SYSROOT vs --with-xxx-prefix

[Alon Bar-Lev]

On Mon, Oct 8, 2018 at 3:40 AM NIIBE Yutaka <gniibe at fsij.org> wrote:
>
> Hello,
>
> Alon Bar-Lev <alon.barlev at gmail.com> wrote:
> > 1. Farfetched... can we support pkg-config? I can help to support this
> > in parallel to the existing mechanism.
>
> Thank you.
>
> Somehow, we have started into this way (from libgpg-error).  I put some
> effort providing gpg-error.pc (as well as the gpg-error-config script)
> in the master branch of libgpg-error.  My plan is to extend it to other
> libraries.  Please have a look.

OK, so while we are at this... the config script should also support
SYSROOT and output directories relevant to SYSROOT.
For example, when cross compling and acquiring CFLAGS or LDFLAGS
outputting -I/usr/include and -L/usr/lib will not allow to build.

Three tasks to help cross compile work:
1. *.m4: complete supporting SYSROOT to look for the *-config script
within that prefix.
2. *.m4: support both SYSROOT/bin and SYSROOT/usr/bin when looking for
*-config scripts.
3. *-config: add support of SYSROOT to output directories

> Please note that we need to keep the requirment of GnuPG build, as small
> as possible.  GnuPG build should not require pkg-config.  This is
> (still) important for older Unixen.

I do not think there is a problem to try pkg-config and fallback to
*-config in autoconf, and in any case provide pkg-config for consumers
that do not have this concern.

Thanks!