chore: replace no-op final-newline lint with a real check

Author: philippemnoel

.github/workflows/lint-format.yml

@@ -46,13 +46,21 @@ jobs:
             exit 1
           fi
 
-      - name: Print Modified Files
+      - name: Check for Missing Final Newlines
         run: |
-          FILES=$(git ls-files --modified)
-          if [[ ! -z "$FILES" ]]; then
-            echo "The following files have incorrect trailing newlines:"
-            echo "$FILES"
-            echo "Please fix them using:"
-            echo -e 'if [[ -f "$1" ]]; then\n  echo -n "$1"\n  if (diff /dev/null "$1" || true) | tail -1 | grep -q "^\\ No newline"; then\n    echo >> "$1"\n    echo "...fixed"\n  else\n    echo ""\n  fi\nfi'
-            false
+          MISSING=""
+          while IFS= read -r file; do
+            if [[ -s "$file" && -n "$(tail -c1 "$file")" ]]; then
+              MISSING="${MISSING}${file}"$'\n'
+            fi
+          done < <(git grep -Il '.' -- \
+            ':(exclude)*.nix' \
+            ':(exclude)*.sql' \
+            ':(exclude)*.out' \
+            ':(exclude)*.rs' \
+            ':(exclude)docker/manifests/**')
+          if [[ -n "$MISSING" ]]; then
+            echo "The following files are missing a trailing newline:"
+            echo "$MISSING"
+            exit 1
           fi