[MPlayer-dev-eng] configure vs #undef

[Rich Felker]

On Mon, Aug 21, 2006 at 02:51:23PM +0200, Diego Biurrun wrote:
> Currently configure sets "#define FOO" if a test succeeds and if it
> fails it sets "#undef FOO" in config.h.  I wonder if this is necessary.
> AFAICT we only depend on defined and not on undefine things.
> 
> I'm tempted to remove all the #undef, which should get rid of 250 or
> more lines in configure.  Am I overlooking something?

You're overlooking the fact that the #undef makes debugging easier.
Users can _see_ the #undef in config.h and know that the option was
disabled by configure, as opposed to having to look all over various
headers to make sure it's not implicitly defined because of something
else. It also makes it easier to then override the decisions of
configure to see if something works before modifying configure to fix
whatever bug prevented detection from working.

So in the absence of a compelling reason to remove #undefs I'm
inclined to leave them. However we could surely consider an option to
automate the #define/#undef thing better to reduce the code size in
configure!

Rich