re PR c++/51614 (ICE with ambiguous base class)

	PR c++/51614
	* class.c (build_base_path): Diagnose ambiguous base.

From-SVN: r183088

gcc/cp/ChangeLog

 2012-01-10  Jason Merrill  <jason@redhat.com>
 
+	PR c++/51614
+	* class.c (build_base_path): Diagnose ambiguous base.
+
 	PR c++/51433
 	* semantics.c (cxx_eval_call_expression): Always retry previously
 	non-constant expressions.

gcc/cp/class.c

@@ -266,10 +266,25 @@ build_base_path (enum tree_code code,
   if (want_pointer)
     probe = TYPE_MAIN_VARIANT (TREE_TYPE (probe));
 
+  if (code == PLUS_EXPR
+      && !SAME_BINFO_TYPE_P (BINFO_TYPE (d_binfo), probe))
+    {
+      /* This can happen when adjust_result_of_qualified_name_lookup can't
+	 find a unique base binfo in a call to a member function.  We
+	 couldn't give the diagnostic then since we might have been calling
+	 a static member function, so we do it now.  */
+      if (complain & tf_error)
+	{
+	  tree base = lookup_base (probe, BINFO_TYPE (d_binfo),
+				   ba_unique, NULL);
+	  gcc_assert (base == error_mark_node);
+	}
+      return error_mark_node;
+    }
+
   gcc_assert ((code == MINUS_EXPR
 	       && SAME_BINFO_TYPE_P (BINFO_TYPE (binfo), probe))
-	      || (code == PLUS_EXPR
-		  && SAME_BINFO_TYPE_P (BINFO_TYPE (d_binfo), probe)));
+	      || code == PLUS_EXPR);
 
   if (binfo == d_binfo)
     /* Nothing to do.  */

gcc/testsuite/ChangeLog

 2012-01-10  Jason Merrill  <jason@redhat.com>
 
+	PR c++/51614
+	* g++.dg/inherit/ambig1.C: New.
+
 	PR c++/51433
 	* g++.dg/cpp0x/constexpr-cache1.C: New.
 

gcc/testsuite/g++.dg/inherit/ambig1.C

+// PR c++/51614
+
+struct A
+{
+  void foo();
+};
+
+struct B : A {};
+struct C : A {};
+
+struct D : B, C
+{
+  D() { A::foo(); }		// { dg-error "ambiguous" }
+};