[libcxx] r216909 - Fix PR#20834 - 'is_trivially_destructible yeilds wrong answer for arrays of unknown bound' Thanks to K-ballo for the bug report. Update a few of the other tests while we're here, and fix a typo in a test name.

[Agustín K-ballo Bergé]

Hi Argyrios

On 30/09/2014 10:45 p.m., Argyrios Kyrtzidis wrote:
> Hi Marshall,
>
> This seems to have caused a regression with Objective-C++, see the following test case:
>
> #include <type_traits>
>
> class CXXForwardClass;
> @class ObjCForwardClass;
>
> static_assert(std::is_trivially_destructible<CXXForwardClass*>::value == true, "it is true"); // true
> static_assert(std::is_trivially_destructible<ObjCForwardClass*>::value == true, "it is true"); // false ?

This sounds like a pre-existing issue to me. Does the following test 
case hold?

   static_assert(std::is_destructible<CXXForwardClass*>::value == true, 
"it is true"); // true
   static_assert(std::is_destructible<ObjCForwardClass*>::value == true, 
"it is true"); // false ?

>> On Sep 2, 2014, at 9:19 AM, Marshall Clow <mclow.lists at gmail.com> wrote:
>>
>> Author: marshall
>> Date: Tue Sep  2 11:19:38 2014
>> New Revision: 216909
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=216909&view=rev
>> Log:
>> Fix PR#20834 - 'is_trivially_destructible yeilds wrong answer for arrays of unknown bound' Thanks to K-ballo for the bug report. Update a few of the other tests while we're here, and fix a typo in a test name.
>>
>> --- libcxx/trunk/include/type_traits (original)
>> +++ libcxx/trunk/include/type_traits Tue Sep  2 11:19:38 2014
>> @@ -2861,7 +2861,7 @@ template <class _Tp> struct _LIBCPP_TYPE
>> #if __has_feature(has_trivial_destructor) || (_GNUC_VER >= 403)
>>
>> template <class _Tp> struct _LIBCPP_TYPE_VIS_ONLY is_trivially_destructible
>> -    : public integral_constant<bool, __has_trivial_destructor(_Tp)> {};
>> +    : public integral_constant<bool, is_destructible<_Tp>::value && __has_trivial_destructor(_Tp)> {};

This is the relevant change ^. Something that is not destructible cannot 
be trivially destructible by definition.

Regards,
-- 
Agustín K-ballo Bergé.-
http://talesofcpp.fusionfenix.com