receive_)
+    ret += 2;
+  if (this->element_type_ != NULL)
+    ret += this->element_type_->hash_for_method(gogo) << 2;
+  return ret << 3;
+}
+
+// Whether this type is the same as T.
+
+bool
+Channel_type::is_identical(const Channel_type* t, Cmp_tags cmp_tags,
+			   bool errors_are_identical) const
+{
+  if (!Type::are_identical_cmp_tags(this->element_type(), t->element_type(),
+				    cmp_tags, errors_are_identical, NULL))
+    return false;
+  return (this->may_send_ == t->may_send_
+	  && this->may_receive_ == t->may_receive_);
+}
+
+// Return the backend representation for a channel type.  A channel is a pointer
+// to a __go_channel struct.  The __go_channel struct is defined in
+// libgo/runtime/channel.h.
+
+Btype*
+Channel_type::do_get_backend(Gogo* gogo)
+{
+  static Btype* backend_channel_type;
+  if (backend_channel_type == NULL)
+    {
+      std::vector<Backend::Btyped_identifier> bfields;
+      Btype* bt = gogo->backend()->struct_type(bfields);
+      bt = gogo->backend()->named_type("__go_channel", bt,
+                                       Linemap::predeclared_location());
+      backend_channel_type = gogo->backend()->pointer_type(bt);
+    }
+  return backend_channel_type;
+}
+
+// Build a type descriptor for a channel type.
+
+Type*
+Channel_type::make_chan_type_descriptor_type()
+{
+  static Type* ret;
+  if (ret == NULL)
+    {
+      Type* tdt = Type::make_type_descriptor_type();
+      Type* ptdt = Type::make_type_descriptor_ptr_type();
+
+      Type* uintptr_type = Type::lookup_integer_type("uintptr");
+
+      Struct_type* sf =
+	Type::make_builtin_struct_type(3,
+				       "", tdt,
+				       "elem", ptdt,
+				       "dir", uintptr_type);
+
+      ret = Type::make_builtin_named_type("ChanType", sf);
+    }
+
+  return ret;
+}
+
+// Build a type descriptor for a map type.
+
+Expression*
+Channel_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  Type* ctdt = Channel_type::make_chan_type_descriptor_type();
+
+  const Struct_field_list* fields = ctdt->struct_type()->fields();
+
+  Expression_list* vals = new Expression_list();
+  vals->reserve(3);
+
+  Struct_field_list::const_iterator p = fields->begin();
+  go_assert(p->is_field_name("_type"));
+  vals->push_back(this->type_descriptor_constructor(gogo,
+						    RUNTIME_TYPE_KIND_CHAN,
+						    name, NULL, true));
+
+  ++p;
+  go_assert(p->is_field_name("elem"));
+  vals->push_back(Expression::make_type_descriptor(this->element_type_, bloc));
+
+  ++p;
+  go_assert(p->is_field_name("dir"));
+  // These bits must match the ones in libgo/runtime/go-type.h.
+  int val = 0;
+  if (this->may_receive_)
+    val |= 1;
+  if (this->may_send_)
+    val |= 2;
+  vals->push_back(Expression::make_integer_ul(val, p->type(), bloc));
+
+  ++p;
+  go_assert(p == fields->end());
+
+  return Expression::make_struct_composite_literal(ctdt, vals, bloc);
+}
+
+// Reflection string.
+
+void
+Channel_type::do_reflection(Gogo* gogo, std::string* ret) const
+{
+  if (!this->may_send_)
+    ret->append("<-");
+  ret->append("chan");
+  if (!this->may_receive_)
+    ret->append("<-");
+  ret->push_back(' ');
+  this->append_reflection(this->element_type_, gogo, ret);
+}
+
+// Export.
+
+void
+Channel_type::do_export(Export* exp) const
+{
+  exp->write_c_string("chan ");
+  if (this->may_send_ && !this->may_receive_)
+    exp->write_c_string("-< ");
+  else if (this->may_receive_ && !this->may_send_)
+    exp->write_c_string("<- ");
+  exp->write_type(this->element_type_);
+}
+
+// Import.
+
+Channel_type*
+Channel_type::do_import(Import* imp)
+{
+  imp->require_c_string("chan ");
+
+  bool may_send;
+  bool may_receive;
+  if (imp->match_c_string("-< "))
+    {
+      imp->advance(3);
+      may_send = true;
+      may_receive = false;
+    }
+  else if (imp->match_c_string("<- "))
+    {
+      imp->advance(3);
+      may_receive = true;
+      may_send = false;
+    }
+  else
+    {
+      may_send = true;
+      may_receive = true;
+    }
+
+  Type* element_type = imp->read_type();
+
+  return Type::make_channel_type(may_send, may_receive, element_type);
+}
+
+// Return the type to manage a select statement with ncases case
+// statements.  A value of this type is allocated on the stack.  This
+// must match the type hselect in libgo/go/runtime/select.go.
+
+Type*
+Channel_type::select_type(int ncases)
+{
+  Type* unsafe_pointer_type = Type::make_pointer_type(Type::make_void_type());
+  Type* uint16_type = Type::lookup_integer_type("uint16");
+
+  static Struct_type* scase_type;
+  if (scase_type == NULL)
+    {
+      Type* uintptr_type = Type::lookup_integer_type("uintptr");
+      Type* uint64_type = Type::lookup_integer_type("uint64");
+      scase_type =
+	Type::make_builtin_struct_type(7,
+				       "elem", unsafe_pointer_type,
+				       "chan", unsafe_pointer_type,
+				       "pc", uintptr_type,
+				       "kind", uint16_type,
+				       "index", uint16_type,
+				       "receivedp", unsafe_pointer_type,
+				       "releasetime", uint64_type);
+      scase_type->set_is_struct_incomparable();
+    }
+
+  Expression* ncases_expr =
+    Expression::make_integer_ul(ncases, NULL, Linemap::predeclared_location());
+  Array_type* scases = Type::make_array_type(scase_type, ncases_expr);
+  scases->set_is_array_incomparable();
+  Array_type* order = Type::make_array_type(uint16_type, ncases_expr);
+  order->set_is_array_incomparable();
+
+  Struct_type* ret =
+    Type::make_builtin_struct_type(7,
+				   "tcase", uint16_type,
+				   "ncase", uint16_type,
+				   "pollorder", unsafe_pointer_type,
+				   "lockorder", unsafe_pointer_type,
+				   "scase", scases,
+				   "lockorderarr", order,
+				   "pollorderarr", order);
+  ret->set_is_struct_incomparable();
+  return ret;
+}
+
+// Make a new channel type.
+
+Channel_type*
+Type::make_channel_type(bool send, bool receive, Type* element_type)
+{
+  return new Channel_type(send, receive, element_type);
+}
+
+// Class Interface_type.
+
+// Return the list of methods.
+
+const Typed_identifier_list*
+Interface_type::methods() const
+{
+  go_assert(this->methods_are_finalized_ || saw_errors());
+  return this->all_methods_;
+}
+
+// Return the number of methods.
+
+size_t
+Interface_type::method_count() const
+{
+  go_assert(this->methods_are_finalized_ || saw_errors());
+  return this->all_methods_ == NULL ? 0 : this->all_methods_->size();
+}
+
+// Traversal.
+
+int
+Interface_type::do_traverse(Traverse* traverse)
+{
+  Typed_identifier_list* methods = (this->methods_are_finalized_
+				    ? this->all_methods_
+				    : this->parse_methods_);
+  if (methods == NULL)
+    return TRAVERSE_CONTINUE;
+  return methods->traverse(traverse);
+}
+
+// Finalize the methods.  This handles interface inheritance.
+
+void
+Interface_type::finalize_methods()
+{
+  if (this->methods_are_finalized_)
+    return;
+  this->methods_are_finalized_ = true;
+  if (this->parse_methods_ == NULL)
+    return;
+
+  this->all_methods_ = new Typed_identifier_list();
+  this->all_methods_->reserve(this->parse_methods_->size());
+  Typed_identifier_list inherit;
+  for (Typed_identifier_list::const_iterator pm =
+	 this->parse_methods_->begin();
+       pm != this->parse_methods_->end();
+       ++pm)
+    {
+      const Typed_identifier* p = &*pm;
+      if (p->name().empty())
+	inherit.push_back(*p);
+      else if (this->find_method(p->name()) == NULL)
+	this->all_methods_->push_back(*p);
+      else
+	go_error_at(p->location(), "duplicate method %qs",
+		 Gogo::message_name(p->name()).c_str());
+    }
+
+  std::vector<Named_type*> seen;
+  seen.reserve(inherit.size());
+  bool issued_recursive_error = false;
+  while (!inherit.empty())
+    {
+      Type* t = inherit.back().type();
+      Location tl = inherit.back().location();
+      inherit.pop_back();
+
+      Interface_type* it = t->interface_type();
+      if (it == NULL)
+	{
+	  if (!t->is_error())
+	    go_error_at(tl, "interface contains embedded non-interface");
+	  continue;
+	}
+      if (it == this)
+	{
+	  if (!issued_recursive_error)
+	    {
+	      go_error_at(tl, "invalid recursive interface");
+	      issued_recursive_error = true;
+	    }
+	  continue;
+	}
+
+      Named_type* nt = t->named_type();
+      if (nt != NULL && it->parse_methods_ != NULL)
+	{
+	  std::vector<Named_type*>::const_iterator q;
+	  for (q = seen.begin(); q != seen.end(); ++q)
+	    {
+	      if (*q == nt)
+		{
+		  go_error_at(tl, "inherited interface loop");
+		  break;
+		}
+	    }
+	  if (q != seen.end())
+	    continue;
+	  seen.push_back(nt);
+	}
+
+      const Typed_identifier_list* imethods = it->parse_methods_;
+      if (imethods == NULL)
+	continue;
+      for (Typed_identifier_list::const_iterator q = imethods->begin();
+	   q != imethods->end();
+	   ++q)
+	{
+	  if (q->name().empty())
+	    inherit.push_back(*q);
+	  else if (this->find_method(q->name()) == NULL)
+	    this->all_methods_->push_back(Typed_identifier(q->name(),
+							   q->type(), tl));
+	  else
+	    go_error_at(tl, "inherited method %qs is ambiguous",
+		     Gogo::message_name(q->name()).c_str());
+	}
+    }
+
+  if (!this->all_methods_->empty())
+    this->all_methods_->sort_by_name();
+  else
+    {
+      delete this->all_methods_;
+      this->all_methods_ = NULL;
+    }
+}
+
+// Return the method NAME, or NULL.
+
+const Typed_identifier*
+Interface_type::find_method(const std::string& name) const
+{
+  go_assert(this->methods_are_finalized_);
+  if (this->all_methods_ == NULL)
+    return NULL;
+  for (Typed_identifier_list::const_iterator p = this->all_methods_->begin();
+       p != this->all_methods_->end();
+       ++p)
+    if (p->name() == name)
+      return &*p;
+  return NULL;
+}
+
+// Return the method index.
+
+size_t
+Interface_type::method_index(const std::string& name) const
+{
+  go_assert(this->methods_are_finalized_ && this->all_methods_ != NULL);
+  size_t ret = 0;
+  for (Typed_identifier_list::const_iterator p = this->all_methods_->begin();
+       p != this->all_methods_->end();
+       ++p, ++ret)
+    if (p->name() == name)
+      return ret;
+  go_unreachable();
+}
+
+// Return whether NAME is an unexported method, for better error
+// reporting.
+
+bool
+Interface_type::is_unexported_method(Gogo* gogo, const std::string& name) const
+{
+  go_assert(this->methods_are_finalized_);
+  if (this->all_methods_ == NULL)
+    return false;
+  for (Typed_identifier_list::const_iterator p = this->all_methods_->begin();
+       p != this->all_methods_->end();
+       ++p)
+    {
+      const std::string& method_name(p->name());
+      if (Gogo::is_hidden_name(method_name)
+	  && name == Gogo::unpack_hidden_name(method_name)
+	  && gogo->pack_hidden_name(name, false) != method_name)
+	return true;
+    }
+  return false;
+}
+
+// Whether this type is identical with T.
+
+bool
+Interface_type::is_identical(const Interface_type* t, Cmp_tags cmp_tags,
+			     bool errors_are_identical) const
+{
+  // If methods have not been finalized, then we are asking whether
+  // func redeclarations are the same.  This is an error, so for
+  // simplicity we say they are never the same.
+  if (!this->methods_are_finalized_ || !t->methods_are_finalized_)
+    return false;
+
+  // We require the same methods with the same types.  The methods
+  // have already been sorted.
+  if (this->all_methods_ == NULL || t->all_methods_ == NULL)
+    return this->all_methods_ == t->all_methods_;
+
+  if (this->assume_identical(this, t) || t->assume_identical(t, this))
+    return true;
+
+  Assume_identical* hold_ai = this->assume_identical_;
+  Assume_identical ai;
+  ai.t1 = this;
+  ai.t2 = t;
+  ai.next = hold_ai;
+  this->assume_identical_ = &ai;
+
+  Typed_identifier_list::const_iterator p1 = this->all_methods_->begin();
+  Typed_identifier_list::const_iterator p2;
+  for (p2 = t->all_methods_->begin(); p2 != t->all_methods_->end(); ++p1, ++p2)
+    {
+      if (p1 == this->all_methods_->end())
+	break;
+      if (p1->name() != p2->name()
+	  || !Type::are_identical_cmp_tags(p1->type(), p2->type(), cmp_tags,
+					   errors_are_identical, NULL))
+	break;
+    }
+
+  this->assume_identical_ = hold_ai;
+
+  return p1 == this->all_methods_->end() && p2 == t->all_methods_->end();
+}
+
+// Return true if T1 and T2 are assumed to be identical during a type
+// comparison.
+
+bool
+Interface_type::assume_identical(const Interface_type* t1,
+				 const Interface_type* t2) const
+{
+  for (Assume_identical* p = this->assume_identical_;
+       p != NULL;
+       p = p->next)
+    if ((p->t1 == t1 && p->t2 == t2) || (p->t1 == t2 && p->t2 == t1))
+      return true;
+  return false;
+}
+
+// Whether we can assign the interface type T to this type.  The types
+// are known to not be identical.  An interface assignment is only
+// permitted if T is known to implement all methods in THIS.
