On Wed, Jul 08, 2026 at 02:08:38PM -0400, Jason Merrill wrote:
> > --- gcc/testsuite/g++.dg/cpp0x/attr-trivial_abi8.C.jj 2026-07-08
> > 18:49:01.145455196 +0200
> > +++ gcc/testsuite/g++.dg/cpp0x/attr-trivial_abi8.C 2026-07-08
> > 18:49:23.583166926 +0200
> > @@ -0,0 +1,20 @@
> > +// { dg-do compile { target c++11 } }
> > +
> > +#if __has_cpp_attribute (clang::trivial_abi) != 1
> > +#error
> > +#endif
> > +#if __has_cpp_attribute (gnu::trivial_abi) != 0
> > +#error
> > +#endif
> > +#if __has_cpp_attribute (trivial_abi) != 1
> > +#error
> > +#endif
>
> This answer seems clearly wrong, since [[trivial_abi]] doesn't work. I'd
> prefer expecting 0 and xfail.
I know, but unfortunately __has_cpp_attribute and __has_attribute
behave identically in C++.
In C __has_attribute (identifier) tests __attribute__((identifier))
or [[identifier]] support and __has_c_attribute (identifier)
tests [[identifier]] only and both with scoped attributes test
[[scope::identifier]].
But I'm not sure it isn't too late to change this when both C++ forms
behaved the same way since GCC 5.1, so 11 years in the wild.
There is a way to differentiate what can be accepted as [[identifier]]
even in C++, if __has_cpp_attribute results in 1, it is the __attribute__
form, if it is >= 2 (or >= 200809, there is nothing in between), then
it is [[identifer]].
Jakub
