[C++ PATCH] Fix final overrider diagnostics (PR c++/21983)

[Jakub Jelinek]

Hi!

Since http://gcc.gnu.org/ml/gcc-patches/2002-11/msg00535.html
find_final_overrider is called not only from update_vtable_entry_for_fn,
but also possibly several times from add_vcall_offset.
But as it is find_final_overrider that issues the diagnostics,
the same error is printed multiple times (in the testcase below
4 times).
My understanding is that update_vtable_entry_for_fn will call
find_final_overrider for each virtual function once, so it should be
enough to warn there (it was certainly enough in GCC 3.2.x).
Ok for HEAD/4.0/3.4 if testing succeeds?

2005-09-05  Jakub Jelinek  <jakub@redhat.com>

	PR c++/21983
	* class.c (find_final_overrider): Move diagnostic about no unique final
	overrider to...
	(update_vtable_entry_for_fn): ... here.

--- gcc/cp/class.c.jj	2005-08-16 16:24:16.000000000 +0200
+++ gcc/cp/class.c	2005-09-05 17:03:08.000000000 +0200
@@ -1906,11 +1906,7 @@ find_final_overrider (tree derived, tree
 
   /* If there was no winner, issue an error message.  */
   if (!ffod.candidates || TREE_CHAIN (ffod.candidates))
-    {
-      error ("no unique final overrider for %qD in %qT", fn,
-	     BINFO_TYPE (derived));
-      return error_mark_node;
-    }
+    return error_mark_node;
 
   return ffod.candidates;
 }
@@ -1970,7 +1966,10 @@ update_vtable_entry_for_fn (tree t, tree
   /* Find the final overrider.  */
   overrider = find_final_overrider (TYPE_BINFO (t), b, target_fn);
   if (overrider == error_mark_node)
-    return;
+    {
+      error ("no unique final overrider for %qD in %qT", target_fn, t);
+      return;
+    }
   overrider_target = overrider_fn = TREE_PURPOSE (overrider);
 
   /* Check for adjusting covariant return types.  */
--- gcc/testsuite/g++.dg/warn/pr21983.C.jj	2005-09-05 17:06:42.000000000 +0200
+++ gcc/testsuite/g++.dg/warn/pr21983.C	2005-09-05 17:08:06.000000000 +0200
@@ -0,0 +1,7 @@
+// PR c++/21983
+// { dg-do compile }
+
+struct B { virtual void foo () = 0; };
+struct D1 : public virtual B { virtual void foo () {} };
+struct D2 : public virtual B { virtual void foo () {} };
+struct D : public D1, public D2 { };	// { dg-warning "no unique final overrider" }

	Jakub