[PATCH] configure.ac: Set 'mym4_revision' to 0 if not a git repo

[Nathan Rossi]

---
It is possible for the source to not be located in a git repository
(e.g. source is from a tarball). In which case the git repository
information is not available. This results in the mym4_revision being an
empty string however this value is used in BUILD_FILEVERSION where it is
assumed to be 4 decimal values. Additionally BUILD_REVISION uses this
value and is also assumed to be non-empty.

In the case of BUILD_FILEVERSION it is used in versioninfo.rc.in, where
it must be populated as 4 decimal values due to the expected syntax. In
cases where it is not (e.g. when BUILD_FILEVERSION = '1,7,5,' a syntax
error is raised.

    windres: versioninfo.rc.in:21: syntax error

This patch changes mym4_revision so that if the 'git rev-parse' returns
non-zero (e.g. not in a git repository) the value falls back to '0'.
This propagates as '0' to both BUILD_FILEVERSION and BUILD_REVISION.

Signed-off-by: Nathan Rossi <nathan at nathanrossi.com>
---
 configure.ac | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 31c0d553fa..a3deffa6e9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -39,7 +39,7 @@ m4_define(mym4_version_micro, [0])
 m4_define(mym4_version,
           [mym4_version_major.mym4_version_minor.mym4_version_micro])
 m4_define([mym4_revision],
-          m4_esyscmd([git rev-parse --short HEAD | tr -d '\n\r']))
+          m4_esyscmd([(git rev-parse --short HEAD || printf '0') | tr -d '\n\r']))
 m4_define([mym4_revision_dec],
           m4_esyscmd_s([echo $((0x$(echo ]mym4_revision[|head -c 4)))]))
 m4_define([mym4_betastring],
-- 
2.11.0