[PATCH] Fix _GLIBCXX_DEBUG tests

[François Dumont]

On 13/12/20 11:17 pm, Jonathan Wakely wrote:
> On 13/12/20 15:52 +0100, François Dumont via Libstdc++ wrote:
>> Some tests are XPASS because array assertions have been disabled for 
>> a good reason in C++11.
>>
>> I wonder if the respective non-constexpr _GLIBCXX_ASSERTION checks 
>> shouldn't target C++14 too. At the moment they are failing as 
>> expected but because of an Undefined Behavior no ?
>
> Hmm, maybe my "fix" for the bug was too hasty, and I should have done
> this instead:
>
> --- a/libstdc++-v3/include/bits/c++config
> +++ b/libstdc++-v3/include/bits/c++config
> @@ -684,7 +684,7 @@ namespace std
>
>  #undef _GLIBCXX_HAS_BUILTIN
>
> -#if _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
> +#if _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED && __cplusplus >= 
> 201402L
>  # define __glibcxx_assert_1(_Condition)                \
>      if (__builtin_is_constant_evaluated())     \
>       {                                         \
>
> That would allow us to keep the std::array runtime assertions for
> C++11, and only disable them in constexpr contexts.

I already tried to restore this check in C++11 runtime without success 
but I didn't try this approach.

I'll have a try but C++11 forces constexpr to be just a return statement 
so I fear that it won't appreciate the additional assertion.

>
>
>> The other test is failing because of some cleanup in headers which 
>> makes <memory> include necessary.
>>
>> Â Â Â  libstdc++: Fix several _GLIBCXX_DEBUG tests
>>
>> Â Â Â  libstdc++-v3/ChangeLog:
>>
>> Â Â Â Â Â Â Â Â Â Â Â  * 
>> testsuite/23_containers/array/debug/back2_neg.cc: target c++14 
>> because assertion
>> Â Â Â Â Â Â Â Â Â Â Â  for constexpr is disabled in C++11.
>> Â Â Â Â Â Â Â Â Â Â Â  * 
>> testsuite/23_containers/array/debug/front2_neg.cc: Likewise.
>> Â Â Â Â Â Â Â Â Â Â Â  * 
>> testsuite/23_containers/array/debug/square_brackets_operator2_neg.cc: 
>> Likewise.
>> Â Â Â Â Â Â Â Â Â Â Â  * 
>> testsuite/23_containers/vector/debug/multithreaded_swap.cc: Include 
>> <memory>
>> Â Â Â Â Â Â Â Â Â Â Â  for shared_ptr.
>>
>> Ok to commit ?
>
> Yes, thanks.
>
>