[PATCH 03/11] locale: Fix --enable-ubsan build failure on some ABIs

[Adhemerval Zanella Netto]

On 20/05/25 09:59, Florian Weimer wrote:
> * Adhemerval Zanella:
> 
>> On mips, arc, powerpc, and s390 gcc 14 triggers the warning
>>
>> In function ‘charmap_new_char’,
>>     inlined from ‘parse_charmap.isra’ at ../locale/programs/charmap.c:570:6:
>> ../locale/programs/charmap.c:1017:32: error: ‘strncmp’ specified bound [2147483649, 4294967295] exceeds maximum object size 2147483647 [-Werror=stringop-overread]
>>  1017 |   if (cp == &from[len1 - 1] || strncmp (from, to, prefix_len) != 0)
>>       |                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> ../locale/programs/charmap.c:1017:32: error: ‘strncmp’ specified bound [2147483649, 4294967295] exceeds maximum object size 2147483647 [-Werror=stringop-overread]
>> cc1: all warnings being treated as errors
>>
>> So move the case to an special function and disable the sanitizer.
> 
> Isn't this either a real source bug or a GCC bug?  Why paper over it?

Because 1. I could not disable it with libc-diag.h because it seems that 
it does not interop with -fsanitize=undefined (-fsanitize always enable 
the warning), and 2. we required it to allow the module be built with
ubsan because  it uses on make check to generated some locales.

An option would to build this modules without ubsan, but I think this
defeat the whole --enable-ubsan idea.