[Bug libstdc++/82417] Macros from <complex.h> defined in C++11

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82417

--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #2)
> Thinking about this further, I think we must not include <complex.h> at all
> for strict -std=c++1* modes,

Yes.

Can we get a #warning in that case which explains that including <complex.h> in
strict C++11+ mode makes no sense? Actually, <ccomplex> could also do with a
#warning explaining that it never makes sense to include it.