--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/attr-weakref-1.c	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,235 @@
+// { dg-do run }
+// { dg-require-weak "" }
+// On darwin, we use attr-weakref-1-darwin.c.
+
+// This test requires support for undefined weak symbols.  This support
+// is not available on the following targets.  The test is skipped rather than
+// xfailed to suppress the warning that would otherwise arise.
+// { dg-skip-if "" { "hppa*-*-hpux*" "*-*-aix*" "nvptx-*-*" } }
+
+// For kernel modules and static RTPs, the loader treats undefined weak
+// symbols in the same way as undefined strong symbols.  The test
+// therefore fails to load, so skip it.
+// { dg-skip-if "" { "*-*-vxworks*" && nonpic } "*" { "-non-static" } }
+// { dg-options "-O2" }
+// { dg-additional-options "-Wl,-undefined,dynamic_lookup" { target *-*-darwin* } }
+// { dg-additional-options "-Wl,-flat_namespace" { target *-*-darwin[89]* } }
+// { dg-additional-sources "attr-weakref-1a.c" }
+
+// Copyright 2005 Free Software Foundation, Inc.
+// Contributed by Alexandre Oliva <aoliva@redhat.com>
+
+// Torture test for weakrefs.  The first letter of an identifier
+// indicates whether/how it is defined; the second letter indicates
+// whether it is part of a variable or function test; the number that
+// follows is a test counter, and a letter that may follow enables
+// multiple identifiers within the same test (e.g., multiple weakrefs
+// or pointers to the same identifier).
+
+// Identifiers starting with W are weakrefs; those with p are
+// pointers; those with g are global definitions; those with l are
+// local definitions; those with w are expected to be weak undefined
+// in the symbol table; those with u are expected to be marked as
+// non-weak undefined in the symbol table.
+
+#include <stdlib.h>
+
+#define USED __attribute__((used))
+
+typedef int vtype;
+
+extern vtype wv1;
+static vtype Wv1a __attribute__((weakref ("wv1")));
+static vtype *pv1a USED = &Wv1a;
+
+vtype gv2;
+static vtype Wv2a __attribute__((weakref ("gv2")));
+static vtype *pv2a USED = &Wv2a;
+
+static vtype lv3;
+static vtype Wv3a __attribute__((weakref ("lv3")));
+static vtype *pv3a USED = &Wv3a;
+
+extern vtype uv4;
+static vtype Wv4a __attribute__((weakref ("uv4")));
+static vtype *pv4a USED = &Wv4a;
+static vtype *pv4 USED = &uv4;
+
+static vtype Wv5a __attribute__((weakref ("uv5")));
+static vtype *pv5a USED = &Wv5a;
+extern vtype uv5;
+static vtype *pv5 USED = &uv5;
+
+static vtype Wv6a __attribute__((weakref ("wv6")));
+static vtype *pv6a USED = &Wv6a;
+extern vtype wv6;
+
+static vtype Wv7a __attribute__((weakref ("uv7")));
+static vtype* USED fv7 (void) {
+  return &Wv7a;
+}
+extern vtype uv7;
+static vtype* USED fv7a (void) {
+  return &uv7;
+}
+
+extern vtype uv8;
+static vtype* USED fv8a (void) {
+  return &uv8;
+}
+static vtype Wv8a __attribute__((weakref ("uv8")));
+static vtype* USED fv8 (void) {
+  return &Wv8a;
+}
+
+extern vtype wv9 __attribute__((weak));
+static vtype Wv9a __attribute__((weakref ("wv9")));
+static vtype *pv9a USED = &Wv9a;
+
+static vtype Wv10a __attribute__((weakref ("Wv10b")));
+static vtype Wv10b __attribute__((weakref ("Wv10c")));
+static vtype Wv10c __attribute__((weakref ("Wv10d")));
+static vtype Wv10d __attribute__((weakref ("wv10")));
+extern vtype wv10;
+
+extern vtype wv11;
+static vtype Wv11d __attribute__((weakref ("wv11")));
+static vtype Wv11c __attribute__((weakref ("Wv11d")));
