diff mbox

[C++] PR 50732

Message ID 4E9882FF.1050407@oracle.com
State New
Headers show

Commit Message

Paolo Carlini Oct. 14, 2011, 6:44 p.m. UTC 
On 10/14/2011 08:30 PM, Paolo Carlini wrote:
> On 10/14/2011 08:23 PM, Paolo Carlini wrote:
>> Hi,
>>
>> submitter complains that, at variance with C++11, __is_base_of 
>> doesn't handle an incomplete base type (the first parameter). The 
>> reason seems simple: in finish_trait_expr we try to complete *both* 
>> types instead of doing it where/when necessary.
> Hmm, maybe we should be even more careful and call complete (type2) 
> only when
>
> NON_UNION_CLASS_TYPE_P (type1) && NON_UNION_CLASS_TYPE_P (type2) && 
> !same_type_ignoring_top_level_qualifiers_p (type1, type2)
>
> is true?
Like this?

Paolo.

///////////////////

Comments

Jason Merrill Oct. 14, 2011, 7:08 p.m. UTC | #1 
How about using complete_type_or_else?

Jason
diff mbox

Patch

Index: testsuite/g++.dg/ext/is_base_of_incomplete.C
===================================================================
--- testsuite/g++.dg/ext/is_base_of_incomplete.C	(revision 0)
+++ testsuite/g++.dg/ext/is_base_of_incomplete.C	(revision 0)
@@ -0,0 +1,7 @@ 
+template <typename T>
+struct non_instantiable
+{
+  typedef typename T::THIS_TYPE_CANNOT_BE_INSTANTIATED type;
+};
+
+int check[__is_base_of(non_instantiable<int>, void) ? -1 : 1];
Index: cp/semantics.c
===================================================================
--- cp/semantics.c	(revision 179997)
+++ cp/semantics.c	(working copy)
@@ -5276,10 +5276,6 @@  finish_trait_expr (cp_trait_kind kind, tree type1,
       return trait_expr;
     }
 
-  complete_type (type1);
-  if (type2)
-    complete_type (type2);
-
   switch (kind)
     {
     case CPTK_HAS_NOTHROW_ASSIGN:
@@ -5297,6 +5293,7 @@  finish_trait_expr (cp_trait_kind kind, tree type1,
     case CPTK_IS_POLYMORPHIC:
     case CPTK_IS_STD_LAYOUT:
     case CPTK_IS_TRIVIAL:
+      complete_type (type1);
       if (!check_trait_type (type1))
 	{
 	  error ("incomplete type %qT not allowed", type1);
@@ -5306,11 +5303,14 @@  finish_trait_expr (cp_trait_kind kind, tree type1,
 
     case CPTK_IS_BASE_OF:
       if (NON_UNION_CLASS_TYPE_P (type1) && NON_UNION_CLASS_TYPE_P (type2)
-	  && !same_type_ignoring_top_level_qualifiers_p (type1, type2)
-	  && !COMPLETE_TYPE_P (type2))
+	  && !same_type_ignoring_top_level_qualifiers_p (type1, type2))
 	{
-	  error ("incomplete type %qT not allowed", type2);
-	  return error_mark_node;
+	  complete_type (type2);
+	  if (!COMPLETE_TYPE_P (type2))
+	    {
+	      error ("incomplete type %qT not allowed", type2);
+	      return error_mark_node;
+	    }
 	}
       break;