Strange C++ function pointer test

[Jonathan Wakely]

On 31 December 2015 at 11:37, Marc Glisse wrote:
> That's what I called "bug" in my message (there are a few bugzilla PRs for
> this). It would probably work on Solaris.

Yes, the <math.h> case is still a mess in the standard and in glibc.
The "only in namespace std in the second case" part is what I meant
was not accurate. C++11 changed to allow <cmath> to declare it in the
global namespace, but as you say didn't go far enough.