Re: [PATCH v5] c-family: Implement __has_feature and __has_extension [PR60512]

[Jason Merrill <jason@redhat.com>]

On 11/28/23 11:03, Thomas Schwinge wrote:
> Hi!
> 
> On 2023-11-17T14:50:45+0000, Alex Coplan <alex.coplan@arm.com> wrote:
>> --- a/gcc/cp/cp-objcp-common.cc
>> +++ b/gcc/cp/cp-objcp-common.cc
> 
>> +/* Table of features for __has_{feature,extension}.  */
>> +
>> +static constexpr cp_feature_info cp_feature_table[] =
>> +{
>> +  { "cxx_exceptions", &flag_exceptions },
>> +  { "cxx_rtti", &flag_rtti },
>> +  { "cxx_access_control_sfinae", { cxx11, cxx98 } },
> 
> Here we see that 'cxx_exceptions', 'cxx_rtti' are dependent on
> '-fexceptions', '-frtti'.  Certain GCC configurations may decide to
> default to '-fno-exceptions' and/or '-fno-rtti'...
> 
>> --- /dev/null
>> +++ b/gcc/testsuite/g++.dg/ext/has-feature.C
>> @@ -0,0 +1,206 @@
>> +// { dg-do compile }
>> +// { dg-options "" }
>> +
>> +#define FEAT(x) (__has_feature(x) && __has_extension(x))
>> +#define CXX11 (__cplusplus >= 201103L)
>> +#define CXX14 (__cplusplus >= 201402L)
>> +
>> +#if !FEAT(cxx_exceptions) || !FEAT(cxx_rtti)
>> +#error
>> +#endif
> 
> ..., but here, they are assumed available unconditionally.  OK to push
> "Adjust 'g++.dg/ext/has-feature.C' for default-'-fno-exceptions', '-fno-rtti' configurations",
> see attached?

OK.

> Grüße
>   Thomas
> 
> 
> -----------------
> Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, 80634 München; Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas Heurung, Frank Thürauf; Sitz der Gesellschaft: München; Registergericht München, HRB 106955