[OE-core] Issue with pkgconfig and ncurses

[Alexandre Belloni]

Hi,

While building alsa-utils I ran in a weird issue. The build system was
trying to link alsa-utils with the x86_64 ncurses lib. That issue didn't
appear on another machine but could be reproduced 9 out of 10 times on
my main machine.

I tracked down the issue: when configuring alsa-utils, configure tries
to use pkg-config to fin CFLAGS/LDFLAGS for ncurses. This was failing so
it is falling back to use ncursesw5-config which points cflags and
ldflags to the x86_64 sysroot.

That is were this is nasty: the reason why pkg-config is failing is that
the configure for ncurses is doing that:
        PKG_CONFIG_LIBDIR=`echo "$PKG_CONFIG_LIBDIR" | sed -e 's/^://' -e 's/:.*//'`
        if test -n "$PKG_CONFIG_LIBDIR" && test -d "$PKG_CONFIG_LIBDIR" ; then

That test fails one my main machine because at the time ncurses is
configured, PKG_CONFIG_LIBDIR (that is
tmp-external-linaro-toolchain/sysroots/am335x-evm/usr/lib/pkgconfig/) is
not yet created as ncurses is the first package trying to install .pc
files. The configure script then continues with only a warning but
deactivate .pc files installation.

This doesn't happen on my other machine because it has more cores
and finishes to build zlib before trying to configure ncurses!

I tried multiple thing ot fix that but I couldn't decide what is the
best way.

Should we fix the configure script for ncurses but then it may happen
again with another package.

Or should we enforce the creation of ${SYSROOT_DESTDIR}/usr/lib/pkgconfig/
from pkg-config. the main issue being that we actually compile
pkg-config-native and we want to create that in ${SYSROOT_DESTDIR} for
the machine.

Any help would be greatly appreciated.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com