PR c++/61825

	* c-family/c-common.c (handle_alias_ifunc_attribute): Check
	that visibility change is possible
	(handle_weakref_attribute): Likewise.
	* cgraph.h (symtab_node): Add method get_create and
	field refuse_visibility_changes.
	(symtab_node::get_create): New method.
	* fold-const.c (tree_single_nonzero_warnv_p): Use get_create.
	* varasm.c (mark_weak): Verify that visibility change is
	possible.

	* gcc.dg/tree-ssa/nonzero-1.c: Require error to be output.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@215409 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 18 insertions, 12 deletions

diff --git a/gcc/symtab.c b/gcc/symtab.c
index 792b3b50ea6..9590fc83dd2 100644
--- a/gcc/symtab.c
+++ b/gcc/symtab.c
@@ -1811,9 +1811,9 @@ bool
 symtab_node::nonzero_address ()
 {
   /* Weakrefs may be NULL when their target is not defined.  */
-  if (this->alias && this->weakref)
+  if (alias && weakref)
     {
-      if (this->analyzed)
+      if (analyzed)
 	{
 	  symtab_node *target = ultimate_alias_target ();
 
@@ -1828,7 +1828,7 @@ symtab_node::nonzero_address ()
 	     could be useful to eliminate the NULL pointer checks in LTO
 	     programs.  */
 	  if (target->definition && !DECL_EXTERNAL (target->decl))
-	    return true;
+	      return true;
 	  if (target->resolution != LDPR_UNKNOWN
 	      && target->resolution != LDPR_UNDEF
 	      && flag_delete_null_pointer_checks)
@@ -1847,22 +1847,28 @@ symtab_node::nonzero_address ()
      Those are handled by later check for definition.
 
      When parsing, beware the cases when WEAK attribute is added later.  */
-  if (!DECL_WEAK (this->decl)
-      && flag_delete_null_pointer_checks
-      && symtab->state > PARSING)
-    return true;
+  if (!DECL_WEAK (decl)
+      && flag_delete_null_pointer_checks)
+    {
+      refuse_visibility_changes = true;
+      return true;
+    }
 
   /* If target is defined and not extern, we know it will be output and thus
      it will bind to non-NULL.
      Play safe for flag_delete_null_pointer_checks where weak definition maye
      be re-defined by NULL.  */
-  if (this->definition && !DECL_EXTERNAL (this->decl)
-      && (flag_delete_null_pointer_checks || !DECL_WEAK (this->decl)))
-    return true;
+  if (definition && !DECL_EXTERNAL (decl)
+      && (flag_delete_null_pointer_checks || !DECL_WEAK (decl)))
+    {
+      if (!DECL_WEAK (decl))
+        refuse_visibility_changes = true;
+      return true;
+    }
 
   /* As the last resort, check the resolution info.  */
-  if (this->resolution != LDPR_UNKNOWN
-      && this->resolution != LDPR_UNDEF
+  if (resolution != LDPR_UNKNOWN
+      && resolution != LDPR_UNDEF
       && flag_delete_null_pointer_checks)
     return true;
   return false;