[libdispatch-dev] autoconf HAVE macro conventions

Paolo Bonzini bonzini at gnu.org
Fri Oct 30 12:26:57 PDT 2009


On 10/30/2009 08:24 PM, Kevin Van Vechten wrote:
> I'm not very familiar with autoconf conventions and was wondering why
> some config.h values are merely defined and some are explicitly
> defined to 1.

That's a bad decision in configure.ac usually.  Just look for 
occurrences of AC_DEFINE([FOO],,[Comment]) and add a 1 between the two 
commas.

> Is there a strong convention to do #ifdef HAVE_FOO instead of #if
> HAVE_FOO when testing for configure features?  For various reasons,
> the ability to define a macro to 0 or 1 would be useful for the Mac
> OS X version of config.h — it would let us define certain features in
> terms of other features without as much conditional logic.

... that said, why can't config.h be generated for Mac OS X by running 
configure every time a change to the autoconf source is checked in? 
There should be no need for conditional logic.

Paolo



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