Re: [Jim Meyering] Re: [Bug-gnulib] strftime merge from Emacs

[Dave Love <d.love@dl.ac.uk>]

Paul Eggert <eggert@CS.UCLA.EDU> writes:

> I've found that it's better to avoid those feature-test macros if
> possible, as they tend to explore rarely-used and buggy corners of
> include files, and they tend to disable other useful features.  My
> experience is that it is sometimes necessary to use them on some
> platforms, but it's better not to use them by default.

Surely it's incorrect not to use them if you want to use the features?
It's certainly necessary to enable feature-test macros on various
systems, including GNU, for Emacs.  Even where the default compiler
options don't make it necessary (e.g. Irix), if you change them to
something like `-ansi', you typically lose.  I've seen this actually
happen on systems like Irix and Tru64 where you can change the default
options with a configuration file or environment variable.

I'm thinking of things like _XOPEN_SOURCE, which won't disable much.