bpo-39056: Fix handling invalid warning category in the -W option. (GH-17618)

No longer import the re module if it is not needed. (cherry picked from commit 41ec17e) Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Author: miss-islington

Lib/test/test_warnings/__init__.py

@@ -43,6 +43,10 @@ def warnings_state(module):
  module.filters = original_filters
 
 
+class TestWarning(Warning):
+ pass
+
+
 class BaseTest:
 
  """Basic bookkeeping required for testing."""
@@ -629,9 +633,28 @@ def test_improper_input(self):
  self.module._setoption, 'bogus::Warning')
  self.assertRaises(self.module._OptionError,
  self.module._setoption, 'ignore:2::4:-5')
+ with self.assertRaises(self.module._OptionError):
+ self.module._setoption('ignore::123')
+ with self.assertRaises(self.module._OptionError):
+ self.module._setoption('ignore::123abc')
+ with self.assertRaises(self.module._OptionError):
+ self.module._setoption('ignore::===')
+ with self.assertRaisesRegex(self.module._OptionError, 'Wärning'):
+ self.module._setoption('ignore::Wärning')
  self.module._setoption('error::Warning::0')
  self.assertRaises(UserWarning, self.module.warn, 'convert to error')
 
+ def test_import_from_module(self):
+ with original_warnings.catch_warnings(module=self.module):
+ self.module._setoption('ignore::Warning')
+ with self.assertRaises(self.module._OptionError):
+ self.module._setoption('ignore::TestWarning')
+ with self.assertRaises(self.module._OptionError):
+ self.module._setoption('ignore::test.test_warnings.bogus')
+ self.module._setoption('error::test.test_warnings.TestWarning')
+ with self.assertRaises(TestWarning):
+ self.module.warn('test warning', TestWarning)
+
 
 class CWCmdLineTests(WCmdLineTests, unittest.TestCase):
  module = c_warnings

Lib/warnings.py

@@ -211,7 +211,6 @@ def _processoptions(args):
 
 # Helper for _processoptions()
 def _setoption(arg):
- import re
  parts = arg.split(':')
  if len(parts) > 5:
  raise _OptionError("too many fields (max 5): %r" % (arg,))
@@ -220,11 +219,13 @@ def _setoption(arg):
  action, message, category, module, lineno = [s.strip()
  for s in parts]
  action = _getaction(action)
- message = re.escape(message)
  category = _getcategory(category)
- module = re.escape(module)
+ if message or module:
+ import re
+ if message:
+ message = re.escape(message)
  if module:
- module = module + '$'
+ module = re.escape(module) + r'\Z'
  if lineno:
  try:
  lineno = int(lineno)
@@ -248,26 +249,21 @@ def _getaction(action):
 
 # Helper for _setoption()
 def _getcategory(category):
- import re
  if not category:
  return Warning
- if re.match("^[a-zA-Z0-9_]+$", category):
- try:
- cat = eval(category)
- except NameError:
- raise _OptionError("unknown warning category: %r" % (category,)) from None
+ if '.' not in category:
+ import builtins as m
+ klass = category
  else:
- i = category.rfind(".")
- module = category[:i]
- klass = category[i+1:]
+ module, _, klass = category.rpartition('.')
  try:
  m = __import__(module, None, None, [klass])
  except ImportError:
  raise _OptionError("invalid module name: %r" % (module,)) from None
-  try:
-  cat = getattr(m, klass)
-  except AttributeError:
-  raise _OptionError("unknown warning category: %r" % (category,)) from None
+ try:
+ cat = getattr(m, klass)
+ except AttributeError:
+ raise _OptionError("unknown warning category: %r" % (category,)) from None
  if not issubclass(cat, Warning):
  raise _OptionError("invalid warning category: %r" % (category,))
  return cat

Misc/NEWS.d/next/Library/2019-12-15-21-05-16.bpo-39056.nEfUM9.rst

@@ -0,0 +1,2 @@
+Fixed handling invalid warning category in the -W option. No longer import
+the re module if it is not needed.