Re: [PATCH] stdlib: Suppress gcc diagnostic that char8_t is a keyword in C++20 in uchar.h.

[Tom Honermann <tom@honermann.net>]

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.