meson: generate pkg-config -uninstalled pc files

Generating those files is useful for users building the GStreamer stack
using meson and having to link it to another project which is still
using the autotools.

https://bugzilla.gnome.org/show_bug.cgi?id=776810

pkgconfig/Makefile.am

@@ -31,7 +31,15 @@ cp_verbose_0 = @echo "  CP     $@";
 %-@GST_API_VERSION@.pc: %.pc
 	$(cp_verbose_0)cp $< $@
 %-@GST_API_VERSION@-uninstalled.pc: %-uninstalled.pc
-	$(cp_verbose_0)cp $< $@
+### the uninstalled libdir is depend of the build system used so set it here
+### rather than hardcoding it in the file directly.
+	$(AM_V_GEN) sed \
+		-e "s|[@]gstlibdir[@]|$(abs_top_builddir)/gst/.libs|" \
+		-e "s|[@]checklibdir[@]|$(abs_top_builddir)/libs/gst/check/.libs|" \
+		-e "s|[@]baselibdir[@]|$(abs_top_builddir)/libs/gst/base/.libs|" \
+		-e "s|[@]netlibdir[@]|$(abs_top_builddir)/libs/gst/net/.libs|" \
+		-e "s|[@]controllerlibdir[@]|$(abs_top_builddir)/libs/gst/controller/.libs|" \
+		$< > $@.tmp && mv $@.tmp $@
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = $(pcfiles)

pkgconfig/gstreamer-base-uninstalled.pc.in

@@ -1,7 +1,7 @@
 # the standard variables don't make sense for an uninstalled copy
 prefix=
 exec_prefix=
-libdir=@abs_top_builddir@/libs/gst/base/.libs
+libdir=@baselibdir@
 includedir=
 girdir=@abs_top_builddir@/libs/gst/base
 typelibdir=@abs_top_builddir@/libs/gst/base

pkgconfig/gstreamer-check-uninstalled.pc.in

@@ -1,7 +1,7 @@
 # the standard variables don't make sense for an uninstalled copy
 prefix=
 exec_prefix=
-libdir=@abs_top_builddir@/libs/gst/check/.libs
+libdir=@checklibdir@
 includedir=
 girdir=@abs_top_builddir@/libs/gst/check
 typelibdir=@abs_top_builddir@/libs/gst/check

pkgconfig/gstreamer-controller-uninstalled.pc.in

@@ -1,7 +1,7 @@
 # the standard variables don't make sense for an uninstalled copy
 prefix=
 exec_prefix=
-libdir=@abs_top_builddir@/libs/gst/controller/.libs
+libdir=@controllerlibdir@
 includedir=
 girdir=@abs_top_builddir@/libs/gst/controller
 typelibdir=@abs_top_builddir@/libs/gst/controller

pkgconfig/gstreamer-net-uninstalled.pc.in

@@ -1,7 +1,7 @@
 # the standard variables don't make sense for an uninstalled copy
 prefix=
 exec_prefix=
-libdir=@abs_top_builddir@/libs/gst/net/.libs
+libdir=@netlibdir@
 includedir=
 girdir=@abs_top_builddir@/libs/gst/net
 typelibdir=@abs_top_builddir@/libs/gst/net

pkgconfig/gstreamer-uninstalled.pc.in

@@ -1,7 +1,7 @@
 # the standard variables don't make sense for an uninstalled copy
 prefix=
 exec_prefix=
-libdir=@abs_top_builddir@/gst/.libs
+libdir=@gstlibdir@
 # includedir is builddir because it is used to find gstconfig.h in places
 includedir=@abs_top_builddir@
 toolsdir=@abs_top_builddir@/tools

pkgconfig/meson.build

@@ -7,6 +7,15 @@ pkgconf.set('includedir', '${prefix}/@0@'.format(get_option('includedir')))
 pkgconf.set('GST_API_VERSION', apiversion)
 pkgconf.set('VERSION', gst_version)
 
+# needed for generating -uninstalled.pc files
+pkgconf.set('abs_top_builddir', join_paths(meson.current_build_dir(), '..'))
+pkgconf.set('abs_top_srcdir', join_paths(meson.current_source_dir(), '..'))
+pkgconf.set('gstlibdir', join_paths(meson.build_root(), libgst.outdir()))
+pkgconf.set('checklibdir', join_paths(meson.build_root(), gst_check.outdir()))
+pkgconf.set('baselibdir', join_paths(meson.build_root(), gst_base.outdir()))
+pkgconf.set('controllerlibdir', join_paths(meson.build_root(), gst_controller.outdir()))
+pkgconf.set('netlibdir', join_paths(meson.build_root(), gst_net.outdir()))
+
 pkg_install_dir = '@0@/pkgconfig'.format(get_option('libdir'))
 
 pkg_files = ['gstreamer-base',
@@ -23,4 +32,10 @@ foreach p : pkg_files
     output : outfile,
     configuration : pkgconf,
     install_dir : pkg_install_dir)
+
+  infile = p + '-uninstalled.pc.in'
+  outfile = p + '-1.0-uninstalled.pc'
+  configure_file(input : infile,
+    output : outfile,
+    configuration : pkgconf)
 endforeach