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[C++,Patch/RFC] PR 63757

Message ID 5476282F.9020007@oracle.com
State New
Headers show

Commit Message

Paolo Carlini Nov. 26, 2014, 7:21 p.m. UTC 
Hi,

On 11/26/2014 05:24 PM, Jason Merrill wrote:
> On 11/24/2014 01:55 PM, Paolo Carlini wrote:
>> in this rejects-valid, as part of build_user_type_conversion_1,
>> standard_conversion is called by implicit_conversion with a *null* expr,
>> thus the condition in standard_conversion
>>
>>    /* [conv.ptr]
>>       A null pointer constant can be converted to a pointer type; ... A
>>       null pointer constant of integral type can be converted to an
>>       rvalue of type std::nullptr_t. */
>>    if ((tcode == POINTER_TYPE || TYPE_PTRMEM_P (to)
>>         || NULLPTR_TYPE_P (to))
>>        && expr && null_ptr_cst_p (expr))
>>      conv = build_conv (ck_std, to, conv);
>>
>> is false and the snippet is rejected. Should we pass a nullptr_node as
>> expr in such cases, ie, when handling conversions functions returning
>> std::nullptr_t?!?
>
> I'd prefer to change the test quoted above to not require expr to be 
> non-null in the case of NULLPTR_TYPE_P.
Oh good, I was unsure about that. The below also passes testing.

Thanks,
Paolo.

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

Comments

Jason Merrill Nov. 26, 2014, 7:27 p.m. UTC | #1 
OK.

Jason
diff mbox

Patch

Index: cp/call.c
===================================================================
--- cp/call.c	(revision 218089)
+++ cp/call.c	(working copy)
@@ -1194,7 +1194,8 @@  standard_conversion (tree to, tree from, tree expr
      rvalue of type std::nullptr_t. */
   if ((tcode == POINTER_TYPE || TYPE_PTRMEM_P (to)
        || NULLPTR_TYPE_P (to))
-      && expr && null_ptr_cst_p (expr))
+      && ((expr && null_ptr_cst_p (expr))
+	  || NULLPTR_TYPE_P (from)))
     conv = build_conv (ck_std, to, conv);
   else if ((tcode == INTEGER_TYPE && fcode == POINTER_TYPE)
 	   || (tcode == POINTER_TYPE && fcode == INTEGER_TYPE))
Index: testsuite/g++.dg/cpp0x/nullptr33.C
===================================================================
--- testsuite/g++.dg/cpp0x/nullptr33.C	(revision 0)
+++ testsuite/g++.dg/cpp0x/nullptr33.C	(working copy)
@@ -0,0 +1,19 @@ 
+// PR c++/63757
+// { dg-do compile { target c++11 } }
+
+typedef decltype(nullptr) nullptr_t;
+
+void bar(void*) {}
+ 
+struct foo
+{
+  operator nullptr_t()
+  {
+    return nullptr;
+  }
+};
+
+int main()
+{
+  bar(foo());
+}