+// Otherwise a type guard is required.
+
+bool
+Interface_type::is_compatible_for_assign(const Interface_type* t,
+					 std::string* reason) const
+{
+  go_assert(this->methods_are_finalized_ && t->methods_are_finalized_);
+  if (this->all_methods_ == NULL)
+    return true;
+  for (Typed_identifier_list::const_iterator p = this->all_methods_->begin();
+       p != this->all_methods_->end();
+       ++p)
+    {
+      const Typed_identifier* m = t->find_method(p->name());
+      if (m == NULL)
+	{
+	  if (reason != NULL)
+	    {
+	      char buf[200];
+	      snprintf(buf, sizeof buf,
+		       _("need explicit conversion; missing method %s%s%s"),
+		       go_open_quote(), Gogo::message_name(p->name()).c_str(),
+		       go_close_quote());
+	      reason->assign(buf);
+	    }
+	  return false;
+	}
+
+      std::string subreason;
+      if (!Type::are_identical(p->type(), m->type(), true, &subreason))
+	{
+	  if (reason != NULL)
+	    {
+	      std::string n = Gogo::message_name(p->name());
+	      size_t len = 100 + n.length() + subreason.length();
+	      char* buf = new char[len];
+	      if (subreason.empty())
+		snprintf(buf, len, _("incompatible type for method %s%s%s"),
+			 go_open_quote(), n.c_str(), go_close_quote());
+	      else
+		snprintf(buf, len,
+			 _("incompatible type for method %s%s%s (%s)"),
+			 go_open_quote(), n.c_str(), go_close_quote(),
+			 subreason.c_str());
+	      reason->assign(buf);
+	      delete[] buf;
+	    }
+	  return false;
+	}
+    }
+
+  return true;
+}
+
+// Hash code.
+
+unsigned int
+Interface_type::do_hash_for_method(Gogo*) const
+{
+  go_assert(this->methods_are_finalized_);
+  unsigned int ret = 0;
+  if (this->all_methods_ != NULL)
+    {
+      for (Typed_identifier_list::const_iterator p =
+	     this->all_methods_->begin();
+	   p != this->all_methods_->end();
+	   ++p)
+	{
+	  ret = Type::hash_string(p->name(), ret);
+	  // We don't use the method type in the hash, to avoid
+	  // infinite recursion if an interface method uses a type
+	  // which is an interface which inherits from the interface
+	  // itself.
+	  // type T interface { F() interface {T}}
+	  ret <<= 1;
+	}
+    }
+  return ret;
+}
+
+// Return true if T implements the interface.  If it does not, and
+// REASON is not NULL, set *REASON to a useful error message.
+
+bool
+Interface_type::implements_interface(const Type* t, std::string* reason) const
+{
+  go_assert(this->methods_are_finalized_);
+  if (this->all_methods_ == NULL)
+    return true;
+
+  bool is_pointer = false;
+  const Named_type* nt = t->named_type();
+  const Struct_type* st = t->struct_type();
+  // If we start with a named type, we don't dereference it to find
+  // methods.
+  if (nt == NULL)
+    {
+      const Type* pt = t->points_to();
+      if (pt != NULL)
+	{
+	  // If T is a pointer to a named type, then we need to look at
+	  // the type to which it points.
+	  is_pointer = true;
+	  nt = pt->named_type();
+	  st = pt->struct_type();
+	}
+    }
+
+  // If we have a named type, get the methods from it rather than from
+  // any struct type.
+  if (nt != NULL)
+    st = NULL;
+
+  // Only named and struct types have methods.
+  if (nt == NULL && st == NULL)
+    {
+      if (reason != NULL)
+	{
+	  if (t->points_to() != NULL
+	      && t->points_to()->interface_type() != NULL)
+	    reason->assign(_("pointer to interface type has no methods"));
+	  else
+	    reason->assign(_("type has no methods"));
+	}
+      return false;
+    }
+
+  if (nt != NULL ? !nt->has_any_methods() : !st->has_any_methods())
+    {
+      if (reason != NULL)
+	{
+	  if (t->points_to() != NULL
+	      && t->points_to()->interface_type() != NULL)
+	    reason->assign(_("pointer to interface type has no methods"));
+	  else
+	    reason->assign(_("type has no methods"));
+	}
+      return false;
+    }
+
+  for (Typed_identifier_list::const_iterator p = this->all_methods_->begin();
+       p != this->all_methods_->end();
+       ++p)
+    {
+      bool is_ambiguous = false;
+      Method* m = (nt != NULL
+		   ? nt->method_function(p->name(), &is_ambiguous)
+		   : st->method_function(p->name(), &is_ambiguous));
+      if (m == NULL)
+	{
+	  if (reason != NULL)
+	    {
+	      std::string n = Gogo::message_name(p->name());
+	      size_t len = n.length() + 100;
+	      char* buf = new char[len];
+	      if (is_ambiguous)
+		snprintf(buf, len, _("ambiguous method %s%s%s"),
+			 go_open_quote(), n.c_str(), go_close_quote());
+	      else
+		snprintf(buf, len, _("missing method %s%s%s"),
+			 go_open_quote(), n.c_str(), go_close_quote());
+	      reason->assign(buf);
+	      delete[] buf;
+	    }
+	  return false;
+	}
+
+      Function_type *p_fn_type = p->type()->function_type();
+      Function_type* m_fn_type = m->type()->function_type();
+      go_assert(p_fn_type != NULL && m_fn_type != NULL);
+      std::string subreason;
+      if (!p_fn_type->is_identical(m_fn_type, true, COMPARE_TAGS, true,
+				   &subreason))
+	{
+	  if (reason != NULL)
+	    {
+	      std::string n = Gogo::message_name(p->name());
+	      size_t len = 100 + n.length() + subreason.length();
+	      char* buf = new char[len];
+	      if (subreason.empty())
+		snprintf(buf, len, _("incompatible type for method %s%s%s"),
+			 go_open_quote(), n.c_str(), go_close_quote());
+	      else
+		snprintf(buf, len,
+			 _("incompatible type for method %s%s%s (%s)"),
+			 go_open_quote(), n.c_str(), go_close_quote(),
+			 subreason.c_str());
+	      reason->assign(buf);
+	      delete[] buf;
+	    }
+	  return false;
+	}
+
+      if (!is_pointer && !m->is_value_method())
+	{
+	  if (reason != NULL)
+	    {
+	      std::string n = Gogo::message_name(p->name());
+	      size_t len = 100 + n.length();
+	      char* buf = new char[len];
+	      snprintf(buf, len,
+		       _("method %s%s%s requires a pointer receiver"),
+		       go_open_quote(), n.c_str(), go_close_quote());
+	      reason->assign(buf);
+	      delete[] buf;
+	    }
+	  return false;
+	}
+
+      // If the magic //go:nointerface comment was used, the method
+      // may not be used to implement interfaces.
+      if (m->nointerface())
+	{
+	  if (reason != NULL)
+	    {
+	      std::string n = Gogo::message_name(p->name());
+	      size_t len = 100 + n.length();
+	      char* buf = new char[len];
+	      snprintf(buf, len,
+		       _("method %s%s%s is marked go:nointerface"),
+		       go_open_quote(), n.c_str(), go_close_quote());
+	      reason->assign(buf);
+	      delete[] buf;
+	    }
+	  return false;
+	}
+    }
+
+  return true;
+}
+
+// Return the backend representation of the empty interface type.  We
+// use the same struct for all empty interfaces.
+
+Btype*
+Interface_type::get_backend_empty_interface_type(Gogo* gogo)
+{
+  static Btype* empty_interface_type;
+  if (empty_interface_type == NULL)
+    {
+      std::vector<Backend::Btyped_identifier> bfields(2);
+
+      Location bloc = Linemap::predeclared_location();
+
+      Type* pdt = Type::make_type_descriptor_ptr_type();
+      bfields[0].name = "__type_descriptor";
+      bfields[0].btype = pdt->get_backend(gogo);
+      bfields[0].location = bloc;
+
+      Type* vt = Type::make_pointer_type(Type::make_void_type());
+      bfields[1].name = "__object";
+      bfields[1].btype = vt->get_backend(gogo);
+      bfields[1].location = bloc;
+
+      empty_interface_type = gogo->backend()->struct_type(bfields);
+    }
+  return empty_interface_type;
+}
+
+// Return a pointer to the backend representation of the method table.
+
+Btype*
+Interface_type::get_backend_methods(Gogo* gogo)
+{
+  if (this->bmethods_ != NULL && !this->bmethods_is_placeholder_)
+    return this->bmethods_;
+
+  Location loc = this->location();
+
+  std::vector<Backend::Btyped_identifier>
+    mfields(this->all_methods_->size() + 1);
+
+  Type* pdt = Type::make_type_descriptor_ptr_type();
+  mfields[0].name = "__type_descriptor";
+  mfields[0].btype = pdt->get_backend(gogo);
+  mfields[0].location = loc;
+
+  std::string last_name = "";
+  size_t i = 1;
+  for (Typed_identifier_list::const_iterator p = this->all_methods_->begin();
+       p != this->all_methods_->end();
+       ++p, ++i)
+    {
+      // The type of the method in Go only includes the parameters.
+      // The actual method also has a receiver, which is always a
+      // pointer.  We need to add that pointer type here in order to
+      // generate the correct type for the backend.
+      Function_type* ft = p->type()->function_type();
+      go_assert(ft->receiver() == NULL);
+
+      const Typed_identifier_list* params = ft->parameters();
+      Typed_identifier_list* mparams = new Typed_identifier_list();
+      if (params != NULL)
+	mparams->reserve(params->size() + 1);
+      Type* vt = Type::make_pointer_type(Type::make_void_type());
+      mparams->push_back(Typed_identifier("", vt, ft->location()));
+      if (params != NULL)
+	{
+	  for (Typed_identifier_list::const_iterator pp = params->begin();
+	       pp != params->end();
+	       ++pp)
+	    mparams->push_back(*pp);
+	}
+
+      Typed_identifier_list* mresults = (ft->results() == NULL
+					 ? NULL
+					 : ft->results()->copy());
+      Function_type* mft = Type::make_function_type(NULL, mparams, mresults,
+						    ft->location());
+
+      mfields[i].name = Gogo::unpack_hidden_name(p->name());
+      mfields[i].btype = mft->get_backend_fntype(gogo);
+      mfields[i].location = loc;
+
+      // Sanity check: the names should be sorted.
+      go_assert(Gogo::unpack_hidden_name(p->name())
+		> Gogo::unpack_hidden_name(last_name));
+      last_name = p->name();
+    }
+
+  Btype* st = gogo->backend()->struct_type(mfields);
+  Btype* ret = gogo->backend()->pointer_type(st);
+
+  if (this->bmethods_ != NULL && this->bmethods_is_placeholder_)
+    gogo->backend()->set_placeholder_pointer_type(this->bmethods_, ret);
+  this->bmethods_ = ret;
+  this->bmethods_is_placeholder_ = false;
+  return ret;
+}
+
+// Return a placeholder for the pointer to the backend methods table.
+
+Btype*
+Interface_type::get_backend_methods_placeholder(Gogo* gogo)
+{
+  if (this->bmethods_ == NULL)
+    {
+      Location loc = this->location();
+      this->bmethods_ = gogo->backend()->placeholder_pointer_type("", loc,
+								  false);
+      this->bmethods_is_placeholder_ = true;
+    }
+  return this->bmethods_;
+}
+
+// Return the fields of a non-empty interface type.  This is not
+// declared in types.h so that types.h doesn't have to #include
+// backend.h.
+
+static void
+get_backend_interface_fields(Gogo* gogo, Interface_type* type,
+			     bool use_placeholder,
+			     std::vector<Backend::Btyped_identifier>* bfields)
+{
+  Location loc = type->location();
+
+  bfields->resize(2);
+
+  (*bfields)[0].name = "__methods";
+  (*bfields)[0].btype = (use_placeholder
+			 ? type->get_backend_methods_placeholder(gogo)
+			 : type->get_backend_methods(gogo));
+  (*bfields)[0].location = loc;
+
+  Type* vt = Type::make_pointer_type(Type::make_void_type());
+  (*bfields)[1].name = "__object";
+  (*bfields)[1].btype = vt->get_backend(gogo);
+  (*bfields)[1].location = Linemap::predeclared_location();
+}
+
+// Return the backend representation for an interface type.  An interface is a
+// pointer to a struct.  The struct has three fields.  The first field is a
+// pointer to the type descriptor for the dynamic type of the object.
+// The second field is a pointer to a table of methods for the
+// interface to be used with the object.  The third field is the value
+// of the object itself.
+
+Btype*
+Interface_type::do_get_backend(Gogo* gogo)
+{
+  if (this->is_empty())
+    return Interface_type::get_backend_empty_interface_type(gogo);
+  else
+    {
+      if (this->interface_btype_ != NULL)
+	return this->interface_btype_;
+      this->interface_btype_ =
+	gogo->backend()->placeholder_struct_type("", this->location_);
+      std::vector<Backend::Btyped_identifier> bfields;
+      get_backend_interface_fields(gogo, this, false, &bfields);
+      if (!gogo->backend()->set_placeholder_struct_type(this->interface_btype_,
+							bfields))
+	this->interface_btype_ = gogo->backend()->error_type();
+      return this->interface_btype_;
+    }
+}
+
+// Finish the backend representation of the methods.
+
+void
+Interface_type::finish_backend_methods(Gogo* gogo)
+{
+  if (!this->is_empty())
+    {
+      const Typed_identifier_list* methods = this->methods();
+      if (methods != NULL)
+	{
+	  for (Typed_identifier_list::const_iterator p = methods->begin();
+	       p != methods->end();
+	       ++p)
+	    p->type()->get_backend(gogo);
+	}
+
+      // Getting the backend methods now will set the placeholder
+      // pointer.
+      this->get_backend_methods(gogo);
+    }
+}
+
+// The type of an interface type descriptor.
