configure: add support for helper script to compute version string

Some projects are using (or planning to use) crosstool-NG, and are storing
it in their VCS, which might not be Mercurial. At the same time, those
projects may want to track development snapshots versions the way we do
with the Hg identity string (hg id).

Provide a way for these project to do so, without having to patch
./configure, and maintain that patch over-and-over again.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

1 files changed, 29 insertions, 15 deletions

diff --git a/configure b/configure
index 6a68b382..76194b96 100755
--- a/configure
+++ b/configure
@@ -536,21 +536,35 @@ has_or_abort lib="${ncurses_libs}"                                          \
 # If this version is n hg clone, try to get the revision number
 # If we can't get the revision number, use date
 printf "\nComputing version string... "
-case "${VERSION}" in
-    *+hg|hg)
-        REVISION="$( hg id -n 2>/dev/null || true )"
-        case "${REVISION}" in
-            "")
-                VERSION="${VERSION}_unknown@$( date +%Y%m%d.%H%M%S )";;
-            *)
-                VERSION="${VERSION}_$( hg id -b )@${REVISION%%+}_$( hg id -i )"
-                ;;
-        esac
-        # Arrange to have no / in the directory name, no need to create an
-        # arbitrarily deep directory structure
-        VERSION="$( printf "${VERSION}\n" |"${sed}" -r -e 's|/+|_|g;' )"
-        ;;
-esac
+
+# Pass the version to the version helper script, if present, to compute
+# a local version string, if needed.
+if [ -f version.sh -a -x version.sh ]; then
+    V="$( ./version.sh "${VERSION}" 2>/dev/null |head -n 1 )"
+fi
+
+# If the script returns an empty string, revert to using the version
+# we just computed, above.
+if [ -n "${V}" ]; then
+    VERSION="${V}"
+else
+    case "${VERSION}" in
+        *+hg|hg)
+            REVISION="$( hg id -n 2>/dev/null || true )"
+            case "${REVISION}" in
+                "")
+                    VERSION="${VERSION}_unknown@$( date +%Y%m%d.%H%M%S )";;
+                *)
+                    VERSION="${VERSION}_$( hg id -b )@${REVISION%%+}_$( hg id -i )"
+                    ;;
+            esac
+            # Arrange to have no / in the directory name, no need to create an
+            # arbitrarily deep directory structure
+            VERSION="$( printf "${VERSION}\n" |"${sed}" -r -e 's|/+|_|g;' )"
+            ;;
+    esac
+fi
+
 printf "${VERSION}\n"
 
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