Add DUK_GIT_DESCRIBE to the public C API

src/duk_api_public.h.in

@@ -83,6 +83,12 @@ struct duk_number_list_entry {
  */
 #define DUK_VERSION                       10099L
 
+/* Git describe for Duktape build.  Useful for non-official snapshot builds
+ * so that application code can easily log which Duktape snapshot was used.
+ * Not available in the Ecmascript environment.
+ */
+#define DUK_GIT_DESCRIBE                  @GIT_DESCRIBE_CSTRING@
+
 /* Used to represent invalid index; if caller uses this without checking,
  * this index will map to a non-existent stack entry.  Also used in some
  * API calls as a marker to denote "no value".

util/make_dist.sh

@@ -43,7 +43,7 @@ DUK_MINOR=`echo "$DUK_VERSION % 10000 / 100" | bc`
 DUK_PATCH=`echo "$DUK_VERSION % 100" | bc`
 DUK_VERSION_FORMATTED=$DUK_MAJOR.$DUK_MINOR.$DUK_PATCH
 GIT_COMMIT=`git rev-parse HEAD`
-GIT_DESCRIBE=`git describe`
+GIT_DESCRIBE=`git describe --always --dirty`
 
 echo "DUK_VERSION: $DUK_VERSION"
 echo "GIT_COMMIT: $GIT_COMMIT"
@@ -373,6 +373,7 @@ cat src/duktape.h.in | sed -e '
 	-e "s/@DUK_VERSION_FORMATTED@/$DUK_VERSION_FORMATTED/" \
 	-e "s/@GIT_COMMIT@/$GIT_COMMIT/" \
 	-e "s/@GIT_DESCRIBE@/$GIT_DESCRIBE/" \
+	-e "s/@GIT_DESCRIBE_CSTRING@/\"$GIT_DESCRIBE\"/" \
 	> $DISTSRCCOM/duktape.h
 
 # keep the line so line numbers match between the two variant headers

website/api/defines.html

@@ -16,6 +16,12 @@ For example, version 1.2.3 would have <code>DUK_VERSION</code> and
 actual release, e.g. 1199 for a 0.12.0 pre-release and 10299 for a 1.3.0
 pre-release.  See <a href="guide.html#versioning">Versioning</a>.</p>
 
+<p>The <code>DUK_GIT_DESCRIBE</code> define provides a git describe string for
+the Duktape build.  For official releases this is just "v1.0.0" or similar,
+but for snapshot builds it provides useful version information (e.g.
+"v1.0.0-155-g5b7ef1f-dirty").  There is no equivalent of this define in the
+Ecmascript environment.</p>
+
 <h2>Structs and typedefs</h2>
 <pre class="c-code">
 typedef void duk_context;