+
+Type*
+Interface_type::make_interface_type_descriptor_type()
+{
+  static Type* ret;
+  if (ret == NULL)
+    {
+      Type* tdt = Type::make_type_descriptor_type();
+      Type* ptdt = Type::make_type_descriptor_ptr_type();
+
+      Type* string_type = Type::lookup_string_type();
+      Type* pointer_string_type = Type::make_pointer_type(string_type);
+
+      Struct_type* sm =
+	Type::make_builtin_struct_type(3,
+				       "name", pointer_string_type,
+				       "pkgPath", pointer_string_type,
+				       "typ", ptdt);
+
+      Type* nsm = Type::make_builtin_named_type("imethod", sm);
+
+      Type* slice_nsm = Type::make_array_type(nsm, NULL);
+
+      Struct_type* s = Type::make_builtin_struct_type(2,
+						      "", tdt,
+						      "methods", slice_nsm);
+
+      ret = Type::make_builtin_named_type("InterfaceType", s);
+    }
+
+  return ret;
+}
+
+// Build a type descriptor for an interface type.
+
+Expression*
+Interface_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  Location bloc = Linemap::predeclared_location();
+
+  Type* itdt = Interface_type::make_interface_type_descriptor_type();
+
+  const Struct_field_list* ifields = itdt->struct_type()->fields();
+
+  Expression_list* ivals = new Expression_list();
+  ivals->reserve(2);
+
+  Struct_field_list::const_iterator pif = ifields->begin();
+  go_assert(pif->is_field_name("_type"));
+  const int rt = RUNTIME_TYPE_KIND_INTERFACE;
+  ivals->push_back(this->type_descriptor_constructor(gogo, rt, name, NULL,
+						     true));
+
+  ++pif;
+  go_assert(pif->is_field_name("methods"));
+
+  Expression_list* methods = new Expression_list();
+  if (this->all_methods_ != NULL)
+    {
+      Type* elemtype = pif->type()->array_type()->element_type();
+
+      methods->reserve(this->all_methods_->size());
+      for (Typed_identifier_list::const_iterator pm =
+	     this->all_methods_->begin();
+	   pm != this->all_methods_->end();
+	   ++pm)
+	{
+	  const Struct_field_list* mfields = elemtype->struct_type()->fields();
+
+	  Expression_list* mvals = new Expression_list();
+	  mvals->reserve(3);
+
+	  Struct_field_list::const_iterator pmf = mfields->begin();
+	  go_assert(pmf->is_field_name("name"));
+	  std::string s = Gogo::unpack_hidden_name(pm->name());
+	  Expression* e = Expression::make_string(s, bloc);
+	  mvals->push_back(Expression::make_unary(OPERATOR_AND, e, bloc));
+
+	  ++pmf;
+	  go_assert(pmf->is_field_name("pkgPath"));
+	  if (!Gogo::is_hidden_name(pm->name()))
+	    mvals->push_back(Expression::make_nil(bloc));
+	  else
+	    {
+	      s = Gogo::hidden_name_pkgpath(pm->name());
+	      e = Expression::make_string(s, bloc);
+	      mvals->push_back(Expression::make_unary(OPERATOR_AND, e, bloc));
+	    }
+
+	  ++pmf;
+	  go_assert(pmf->is_field_name("typ"));
+	  mvals->push_back(Expression::make_type_descriptor(pm->type(), bloc));
+
+	  ++pmf;
+	  go_assert(pmf == mfields->end());
+
+	  e = Expression::make_struct_composite_literal(elemtype, mvals,
+							bloc);
+	  methods->push_back(e);
+	}
+    }
+
+  ivals->push_back(Expression::make_slice_composite_literal(pif->type(),
+							    methods, bloc));
+
+  ++pif;
+  go_assert(pif == ifields->end());
+
+  return Expression::make_struct_composite_literal(itdt, ivals, bloc);
+}
+
+// Reflection string.
+
+void
+Interface_type::do_reflection(Gogo* gogo, std::string* ret) const
+{
+  ret->append("interface {");
+  const Typed_identifier_list* methods = this->parse_methods_;
+  if (methods != NULL)
+    {
+      ret->push_back(' ');
+      for (Typed_identifier_list::const_iterator p = methods->begin();
+	   p != methods->end();
+	   ++p)
+	{
+	  if (p != methods->begin())
+	    ret->append("; ");
+	  if (p->name().empty())
+	    this->append_reflection(p->type(), gogo, ret);
+	  else
+	    {
+	      if (!Gogo::is_hidden_name(p->name()))
+		ret->append(p->name());
+	      else if (gogo->pkgpath_from_option())
+		ret->append(p->name().substr(1));
+	      else
+		{
+		  // If no -fgo-pkgpath option, backward compatibility
+		  // for how this used to work before -fgo-pkgpath was
+		  // introduced.
+		  std::string pkgpath = Gogo::hidden_name_pkgpath(p->name());
+		  ret->append(pkgpath.substr(pkgpath.find('.') + 1));
+		  ret->push_back('.');
+		  ret->append(Gogo::unpack_hidden_name(p->name()));
+		}
+	      std::string sub = p->type()->reflection(gogo);
+	      go_assert(sub.compare(0, 4, "func") == 0);
+	      sub = sub.substr(4);
+	      ret->append(sub);
+	    }
+	}
+      ret->push_back(' ');
+    }
+  ret->append("}");
+}
+
+// Export.
+
+void
+Interface_type::do_export(Export* exp) const
+{
+  exp->write_c_string("interface { ");
+
+  const Typed_identifier_list* methods = this->parse_methods_;
+  if (methods != NULL)
+    {
+      for (Typed_identifier_list::const_iterator pm = methods->begin();
+	   pm != methods->end();
+	   ++pm)
+	{
+	  if (pm->name().empty())
+	    {
+	      exp->write_c_string("? ");
+	      exp->write_type(pm->type());
+	    }
+	  else
+	    {
+	      exp->write_string(pm->name());
+	      exp->write_c_string(" (");
+
+	      const Function_type* fntype = pm->type()->function_type();
+
+	      bool first = true;
+	      const Typed_identifier_list* parameters = fntype->parameters();
+	      if (parameters != NULL)
+		{
+		  bool is_varargs = fntype->is_varargs();
+		  for (Typed_identifier_list::const_iterator pp =
+			 parameters->begin();
+		       pp != parameters->end();
+		       ++pp)
+		    {
+		      if (first)
+			first = false;
+		      else
+			exp->write_c_string(", ");
+		      exp->write_name(pp->name());
+		      exp->write_c_string(" ");
+		      if (!is_varargs || pp + 1 != parameters->end())
+			exp->write_type(pp->type());
+		      else
+			{
+			  exp->write_c_string("...");
+			  Type *pptype = pp->type();
+			  exp->write_type(pptype->array_type()->element_type());
+			}
+		    }
+		}
+
+	      exp->write_c_string(")");
+
+	      const Typed_identifier_list* results = fntype->results();
+	      if (results != NULL)
+		{
+		  exp->write_c_string(" ");
+		  if (results->size() == 1 && results->begin()->name().empty())
+		    exp->write_type(results->begin()->type());
+		  else
+		    {
+		      first = true;
+		      exp->write_c_string("(");
+		      for (Typed_identifier_list::const_iterator p =
+			     results->begin();
+			   p != results->end();
+			   ++p)
+			{
+			  if (first)
+			    first = false;
+			  else
+			    exp->write_c_string(", ");
+			  exp->write_name(p->name());
+			  exp->write_c_string(" ");
+			  exp->write_type(p->type());
+			}
+		      exp->write_c_string(")");
+		    }
+		}
+	    }
+
+	  exp->write_c_string("; ");
+	}
+    }
+
+  exp->write_c_string("}");
+}
+
+// Import an interface type.
+
+Interface_type*
+Interface_type::do_import(Import* imp)
+{
+  imp->require_c_string("interface { ");
+
+  Typed_identifier_list* methods = new Typed_identifier_list;
+  while (imp->peek_char() != '}')
+    {
+      std::string name = imp->read_identifier();
+
+      if (name == "?")
+	{
+	  imp->require_c_string(" ");
+	  Type* t = imp->read_type();
+	  methods->push_back(Typed_identifier("", t, imp->location()));
+	  imp->require_c_string("; ");
+	  continue;
+	}
+
+      imp->require_c_string(" (");
+
+      Typed_identifier_list* parameters;
+      bool is_varargs = false;
+      if (imp->peek_char() == ')')
+	parameters = NULL;
+      else
+	{
+	  parameters = new Typed_identifier_list;
+	  while (true)
+	    {
+	      std::string name = imp->read_name();
+	      imp->require_c_string(" ");
+
+	      if (imp->match_c_string("..."))
+		{
+		  imp->advance(3);
+		  is_varargs = true;
+		}
+
+	      Type* ptype = imp->read_type();
+	      if (is_varargs)
+		ptype = Type::make_array_type(ptype, NULL);
+	      parameters->push_back(Typed_identifier(name, ptype,
+						     imp->location()));
+	      if (imp->peek_char() != ',')
+		break;
+	      go_assert(!is_varargs);
+	      imp->require_c_string(", ");
+	    }
+	}
+      imp->require_c_string(")");
+
+      Typed_identifier_list* results;
+      if (imp->peek_char() != ' ')
+	results = NULL;
+      else
+	{
+	  results = new Typed_identifier_list;
+	  imp->advance(1);
+	  if (imp->peek_char() != '(')
+	    {
+	      Type* rtype = imp->read_type();
+	      results->push_back(Typed_identifier("", rtype, imp->location()));
+	    }
+	  else
+	    {
+	      imp->advance(1);
+	      while (true)
+		{
+		  std::string name = imp->read_name();
+		  imp->require_c_string(" ");
+		  Type* rtype = imp->read_type();
+		  results->push_back(Typed_identifier(name, rtype,
+						      imp->location()));
+		  if (imp->peek_char() != ',')
+		    break;
+		  imp->require_c_string(", ");
+		}
+	      imp->require_c_string(")");
+	    }
+	}
+
+      Function_type* fntype = Type::make_function_type(NULL, parameters,
+						       results,
+						       imp->location());
+      if (is_varargs)
+	fntype->set_is_varargs();
+      methods->push_back(Typed_identifier(name, fntype, imp->location()));
+
+      imp->require_c_string("; ");
+    }
+
+  imp->require_c_string("}");
+
+  if (methods->empty())
+    {
+      delete methods;
+      methods = NULL;
+    }
+
+  Interface_type* ret = Type::make_interface_type(methods, imp->location());
+  ret->package_ = imp->package();
+  return ret;
+}
+
+// Make an interface type.
+
+Interface_type*
+Type::make_interface_type(Typed_identifier_list* methods,
+			  Location location)
+{
+  return new Interface_type(methods, location);
+}
+
+// Make an empty interface type.
+
+Interface_type*
+Type::make_empty_interface_type(Location location)
+{
+  Interface_type* ret = new Interface_type(NULL, location);
+  ret->finalize_methods();
+  return ret;
+}
+
+// Class Method.
+
+// Bind a method to an object.
+
+Expression*
+Method::bind_method(Expression* expr, Location location) const
+{
+  if (this->stub_ == NULL)
+    {
+      // When there is no stub object, the binding is determined by
+      // the child class.
+      return this->do_bind_method(expr, location);
+    }
+  return Expression::make_bound_method(expr, this, this->stub_, location);
+}
+
+// Return the named object associated with a method.  This may only be
+// called after methods are finalized.
+
+Named_object*
+Method::named_object() const
+{
+  if (this->stub_ != NULL)
+    return this->stub_;
+  return this->do_named_object();
+}
+
+// Class Named_method.
+
+// The type of the method.
+
+Function_type*
+Named_method::do_type() const
+{
+  if (this->named_object_->is_function())
+    return this->named_object_->func_value()->type();
+  else if (this->named_object_->is_function_declaration())
+    return this->named_object_->func_declaration_value()->type();
+  else
+    go_unreachable();
+}
+
+// Return the location of the method receiver.
+
+Location
+Named_method::do_receiver_location() const
+{
+  return this->do_type()->receiver()->location();
+}
+
+// Bind a method to an object.
+
+Expression*
+Named_method::do_bind_method(Expression* expr, Location location) const
+{
+  Named_object* no = this->named_object_;
+  Bound_method_expression* bme = Expression::make_bound_method(expr, this,
+							       no, location);
+  // If this is not a local method, and it does not use a stub, then
+  // the real method expects a different type.  We need to cast the
+  // first argument.
+  if (this->depth() > 0 && !this->needs_stub_method())
+    {
+      Function_type* ftype = this->do_type();
+      go_assert(ftype->is_method());
+      Type* frtype = ftype->receiver()->type();
+      bme->set_first_argument_type(frtype);
+    }
+  return bme;
+}
+
+// Return whether this method should not participate in interfaces.
+
+bool
+Named_method::do_nointerface() const
+{
+  Named_object* no = this->named_object_;
+  return no->is_function() && no->func_value()->nointerface();
+}
+
+// Class Interface_method.
+
+// Bind a method to an object.
+
+Expression*
+Interface_method::do_bind_method(Expression* expr,
+				 Location location) const
+{
+  return Expression::make_interface_field_reference(expr, this->name_,
+						    location);
+}
+
+// Class Methods.
+
+// Insert a new method.  Return true if it was inserted, false
+// otherwise.
+
+bool
+Methods::insert(const std::string& name, Method* m)
+{
+  std::pair<Method_map::iterator, bool> ins =
+    this->methods_.insert(std::make_pair(name, m));
+  if (ins.second)
+    return true;
+  else
+    {
+      Method* old_method = ins.first->second;
+      if (m->depth() < old_method->depth())
+	{
+	  delete old_method;
+	  ins.first->second = m;
+	  return true;
+	}
+      else
+	{
+	  if (m->depth() == old_method->depth())
+	    old_method->set_is_ambiguous();
+	  return false;
+	}
+    }
+}
+
+// Return the number of unambiguous methods.
+
+size_t
+Methods::count() const
+{
+  size_t ret = 0;
+  for (Method_map::const_iterator p = this->methods_.begin();
+       p != this->methods_.end();
+       ++p)
+    if (!p->second->is_ambiguous())
+      ++ret;
+  return ret;
+}
+
+// Class Named_type.
+
+// Return the name of the type.
