[PATCH] stdlib: Suppress gcc diagnostic that char8_t is a keyword in C++20 in uchar.h.
Tom Honermann
tom@honermann.net
Mon Aug 1 15:27:56 GMT 2022
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.
Tom.
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