[PATCH] Fix _GLIBCXX_DEBUG tests

[Jonathan Wakely]

On 14/12/20 22:36 +0100, François Dumont wrote:
>On 14/12/20 11:08 am, Jonathan Wakely wrote:
>>
>>
>>On Mon, 14 Dec 2020, 06:51 François Dumont via Libstdc++, 
>><libstdc++@gcc.gnu.org <mailto:libstdc%2B%2B@gcc.gnu.org>> wrote:
>>
>>    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.
>>
>>
>>
>>Ah yes, we'd need something like Daniel suggested, and it's not 
>>worth it just for C++11.
>>
>>Just limiting the tests to c++14 is fine.
>>
>>
>Attached patch committed then.

Thanks.