+
+const std::string&
+Named_type::name() const
+{
+  return this->named_object_->name();
+}
+
+// Return the name of the type to use in an error message.
+
+std::string
+Named_type::message_name() const
+{
+  return this->named_object_->message_name();
+}
+
+// Return the base type for this type.  We have to be careful about
+// circular type definitions, which are invalid but may be seen here.
+
+Type*
+Named_type::named_base()
+{
+  if (this->seen_)
+    return this;
+  this->seen_ = true;
+  Type* ret = this->type_->base();
+  this->seen_ = false;
+  return ret;
+}
+
+const Type*
+Named_type::named_base() const
+{
+  if (this->seen_)
+    return this;
+  this->seen_ = true;
+  const Type* ret = this->type_->base();
+  this->seen_ = false;
+  return ret;
+}
+
+// Return whether this is an error type.  We have to be careful about
+// circular type definitions, which are invalid but may be seen here.
+
+bool
+Named_type::is_named_error_type() const
+{
+  if (this->seen_)
+    return false;
+  this->seen_ = true;
+  bool ret = this->type_->is_error_type();
+  this->seen_ = false;
+  return ret;
+}
+
+// Whether this type is comparable.  We have to be careful about
+// circular type definitions.
+
+bool
+Named_type::named_type_is_comparable(std::string* reason) const
+{
+  if (this->seen_)
+    return false;
+  this->seen_ = true;
+  bool ret = Type::are_compatible_for_comparison(true, this->type_,
+						 this->type_, reason);
+  this->seen_ = false;
+  return ret;
+}
+
+// Add a method to this type.
+
+Named_object*
+Named_type::add_method(const std::string& name, Function* function)
+{
+  go_assert(!this->is_alias_);
+  if (this->local_methods_ == NULL)
+    this->local_methods_ = new Bindings(NULL);
+  return this->local_methods_->add_function(name, NULL, function);
+}
+
+// Add a method declaration to this type.
+
+Named_object*
+Named_type::add_method_declaration(const std::string& name, Package* package,
+				   Function_type* type,
+				   Location location)
+{
+  go_assert(!this->is_alias_);
+  if (this->local_methods_ == NULL)
+    this->local_methods_ = new Bindings(NULL);
+  return this->local_methods_->add_function_declaration(name, package, type,
+							location);
+}
+
+// Add an existing method to this type.
+
+void
+Named_type::add_existing_method(Named_object* no)
+{
+  go_assert(!this->is_alias_);
+  if (this->local_methods_ == NULL)
+    this->local_methods_ = new Bindings(NULL);
+  this->local_methods_->add_named_object(no);
+}
+
+// Look for a local method NAME, and returns its named object, or NULL
+// if not there.
+
+Named_object*
+Named_type::find_local_method(const std::string& name) const
+{
+  if (this->is_error_)
+    return NULL;
+  if (this->is_alias_)
+    {
+      Named_type* nt = this->type_->named_type();
+      if (nt != NULL)
+	{
+	  if (this->seen_alias_)
+	    return NULL;
+	  this->seen_alias_ = true;
+	  Named_object* ret = nt->find_local_method(name);
+	  this->seen_alias_ = false;
+	  return ret;
+	}
+      return NULL;
+    }
+  if (this->local_methods_ == NULL)
+    return NULL;
+  return this->local_methods_->lookup(name);
+}
+
+// Return the list of local methods.
+
+const Bindings*
+Named_type::local_methods() const
+{
+  if (this->is_error_)
+    return NULL;
+  if (this->is_alias_)
+    {
+      Named_type* nt = this->type_->named_type();
+      if (nt != NULL)
+	{
+	  if (this->seen_alias_)
+	    return NULL;
+	  this->seen_alias_ = true;
+	  const Bindings* ret = nt->local_methods();
+	  this->seen_alias_ = false;
+	  return ret;
+	}
+      return NULL;
+    }
+  return this->local_methods_;
+}
+
+// Return whether NAME is an unexported field or method, for better
+// error reporting.
+
+bool
+Named_type::is_unexported_local_method(Gogo* gogo,
+				       const std::string& name) const
+{
+  if (this->is_error_)
+    return false;
+  if (this->is_alias_)
+    {
+      Named_type* nt = this->type_->named_type();
+      if (nt != NULL)
+	{
+	  if (this->seen_alias_)
+	    return false;
+	  this->seen_alias_ = true;
+	  bool ret = nt->is_unexported_local_method(gogo, name);
+	  this->seen_alias_ = false;
+	  return ret;
+	}
+      return false;
+    }
+  Bindings* methods = this->local_methods_;
+  if (methods != NULL)
+    {
+      for (Bindings::const_declarations_iterator p =
+	     methods->begin_declarations();
+	   p != methods->end_declarations();
+	   ++p)
+	{
+	  if (Gogo::is_hidden_name(p->first)
+	      && name == Gogo::unpack_hidden_name(p->first)
+	      && gogo->pack_hidden_name(name, false) != p->first)
+	    return true;
+	}
+    }
+  return false;
+}
+
+// Build the complete list of methods for this type, which means
+// recursively including all methods for anonymous fields.  Create all
+// stub methods.
+
+void
+Named_type::finalize_methods(Gogo* gogo)
+{
+  if (this->is_alias_)
+    return;
+  if (this->all_methods_ != NULL)
+    return;
+
+  if (this->local_methods_ != NULL
+      && (this->points_to() != NULL || this->interface_type() != NULL))
+    {
+      const Bindings* lm = this->local_methods_;
+      for (Bindings::const_declarations_iterator p = lm->begin_declarations();
+	   p != lm->end_declarations();
+	   ++p)
+	go_error_at(p->second->location(),
+		    "invalid pointer or interface receiver type");
+      delete this->local_methods_;
+      this->local_methods_ = NULL;
+      return;
+    }
+
+  Type::finalize_methods(gogo, this, this->location_, &this->all_methods_);
+}
+
+// Return whether this type has any methods.
+
+bool
+Named_type::has_any_methods() const
+{
+  if (this->is_error_)
+    return false;
+  if (this->is_alias_)
+    {
+      if (this->type_->named_type() != NULL)
+	{
+	  if (this->seen_alias_)
+	    return false;
+	  this->seen_alias_ = true;
+	  bool ret = this->type_->named_type()->has_any_methods();
+	  this->seen_alias_ = false;
+	  return ret;
+	}
+      if (this->type_->struct_type() != NULL)
+	return this->type_->struct_type()->has_any_methods();
+      return false;
+    }
+  return this->all_methods_ != NULL;
+}
+
+// Return the methods for this type.
+
+const Methods*
+Named_type::methods() const
+{
+  if (this->is_error_)
+    return NULL;
+  if (this->is_alias_)
+    {
+      if (this->type_->named_type() != NULL)
+	{
+	  if (this->seen_alias_)
+	    return NULL;
+	  this->seen_alias_ = true;
+	  const Methods* ret = this->type_->named_type()->methods();
+	  this->seen_alias_ = false;
+	  return ret;
+	}
+      if (this->type_->struct_type() != NULL)
+	return this->type_->struct_type()->methods();
+      return NULL;
+    }
+  return this->all_methods_;
+}
+
+// Return the method NAME, or NULL if there isn't one or if it is
+// ambiguous.  Set *IS_AMBIGUOUS if the method exists but is
+// ambiguous.
+
+Method*
+Named_type::method_function(const std::string& name, bool* is_ambiguous) const
+{
+  if (this->is_error_)
+    return NULL;
+  if (this->is_alias_)
+    {
+      if (is_ambiguous != NULL)
+	*is_ambiguous = false;
+      if (this->type_->named_type() != NULL)
+	{
+	  if (this->seen_alias_)
+	    return NULL;
+	  this->seen_alias_ = true;
+	  Named_type* nt = this->type_->named_type();
+	  Method* ret = nt->method_function(name, is_ambiguous);
+	  this->seen_alias_ = false;
+	  return ret;
+	}
+      if (this->type_->struct_type() != NULL)
+	return this->type_->struct_type()->method_function(name, is_ambiguous);
+      return NULL;
+    }
+  return Type::method_function(this->all_methods_, name, is_ambiguous);
+}
+
+// Return a pointer to the interface method table for this type for
+// the interface INTERFACE.  IS_POINTER is true if this is for a
+// pointer to THIS.
+
+Expression*
+Named_type::interface_method_table(Interface_type* interface, bool is_pointer)
+{
+  if (this->is_error_)
+    return Expression::make_error(this->location_);
+  if (this->is_alias_)
+    {
+      if (this->type_->named_type() != NULL)
+	{
+	  if (this->seen_alias_)
+	    return Expression::make_error(this->location_);
+	  this->seen_alias_ = true;
+	  Named_type* nt = this->type_->named_type();
+	  Expression* ret = nt->interface_method_table(interface, is_pointer);
+	  this->seen_alias_ = false;
+	  return ret;
+	}
+      if (this->type_->struct_type() != NULL)
+	return this->type_->struct_type()->interface_method_table(interface,
+								  is_pointer);
+      go_unreachable();
+    }
+  return Type::interface_method_table(this, interface, is_pointer,
+                                      &this->interface_method_tables_,
+                                      &this->pointer_interface_method_tables_);
+}
+
+// Look for a use of a complete type within another type.  This is
+// used to check that we don't try to use a type within itself.
+
+class Find_type_use : public Traverse
+{
+ public:
+  Find_type_use(Named_type* find_type)
+    : Traverse(traverse_types),
+      find_type_(find_type), found_(false)
+  { }
+
+  // Whether we found the type.
+  bool
+  found() const
+  { return this->found_; }
+
+ protected:
+  int
+  type(Type*);
+
+ private:
+  // The type we are looking for.
+  Named_type* find_type_;
+  // Whether we found the type.
+  bool found_;
+};
+
+// Check for FIND_TYPE in TYPE.
+
+int
+Find_type_use::type(Type* type)
+{
+  if (type->named_type() != NULL && this->find_type_ == type->named_type())
+    {
+      this->found_ = true;
+      return TRAVERSE_EXIT;
+    }
+
+  // It's OK if we see a reference to the type in any type which is
+  // essentially a pointer: a pointer, a slice, a function, a map, or
+  // a channel.
+  if (type->points_to() != NULL
+      || type->is_slice_type()
+      || type->function_type() != NULL
+      || type->map_type() != NULL
+      || type->channel_type() != NULL)
+    return TRAVERSE_SKIP_COMPONENTS;
+
+  // For an interface, a reference to the type in a method type should
+  // be ignored, but we have to consider direct inheritance.  When
+  // this is called, there may be cases of direct inheritance
+  // represented as a method with no name.
+  if (type->interface_type() != NULL)
+    {
+      const Typed_identifier_list* methods = type->interface_type()->methods();
+      if (methods != NULL)
+	{
+	  for (Typed_identifier_list::const_iterator p = methods->begin();
+	       p != methods->end();
+	       ++p)
+	    {
+	      if (p->name().empty())
+		{
+		  if (Type::traverse(p->type(), this) == TRAVERSE_EXIT)
+		    return TRAVERSE_EXIT;
+		}
+	    }
+	}
+      return TRAVERSE_SKIP_COMPONENTS;
+    }
+
+  // Otherwise, FIND_TYPE_ depends on TYPE, in the sense that we need
+  // to convert TYPE to the backend representation before we convert
+  // FIND_TYPE_.
+  if (type->named_type() != NULL)
+    {
+      switch (type->base()->classification())
+	{
+	case Type::TYPE_ERROR:
+	case Type::TYPE_BOOLEAN:
+	case Type::TYPE_INTEGER:
+	case Type::TYPE_FLOAT:
+	case Type::TYPE_COMPLEX:
+	case Type::TYPE_STRING:
+	case Type::TYPE_NIL:
+	  break;
+
+	case Type::TYPE_ARRAY:
+	case Type::TYPE_STRUCT:
+	  this->find_type_->add_dependency(type->named_type());
+	  break;
+
+	case Type::TYPE_NAMED:
+	case Type::TYPE_FORWARD:
+	  go_assert(saw_errors());
+	  break;
+
+	case Type::TYPE_VOID:
+	case Type::TYPE_SINK:
+	case Type::TYPE_FUNCTION:
+	case Type::TYPE_POINTER:
+	case Type::TYPE_CALL_MULTIPLE_RESULT:
+	case Type::TYPE_MAP:
+	case Type::TYPE_CHANNEL:
+	case Type::TYPE_INTERFACE:
+	default:
+	  go_unreachable();
+	}
+    }
+
+  return TRAVERSE_CONTINUE;
+}
+
+// Look for a circular reference of an alias.
+
+class Find_alias : public Traverse
+{
+ public:
+  Find_alias(Named_type* find_type)
+    : Traverse(traverse_types),
+      find_type_(find_type), found_(false)
+  { }
+
+  // Whether we found the type.
+  bool
+  found() const
+  { return this->found_; }
+
+ protected:
+  int
+  type(Type*);
+
+ private:
+  // The type we are looking for.
+  Named_type* find_type_;
+  // Whether we found the type.
+  bool found_;
+};
+
+int
+Find_alias::type(Type* type)
+{
+  Named_type* nt = type->named_type();
+  if (nt != NULL)
+    {
+      if (nt == this->find_type_)
+	{
+	  this->found_ = true;
+	  return TRAVERSE_EXIT;
+	}
+
+      // We started from `type T1 = T2`, where T1 is find_type_ and T2
+      // is, perhaps indirectly, the parameter TYPE.  If TYPE is not
+      // an alias itself, it's OK if whatever T2 is defined as refers
+      // to T1.
+      if (!nt->is_alias())
+	return TRAVERSE_SKIP_COMPONENTS;
+    }
+
+  return TRAVERSE_CONTINUE;
+}
+
+// Verify that a named type does not refer to itself.
