configtypes: Handle invalid escapes in regexes.

qutebrowser/config/configtypes.py

@@ -26,6 +26,7 @@ import codecs
 import os.path
 import itertools
 import collections
+import warnings
 
 from PyQt5.QtCore import QUrl
 from PyQt5.QtGui import QColor, QFont
@@ -45,11 +46,21 @@ BOOLEAN_STATES = {'1': True, 'yes': True, 'true': True, 'on': True,
 
 
 def _validate_regex(pattern, flags):
-    try:
+    with warnings.catch_warnings(record=True) as recorded_warnings:
-        re.compile(pattern, flags)
+        warnings.simplefilter('always')
-    except re.error as e:
+        try:
-        raise configexc.ValidationError(pattern, "must be a valid regex - " +
+            re.compile(pattern, flags)
-                                        str(e))
+        except re.error as e:
+            raise configexc.ValidationError(
+                pattern, "must be a valid regex - " + str(e))
+
+    for w in recorded_warnings:
+        if (issubclass(w.category, DeprecationWarning) and
+                str(w.message).startswith('bad escape')):
+            raise configexc.ValidationError(
+                pattern, "must be a valid regex - " + str(w.message))
+        else:
+            warnings.warn(w.message)
 
 
 class ValidValues:

tests/unit/config/test_configtypes.py

@@ -23,6 +23,7 @@ import collections
 import itertools
 import os.path
 import base64
+import warnings
 
 import pytest
 from PyQt5.QtCore import QUrl
@@ -1064,6 +1065,22 @@ class TestRegex:
         with pytest.raises(configexc.ValidationError):
             klass().validate(val)
 
+    @pytest.mark.parametrize('val', [
+        r'foo\Xbar',
+        r'foo\Cbar',
+    ])
+    def test_validate_maybe_valid(self, klass, val):
+        """Those values are valid on some Python versions (and systems?).
+
+        On others, they raise a DeprecationWarning because of an invalid
+        escape. This tests makes sure this gets translated to a
+        ValidationError.
+        """
+        try:
+            klass().validate(val)
+        except configexc.ValidationError:
+            pass
+
     @pytest.mark.parametrize('val, expected', [
         (r'foobar', RegexEq(r'foobar')),
         ('', None),
@@ -1071,6 +1088,16 @@ class TestRegex:
     def test_transform_empty(self, klass, val, expected):
         assert klass().transform(val) == expected
 
+    @pytest.mark.parametrize('warning', [
+        Warning('foo'), DeprecationWarning('foo'),
+    ])
+    def test_passed_warnings(self, mocker, klass, warning):
+        m = mocker.patch('qutebrowser.config.configtypes.re')
+        m.compile.side_effect = lambda *args: warnings.warn(warning)
+        m.error = re.error
+        with pytest.raises(type(warning)):
+            klass().validate('foo')
+
 
 class TestRegexList:
 
@@ -1097,6 +1124,22 @@ class TestRegexList:
         with pytest.raises(configexc.ValidationError):
             klass().validate(val)
 
+    @pytest.mark.parametrize('val', [
+        r'foo\Xbar',
+        r'foo\Cbar',
+    ])
+    def test_validate_maybe_valid(self, klass, val):
+        """Those values are valid on some Python versions (and systems?).
+
+        On others, they raise a DeprecationWarning because of an invalid
+        escape. This tests makes sure this gets translated to a
+        ValidationError.
+        """
+        try:
+            klass().validate(val)
+        except configexc.ValidationError:
+            pass
+
     @pytest.mark.parametrize('val, expected', [
         ('foo', [RegexEq('foo')]),
         ('foo,bar,baz', [RegexEq('foo'), RegexEq('bar'),