Add dg-require-wchars to libstdc++ testsuite

[Jonathan Wakely]

On Fri, 15 Jan 2021, 19:47 Jonathan Wakely, <jwakely.gcc@gmail.com> wrote:

>
>
> On Fri, 15 Jan 2021, 16:19 Alexandre Oliva, <oliva@adacore.com> wrote:
>
>> On Jan 15, 2021, Jonathan Wakely <jwakely.gcc@gmail.com> wrote:
>>
>> > On Thu, 14 Jan 2021, 22:22 Alexandre Oliva, <oliva@adacore.com> wrote:
>> >> ... it is definitely the case that the target currently defines
>> wchar_t,
>> >> and it even offers wchar.h and a lot of (maybe all?) wcs* functions.
>> >> This was likely not the case when the patch was first written.
>> >>
>> >> I'll double check whether any of the patch is still needed for current
>> >> versions.
>>
>> With the tests I've run since yesterday, I've determined that:
>>
>> - the wchar-related patches for the libstdc++ testsuite, that I had
>>   proposed last year, are no longer needed
>>
>> - your two patchlets did not bring about any regressions to test
>>   results, not in mainline x86_64-linux-gnu native, not with the trivial
>>   backports to the gcc-10 tree for x-arm-vxw7r2 that was the focus of my
>>   immediate attention.
>>
>> So, I withdraw my submissions of the testsuite patches, and I encourage
>> you to proceed with the two changes you proposed.
>>
>
> Great, I'll save them in a git branch to be revisited in stage 1.
>

I've committed a series of 8 patches to enable partial wchar_t support even
without a working <wchar.h> in libc. std::wstring and std::wstring_view
should work fine now (albeit slower than if libc provides optimised wcslen
etc.)

Wide character I/O and charset conversions still require libc support, so
are disabled when _GLIBCXX_USE_WCHAR_T is not defined.

I would appreciate confirmation that this hasn't caused any problems for
vxworks (understanding that vxworks does have wide character support in
libc now, as discussed back in January).




>
>
>> However, for avoidance of any doubt, I'll restate that I cannot vow for
>> whether they're enough to fix the issues we'd run into back when
>> wchar/wcs* were not supported in the target system, because now they
>> are, so the changes do not bring any visible improvements to our results
>> either.
>>
>
> Understood, thanks for checking them though.
>
>
>>