+static vtype Wv11b __attribute__((weakref ("Wv11c")));
+static vtype Wv11a __attribute__((weakref ("Wv11b")));
+
+static vtype Wv12 __attribute__((weakref ("wv12")));
+extern vtype wv12 __attribute__((weak));
+
+static vtype Wv13 __attribute__((weakref ("wv13")));
+extern vtype wv13 __attribute__((weak));
+
+static vtype Wv14a __attribute__((weakref ("wv14")));
+static vtype Wv14b __attribute__((weakref ("wv14")));
+extern vtype wv14 __attribute__((weak));
+
+typedef void ftype(void);
+
+extern ftype wf1;
+static ftype Wf1a __attribute__((weakref ("wf1")));
+static ftype *pf1a USED = &Wf1a;
+static ftype Wf1c __attribute__((weakref));
+extern ftype Wf1c __attribute__((alias ("wf1")));
+static ftype *pf1c USED = &Wf1c;
+
+void gf2(void) {}
+static ftype Wf2a __attribute__((weakref ("gf2")));
+static ftype *pf2a USED = &Wf2a;
+
+static void lf3(void) {}
+static ftype Wf3a __attribute__((weakref ("lf3")));
+static ftype *pf3a USED = &Wf3a;
+
+extern ftype uf4;
+static ftype Wf4a __attribute__((weakref ("uf4")));
+static ftype *pf4a USED = &Wf4a;
+static ftype *pf4 USED = &uf4;
+
+static ftype Wf5a __attribute__((weakref ("uf5")));
+static ftype *pf5a USED = &Wf5a;
+extern ftype uf5;
+static ftype *pf5 USED = &uf5;
+
+static ftype Wf6a __attribute__((weakref ("wf6")));
+static ftype *pf6a USED = &Wf6a;
+extern ftype wf6;
+
+static ftype Wf7a __attribute__((weakref ("uf7")));
+static ftype* USED ff7 (void) {
+  return &Wf7a;
+}
+extern ftype uf7;
+static ftype* USED ff7a (void) {
+  return &uf7;
+}
+
+extern ftype uf8;
+static ftype* USED ff8a (void) {
+  return &uf8;
+}
+static ftype Wf8a __attribute__((weakref ("uf8")));
+static ftype* USED ff8 (void) {
+  return &Wf8a;
+}
+
+extern ftype wf9 __attribute__((weak));
+static ftype Wf9a __attribute__((weakref ("wf9")));
+static ftype *pf9a USED = &Wf9a;
+
+static ftype Wf10a __attribute__((weakref ("Wf10b")));
+static ftype Wf10b __attribute__((weakref ("Wf10c")));
+static ftype Wf10c __attribute__((weakref ("Wf10d")));
+static ftype Wf10d __attribute__((weakref ("wf10")));
+extern ftype wf10;
+
+extern ftype wf11;
+static ftype Wf11d __attribute__((weakref ("wf11")));
+static ftype Wf11c __attribute__((weakref ("Wf11d")));
+static ftype Wf11b __attribute__((weakref ("Wf11c")));
+static ftype Wf11a __attribute__((weakref ("Wf11b")));
+
+static ftype Wf12 __attribute__((weakref ("wf12")));
+extern ftype wf12 __attribute__((weak));
+
+static ftype Wf13 __attribute__((weakref ("wf13")));
+extern ftype wf13 __attribute__((weak));
+
+static ftype Wf14a __attribute__((weakref ("wf14")));
+static ftype Wf14b __attribute__((weakref ("wf14")));
+extern ftype wf14 __attribute__((weak));
+
+#ifndef __APPLE__
+#define chk(p) do { if (!p) abort (); } while (0)
+#else
+#define chk(p) /* */
+#endif
+
+int main () {
+  chk (!pv1a);
+  chk (pv2a);
+  chk (pv3a);
+  chk (pv4a);
+  chk (pv4);
+  chk (pv5a);
+  chk (pv5);
+  chk (!pv6a);
+  chk (fv7 ());
+  chk (fv7a ());
+  chk (fv8 ());
+  chk (fv8a ());
+  chk (!pv9a);
+  chk (!&Wv10a);
+  chk (!&Wv11a);
+  chk (!&Wv12);
+  chk (!&wv12);
+  chk (!&wv13);
+  chk (!&Wv14a);
+
+  chk (!pf1a);
+  chk (!pf1c);
+  chk (pf2a);
+  chk (pf3a);
+  chk (pf4a);
+  chk (pf4);
+  chk (pf5a);
+  chk (pf5);
+  chk (!pf6a);
+  chk (ff7 ());
+  chk (ff7a ());
+  chk (ff8 ());
+  chk (ff8a ());
+  chk (!pf9a);
+  chk (!&Wf10a);
+  chk (!&Wf11a);
+  chk (!&Wf12);
+  chk (!&wf12);
+  chk (!&wf13);
+  chk (!&Wf14a);
+
+  exit (0);
+}