[Mesa-dev] [PATCH 2/2] configure.ac: drop support for ancient expat versions

[Emil Velikov]

On 3 August 2017 at 14:58, Chuck Atkins <chuck.atkins at kitware.com> wrote:
> I was a bit confused by this at first but I think I understand it.  Just to
> clarify, this isn't actually dropping support for any version of expat, it's
> just dropping support for automatic detection without a pkg-config file,
> which coincidentally started shipping in 2.1.0.  But it's not like there's
> an actual API change from that version that is now being required.  So if
> you did happen to have an older expat version that you manually created a
> .pc file for, then things should build and work just fine, barring of course
> any expat bugs from untested older versions.  Do I have that right?
>
Right - the version and .pc is more of a happy coincidence.
If one has manually added the file, regardless of the versions things
should just work.

Show does the following sound?

"configure.ac: drop manual detection of expat header/library

Use the .pc file, as provided by version prior 2.1.0 onward and
dropping the manual header/library check.
Version 2.1.0 was released back in Mar 2012 and all major distributions use it.
"

> My motivator for this line of inquiry is this really:  Is there still a way
> to "convince" Mesa to use a given expat library if you don't have a .pc file
> for it, even if it's a long irritating process of manually specifying
> include and link info in some way through stuffing flags into extra
> --with-expat= options or EXPAT_CFLAGS env vars or anything like that?
>
Setting the _CFLAGS/_LIBS variables will override the detection... use
it wisely ;-)

-Emil