[gnome-builder/gnome-builder-3-18] vala: check for vapigen, which is required to build vala pack

[Christian Hergert <chergert src gnome org>]

commit d2547cd81d7dc2e392b678e63be869666f356415
Author: Christian Hergert <chergert redhat com>
Date:   Wed Oct 7 16:39:04 2015 -0400

    vala: check for vapigen, which is required to build vala pack
    
    We need vapigen so that we will have generated libide-1.0.vapi and
    gnome-builder-1.0.vapi. This also cleans up our
    --enable-vala-pack-plugin=auto check so that it is a bit more straight
    forward.

 plugins/vala-pack/configure.ac |   20 +++++++++++++-------
 1 files changed, 13 insertions(+), 7 deletions(-)
---
diff --git a/plugins/vala-pack/configure.ac b/plugins/vala-pack/configure.ac
index aa1def3..5878f1a 100644
--- a/plugins/vala-pack/configure.ac
+++ b/plugins/vala-pack/configure.ac
@@ -1,3 +1,6 @@
+VAPIGEN_CHECK
+PKG_CHECK_MODULES(VALA, [libvala-0.30 >= 0.29.3],[have_libvala=yes],[have_libvala=no])
+
 # --enable-vala-pack-plugin=auto/yes/no
 AC_ARG_ENABLE([vala-pack-plugin],
               [AS_HELP_STRING([--enable-vala-pack-plugin=@<:@auto/yes/no@:>@],
@@ -5,17 +8,20 @@ AC_ARG_ENABLE([vala-pack-plugin],
               [enable_vala_pack_plugin=$enableval],
               [enable_vala_pack_plugin=auto])
 
-AS_IF([test x$enable_vala_pack_plugin != xno],[
-       PKG_CHECK_MODULES(VALA, [libvala-0.30 >= 0.29.3],[enable_vala_pack_plugin=yes],[
-               AS_IF([test x$enable_vala_pack_plugin = xyes],[
-                       AC_MSG_ERROR([Failed to locate vala. Please install the vala-devel package.])
-               ])
-               enable_vala_pack_plugin=no
+AS_IF([test x$enable_vala_pack_plugin = xauto],[
+       AS_IF([test x$have_libvala = xyes && test x$enable_vala = xyes],
+             [enable_vala_pack_plugin=yes],
+             [enable_vala_pack_plugin=no])
+])
+
+AS_IF([test x$enable_vala_pack_plugin = xyes],[
+       AS_IF([test x$enable_vala != xyes || test x$have_libvala != xyes],[
+               AC_MSG_ERROR([Please install both the vala compiler and vapigen. vapigen may be part of your 
systems vala-tools package.])
        ])
 ])
 
 # for if ENABLE_VALA_PACK_PLUGIN in Makefile.am
-AM_CONDITIONAL(ENABLE_VALA_PACK_PLUGIN, test x$enable_vala_pack_plugin != xno)
+AM_CONDITIONAL(ENABLE_VALA_PACK_PLUGIN, test x$enable_vala_pack_plugin = xyes)
 
 # Ensure our makefile is generated by autoconf
 AC_CONFIG_FILES([plugins/vala-pack/Makefile])