+
+bool
+Named_type::do_verify()
+{
+  if (this->is_verified_)
+    return true;
+  this->is_verified_ = true;
+
+  if (this->is_error_)
+    return false;
+
+  if (this->is_alias_)
+    {
+      Find_alias find(this);
+      Type::traverse(this->type_, &find);
+      if (find.found())
+	{
+	  go_error_at(this->location_, "invalid recursive alias %qs",
+		      this->message_name().c_str());
+	  this->is_error_ = true;
+	  return false;
+	}
+    }
+
+  Find_type_use find(this);
+  Type::traverse(this->type_, &find);
+  if (find.found())
+    {
+      go_error_at(this->location_, "invalid recursive type %qs",
+		  this->message_name().c_str());
+      this->is_error_ = true;
+      return false;
+    }
+
+  // Check whether any of the local methods overloads an existing
+  // struct field or interface method.  We don't need to check the
+  // list of methods against itself: that is handled by the Bindings
+  // code.
+  if (this->local_methods_ != NULL)
+    {
+      Struct_type* st = this->type_->struct_type();
+      if (st != NULL)
+	{
+	  for (Bindings::const_declarations_iterator p =
+		 this->local_methods_->begin_declarations();
+	       p != this->local_methods_->end_declarations();
+	       ++p)
+	    {
+	      const std::string& name(p->first);
+	      if (st != NULL && st->find_local_field(name, NULL) != NULL)
+		{
+		  go_error_at(p->second->location(),
+			      "method %qs redeclares struct field name",
+			      Gogo::message_name(name).c_str());
+		}
+	    }
+	}
+    }
+
+  return true;
+}
+
+// Return whether this type is or contains a pointer.
+
+bool
+Named_type::do_has_pointer() const
+{
+  if (this->seen_)
+    return false;
+  this->seen_ = true;
+  bool ret = this->type_->has_pointer();
+  this->seen_ = false;
+  return ret;
+}
+
+// Return whether comparisons for this type can use the identity
+// function.
+
+bool
+Named_type::do_compare_is_identity(Gogo* gogo)
+{
+  // We don't use this->seen_ here because compare_is_identity may
+  // call base() later, and that will mess up if seen_ is set here.
+  if (this->seen_in_compare_is_identity_)
+    return false;
+  this->seen_in_compare_is_identity_ = true;
+  bool ret = this->type_->compare_is_identity(gogo);
+  this->seen_in_compare_is_identity_ = false;
+  return ret;
+}
+
+// Return whether this type is reflexive--whether it is always equal
+// to itself.
+
+bool
+Named_type::do_is_reflexive()
+{
+  if (this->seen_in_compare_is_identity_)
+    return false;
+  this->seen_in_compare_is_identity_ = true;
+  bool ret = this->type_->is_reflexive();
+  this->seen_in_compare_is_identity_ = false;
+  return ret;
+}
+
+// Return whether this type needs a key update when used as a map key.
+
+bool
+Named_type::do_needs_key_update()
+{
+  if (this->seen_in_compare_is_identity_)
+    return true;
+  this->seen_in_compare_is_identity_ = true;
+  bool ret = this->type_->needs_key_update();
+  this->seen_in_compare_is_identity_ = false;
+  return ret;
+}
+
+// Return a hash code.  This is used for method lookup.  We simply
+// hash on the name itself.
+
+unsigned int
+Named_type::do_hash_for_method(Gogo* gogo) const
+{
+  if (this->is_error_)
+    return 0;
+
+  // Aliases are handled in Type::hash_for_method.
+  go_assert(!this->is_alias_);
+
+  const std::string& name(this->named_object()->name());
+  unsigned int ret = Type::hash_string(name, 0);
+
+  // GOGO will be NULL here when called from Type_hash_identical.
+  // That is OK because that is only used for internal hash tables
+  // where we are going to be comparing named types for equality.  In
+  // other cases, which are cases where the runtime is going to
+  // compare hash codes to see if the types are the same, we need to
+  // include the pkgpath in the hash.
+  if (gogo != NULL && !Gogo::is_hidden_name(name) && !this->is_builtin())
+    {
+      const Package* package = this->named_object()->package();
+      if (package == NULL)
+	ret = Type::hash_string(gogo->pkgpath(), ret);
+      else
+	ret = Type::hash_string(package->pkgpath(), ret);
+    }
+
+  return ret;
+}
+
+// Convert a named type to the backend representation.  In order to
+// get dependencies right, we fill in a dummy structure for this type,
+// then convert all the dependencies, then complete this type.  When
+// this function is complete, the size of the type is known.
+
+void
+Named_type::convert(Gogo* gogo)
+{
+  if (this->is_error_ || this->is_converted_)
+    return;
+
+  this->create_placeholder(gogo);
+
+  // If we are called to turn unsafe.Sizeof into a constant, we may
+  // not have verified the type yet.  We have to make sure it is
+  // verified, since that sets the list of dependencies.
+  this->verify();
+
+  // Convert all the dependencies.  If they refer indirectly back to
+  // this type, they will pick up the intermediate representation we just
+  // created.
+  for (std::vector<Named_type*>::const_iterator p = this->dependencies_.begin();
+       p != this->dependencies_.end();
+       ++p)
+    (*p)->convert(gogo);
+
+  // Complete this type.
+  Btype* bt = this->named_btype_;
+  Type* base = this->type_->base();
+  switch (base->classification())
+    {
+    case TYPE_VOID:
+    case TYPE_BOOLEAN:
+    case TYPE_INTEGER:
+    case TYPE_FLOAT:
+    case TYPE_COMPLEX:
+    case TYPE_STRING:
+    case TYPE_NIL:
+      break;
+
+    case TYPE_MAP:
+    case TYPE_CHANNEL:
+      break;
+
+    case TYPE_FUNCTION:
+    case TYPE_POINTER:
+      // The size of these types is already correct.  We don't worry
+      // about filling them in until later, when we also track
+      // circular references.
+      break;
+
+    case TYPE_STRUCT:
+      {
+	std::vector<Backend::Btyped_identifier> bfields;
+	get_backend_struct_fields(gogo, base->struct_type()->fields(),
+				  true, &bfields);
+	if (!gogo->backend()->set_placeholder_struct_type(bt, bfields))
+	  bt = gogo->backend()->error_type();
+      }
+      break;
+
+    case TYPE_ARRAY:
+      // Slice types were completed in create_placeholder.
+      if (!base->is_slice_type())
+	{
+	  Btype* bet = base->array_type()->get_backend_element(gogo, true);
+	  Bexpression* blen = base->array_type()->get_backend_length(gogo);
+	  if (!gogo->backend()->set_placeholder_array_type(bt, bet, blen))
+	    bt = gogo->backend()->error_type();
+	}
+      break;
+
+    case TYPE_INTERFACE:
+      // Interface types were completed in create_placeholder.
+      break;
+
+    case TYPE_ERROR:
+      return;
+
+    default:
+    case TYPE_SINK:
+    case TYPE_CALL_MULTIPLE_RESULT:
+    case TYPE_NAMED:
+    case TYPE_FORWARD:
+      go_unreachable();
+    }
+
+  this->named_btype_ = bt;
+  this->is_converted_ = true;
+  this->is_placeholder_ = false;
+}
+
+// Create the placeholder for a named type.  This is the first step in
+// converting to the backend representation.
+
+void
+Named_type::create_placeholder(Gogo* gogo)
+{
+  if (this->is_error_)
+    this->named_btype_ = gogo->backend()->error_type();
+
+  if (this->named_btype_ != NULL)
+    return;
+
+  // Create the structure for this type.  Note that because we call
+  // base() here, we don't attempt to represent a named type defined
+  // as another named type.  Instead both named types will point to
+  // different base representations.
+  Type* base = this->type_->base();
+  Btype* bt;
+  bool set_name = true;
+  switch (base->classification())
+    {
+    case TYPE_ERROR:
+      this->is_error_ = true;
+      this->named_btype_ = gogo->backend()->error_type();
+      return;
+
+    case TYPE_VOID:
+    case TYPE_BOOLEAN:
+    case TYPE_INTEGER:
+    case TYPE_FLOAT:
+    case TYPE_COMPLEX:
+    case TYPE_STRING:
+    case TYPE_NIL:
+      // These are simple basic types, we can just create them
+      // directly.
+      bt = Type::get_named_base_btype(gogo, base);
+      break;
+
+    case TYPE_MAP:
+    case TYPE_CHANNEL:
+      // All maps and channels have the same backend representation.
+      bt = Type::get_named_base_btype(gogo, base);
+      break;
+
+    case TYPE_FUNCTION:
+    case TYPE_POINTER:
+      {
+	bool for_function = base->classification() == TYPE_FUNCTION;
+	bt = gogo->backend()->placeholder_pointer_type(this->name(),
+						       this->location_,
+						       for_function);
+	set_name = false;
+      }
+      break;
+
+    case TYPE_STRUCT:
+      bt = gogo->backend()->placeholder_struct_type(this->name(),
+						    this->location_);
+      this->is_placeholder_ = true;
+      set_name = false;
+      break;
+
+    case TYPE_ARRAY:
+      if (base->is_slice_type())
+	bt = gogo->backend()->placeholder_struct_type(this->name(),
+						      this->location_);
+      else
+	{
+	  bt = gogo->backend()->placeholder_array_type(this->name(),
+						       this->location_);
+	  this->is_placeholder_ = true;
+	}
+      set_name = false;
+      break;
+
+    case TYPE_INTERFACE:
+      if (base->interface_type()->is_empty())
+	bt = Interface_type::get_backend_empty_interface_type(gogo);
+      else
+	{
+	  bt = gogo->backend()->placeholder_struct_type(this->name(),
+							this->location_);
+	  set_name = false;
+	}
+      break;
+
+    default:
+    case TYPE_SINK:
+    case TYPE_CALL_MULTIPLE_RESULT:
+    case TYPE_NAMED:
+    case TYPE_FORWARD:
+      go_unreachable();
+    }
+
+  if (set_name)
+    bt = gogo->backend()->named_type(this->name(), bt, this->location_);
+
+  this->named_btype_ = bt;
+
+  if (base->is_slice_type())
+    {
+      // We do not record slices as dependencies of other types,
+      // because we can fill them in completely here with the final
+      // size.
+      std::vector<Backend::Btyped_identifier> bfields;
+      get_backend_slice_fields(gogo, base->array_type(), true, &bfields);
+      if (!gogo->backend()->set_placeholder_struct_type(bt, bfields))
+	this->named_btype_ = gogo->backend()->error_type();
+    }
+  else if (base->interface_type() != NULL
+	   && !base->interface_type()->is_empty())
+    {
+      // We do not record interfaces as dependencies of other types,
+      // because we can fill them in completely here with the final
+      // size.
+      std::vector<Backend::Btyped_identifier> bfields;
+      get_backend_interface_fields(gogo, base->interface_type(), true,
+				   &bfields);
+      if (!gogo->backend()->set_placeholder_struct_type(bt, bfields))
+	this->named_btype_ = gogo->backend()->error_type();
+    }
+}
+
+// Get the backend representation for a named type.
+
+Btype*
+Named_type::do_get_backend(Gogo* gogo)
+{
+  if (this->is_error_)
+    return gogo->backend()->error_type();
+
+  Btype* bt = this->named_btype_;
+
+  if (!gogo->named_types_are_converted())
+    {
+      // We have not completed converting named types.  NAMED_BTYPE_
+      // is a placeholder and we shouldn't do anything further.
+      if (bt != NULL)
+	return bt;
+
+      // We don't build dependencies for types whose sizes do not
+      // change or are not relevant, so we may see them here while
+      // converting types.
+      this->create_placeholder(gogo);
+      bt = this->named_btype_;
+      go_assert(bt != NULL);
+      return bt;
+    }
+
+  // We are not converting types.  This should only be called if the
+  // type has already been converted.
+  if (!this->is_converted_)
+    {
+      go_assert(saw_errors());
+      return gogo->backend()->error_type();
+    }
+
+  go_assert(bt != NULL);
+
+  // Complete the backend representation.
+  Type* base = this->type_->base();
+  Btype* bt1;
+  switch (base->classification())
+    {
+    case TYPE_ERROR:
+      return gogo->backend()->error_type();
+
+    case TYPE_VOID:
+    case TYPE_BOOLEAN:
+    case TYPE_INTEGER:
+    case TYPE_FLOAT:
+    case TYPE_COMPLEX:
+    case TYPE_STRING:
+    case TYPE_NIL:
+    case TYPE_MAP:
+    case TYPE_CHANNEL:
+      return bt;
+
+    case TYPE_STRUCT:
+      if (!this->seen_in_get_backend_)
+	{
+	  this->seen_in_get_backend_ = true;
+	  base->struct_type()->finish_backend_fields(gogo);
+	  this->seen_in_get_backend_ = false;
+	}
+      return bt;
+
+    case TYPE_ARRAY:
+      if (!this->seen_in_get_backend_)
+	{
+	  this->seen_in_get_backend_ = true;
+	  base->array_type()->finish_backend_element(gogo);
+	  this->seen_in_get_backend_ = false;
+	}
+      return bt;
+
+    case TYPE_INTERFACE:
+      if (!this->seen_in_get_backend_)
+	{
+	  this->seen_in_get_backend_ = true;
+	  base->interface_type()->finish_backend_methods(gogo);
+	  this->seen_in_get_backend_ = false;
+	}
+      return bt;
+
+    case TYPE_FUNCTION:
+      // Don't build a circular data structure.  GENERIC can't handle
+      // it.
+      if (this->seen_in_get_backend_)
+	{
+	  this->is_circular_ = true;
+	  return gogo->backend()->circular_pointer_type(bt, true);
+	}
+      this->seen_in_get_backend_ = true;
+      bt1 = Type::get_named_base_btype(gogo, base);
+      this->seen_in_get_backend_ = false;
+      if (this->is_circular_)
+	bt1 = gogo->backend()->circular_pointer_type(bt, true);
+      if (!gogo->backend()->set_placeholder_pointer_type(bt, bt1))
+	bt = gogo->backend()->error_type();
+      return bt;
+
+    case TYPE_POINTER:
+      // Don't build a circular data structure. GENERIC can't handle
+      // it.
