Require effective target weak_undefined for visibility-22.c

2017-12-14  Tom de Vries  <tom@codesourcery.com>

	* lib/target-supports.exp (check_effective_target_weak_undefined): New
	proc.
	* gcc.dg/visibility-22.c: Require effective target weak_undefined.

	* doc/sourcebuild.texi (Effective-Target Keywords, Other attributes):
	Add item for weak_undefined.

From-SVN: r255637

gcc/ChangeLog

+2017-12-14  Tom de Vries  <tom@codesourcery.com>
+
+	* doc/sourcebuild.texi (Effective-Target Keywords, Other attributes):
+	Add item for weak_undefined.
+
 2017-12-14  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/67842

gcc/doc/sourcebuild.texi

@@ -2238,6 +2238,9 @@ Target supports @code{wchar_t} that is compatible with @code{char32_t}.
 @item comdat_group
 Target uses comdat groups.
 
+@item weak_undefined
+Target supports weak undefined symbols.
+
 @item word_mode_no_slow_unalign
 Target does not have slow unaligned access when doing word size accesses.
 @end table

gcc/testsuite/ChangeLog

+2017-12-14  Tom de Vries  <tom@codesourcery.com>
+
+	* lib/target-supports.exp (check_effective_target_weak_undefined): New
+	proc.
+	* gcc.dg/visibility-22.c: Require effective target weak_undefined.
+
 2017-12-14  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/83326

gcc/testsuite/gcc.dg/visibility-22.c

 /* PR target/32219 */
 /* { dg-do run } */
 /* { dg-require-visibility "" } */
+/* { dg-require-effective-target weak_undefined } */
 /* { dg-options "-O2 -fPIC" { target fpic } } */
-/* This test requires support for undefined weak symbols.  This support
-   is not available on hppa*-*-hpux*.  The test is skipped rather than
-   xfailed to suppress the warning that would otherwise arise.  */
-/* { dg-skip-if "" { "hppa*-*-hpux*" "*-*-aix*" "*-*-darwin*" } }  */
 
 extern void foo () __attribute__((weak,visibility("hidden")));
 int

gcc/testsuite/lib/target-supports.exp

@@ -328,6 +328,15 @@ proc check_weak_available { } {
     }
 }
 
+# return 1 if weak undefined symbols are supported.
+
+proc check_effective_target_weak_undefined { } {
+    return [check_runtime weak_undefined {
+	extern void foo () __attribute__((weak));
+	int main (void) { if (foo) return 1; return 0; }
+    } ""]
+}
+
 ###############################
 # proc check_weak_override_available { }
 ###############################