[Libguestfs] [PATCH] build: Only add 'serial-tests' for automake >= 1.12.

[Richard W.M. Jones]

From: "Richard W.M. Jones" <rjones at redhat.com>

Earlier versions of automake complain if they get a configuration
parameter which they don't understand.  The error is:

configure.ac:27: error: option 'serial-tests' not recognized

Use some m4 hackery to work around this.
---
 configure.ac | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 105b2e7..b0158c7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -24,7 +24,21 @@ m4_define([libguestfs_release], [11])
 
 AC_INIT([libguestfs],libguestfs_major.libguestfs_minor.libguestfs_release)
 AC_CONFIG_AUX_DIR([build-aux])
-AM_INIT_AUTOMAKE([foreign serial-tests])
+
+dnl Initialize automake.  automake < 1.12 didn't have serial-tests and
+dnl gives an error if it sees this, but for automake >= 1.13
+dnl serial-tests is required so we have to include it.  Solution is to
+dnl test for the version of automake (by running an external command)
+dnl and provide it if necessary.  Note we have to do this entirely using
+dnl m4 macros since automake queries this macro by running
+dnl 'autoconf --trace ...'.
+m4_define([serial_tests], [
+    m4_esyscmd([automake --version |
+                head -1 |
+                awk '{split ($NF,a,"."); if (a[1] == 1 && a[2] >= 12) { print "serial-tests" }}'
+    ])
+])
+AM_INIT_AUTOMAKE(foreign serial_tests) dnl NB: Do not [quote] this parameter.
 
 m4_ifndef([AM_SILENT_RULES], [m4_define([AM_SILENT_RULES],[])])
 AM_SILENT_RULES([yes]) # make --enable-silent-rules the default.
-- 
1.8.1.2