Re: multiple vala versions in 3.4

[Michael Terry <mike mterry name>]

I maintain the GNOMEish app deja-dup.  I also would like it if GNOME
supported apps that want to stay on a stable compiler during the
cycle.

I use the following macro in acinclude.m4 to allow specifying a
specific valac-X.XX version with a friendly fallback to valac.

In configure.ac:

DD_PROG_VALAC([0.14.0], [valac-0.14 valac])

In acinclude.m4:

AC_DEFUN([DD_PROG_VALAC],
[AC_PATH_PROGS([VALAC], [$2], [])
 AS_IF([test -z "$VALAC"],
   [AC_MSG_ERROR([No Vala compiler found.])],
   [AS_IF([test -n "$1"],
      [AC_MSG_CHECKING([$VALAC is at least version $1])
       am__vala_version=`$VALAC --version | sed 's/Vala  *//'`
       AS_VERSION_COMPARE([$1], ["$am__vala_version"],
         [AC_MSG_RESULT([yes])],
         [AC_MSG_RESULT([yes])],
         [AC_MSG_RESULT([no])
          AC_MSG_ERROR([Vala $1 not found.])])])])
])

-mt