+      if (this->seen_in_get_backend_)
+	{
+	  this->is_circular_ = true;
+	  return gogo->backend()->circular_pointer_type(bt, false);
+	}
+      this->seen_in_get_backend_ = true;
+      bt1 = Type::get_named_base_btype(gogo, base);
+      this->seen_in_get_backend_ = false;
+      if (this->is_circular_)
+	bt1 = gogo->backend()->circular_pointer_type(bt, false);
+      if (!gogo->backend()->set_placeholder_pointer_type(bt, bt1))
+	bt = gogo->backend()->error_type();
+      return bt;
+
+    default:
+    case TYPE_SINK:
+    case TYPE_CALL_MULTIPLE_RESULT:
+    case TYPE_NAMED:
+    case TYPE_FORWARD:
+      go_unreachable();
+    }
+
+  go_unreachable();
+}
+
+// Build a type descriptor for a named type.
+
+Expression*
+Named_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  if (this->is_error_)
+    return Expression::make_error(this->location_);
+  if (name == NULL && this->is_alias_)
+    {
+      if (this->seen_alias_)
+	return Expression::make_error(this->location_);
+      this->seen_alias_ = true;
+      Expression* ret = this->type_->type_descriptor(gogo, NULL);
+      this->seen_alias_ = false;
+      return ret;
+    }
+
+  // If NAME is not NULL, then we don't really want the type
+  // descriptor for this type; we want the descriptor for the
+  // underlying type, giving it the name NAME.
+  return this->named_type_descriptor(gogo, this->type_,
+				     name == NULL ? this : name);
+}
+
+// Add to the reflection string.  This is used mostly for the name of
+// the type used in a type descriptor, not for actual reflection
+// strings.
+
+void
+Named_type::do_reflection(Gogo* gogo, std::string* ret) const
+{
+  this->append_reflection_type_name(gogo, false, ret);
+}
+
+// Add to the reflection string.  For an alias we normally use the
+// real name, but if USE_ALIAS is true we use the alias name itself.
+
+void
+Named_type::append_reflection_type_name(Gogo* gogo, bool use_alias,
+					std::string* ret) const
+{
+  if (this->is_error_)
+    return;
+  if (this->is_alias_ && !use_alias)
+    {
+      if (this->seen_alias_)
+	return;
+      this->seen_alias_ = true;
+      this->append_reflection(this->type_, gogo, ret);
+      this->seen_alias_ = false;
+      return;
+    }
+  if (!this->is_builtin())
+    {
+      // When -fgo-pkgpath or -fgo-prefix is specified, we use it to
+      // make a unique reflection string, so that the type
+      // canonicalization in the reflect package will work.  In order
+      // to be compatible with the gc compiler, we put tabs into the
+      // package path, so that the reflect methods can discard it.
+      const Package* package = this->named_object_->package();
+      ret->push_back('\t');
+      ret->append(package != NULL
+		  ? package->pkgpath_symbol()
+		  : gogo->pkgpath_symbol());
+      ret->push_back('\t');
+      ret->append(package != NULL
+		  ? package->package_name()
+		  : gogo->package_name());
+      ret->push_back('.');
+    }
+  if (this->in_function_ != NULL)
+    {
+      ret->push_back('\t');
+      const Typed_identifier* rcvr =
+	this->in_function_->func_value()->type()->receiver();
+      if (rcvr != NULL)
+	{
+	  Named_type* rcvr_type = rcvr->type()->deref()->named_type();
+	  ret->append(Gogo::unpack_hidden_name(rcvr_type->name()));
+	  ret->push_back('.');
+	}
+      ret->append(Gogo::unpack_hidden_name(this->in_function_->name()));
+      ret->push_back('$');
+      if (this->in_function_index_ > 0)
+	{
+	  char buf[30];
+	  snprintf(buf, sizeof buf, "%u", this->in_function_index_);
+	  ret->append(buf);
+	  ret->push_back('$');
+	}
+      ret->push_back('\t');
+    }
+  ret->append(Gogo::unpack_hidden_name(this->named_object_->name()));
+}
+
+// Export the type.  This is called to export a global type.
+
+void
+Named_type::export_named_type(Export* exp, const std::string&) const
+{
+  // We don't need to write the name of the type here, because it will
+  // be written by Export::write_type anyhow.
+  exp->write_c_string("type ");
+  exp->write_type(this);
+  exp->write_c_string(";\n");
+}
+
+// Import a named type.
+
+void
+Named_type::import_named_type(Import* imp, Named_type** ptype)
+{
+  imp->require_c_string("type ");
+  Type *type = imp->read_type();
+  *ptype = type->named_type();
+  go_assert(*ptype != NULL);
+  imp->require_c_string(";\n");
+}
+
+// Export the type when it is referenced by another type.  In this
+// case Export::export_type will already have issued the name.
+
+void
+Named_type::do_export(Export* exp) const
+{
+  exp->write_type(this->type_);
+
+  // To save space, we only export the methods directly attached to
+  // this type.
+  Bindings* methods = this->local_methods_;
+  if (methods == NULL)
+    return;
+
+  exp->write_c_string("\n");
+  for (Bindings::const_definitions_iterator p = methods->begin_definitions();
+       p != methods->end_definitions();
+       ++p)
+    {
+      exp->write_c_string(" ");
+      (*p)->export_named_object(exp);
+    }
+
+  for (Bindings::const_declarations_iterator p = methods->begin_declarations();
+       p != methods->end_declarations();
+       ++p)
+    {
+      if (p->second->is_function_declaration())
+	{
+	  exp->write_c_string(" ");
+	  p->second->export_named_object(exp);
+	}
+    }
+}
+
+// Make a named type.
+
+Named_type*
+Type::make_named_type(Named_object* named_object, Type* type,
+		      Location location)
+{
+  return new Named_type(named_object, type, location);
+}
+
+// Finalize the methods for TYPE.  It will be a named type or a struct
+// type.  This sets *ALL_METHODS to the list of methods, and builds
+// all required stubs.
+
+void
+Type::finalize_methods(Gogo* gogo, const Type* type, Location location,
+		       Methods** all_methods)
+{
+  *all_methods = new Methods();
+  std::vector<const Named_type*> seen;
+  Type::add_methods_for_type(type, NULL, 0, false, false, &seen, *all_methods);
+  if ((*all_methods)->empty())
+    {
+      delete *all_methods;
+      *all_methods = NULL;
+    }
+  Type::build_stub_methods(gogo, type, *all_methods, location);
+}
+
+// Add the methods for TYPE to *METHODS.  FIELD_INDEXES is used to
+// build up the struct field indexes as we go.  DEPTH is the depth of
+// the field within TYPE.  IS_EMBEDDED_POINTER is true if we are
+// adding these methods for an anonymous field with pointer type.
+// NEEDS_STUB_METHOD is true if we need to use a stub method which
+// calls the real method.  TYPES_SEEN is used to avoid infinite
+// recursion.
+
+void
+Type::add_methods_for_type(const Type* type,
+			   const Method::Field_indexes* field_indexes,
+			   unsigned int depth,
+			   bool is_embedded_pointer,
+			   bool needs_stub_method,
+			   std::vector<const Named_type*>* seen,
+			   Methods* methods)
+{
+  // Pointer types may not have methods.
+  if (type->points_to() != NULL)
+    return;
+
+  const Named_type* nt = type->named_type();
+  if (nt != NULL)
+    {
+      for (std::vector<const Named_type*>::const_iterator p = seen->begin();
+	   p != seen->end();
+	   ++p)
+	{
+	  if (*p == nt)
+	    return;
+	}
+
+      seen->push_back(nt);
+
+      Type::add_local_methods_for_type(nt, field_indexes, depth,
+				       is_embedded_pointer, needs_stub_method,
+				       methods);
+    }
+
+  Type::add_embedded_methods_for_type(type, field_indexes, depth,
+				      is_embedded_pointer, needs_stub_method,
+				      seen, methods);
+
+  // If we are called with depth > 0, then we are looking at an
+  // anonymous field of a struct.  If such a field has interface type,
+  // then we need to add the interface methods.  We don't want to add
+  // them when depth == 0, because we will already handle them
+  // following the usual rules for an interface type.
+  if (depth > 0)
+    Type::add_interface_methods_for_type(type, field_indexes, depth, methods);
+
+  if (nt != NULL)
+      seen->pop_back();
+}
+
+// Add the local methods for the named type NT to *METHODS.  The
+// parameters are as for add_methods_to_type.
+
+void
+Type::add_local_methods_for_type(const Named_type* nt,
+				 const Method::Field_indexes* field_indexes,
+				 unsigned int depth,
+				 bool is_embedded_pointer,
+				 bool needs_stub_method,
+				 Methods* methods)
+{
+  const Bindings* local_methods = nt->local_methods();
+  if (local_methods == NULL)
+    return;
+
+  for (Bindings::const_declarations_iterator p =
+	 local_methods->begin_declarations();
+       p != local_methods->end_declarations();
+       ++p)
+    {
+      Named_object* no = p->second;
+      bool is_value_method = (is_embedded_pointer
+			      || !Type::method_expects_pointer(no));
+      Method* m = new Named_method(no, field_indexes, depth, is_value_method,
+				   (needs_stub_method || depth > 0));
+      if (!methods->insert(no->name(), m))
+	delete m;
+    }
+}
+
+// Add the embedded methods for TYPE to *METHODS.  These are the
+// methods attached to anonymous fields.  The parameters are as for
+// add_methods_to_type.
+
+void
+Type::add_embedded_methods_for_type(const Type* type,
+				    const Method::Field_indexes* field_indexes,
+				    unsigned int depth,
+				    bool is_embedded_pointer,
+				    bool needs_stub_method,
+				    std::vector<const Named_type*>* seen,
+				    Methods* methods)
+{
+  // Look for anonymous fields in TYPE.  TYPE has fields if it is a
+  // struct.
+  const Struct_type* st = type->struct_type();
+  if (st == NULL)
+    return;
+
+  const Struct_field_list* fields = st->fields();
+  if (fields == NULL)
+    return;
+
+  unsigned int i = 0;
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf, ++i)
+    {
+      if (!pf->is_anonymous())
+	continue;
+
+      Type* ftype = pf->type();
+      bool is_pointer = false;
+      if (ftype->points_to() != NULL)
+	{
+	  ftype = ftype->points_to();
+	  is_pointer = true;
+	}
+      Named_type* fnt = ftype->named_type();
+      if (fnt == NULL)
+	{
+	  // This is an error, but it will be diagnosed elsewhere.
+	  continue;
+	}
+
+      Method::Field_indexes* sub_field_indexes = new Method::Field_indexes();
+      sub_field_indexes->next = field_indexes;
+      sub_field_indexes->field_index = i;
+
+      Methods tmp_methods;
+      Type::add_methods_for_type(fnt, sub_field_indexes, depth + 1,
+				 (is_embedded_pointer || is_pointer),
+				 (needs_stub_method
+				  || is_pointer
+				  || i > 0),
+				 seen,
+				 &tmp_methods);
+      // Check if there are promoted methods that conflict with field names and
+      // don't add them to the method map.
+      for (Methods::const_iterator p = tmp_methods.begin();
+	   p != tmp_methods.end();
+	   ++p)
+	{
+	  bool found = false;
+	  for (Struct_field_list::const_iterator fp = fields->begin();
+	       fp != fields->end();
+	       ++fp)
+	    {
+	      if (fp->field_name() == p->first)
+		{
+		  found = true;
+		  break;
+		}
+	    }
+	  if (!found &&
+	      !methods->insert(p->first, p->second))
+	    delete p->second;
+	}
+    }
+}
+
+// If TYPE is an interface type, then add its method to *METHODS.
+// This is for interface methods attached to an anonymous field.  The
+// parameters are as for add_methods_for_type.
+
+void
+Type::add_interface_methods_for_type(const Type* type,
+				     const Method::Field_indexes* field_indexes,
+				     unsigned int depth,
+				     Methods* methods)
+{
+  const Interface_type* it = type->interface_type();
+  if (it == NULL)
+    return;
+
+  const Typed_identifier_list* imethods = it->methods();
+  if (imethods == NULL)
+    return;
+
+  for (Typed_identifier_list::const_iterator pm = imethods->begin();
+       pm != imethods->end();
+       ++pm)
+    {
+      Function_type* fntype = pm->type()->function_type();
+      if (fntype == NULL)
+	{
+	  // This is an error, but it should be reported elsewhere
+	  // when we look at the methods for IT.
+	  continue;
+	}
+      go_assert(!fntype->is_method());
+      fntype = fntype->copy_with_receiver(const_cast<Type*>(type));
+      Method* m = new Interface_method(pm->name(), pm->location(), fntype,
+				       field_indexes, depth);
+      if (!methods->insert(pm->name(), m))
+	delete m;
+    }
+}
+
+// Build stub methods for TYPE as needed.  METHODS is the set of
+// methods for the type.  A stub method may be needed when a type
+// inherits a method from an anonymous field.  When we need the
+// address of the method, as in a type descriptor, we need to build a
+// little stub which does the required field dereferences and jumps to
+// the real method.  LOCATION is the location of the type definition.
+
+void
+Type::build_stub_methods(Gogo* gogo, const Type* type, const Methods* methods,
+			 Location location)
+{
+  if (methods == NULL)
+    return;
+  for (Methods::const_iterator p = methods->begin();
+       p != methods->end();
+       ++p)
+    {
+      Method* m = p->second;
+      if (m->is_ambiguous() || !m->needs_stub_method())
+	continue;
+
+      const std::string& name(p->first);
+
+      // Build a stub method.
+
+      const Function_type* fntype = m->type();
+
+      static unsigned int counter;
+      char buf[100];
+      snprintf(buf, sizeof buf, "$this%u", counter);
+      ++counter;
+
+      Type* receiver_type = const_cast<Type*>(type);
+      if (!m->is_value_method())
+	receiver_type = Type::make_pointer_type(receiver_type);
+      Location receiver_location = m->receiver_location();
+      Typed_identifier* receiver = new Typed_identifier(buf, receiver_type,
+							receiver_location);
+
+      const Typed_identifier_list* fnparams = fntype->parameters();
+      Typed_identifier_list* stub_params;
+      if (fnparams == NULL || fnparams->empty())
+	stub_params = NULL;
+      else
+	{
+	  // We give each stub parameter a unique name.
