> On 17 Jan 2022, at 11:09, Sam James <sam@gentoo.org> wrote:
> 
> We need to instruct aclocal that it might find macros in both
> ${BROOT} _and_ ${SYSROOT}.
> 
> - A classic example within BROOT is autoconf-archive.
> 
> - A classic example within SYSROOT is, say, libogg. A fair amount of
>  codec software installs its own macro to help locating it (but this
>  is in no ways limited to that genre/area).
> 
>  The correct position for a dependency like libogg is DEPEND, and yet
>  the status quo doesn't mean that aclocal is obligated to check in ${ESYSROOT}
>  which is where DEPEND-class dependencies are guaranteed to be installed.
> 
>  We can't rely on these being in BDEPEND -- in fact, most of the time,
>  they won't be. If we wanted to rely on macros always being provided by
>  BDEPEND, we'd have to duplicate a considerable number of dependencies
>  in both BDEPEND + DEPEND, with the unnecessary cross-compilation that would
>  entail too: it makes far more sense to just tell aclocal to look in the
>  right place (an extra location).
> 
> Bug: https://bugs.gentoo.org/710792
> Closes: https://bugs.gentoo.org/677002
> Closes: https://bugs.gentoo.org/738918
> Thanks-to: David Michael <fedora.dm0@gmail.com> (for the suggestion)
> Thanks-to: James Le Cuirot <chewi@gentoo.org> (rubberducking & sounding board)
> Signed-off-by: Sam James <sam@gentoo.org>
> ---
> eclass/autotools.eclass | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/eclass/autotools.eclass b/eclass/autotools.eclass
> index e2572290f0cbe..2cf7c076d01ed 100644
> --- a/eclass/autotools.eclass
> +++ b/eclass/autotools.eclass
> @@ -332,8 +332,22 @@ eaclocal_amflags() {
> # They also force installing the support files for safety.
> # Respects AT_M4DIR for additional directories to search for macros.
> eaclocal() {
> +	# Feed in a list of paths:
> +	# - ${BROOT}/usr/share/aclocal
> +	# - ${ESYSROOT}/usr/share/aclocal
> +	# See bug #677002
> +	if [[ ! -f "${T}"/aclocal/dirlist ]] ; then
> +		mkdir "${T}"/aclocal || die
> +		cat <<- EOF > "${T}"/aclocal/dirlist || die
> +			${BROOT}/usr/share/aclocal
> +			${ESYSROOT}/usr/share/aclocal
> +		EOF
> +	fi
> +
> +	local system_acdir=" --system-acdir=${T}/aclocal"
> +
> 	[[ ! -f aclocal.m4 || -n $(grep -e 'generated.*by aclocal' aclocal.m4) ]] && \
> -		autotools_run_tool --at-m4flags aclocal "$@" $(eaclocal_amflags)
> +		autotools_run_tool --at-m4flags aclocal "$@" $(eaclocal_amflags) ${system_acdir}
> }

I've changed this locally to just skip the add-system-acdir-logic for older EAPIs. Forgot to amend the commit,
Chewi had already pointed this out privately.

best,
sam