Version += git revision (#1331)

* Add the git revision to the version number for 'alpha' builds

* Ensure there is a .git folder

* Use `./version.sh` relative path

* Fix equality operator for a real bourne shell (like on TravisCI)

configure.ac

@@ -1,5 +1,6 @@
 # Process this file with autoconf to produce a configure script.
-AC_INIT(meep, 1.16.0-alpha)
+
+AC_INIT(meep, m4_esyscmd([./version.sh 1.16.0 alpha]))
 AC_CONFIG_SRCDIR(src/step.cpp)
 
 # Shared-library version number; indicates api compatibility, and is

version.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+#
+# Build a version number, possibly including the Git revision number. Called
+# from configure.ac via AC_INIT.
+#
+
+#set -x
+
+VERSION=$1
+TAG=$2
+
+# Include the Git revision when the release tag is "alpha"
+if [ "$TAG" = "alpha" -a -e .git ]; then
+    REV=$(git rev-parse --short=6 HEAD)
+fi
+
+# Print the version string, depending on how many components are available
+if [ "$TAG" != "" -a "$REV" != "" ]; then
+    printf "%s-%s.%s" $VERSION $TAG $REV
+elif [ "$TAG" != "" ]; then
+    printf "%s-%s" $VERSION $TAG
+else
+    printf "%s" $VERSION
+fi