+	  stub_params = new Typed_identifier_list();
+	  for (Typed_identifier_list::const_iterator pp = fnparams->begin();
+	       pp != fnparams->end();
+	       ++pp)
+	    {
+	      char pbuf[100];
+	      snprintf(pbuf, sizeof pbuf, "$p%u", counter);
+	      stub_params->push_back(Typed_identifier(pbuf, pp->type(),
+						      pp->location()));
+	      ++counter;
+	    }
+	}
+
+      const Typed_identifier_list* fnresults = fntype->results();
+      Typed_identifier_list* stub_results;
+      if (fnresults == NULL || fnresults->empty())
+	stub_results = NULL;
+      else
+	{
+	  // We create the result parameters without any names, since
+	  // we won't refer to them.
+	  stub_results = new Typed_identifier_list();
+	  for (Typed_identifier_list::const_iterator pr = fnresults->begin();
+	       pr != fnresults->end();
+	       ++pr)
+	    stub_results->push_back(Typed_identifier("", pr->type(),
+						     pr->location()));
+	}
+
+      Function_type* stub_type = Type::make_function_type(receiver,
+							  stub_params,
+							  stub_results,
+							  fntype->location());
+      if (fntype->is_varargs())
+	stub_type->set_is_varargs();
+
+      // We only create the function in the package which creates the
+      // type.
+      const Package* package;
+      if (type->named_type() == NULL)
+	package = NULL;
+      else
+	package = type->named_type()->named_object()->package();
+      std::string stub_name = gogo->stub_method_name(name);
+      Named_object* stub;
+      if (package != NULL)
+	stub = Named_object::make_function_declaration(stub_name, package,
+						       stub_type, location);
+      else
+	{
+	  stub = gogo->start_function(stub_name, stub_type, false,
+				      fntype->location());
+	  Type::build_one_stub_method(gogo, m, buf, stub_params,
+				      fntype->is_varargs(), location);
+	  gogo->finish_function(fntype->location());
+
+	  if (type->named_type() == NULL && stub->is_function())
+	    stub->func_value()->set_is_unnamed_type_stub_method();
+	  if (m->nointerface() && stub->is_function())
+	    stub->func_value()->set_nointerface();
+	}
+
+      m->set_stub_object(stub);
+    }
+}
+
+// Build a stub method which adjusts the receiver as required to call
+// METHOD.  RECEIVER_NAME is the name we used for the receiver.
+// PARAMS is the list of function parameters.
+
+void
+Type::build_one_stub_method(Gogo* gogo, Method* method,
+			    const char* receiver_name,
+			    const Typed_identifier_list* params,
+			    bool is_varargs,
+			    Location location)
+{
+  Named_object* receiver_object = gogo->lookup(receiver_name, NULL);
+  go_assert(receiver_object != NULL);
+
+  Expression* expr = Expression::make_var_reference(receiver_object, location);
+  expr = Type::apply_field_indexes(expr, method->field_indexes(), location);
+  if (expr->type()->points_to() == NULL)
+    expr = Expression::make_unary(OPERATOR_AND, expr, location);
+
+  Expression_list* arguments;
+  if (params == NULL || params->empty())
+    arguments = NULL;
+  else
+    {
+      arguments = new Expression_list();
+      for (Typed_identifier_list::const_iterator p = params->begin();
+	   p != params->end();
+	   ++p)
+	{
+	  Named_object* param = gogo->lookup(p->name(), NULL);
+	  go_assert(param != NULL);
+	  Expression* param_ref = Expression::make_var_reference(param,
+								 location);
+	  arguments->push_back(param_ref);
+	}
+    }
+
+  Expression* func = method->bind_method(expr, location);
+  go_assert(func != NULL);
+  Call_expression* call = Expression::make_call(func, arguments, is_varargs,
+						location);
+
+  gogo->add_statement(Statement::make_return_from_call(call, location));
+}
+
+// Apply FIELD_INDEXES to EXPR.  The field indexes have to be applied
+// in reverse order.
+
+Expression*
+Type::apply_field_indexes(Expression* expr,
+			  const Method::Field_indexes* field_indexes,
+			  Location location)
+{
+  if (field_indexes == NULL)
+    return expr;
+  expr = Type::apply_field_indexes(expr, field_indexes->next, location);
+  Struct_type* stype = expr->type()->deref()->struct_type();
+  go_assert(stype != NULL
+	     && field_indexes->field_index < stype->field_count());
+  if (expr->type()->struct_type() == NULL)
+    {
+      go_assert(expr->type()->points_to() != NULL);
+      expr = Expression::make_unary(OPERATOR_MULT, expr, location);
+      go_assert(expr->type()->struct_type() == stype);
+    }
+  return Expression::make_field_reference(expr, field_indexes->field_index,
+					  location);
+}
+
+// Return whether NO is a method for which the receiver is a pointer.
+
+bool
+Type::method_expects_pointer(const Named_object* no)
+{
+  const Function_type *fntype;
+  if (no->is_function())
+    fntype = no->func_value()->type();
+  else if (no->is_function_declaration())
+    fntype = no->func_declaration_value()->type();
+  else
+    go_unreachable();
+  return fntype->receiver()->type()->points_to() != NULL;
+}
+
+// Given a set of methods for a type, METHODS, return the method NAME,
+// or NULL if there isn't one or if it is ambiguous.  If IS_AMBIGUOUS
+// is not NULL, then set *IS_AMBIGUOUS to true if the method exists
+// but is ambiguous (and return NULL).
+
+Method*
+Type::method_function(const Methods* methods, const std::string& name,
+		      bool* is_ambiguous)
+{
+  if (is_ambiguous != NULL)
+    *is_ambiguous = false;
+  if (methods == NULL)
+    return NULL;
+  Methods::const_iterator p = methods->find(name);
+  if (p == methods->end())
+    return NULL;
+  Method* m = p->second;
+  if (m->is_ambiguous())
+    {
+      if (is_ambiguous != NULL)
+	*is_ambiguous = true;
+      return NULL;
+    }
+  return m;
+}
+
+// Return a pointer to the interface method table for TYPE for the
+// interface INTERFACE.
+
+Expression*
+Type::interface_method_table(Type* type,
+			     Interface_type *interface,
+			     bool is_pointer,
+			     Interface_method_tables** method_tables,
+			     Interface_method_tables** pointer_tables)
+{
+  go_assert(!interface->is_empty());
+
+  Interface_method_tables** pimt = is_pointer ? method_tables : pointer_tables;
+
+  if (*pimt == NULL)
+    *pimt = new Interface_method_tables(5);
+
+  std::pair<Interface_type*, Expression*> val(interface, NULL);
+  std::pair<Interface_method_tables::iterator, bool> ins = (*pimt)->insert(val);
+
+  Location loc = Linemap::predeclared_location();
+  if (ins.second)
+    {
+      // This is a new entry in the hash table.
+      go_assert(ins.first->second == NULL);
+      ins.first->second =
+	Expression::make_interface_mtable_ref(interface, type, is_pointer, loc);
+    }
+  return Expression::make_unary(OPERATOR_AND, ins.first->second, loc);
+}
+
+// Look for field or method NAME for TYPE.  Return an Expression for
+// the field or method bound to EXPR.  If there is no such field or
+// method, give an appropriate error and return an error expression.
+
+Expression*
+Type::bind_field_or_method(Gogo* gogo, const Type* type, Expression* expr,
+			   const std::string& name,
+			   Location location)
+{
+  if (type->deref()->is_error_type())
+    return Expression::make_error(location);
+
+  const Named_type* nt = type->deref()->named_type();
+  const Struct_type* st = type->deref()->struct_type();
+  const Interface_type* it = type->interface_type();
+
+  // If this is a pointer to a pointer, then it is possible that the
+  // pointed-to type has methods.
+  bool dereferenced = false;
+  if (nt == NULL
+      && st == NULL
+      && it == NULL
+      && type->points_to() != NULL
+      && type->points_to()->points_to() != NULL)
+    {
+      expr = Expression::make_unary(OPERATOR_MULT, expr, location);
+      type = type->points_to();
+      if (type->deref()->is_error_type())
+	return Expression::make_error(location);
+      nt = type->points_to()->named_type();
+      st = type->points_to()->struct_type();
+      dereferenced = true;
+    }
+
+  bool receiver_can_be_pointer = (expr->type()->points_to() != NULL
+				  || expr->is_addressable());
+  std::vector<const Named_type*> seen;
+  bool is_method = false;
+  bool found_pointer_method = false;
+  std::string ambig1;
+  std::string ambig2;
+  if (Type::find_field_or_method(type, name, receiver_can_be_pointer,
+				 &seen, NULL, &is_method,
+				 &found_pointer_method, &ambig1, &ambig2))
+    {
+      Expression* ret;
+      if (!is_method)
+	{
+	  go_assert(st != NULL);
+	  if (type->struct_type() == NULL)
+	    {
+              if (dereferenced)
+                {
+                  go_error_at(location, "pointer type has no field %qs",
+                              Gogo::message_name(name).c_str());
+                  return Expression::make_error(location);
+                }
+	      go_assert(type->points_to() != NULL);
+	      expr = Expression::make_unary(OPERATOR_MULT, expr,
+					    location);
+	      go_assert(expr->type()->struct_type() == st);
+	    }
+	  ret = st->field_reference(expr, name, location);
+          if (ret == NULL)
+            {
+              go_error_at(location, "type has no field %qs",
+                          Gogo::message_name(name).c_str());
+              return Expression::make_error(location);
+            }
+	}
+      else if (it != NULL && it->find_method(name) != NULL)
+	ret = Expression::make_interface_field_reference(expr, name,
+							 location);
+      else
+	{
+	  Method* m;
+	  if (nt != NULL)
+	    m = nt->method_function(name, NULL);
+	  else if (st != NULL)
+	    m = st->method_function(name, NULL);
+	  else
+	    go_unreachable();
+	  go_assert(m != NULL);
+	  if (dereferenced)
+	    {
+	      go_error_at(location,
+			  "calling method %qs requires explicit dereference",
+			  Gogo::message_name(name).c_str());
+	      return Expression::make_error(location);
+	    }
+	  if (!m->is_value_method() && expr->type()->points_to() == NULL)
+	    expr = Expression::make_unary(OPERATOR_AND, expr, location);
+	  ret = m->bind_method(expr, location);
+	}
+      go_assert(ret != NULL);
+      return ret;
+    }
+  else
+    {
+      if (Gogo::is_erroneous_name(name))
+	{
+	  // An error was already reported.
+	}
+      else if (!ambig1.empty())
+	go_error_at(location, "%qs is ambiguous via %qs and %qs",
+		    Gogo::message_name(name).c_str(), ambig1.c_str(),
+		    ambig2.c_str());
+      else if (found_pointer_method)
+	go_error_at(location, "method requires a pointer receiver");
+      else if (nt == NULL && st == NULL && it == NULL)
+	go_error_at(location,
+		    ("reference to field %qs in object which "
+		     "has no fields or methods"),
+		    Gogo::message_name(name).c_str());
+      else
+	{
+	  bool is_unexported;
+	  // The test for 'a' and 'z' is to handle builtin names,
+	  // which are not hidden.
+	  if (!Gogo::is_hidden_name(name) && (name[0] < 'a' || name[0] > 'z'))
+	    is_unexported = false;
+	  else
+	    {
+	      std::string unpacked = Gogo::unpack_hidden_name(name);
+	      seen.clear();
+	      is_unexported = Type::is_unexported_field_or_method(gogo, type,
+								  unpacked,
+								  &seen);
+	    }
+	  if (is_unexported)
+	    go_error_at(location, "reference to unexported field or method %qs",
+			Gogo::message_name(name).c_str());
+	  else
+	    go_error_at(location, "reference to undefined field or method %qs",
+			Gogo::message_name(name).c_str());
+	}
+      return Expression::make_error(location);
+    }
+}
+
+// Look in TYPE for a field or method named NAME, return true if one
+// is found.  This looks through embedded anonymous fields and handles
+// ambiguity.  If a method is found, sets *IS_METHOD to true;
+// otherwise, if a field is found, set it to false.  If
+// RECEIVER_CAN_BE_POINTER is false, then the receiver is a value
+// whose address can not be taken.  SEEN is used to avoid infinite
+// recursion on invalid types.
+
+// When returning false, this sets *FOUND_POINTER_METHOD if we found a
+// method we couldn't use because it requires a pointer.  LEVEL is
+// used for recursive calls, and can be NULL for a non-recursive call.
+// When this function returns false because it finds that the name is
+// ambiguous, it will store a path to the ambiguous names in *AMBIG1
+// and *AMBIG2.  If the name is not found at all, *AMBIG1 and *AMBIG2
+// will be unchanged.
+
+// This function just returns whether or not there is a field or
+// method, and whether it is a field or method.  It doesn't build an
+// expression to refer to it.  If it is a method, we then look in the
+// list of all methods for the type.  If it is a field, the search has
+// to be done again, looking only for fields, and building up the
+// expression as we go.
+
+bool
+Type::find_field_or_method(const Type* type,
+			   const std::string& name,
+			   bool receiver_can_be_pointer,
+			   std::vector<const Named_type*>* seen,
+			   int* level,
+			   bool* is_method,
+			   bool* found_pointer_method,
+			   std::string* ambig1,
+			   std::string* ambig2)
+{
+  // Named types can have locally defined methods.
+  const Named_type* nt = type->named_type();
+  if (nt == NULL && type->points_to() != NULL)
+    nt = type->points_to()->named_type();
+  if (nt != NULL)
+    {
+      Named_object* no = nt->find_local_method(name);
+      if (no != NULL)
+	{
+	  if (receiver_can_be_pointer || !Type::method_expects_pointer(no))
+	    {
+	      *is_method = true;
+	      return true;
+	    }
+
+	  // Record that we have found a pointer method in order to
+	  // give a better error message if we don't find anything
+	  // else.
+	  *found_pointer_method = true;
+	}
+
+      for (std::vector<const Named_type*>::const_iterator p = seen->begin();
+	   p != seen->end();
+	   ++p)
+	{
+	  if (*p == nt)
+	    {
+	      // We've already seen this type when searching for methods.
+	      return false;
+	    }
+	}
+    }
+
+  // Interface types can have methods.
+  const Interface_type* it = type->interface_type();
+  if (it != NULL && it->find_method(name) != NULL)
+    {
+      *is_method = true;
+      return true;
+    }
+
+  // Struct types can have fields.  They can also inherit fields and
+  // methods from anonymous fields.
