Problems with evolving feature test macros?

[Joseph S. Myers]

On Tue, 11 Mar 2014, Rich Felker wrote:

> Random thought: would it hurt to do something like this in feastures.h
> and leave it in place for at least the next few release cycles?
> 
> #if (defined(_SVID_SOURCE) || defined(_BSD_SOURCE)) && !defined(_DEFAULT_SOURCE)
> #define _DEFAULT_SOURCE 1
> #endif

_BSD_SOURCE and _SVID_SOURCE already do define _DEFAULT_SOURCE like that 
(with a deprecation working, unless _DEFAULT_SOURCE was explicitly defined 
by the user).

-- 
Joseph S. Myers
joseph@codesourcery.com