[Libguestfs] [PATCH] build: improve Gtk check

[Pino Toscano]

Check the presence of Gtk properly depending on the value of --with-gtk:
if a specific version is chosen, then let PKG_CHECK_MODULES fail if that
version if not found, otherwise fallback from gtk3 to gtk2 to no gtk.

Also move few common AC_SUBST in a single place.
---
 m4/guestfs_misc_libraries.m4 | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/m4/guestfs_misc_libraries.m4 b/m4/guestfs_misc_libraries.m4
index 4ae0576..fee265b 100644
--- a/m4/guestfs_misc_libraries.m4
+++ b/m4/guestfs_misc_libraries.m4
@@ -85,29 +85,31 @@ AC_ARG_WITH([gtk],
      AC_MSG_RESULT([not set, will check for installed Gtk])]
 )
 
-if test "x$GTK_LIBS" = "x" && \
-        ( test "x$with_gtk" = "x3" || test "x$with_gtk" = "xcheck" ) ; then
+if test "x$with_gtk" = "x3"; then
     PKG_CHECK_MODULES([GTK], [gtk+-3.0], [
-        AC_SUBST([GTK_CFLAGS])
-        AC_SUBST([GTK_LIBS])
         GTK_VERSION=3
-        AC_SUBST([GTK_VERSION])
-    ], [])
-fi
-if test "x$GTK_LIBS" = "x" && \
-        ( test "x$with_gtk" = "x2" || test "x$with_gtk" = "xcheck" ) ; then
+    ])
+elif test "x$with_gtk" = "x2"; then
     PKG_CHECK_MODULES([GTK], [gtk+-2.0], [
-        AC_SUBST([GTK_CFLAGS])
-        AC_SUBST([GTK_LIBS])
         GTK_VERSION=2
-        AC_SUBST([GTK_VERSION])
     ], [])
+elif test "x$with_gtk" = "xcheck"; then
+    PKG_CHECK_MODULES([GTK], [gtk+-3.0], [
+        GTK_VERSION=3
+    ], [
+        PKG_CHECK_MODULES([GTK], [gtk+-2.0], [
+            GTK_VERSION=2
+        ], [:])
+    ])
 fi
 
 dnl Can we build virt-p2v?
 AC_MSG_CHECKING([if we can build virt-p2v])
 if test "x$GTK_LIBS" != "x"; then
     AC_MSG_RESULT([yes, with Gtk $GTK_VERSION])
+    AC_SUBST([GTK_CFLAGS])
+    AC_SUBST([GTK_LIBS])
+    AC_SUBST([GTK_VERSION])
 else
     AC_MSG_RESULT([no])
 fi
-- 
2.7.4