On 31/10/2019 09:35, Jakub Jelinek wrote:
> On Thu, Oct 31, 2019 at 09:16:00AM +0000, Richard Sandiford wrote:
>>> Yes, it is indeed not clear, subject to ongoing discussions.
>>> My reading of the spec was that all the *-name-list are comma
>>> separated lists of identifiers, some others in the committee
>>> want now (yesterday's discussions) string literals instead
>>> when I and others pointed out that isa(core-avx512) can't be valid,
>>> but strangely only for isa/arch/extension but not e.g. for
>>> kind or vendor which would still take identifier lists etc.
>>
>> Might be completely wrong, but wouldn't the identifiers be subject to
>> macro expansion? That would make it harder to use the pragmas safely
>> in system headers.
>
> Well, all the identifiers in the OpenMP/OpenACC pragmas after the omp
> are subject to macro expansion, including clause names etc., so even
> #define device foobar
> #pragma omp declare variant (foo) match (device={kind(host)})
> is a problem, or macro redefinition of declare, variant, match,
> kind or host. That said, for the arch and isa it is perhaps a bigger
> problem, as can be seen in the c-c++-common/gomp/declare-variant-9.c
> testcase where I had to #undef i386 because in non-strict modes
> that is defined...
that is surprising, preproc directives are normally not
subject to macro expansion unless stated explicitly so
gcc normally don't macro expand pragmas.. i consider this
a bug in the omp spec and one more reason why _Pragma
should be used instead of #pragma.
