Back to "git describe" to yield version number

src/build.sh

@@ -41,6 +41,13 @@ function update_repo {
   cd "$old_path" || return 1
 }
 
+function git_version_from_commit_msg {
+  local version
+  local sha
+  read -r sha version <<< "$(git log --pretty=format:'%h %s' | grep -E "[0-9.]+\.[0-9]+$" | head -n 1)"
+  echo "$version-$(git rev-list --count "$sha"..HEAD)"
+}
+
 function pkg_exists {
   local version; version=$(apt-cache policy "$(deb_pkg_name "$1")" | sed -n 's#^\s*Candidate:\s\(.*\)#\1#p')
   if [ "$SKIP_EXISTING" == "true" ] && [ -n "$version" ] && [ "$version" != "(none)" ]; then
@@ -72,12 +79,22 @@ function build_pkg {
   # https://github.com/ros-infrastructure/bloom/pull/643
   echo 11 > debian/compat
 
-  # Set version based on last changelog entry and append build timestamp (following official ROS scheme)
-  # <changelog version>-<increment><debian distro>.date.time
-  # This way, we cannot yet distinguish different, not-yet-released versions (which git describe would do)
-  # However, git describe relied on tags being available, which is often not the case!
-  # TODO: Increase the increment on each build
-  version="$(dpkg-parsechangelog --show-field Version).$(date +%Y%m%d.%H%M)"
+  # version from last changelog entry: <changelog version>-<increment><debian distro>
+  deb_version="$(dpkg-parsechangelog --show-field Version)"
+  # version from last (numeric) git release tag: <release version>-<git offset>
+  # - stripping any leading non digits as they are not part of the version number
+  # - stripping trailing -g<sha>
+  git_version="$(git describe --tag --long --match "*[0-9]*" 2>/dev/null | sed 's@^[^0-9]*@@;s@-g[0-9a-f]*$@@')"
+  if [ -z "$git_version" ] || [ "$git_version$DEB_DISTRO" \< "$deb_version" ]; then
+    gha_warning "git version ($git_version) is older than changelog version ($deb_version)"
+    git_version=$(git_version_from_commit_msg)
+  fi
+  if [ "$git_version$DEB_DISTRO" \< "$deb_version" ]; then
+    return 5
+  fi
+
+  # Apppend build timestamp (following ROS scheme): <release version>-<git offset><debian distro>.date.time
+  version="$git_version$DEB_DISTRO.$(date +%Y%m%d.%H%M)"
   debchange -v "$version" \
     --preserve --force-distribution "$DEB_DISTRO" \
     --urgency high -m "Append timestamp when binarydeb was built." || return 3
@@ -143,6 +160,7 @@ function build_source {
         2) msg_prefix="bloom-generate failed" ;;
         3) msg_prefix="debchange failed" ;;
         4) msg_prefix="sbuild failed" ;;
+        5) msg_prefix="missing release tag for latest version" ;;
         *) msg_prefix="unnamed step failed ($exit_code)" ;;
       esac