[cfe-dev] clang++: std::is_aggregate unusable with clang-5.0/libstdc++-7

[Katsuhiko Nishimra via cfe-dev]

On Fri, Jul 07, 2017 at 12:50:24PM -0700, Richard Smith wrote:
> __has_builtin detects builtin functions. __is_aggregate is not a builtin
> function -- it's not a function at all, since it takes a type, not a value.
> But if libstdc++7 is assuming that __has_builtin can be used to detect type
> trait keywords, perhaps we should make it so; it's not unreasonable to
> expect it to be usable for this purpose.

I see. Sorry to have misunderstood.
> 
> Would you be interested in providing a patch to Clang to implement this?

I don't know much about Clang's codebase, so I think it's better to send
one to libstdc++. But how can I detect if __is_aggregate macro is
usable? I've tried #ifdef directive but with no luck.