libpkgconf: fragment: handle -idirafter in the same way as -isystem

(https://bugs.freedesktop.org/show_bug.cgi?id=97337)

Makefile.am

@@ -54,6 +54,7 @@ EXTRA_DIST =	pkg.m4 \
 		tests/lib1/conflicts.pc \
 		tests/lib1/omg-uninstalled.pc \
 		tests/lib1/isystem.pc \
+		tests/lib1/idirafter.pc \
 		tests/lib1/depgraph-break.pc \
 		tests/lib1/cflags-whitespace.pc \
 		tests/lib1/cflags-whitespace-trailing.pc \

libpkgconf/fragment.c

@@ -37,6 +37,7 @@ pkgconf_fragment_is_unmergeable(const char *string)
 	static struct pkgconf_fragment_check check_fragments[] = {
 		{"-framework", 10},
 		{"-isystem", 8},
+		{"-idirafter", 10},
 	};
 
 	if (*string != '-')
@@ -54,6 +55,7 @@ pkgconf_fragment_should_munge(const char *string, const char *sysroot_dir)
 {
 	static struct pkgconf_fragment_check check_fragments[] = {
 		{"-isystem", 8},
+		{"-idirafter", 10},
 	};
 
 	if (*string != '/')

tests/lib1/idirafter.pc

@@ -0,0 +1,4 @@
+Name: Bad
+Description: Demonstrates problems with -idirafter in both old pkg-config and current pkgconf; see also https://bugs.freedesktop.org/show_bug.cgi?id=97337
+Version: 1
+Cflags: -idirafter /opt/bad/include -idirafter /opt/bad2/include

tests/regress.sh

@@ -19,6 +19,8 @@ tests_init \
 	incomplete_cflags \
 	isystem_munge_order \
 	isystem_munge_sysroot \
+	idirafter_munge_order \
+	idirafter_munge_sysroot \
 	pcpath \
 	sysroot_munge
 
@@ -152,6 +154,22 @@ isystem_munge_sysroot_body()
 		pkgconf --cflags isystem
 }
 
+idirafter_munge_order_body()
+{
+	export PKG_CONFIG_PATH="${selfdir}/lib1"
+	atf_check \
+		-o inline:"-idirafter /opt/bad/include -idirafter /opt/bad2/include  \n" \
+		pkgconf --cflags idirafter
+}
+
+idirafter_munge_sysroot_body()
+{
+	export PKG_CONFIG_PATH="${selfdir}/lib1" PKG_CONFIG_SYSROOT_DIR='/test'
+	atf_check \
+		-o match:"-idirafter /test/opt/bad/include" \
+		pkgconf --cflags idirafter
+}
+
 pcpath_body()
 {
 	export PKG_CONFIG_PATH="${selfdir}/lib2"