--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/d/d-incpath.cc	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,195 @@
+/* d-incpath.cc -- Set up combined import paths for the D frontend.
+   Copyright (C) 2006-2020 Free Software Foundation, Inc.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+
+#include "dmd/globals.h"
+
+#include "cppdefault.h"
+
+/* Look for directories that start with the standard prefix.
+   "Translate" them, i.e: replace /usr/local/lib/gcc with
+   IPREFIX and search them first.  Based on incpath.c.  */
+
+static char *
+prefixed_path (const char *path, const char *iprefix)
+{
+  size_t len;
+
+  if (cpp_relocated () && (len = cpp_PREFIX_len) != 0)
+  {
+    if (!strncmp (path, cpp_PREFIX, len))
+      {
+	static const char *relocated_prefix;
+	/* If this path starts with the configure-time prefix,
+	   but the compiler has been relocated, replace it
+	   with the run-time prefix.  */
+	if (!relocated_prefix)
+	  {
+	    /* Make relative prefix expects the first argument
+	       to be a program, not a directory.  */
+	    char *dummy = concat (gcc_exec_prefix, "dummy", NULL);
+	    relocated_prefix
+	      = make_relative_prefix (dummy,
+				      cpp_EXEC_PREFIX,
+				      cpp_PREFIX);
+	    free (dummy);
+	  }
+
+	return concat (relocated_prefix, path + len, NULL);
+      }
+  }
+
+  if (iprefix && (len = cpp_GCC_INCLUDE_DIR_len) != 0)
+    {
+      if (!strncmp (path, cpp_GCC_INCLUDE_DIR, len))
+	return concat (iprefix, path + len, NULL);
+    }
+
+  return xstrdup (path);
+}
+
+/* Add PATHS to the global import lookup path.  */
+
+static void
+add_globalpaths (Strings *paths)
+{
+  if (paths)
+    {
+      if (!global.path)
+	global.path = new Strings ();
+
+      for (size_t i = 0; i < paths->dim; i++)
+	{
+	  const char *path = (*paths)[i];
+	  const char *target = lrealpath (path);
+
+	  if (target == NULL || !FileName::exists (target))
+	    {
+	      if (target)
+		free (CONST_CAST (char *, target));
+	      continue;
+	    }
+
+	  global.path->push (target);
+	}
+    }
+}
+
+/* Add PATHS to the global file import lookup path.  */
+
+static void
+add_filepaths (Strings *paths)
+{
+  if (paths)
+    {
+      if (!global.filePath)
+	global.filePath = new Strings ();
+
+      for (size_t i = 0; i < paths->dim; i++)
+	{
+	  const char *path = (*paths)[i];
+	  const char *target = lrealpath (path);
+
+	  if (!FileName::exists (target))
+	    {
+	      free (CONST_CAST (char *, target));
+	      continue;
+	    }
+
+	  global.filePath->push (target);
+	}
+    }
+}
+
+/* Add all search directories to compiler runtime.
+   if STDINC, also include standard library paths.  */
+
+void
+add_import_paths (const char *iprefix, const char *imultilib, bool stdinc)
+{
+  if (stdinc)
+    {
+      for (const default_include *p = cpp_include_defaults; p->fname; p++)
+	{
+	  char *path;
+
+	  /* Ignore C++ paths.  */
+	  if (p->cplusplus)
+	    continue;
+
+	  if (!p->add_sysroot)
+	    path = prefixed_path (p->fname, iprefix);
+	  else
+	    path = xstrdup (p->fname);
+
+	  /* Add D-specific suffix.  */
+	  path = concat (path, "/d", NULL);
+
+	  /* Ignore duplicate entries.  */
+	  bool found = false;
+	  for (size_t i = 0; i < global.params.imppath->dim; i++)
+	    {
+	      if (strcmp (path, (*global.params.imppath)[i]) == 0)
+		{
+		  found = true;
+		  break;
+		}
+	    }
+
+	  if (found)
+	    {
+	      free (path);
+	      continue;
+	    }
+
+	  /* Multilib support.  */
+	  if (imultilib)
+	    {
+	      char *target_path = concat (path, "/", imultilib, NULL);
+	      global.params.imppath->shift (target_path);
+	    }
+
+	  global.params.imppath->shift (path);
+	}
+    }
+
+  /* Add import search paths.  */
+  if (global.params.imppath)
+    {
+      for (size_t i = 0; i < global.params.imppath->dim; i++)
+	{
+	  const char *path = (*global.params.imppath)[i];
+	  if (path)
+	    add_globalpaths (FileName::splitPath (path));
+	}
+    }
+
+  /* Add string import search paths.  */
+  if (global.params.fileImppath)
+    {
+      for (size_t i = 0; i < global.params.fileImppath->dim; i++)
+	{
+	  const char *path = (*global.params.fileImppath)[i];
+	  if (path)
+	    add_filepaths (FileName::splitPath (path));
+	}
+    }
+}
+