gh-101979: fix a bug that parentheses in metavar argument of add_argument() were dropped

Lib/argparse.py

@@ -403,10 +403,18 @@ def _format_actions_usage(self, actions, groups):
  except ValueError:
  continue
  else:
- end = start + len(group._group_actions)
+ group_action_count = len(group._group_actions)
+ end = start + group_action_count
  if actions[start:end] == group._group_actions:
+
+ suppressed_actions_count = 0
  for action in group._group_actions:
  group_actions.add(action)
+ if action.help is SUPPRESS:
+ suppressed_actions_count += 1
+
+ exposed_actions_count = group_action_count - suppressed_actions_count
+
  if not group.required:
  if start in inserts:
  inserts[start] += ' ['
@@ -416,7 +424,7 @@ def _format_actions_usage(self, actions, groups):
  inserts[end] += ']'
  else:
  inserts[end] = ']'
-else:
+elif exposed_actions_count > 1:
  if start in inserts:
  inserts[start] += ' ('
  else:
@@ -490,7 +498,6 @@ def _format_actions_usage(self, actions, groups):
  text = _re.sub(r'(%s) ' % open, r'\1', text)
  text = _re.sub(r' (%s)' % close, r'\1', text)
  text = _re.sub(r'%s *%s' % (open, close), r'', text)
- text = _re.sub(r'\(([^|]*)\)', r'\1', text)
  text = text.strip()
 
  # return the text

Lib/test/test_argparse.py

@@ -3764,6 +3764,28 @@ class TestHelpUsage(HelpTestCase):
  version = ''
 
 
+class TestHelpUsageWithParentheses(HelpTestCase):
+ parser_signature = Sig(prog='PROG')
+ argument_signatures = [
+ Sig('positional', metavar='(example) positional'),
+ Sig('-p', '--optional', metavar='{1 (option A), 2 (option B)}'),
+ ]
+
+ usage = '''\
+ usage: PROG [-h] [-p {1 (option A), 2 (option B)}] (example) positional
+ '''
+ help = usage + '''\
+
+ positional arguments:
+ (example) positional
+
+ options:
+ -h, --help show this help message and exit
+ -p {1 (option A), 2 (option B)}, --optional {1 (option A), 2 (option B)}
+ '''
+ version = ''
+
+
 class TestHelpOnlyUserGroups(HelpTestCase):
  """Test basic usage messages"""
 

Misc/NEWS.d/next/Library/2023-02-28-09-52-25.gh-issue-101979.or3hXV.rst

@@ -0,0 +1,2 @@
+Fix a bug where parentheses in the ``metavar`` argument to :meth:`argparse.ArgumentParser.add_argument` were
+dropped. Patch by Yeojin Kim.