Problems with evolving feature test macros?

[Paul Eggert]

On 03/11/2014 07:44 AM, Michael Kerrisk (man-pages) wrote:
> I'm guessing programmers will reach for
> the only hammer that does not cause a compiler warning on any glibc
> version:
>
> #define _GNU_SOURCE

That's what most application developers should do, who run into this 
problem.  There's even an Autoconf macro for it: AC_USE_SYSTEM_EXTENSIONS.

> That seems to be a very unfortunate situation.

It's typically only a minor annoyance.