tidy check for vim and emacs modelines.

See https://github.com/servo/servo/issues/10719.

python/tidy/servo_tidy/tidy.py

@@ -133,6 +133,14 @@ def check_license(file_name, lines):
         yield (1, "incorrect license")
 
 
+def check_modeline(file_name, lines):
+    for idx, line in enumerate(lines[:5]):
+        if re.search('^.*[ \t](vi:|vim:|ex:)[ \t]', line):
+            yield (idx + 1, "vi modeline present")
+        elif re.search('-\*-.*-\*-', line, re.IGNORECASE):
+            yield (idx + 1, "emacs file variables present")
+
+
 def check_length(file_name, idx, line):
     if file_name.endswith(".lock") or file_name.endswith(".json"):
         raise StopIteration
@@ -638,7 +646,7 @@ def scan(faster=False, progress=True):
     # standard checks
     files_to_check = filter_files('.', faster, progress)
     checking_functions = (check_flake8, check_lock, check_webidl_spec, check_json)
-    line_checking_functions = (check_license, check_by_line, check_toml, check_rust, check_spec)
+    line_checking_functions = (check_license, check_by_line, check_toml, check_rust, check_spec, check_modeline)
     errors = collect_errors_for_files(files_to_check, checking_functions, line_checking_functions)
     # wpt lint checks
     wpt_lint_errors = check_wpt_lint_errors(get_wpt_files(faster, progress))

python/tidy/servo_tidy_tests/modeline.txt

@@ -0,0 +1,5 @@
+# vim: set noexpandtab:
+// vi: et:
+/* ex: et:
+anything -*-Lisp-*-
+ -*- mode: Lisp -*-

python/tidy/servo_tidy_tests/test_tidy.py

@@ -75,6 +75,14 @@ class CheckTidiness(unittest.TestCase):
         errors = tidy.collect_errors_for_files(iterFile('test.toml'), [tidy.check_toml], [])
         self.assertEqual('found asterisk instead of minimum version number', errors.next()[2])
 
+    def test_modeline(self):
+        errors = tidy.collect_errors_for_files(iterFile('modeline.txt'), [], [tidy.check_modeline])
+        self.assertEqual('vi modeline present', errors.next()[2])
+        self.assertEqual('vi modeline present', errors.next()[2])
+        self.assertEqual('vi modeline present', errors.next()[2])
+        self.assertEqual('emacs file variables present', errors.next()[2])
+        self.assertEqual('emacs file variables present', errors.next()[2])
+
 
 def do_tests():
     suite = unittest.TestLoader().loadTestsFromTestCase(CheckTidiness)