[PATCH] [gdb/build] Fix C inclusion of nat/x86-cpuid.h

[Tom de Vries]

On 8/29/23 18:03, Kevin Buettner wrote:
> On Tue, 29 Aug 2023 17:38:57 +0200
> Tom de Vries via Gdb-patches <gdb-patches@sourceware.org> wrote:
> 
>> When running test-case gdb.arch/i386-avx512.exp, I run into:
>> ...
>>   gdb compile failed, In file included from gdb.arch/i386-avx512.c:20:0:
>>   src/gdb/nat/x86-cpuid.h: In function 'x86_cpuid_count':
>>   src/gdb/nat/x86-cpuid.h:63:16: error: \
>>     'nullptr' undeclared (first use in this function)
>>      if (__eax == nullptr)
>>                   ^~~~~~~
>>   src/gdb/nat/x86-cpuid.h:63:16: note: each \
>>     undeclared identifier is reported only once for each function it appears in
> [...]
>> This is due to commit e85aad4ae76 ("nat/x86-cpuid.h: Add x86_cpuid_count
>> wrapper around __get_cpuid_count"), which introduced the nullptr check.
>>
>> The header file gdb/nat/x86-cpuid.h is a file that is included in the build
>> and compiled as a C++ file, but also in the testsuite and compiled as a C
>> file.
>>
>> Fix this by replacing nullptr with (void *)0.
> [...]
> 
>> -  if (__eax == nullptr)
>> +  if (__eax == (void *)0)
>>       __eax = &__scratch;
>> -  if (__ebx == nullptr)
>> +  if (__ebx == (void *)0)
>>       __ebx = &__scratch;
>> -  if (__ecx == nullptr)
>> +  if (__ecx == (void *)0)
>>       __ecx = &__scratch;
>> -  if (__edx == nullptr)
>> +  if (__edx == (void *)0)
>>       __edx = &__scratch;
> 
> Maybe leave nullptr in place and instead do something like this...
> 
> /* This header file is also used in C code for the gdb.arch/i386-avx512.exp
>     test, so define nullptr to avoid a compile error during testing.  */
> #ifndef __cplusplus
> #define nullptr (void *) 0)
> #endif
> 

Hi Kevin,

thanks for the review.

I'll commit this v2 tomorrow, unless there are further comments.

Thanks,
- Tom

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