Re: AC_SUBST usage to define include or linker flags

[Reuben Thomas]

2009/10/22 Dustin J. Mitchell <address@hidden>:
> On Thu, Oct 22, 2009 at 8:44 AM, Pierre-Henri Trivier
> <address@hidden> wrote:
>> However, not all m4 files do it, and not all of them use the same
>> conventions. So my questions are :
>
> The archive has really only just started to get into the business of
> defining conventions, and in fact this was one of the topics we have
> been discussing.  The method you describe (XXX_INCLUDES, etc.) is,
> IMHO, most flexible.  Macros which simply add their arguments to the
> global CPPFLAGS, LIBS, etc. tend to over-link projects.  For example,
> if one executable in a project requires libxslt, then only that
> executable should be linked with XSLT_LIBS; but if the xslt macro puts
> -lxslt in the global LIBS, then every executable ends up with an
> unused dependency.
>
>> * is it considered good pratice to use AC_SUBST to define such symbols ? If
>> not, how are you supposed to transfer the information of "I found the
>> include files, and they are in this folder" or "I found the lib, and it is
>> in that folder".
>
> Yes, AC_SUBST and AC_DEFINE are the main ways that autoconf scripts
> communicate with the build process.

I think the real question here was whether the macros are expected to
AC_SUBST variables of this sort or whether it's up to the user's
configure.ac usually.

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