[gnome-shell] ci: Prohibit template strings in translatable files

[Florian Müllner <fmuellner src gnome org>]

commit a7d974e670673b331313098b09ebddd627aab8e3
Author: Florian Müllner <fmuellner gnome org>
Date:   Tue Feb 18 17:08:23 2020 +0100

    ci: Prohibit template strings in translatable files
    
    Sadly, xgettext's dealing with template strings is abysimal, so we
    had to stop using them in files with translatable strings.
    
    Make sure we don't accidentally sneak in template strings again(*)
    and enforce that rule in a CI job.
    
    (*) easy "mistake", considering how much nicer they are than
        String.prototype.format()
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/1016

 .gitlab-ci.yml                       |  7 +++++++
 .gitlab-ci/check-template-strings.sh | 23 +++++++++++++++++++++++
 2 files changed, 30 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 3b4d23ab9a..c7f925cc08 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -53,6 +53,13 @@ potfile_check:
         - ./.gitlab-ci/check-potfiles.sh
     <<: *only_default
 
+no_template_check:
+    image: registry.gitlab.gnome.org/gnome/gnome-shell/extension-ci:v1
+    stage: review
+    script:
+        - ./.gitlab-ci/check-template-strings.sh
+    <<: *only_default
+
 build:
     image: registry.gitlab.gnome.org/gnome/mutter/master:v3
     stage: build
diff --git a/.gitlab-ci/check-template-strings.sh b/.gitlab-ci/check-template-strings.sh
new file mode 100755
index 0000000000..efa8afc1f5
--- /dev/null
+++ b/.gitlab-ci/check-template-strings.sh
@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+# find files from POTFILES.in that use js template strings
+baddies=$(grep -l '${' $(grep ^js po/POTFILES.in))
+
+if [ ${#baddies} -eq 0 ]; then
+  exit 0
+fi
+
+cat >&2 <<EOT
+
+xgettext cannot handle template strings properly, so we ban their use
+in files with translatable strings.
+
+The following files are listed in po/POTFILES.in and use template strings:
+
+EOT
+for f in $baddies; do
+  echo "  $f" >&2
+done
+echo >&2
+
+exit 1