[PATCH] stdlib: Suppress gcc diagnostic that char8_t is a keyword in C++20 in uchar.h.
Adhemerval Zanella Netto
adhemerval.zanella@linaro.org
Mon Aug 1 15:48:58 GMT 2022
On 01/08/22 12:27, Tom Honermann wrote:
> On 8/1/22 9:38 AM, Adhemerval Zanella Netto wrote:
>>
>> On 29/07/22 15:22, Tom Honermann wrote:
>>> On 7/25/22 8:34 AM, Adhemerval Zanella Netto via Libc-alpha wrote:
>>>> On 25/07/22 06:07, Florian Weimer wrote:
>>>>> * Tom Honermann via Libc-alpha:
>>>>>
>>>>>> gcc 13 issues the following diagnostic for the uchar.h header when the
>>>>>> -Wc++20-compat option is enabled in C++ modes that do not enable char8_t
>>>>>> as a builtin type (C++17 and earlier by default; subject to _GNU_SOURCE
>>>>>> and the gcc -f[no-]char8_t option).
>>>>>> warning: identifier ‘char8_t’ is a keyword in C++20 [-Wc++20-compat]
>>>>>> This change modifies the uchar.h header to suppress the diagnostic through
>>>>>> the use of '#pragma GCC diagnostic' directives for gcc 10 and later (the
>>>>>> -Wc++20-compat option was added in gcc version 10). Unfortunately, a bug
>>>>>> in gcc currently prevents those directives from having the intended effect
>>>>>> as reported at https://gcc.gnu.org/PR106423. A patch for that issue has
>>>>>> been submitted and is available in the email thread archive linked below.
>>>>>> https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598736.html
>>>>>> ---
>>>>>> wcsmbs/uchar.h | 8 ++++++++
>>>>>> 1 file changed, 8 insertions(+)
>>>>>>
>>>>>> diff --git a/wcsmbs/uchar.h b/wcsmbs/uchar.h
>>>>>> index c37e8619a0..5f7139f279 100644
>>>>>> --- a/wcsmbs/uchar.h
>>>>>> +++ b/wcsmbs/uchar.h
>>>>>> @@ -34,8 +34,16 @@
>>>>>> /* Declare the C2x char8_t typedef in C2x modes, but only if the C++
>>>>>> __cpp_char8_t feature test macro is not defined. */
>>>>>> #if __GLIBC_USE (ISOC2X) && !defined __cpp_char8_t
>>>>>> +#if __GNUC_PREREQ (10, 0) && defined __cplusplus
>>>>>> +/* Suppress the diagnostic regarding char8_t being a keyword in C++20. */
>>>>>> +# pragma GCC diagnostic push
>>>>>> +# pragma GCC diagnostic ignored "-Wc++20-compat"
>>>>>> +#endif
>>>>>> /* Define the 8-bit character type. */
>>>>>> typedef unsigned char char8_t;
>>>>>> +#if __GNUC_PREREQ (10, 0) && defined __cplusplus
>>>>>> +# pragma GCC diagnostic pop
>>>>>> +#endif
>>>>>> #endif
>>>>> Patch looks okay to me. The warning was introduced in GCC 10.
>>>>>
>>>>> This needs RM approval at this point, I think.
>>>>>
>>>>> Thanks,
>>>>> Florian
>>>>>
>>>> This is ok for 2.36, thanks.
>>> Thanks. Please commit on my behalf; I don't have commit access.
>>>
>>> Tom.
>>>
>> Ack, done.
>
> Thank you! Should this (and H.J. Lu's "missing test-c8rtomb/test-mbrtoc8 dependency" patch) be merged for 2.36? Both appear to have been approved for 2.36 but I don't see them on the release/2.36/master branch at the moment.
I think I did it [1].
[1] https://sourceware.org/git/?p=glibc.git;a=shortlog;h=refs/heads/release/2.36/master
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