ci: Add script to check for potfile errors

It's easy to forget to update potfiles. Steal the script that
gnome-shell uses to check for this.

.gitlab-ci.yml

@@ -5,6 +5,7 @@ variables:
 
 stages:
     - image
+    - review
     - test
     - analyze
     - deploy
@@ -43,6 +44,12 @@ nightly@aarch64:
     extends: '.publish_nightly'
     needs: ['flatpak@aarch64']
 
+potfile:
+    image: registry.gitlab.gnome.org/gnome/nautilus:latest
+    stage: review
+    script:
+        - data/check-potfiles.sh
+
 style check:
     image: registry.gitlab.gnome.org/gnome/nautilus:latest
     stage: test

data/check-potfiles.sh

@@ -0,0 +1,38 @@
+#!/usr/bin/env bash
+
+srcdirs="eel extensions src libnautilus-extension"
+uidirs="src/resources/ui src/gtk"
+desktopdirs="data"
+
+# find source files that contain gettext keywords
+files=$(grep -lR --include='*.c' '\(gettext\|[^I_)]_\)(' $srcdirs)
+
+# find ui files that contain translatable string
+files="$files "$(grep -lRi --include='*.ui' 'translatable="[ty1]' $uidirs)
+
+# find .desktop files
+files="$files "$(find $desktopdirs -name '*.desktop*')
+
+# filter out excluded files
+if [ -f po/POTFILES.skip ]; then
+  files=$(for f in $files; do ! grep -q ^$f po/POTFILES.skip && echo $f; done)
+fi
+
+# find those that aren't listed in POTFILES.in
+missing=$(for f in $files; do ! grep -q ^$f po/POTFILES.in && echo $f; done)
+
+if [ ${#missing} -eq 0 ]; then
+  exit 0
+fi
+
+cat >&2 <<EOT
+
+The following files are missing from po/POTFILES.po:
+
+EOT
+for f in $missing; do
+  echo "  $f" >&2
+done
+echo >&2
+
+exit 1