re PR c++/63942 (constexpr conflicts with previous declaration)

	PR c++/63942
	* name-lookup.c (supplement_binding_1): Override a mangling alias.
	* mangle.c (implicit_alias_p, remove_implicit_alias): New.
	(mangle_decl): Avoid creating conflicting alias with
	-fabi-compat-version=0, too.
	* cp-tree.h: Adjust.

From-SVN: r217950

1 files changed, 25 insertions, 2 deletions

diff --git a/gcc/cp/mangle.c b/gcc/cp/mangle.c
index 9f0d9d8..a244669 100644
--- a/gcc/cp/mangle.c
+++ b/gcc/cp/mangle.c
@@ -3428,6 +3428,28 @@ get_mangled_id (tree decl)
   return targetm.mangle_decl_assembler_name (decl, id);
 }
 
+/* If DECL is a mangling alias, remove it from the symbol table and return
+   true; otherwise return false.  */
+
+bool
+maybe_remove_implicit_alias (tree decl)
+{
+  if (DECL_P (decl) && DECL_ARTIFICIAL (decl)
+      && DECL_IGNORED_P (decl)
+      && (TREE_CODE (decl) == FUNCTION_DECL
+	  || (TREE_CODE (decl) == VAR_DECL
+	      && TREE_STATIC (decl))))
+    {
+      symtab_node *n = symtab_node::get (decl);
+      if (n && n->cpp_implicit_alias)
+	{
+	  n->remove();
+	  return true;
+	}
+    }
+  return false;
+}
+
 /* Create an identifier for the external mangled name of DECL.  */
 
 void
@@ -3491,8 +3513,9 @@ mangle_decl (const tree decl)
 	}
 
 #ifdef ASM_OUTPUT_DEF
-      if (flag_abi_compat_version != 0
-	  && IDENTIFIER_GLOBAL_VALUE (id2))
+      /* If there's a declaration already using this mangled name,
+	 don't create a compatibility alias that conflicts.  */
+      if (IDENTIFIER_GLOBAL_VALUE (id2))
 	return;
 
       tree alias = make_alias_for (decl, id2);