[Bug libstdc++/59087] Issues including complex.h in C++11/1y mode because of C's complex.h

[3dw4rd at verizon dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59087

--- Comment #7 from Ed Smith-Rowland <3dw4rd at verizon dot net> ---
OK, it took me a while to remember this (even though I put it in myself).

By default, g++ -std=c++11/1y intercepts numeric suffixes for C++11
user-defined literals.

By default g++ -std=gnu++11/1y allow complex and fixed-point literals suffixes
to be interpreted by the implementation - Allowing iF suffix for example to be
_Complex.

This is why http://melpon.org/wandbox/permlink/CnsddYRxUohlCGF1 "worked" and my
tree (where I used -std=c++1*) "didn't work".

See http://gcc.gnu.org/gcc-4.8/changes.html.

Using g++ -std=c++11 -fext-numeric-literals allows your code.
Using g++ -std=gnu++11 -fno-numeric-literals allows iF to be searched for
user-defined literal (there isn't one so error).

g++ is working as intended.