[Buildroot] [RFC] pkg-autotools: check if host-pkgconf should be part of the dependencies

[Thomas Petazzoni]

There is a good number of autotools-based packages that use the
PKG_CHECK_MODULES() in their configure.{ac,in} file, and the presence
of this macro indicates that the package should depend on
host-pkgconf. However, we very often fail at adding this dependency,
and discover later that it is necessary.

In order to prevent that from happening, this commit proposes to add a
post-patch hook that looks if PKG_CHECK_MODULES is used in the
configure.{ac,in} file, and if it is, it verifies that host-pkgconf is
part of the current package dependencies. If not, it aborts the build
with an error message.

Note that adding this dependency cannot be done automatically, because
by the time the makefiles are parsed, the source code for the packages
are not extracted, so we can't look at configure.{in,ac} to
automatically add the host-pkgconf dependency. The only thing we can
do is what this patch does: a check during the build itself.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
---
This is purely an RFC patch, I just tested it on one package (the
recently added 'smack' package), which was lacking this host-pkgconf
dependency.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
---
 package/pkg-autotools.mk | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/package/pkg-autotools.mk b/package/pkg-autotools.mk
index a646612..842a7c3 100644
--- a/package/pkg-autotools.mk
+++ b/package/pkg-autotools.mk
@@ -230,6 +230,17 @@ $(2)_PRE_CONFIGURE_HOOKS += AUTORECONF_HOOK
 $(2)_DEPENDENCIES += host-automake host-autoconf host-libtool
 endif
 
+define CHECK_PKG_CONFIG_HOOK
+	$(Q)if grep -q PKG_CHECK_MODULES $$($$(PKG)_SRCDIR)/configure.{ac,in}; then \
+		if test -z "$$(filter host-pkgconf,$$($$(PKG)_DEPENDENCIES))" ; then \
+			echo "ERROR: package $$(PKG) uses PKG_CHECK_MODULES but does not depend on host-pkgconf" ; \
+			exit 1 ; \
+		fi ; \
+	fi
+endef
+
+$(2)_POST_PATCH_HOOKS += CHECK_PKG_CONFIG_HOOK
+
 #
 # Build step. Only define it if not already defined by the package .mk
 # file.
-- 
1.9.2