+  const Struct_type* st = type->deref()->struct_type();
+  if (st == NULL)
+    return false;
+  const Struct_field_list* fields = st->fields();
+  if (fields == NULL)
+    return false;
+
+  if (nt != NULL)
+    seen->push_back(nt);
+
+  int found_level = 0;
+  bool found_is_method = false;
+  std::string found_ambig1;
+  std::string found_ambig2;
+  const Struct_field* found_parent = NULL;
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf)
+    {
+      if (pf->is_field_name(name))
+	{
+	  *is_method = false;
+	  if (nt != NULL)
+	    seen->pop_back();
+	  return true;
+	}
+
+      if (!pf->is_anonymous())
+	continue;
+
+      if (pf->type()->deref()->is_error_type()
+	  || pf->type()->deref()->is_undefined())
+	continue;
+
+      Named_type* fnt = pf->type()->named_type();
+      if (fnt == NULL)
+	fnt = pf->type()->deref()->named_type();
+      go_assert(fnt != NULL);
+
+      // Methods with pointer receivers on embedded field are
+      // inherited by the pointer to struct, and also by the struct
+      // type if the field itself is a pointer.
+      bool can_be_pointer = (receiver_can_be_pointer
+			     || pf->type()->points_to() != NULL);
+      int sublevel = level == NULL ? 1 : *level + 1;
+      bool sub_is_method;
+      std::string subambig1;
+      std::string subambig2;
+      bool subfound = Type::find_field_or_method(fnt,
+						 name,
+						 can_be_pointer,
+						 seen,
+						 &sublevel,
+						 &sub_is_method,
+						 found_pointer_method,
+						 &subambig1,
+						 &subambig2);
+      if (!subfound)
+	{
+	  if (!subambig1.empty())
+	    {
+	      // The name was found via this field, but is ambiguous.
+	      // if the ambiguity is lower or at the same level as
+	      // anything else we have already found, then we want to
+	      // pass the ambiguity back to the caller.
+	      if (found_level == 0 || sublevel <= found_level)
+		{
+		  found_ambig1 = (Gogo::message_name(pf->field_name())
+				  + '.' + subambig1);
+		  found_ambig2 = (Gogo::message_name(pf->field_name())
+				  + '.' + subambig2);
+		  found_level = sublevel;
+		}
+	    }
+	}
+      else
+	{
+	  // The name was found via this field.  Use the level to see
+	  // if we want to use this one, or whether it introduces an
+	  // ambiguity.
+	  if (found_level == 0 || sublevel < found_level)
+	    {
+	      found_level = sublevel;
+	      found_is_method = sub_is_method;
+	      found_ambig1.clear();
+	      found_ambig2.clear();
+	      found_parent = &*pf;
+	    }
+	  else if (sublevel > found_level)
+	    ;
+	  else if (found_ambig1.empty())
+	    {
+	      // We found an ambiguity.
+	      go_assert(found_parent != NULL);
+	      found_ambig1 = Gogo::message_name(found_parent->field_name());
+	      found_ambig2 = Gogo::message_name(pf->field_name());
+	    }
+	  else
+	    {
+	      // We found an ambiguity, but we already know of one.
+	      // Just report the earlier one.
+	    }
+	}
+    }
+
+  // Here if we didn't find anything FOUND_LEVEL is 0.  If we found
+  // something ambiguous, FOUND_LEVEL is not 0 and FOUND_AMBIG1 and
+  // FOUND_AMBIG2 are not empty.  If we found the field, FOUND_LEVEL
+  // is not 0 and FOUND_AMBIG1 and FOUND_AMBIG2 are empty.
+
+  if (nt != NULL)
+    seen->pop_back();
+
+  if (found_level == 0)
+    return false;
+  else if (found_is_method
+	   && type->named_type() != NULL
+	   && type->points_to() != NULL)
+    {
+      // If this is a method inherited from a struct field in a named pointer
+      // type, it is invalid to automatically dereference the pointer to the
+      // struct to find this method.
+      if (level != NULL)
+	*level = found_level;
+      *is_method = true;
+      return false;
+    }
+  else if (!found_ambig1.empty())
+    {
+      go_assert(!found_ambig1.empty());
+      ambig1->assign(found_ambig1);
+      ambig2->assign(found_ambig2);
+      if (level != NULL)
+	*level = found_level;
+      return false;
+    }
+  else
+    {
+      if (level != NULL)
+	*level = found_level;
+      *is_method = found_is_method;
+      return true;
+    }
+}
+
+// Return whether NAME is an unexported field or method for TYPE.
+
+bool
+Type::is_unexported_field_or_method(Gogo* gogo, const Type* type,
+				    const std::string& name,
+				    std::vector<const Named_type*>* seen)
+{
+  const Named_type* nt = type->named_type();
+  if (nt == NULL)
+    nt = type->deref()->named_type();
+  if (nt != NULL)
+    {
+      if (nt->is_unexported_local_method(gogo, name))
+	return true;
+
+      for (std::vector<const Named_type*>::const_iterator p = seen->begin();
+	   p != seen->end();
+	   ++p)
+	{
+	  if (*p == nt)
+	    {
+	      // We've already seen this type.
+	      return false;
+	    }
+	}
+    }
+
+  const Interface_type* it = type->interface_type();
+  if (it != NULL && it->is_unexported_method(gogo, name))
+    return true;
+
+  type = type->deref();
+
+  const Struct_type* st = type->struct_type();
+  if (st != NULL && st->is_unexported_local_field(gogo, name))
+    return true;
+
+  if (st == NULL)
+    return false;
+
+  const Struct_field_list* fields = st->fields();
+  if (fields == NULL)
+    return false;
+
+  if (nt != NULL)
+    seen->push_back(nt);
+
+  for (Struct_field_list::const_iterator pf = fields->begin();
+       pf != fields->end();
+       ++pf)
+    {
+      if (pf->is_anonymous()
+	  && !pf->type()->deref()->is_error_type()
+	  && !pf->type()->deref()->is_undefined())
+	{
+	  Named_type* subtype = pf->type()->named_type();
+	  if (subtype == NULL)
+	    subtype = pf->type()->deref()->named_type();
+	  if (subtype == NULL)
+	    {
+	      // This is an error, but it will be diagnosed elsewhere.
+	      continue;
+	    }
+	  if (Type::is_unexported_field_or_method(gogo, subtype, name, seen))
+	    {
+	      if (nt != NULL)
+		seen->pop_back();
+	      return true;
+	    }
+	}
+    }
+
+  if (nt != NULL)
+    seen->pop_back();
+
+  return false;
+}
+
+// Class Forward_declaration.
+
+Forward_declaration_type::Forward_declaration_type(Named_object* named_object)
+  : Type(TYPE_FORWARD),
+    named_object_(named_object->resolve()), warned_(false)
+{
+  go_assert(this->named_object_->is_unknown()
+	     || this->named_object_->is_type_declaration());
+}
+
+// Return the named object.
+
+Named_object*
+Forward_declaration_type::named_object()
+{
+  return this->named_object_->resolve();
+}
+
+const Named_object*
+Forward_declaration_type::named_object() const
+{
+  return this->named_object_->resolve();
+}
+
+// Return the name of the forward declared type.
+
+const std::string&
+Forward_declaration_type::name() const
+{
+  return this->named_object()->name();
+}
+
+// Warn about a use of a type which has been declared but not defined.
+
+void
+Forward_declaration_type::warn() const
+{
+  Named_object* no = this->named_object_->resolve();
+  if (no->is_unknown())
+    {
+      // The name was not defined anywhere.
+      if (!this->warned_)
+	{
+	  go_error_at(this->named_object_->location(),
+		      "use of undefined type %qs",
+		      no->message_name().c_str());
+	  this->warned_ = true;
+	}
+    }
+  else if (no->is_type_declaration())
+    {
+      // The name was seen as a type, but the type was never defined.
+      if (no->type_declaration_value()->using_type())
+	{
+	  go_error_at(this->named_object_->location(),
+		      "use of undefined type %qs",
+		      no->message_name().c_str());
+	  this->warned_ = true;
+	}
+    }
+  else
+    {
+      // The name was defined, but not as a type.
+      if (!this->warned_)
+	{
+	  go_error_at(this->named_object_->location(), "expected type");
+	  this->warned_ = true;
+	}
+    }
+}
+
+// Get the base type of a declaration.  This gives an error if the
+// type has not yet been defined.
+
+Type*
+Forward_declaration_type::real_type()
+{
+  if (this->is_defined())
+    {
+      Named_type* nt = this->named_object()->type_value();
+      if (!nt->is_valid())
+	return Type::make_error_type();
+      return this->named_object()->type_value();
+    }
+  else
+    {
+      this->warn();
+      return Type::make_error_type();
+    }
+}
+
+const Type*
+Forward_declaration_type::real_type() const
+{
+  if (this->is_defined())
+    {
+      const Named_type* nt = this->named_object()->type_value();
+      if (!nt->is_valid())
+	return Type::make_error_type();
+      return this->named_object()->type_value();
+    }
+  else
+    {
+      this->warn();
+      return Type::make_error_type();
+    }
+}
+
+// Return whether the base type is defined.
+
+bool
+Forward_declaration_type::is_defined() const
+{
+  return this->named_object()->is_type();
+}
+
+// Add a method.  This is used when methods are defined before the
+// type.
+
+Named_object*
+Forward_declaration_type::add_method(const std::string& name,
+				     Function* function)
+{
+  Named_object* no = this->named_object();
+  if (no->is_unknown())
+    no->declare_as_type();
+  return no->type_declaration_value()->add_method(name, function);
+}
+
+// Add a method declaration.  This is used when methods are declared
+// before the type.
+
+Named_object*
+Forward_declaration_type::add_method_declaration(const std::string& name,
+						 Package* package,
+						 Function_type* type,
+						 Location location)
+{
+  Named_object* no = this->named_object();
+  if (no->is_unknown())
+    no->declare_as_type();
+  Type_declaration* td = no->type_declaration_value();
+  return td->add_method_declaration(name, package, type, location);
+}
+
+// Add an already created object as a method.
+
+void
+Forward_declaration_type::add_existing_method(Named_object* nom)
+{
+  Named_object* no = this->named_object();
+  if (no->is_unknown())
+    no->declare_as_type();
+  no->type_declaration_value()->add_existing_method(nom);
+}
+
+// Traversal.
+
+int
+Forward_declaration_type::do_traverse(Traverse* traverse)
+{
+  if (this->is_defined()
+      && Type::traverse(this->real_type(), traverse) == TRAVERSE_EXIT)
+    return TRAVERSE_EXIT;
+  return TRAVERSE_CONTINUE;
+}
+
+// Verify the type.
+
+bool
+Forward_declaration_type::do_verify()
+{
+  if (!this->is_defined() && !this->is_nil_constant_as_type())
+    {
+      this->warn();
+      return false;
+    }
+  return true;
+}
+
+// Get the backend representation for the type.
+
+Btype*
+Forward_declaration_type::do_get_backend(Gogo* gogo)
+{
+  if (this->is_defined())
+    return Type::get_named_base_btype(gogo, this->real_type());
+
+  if (this->warned_)
+    return gogo->backend()->error_type();
+
+  // We represent an undefined type as a struct with no fields.  That
+  // should work fine for the backend, since the same case can arise
+  // in C.
+  std::vector<Backend::Btyped_identifier> fields;
+  Btype* bt = gogo->backend()->struct_type(fields);
+  return gogo->backend()->named_type(this->name(), bt,
+				     this->named_object()->location());
+}
+
+// Build a type descriptor for a forwarded type.
+
+Expression*
+Forward_declaration_type::do_type_descriptor(Gogo* gogo, Named_type* name)
+{
+  Location ploc = Linemap::predeclared_location();
+  if (!this->is_defined())
+    return Expression::make_error(ploc);
+  else
+    {
+      Type* t = this->real_type();
+      if (name != NULL)
+	return this->named_type_descriptor(gogo, t, name);
+      else
+	return Expression::make_error(this->named_object_->location());
+    }
+}
+
+// The reflection string.
+
+void
+Forward_declaration_type::do_reflection(Gogo* gogo, std::string* ret) const
+{
+  this->append_reflection(this->real_type(), gogo, ret);
+}
+
+// Export a forward declaration.  This can happen when a defined type
+// refers to a type which is only declared (and is presumably defined
+// in some other file in the same package).
+
+void
+Forward_declaration_type::do_export(Export*) const
+{
+  // If there is a base type, that should be exported instead of this.
+  go_assert(!this->is_defined());
+
+  // We don't output anything.
+}
+
+// Make a forward declaration.
+
+Type*
+Type::make_forward_declaration(Named_object* named_object)
+{
+  return new Forward_declaration_type(named_object);
+}
+
+// Class Typed_identifier_list.
+
+// Sort the entries by name.
+
+struct Typed_identifier_list_sort
+{
+ public:
+  bool
+  operator()(const Typed_identifier& t1, const Typed_identifier& t2) const
+  {
+    return (Gogo::unpack_hidden_name(t1.name())
+	    < Gogo::unpack_hidden_name(t2.name()));
+  }
+};
+
+void
+Typed_identifier_list::sort_by_name()
+{
+  std::sort(this->entries_.begin(), this->entries_.end(),
+	    Typed_identifier_list_sort());
+}
+
+// Traverse types.
+
+int
+Typed_identifier_list::traverse(Traverse* traverse)
+{
+  for (Typed_identifier_list::const_iterator p = this->begin();
+       p != this->end();
+       ++p)
+    {
+      if (Type::traverse(p->type(), traverse) == TRAVERSE_EXIT)
+	return TRAVERSE_EXIT;
+    }
+  return TRAVERSE_CONTINUE;
+}
+
+// Copy the list.
+
+Typed_identifier_list*
+Typed_identifier_list::copy() const
+{
+  Typed_identifier_list* ret = new Typed_identifier_list();
+  for (Typed_identifier_list::const_iterator p = this->begin();
+       p != this->end();
+       ++p)
+    ret->push_back(Typed_identifier(p->name(), p->type(), p->location()));
+  return ret;
+}