gh-99749: Add closest choice if exists in Argparser if wrong choice picked

Lib/argparse.py

@@ -84,7 +84,7 @@
  'ZERO_OR_MORE',
 ]
 
-
+import difflib as _difflib
 import os as _os
 import re as _re
 import sys as _sys
@@ -2541,11 +2541,29 @@ def _get_value(self, action, arg_string):
  return result
 
  def _check_value(self, action, value):
+ if not action.choices and isinstance(action.choices, list):
+ msg = 'Either add options in choices array or remove it'
+ raise ArgumentError(action, msg)
+
  # converted value must be one of the choices (if specified)
  if action.choices is not None and value not in action.choices:
- args ={'value': value,
- 'choices': ', '.join(map(repr, action.choices))}
- msg = _('invalid choice: %(value)r (choose from %(choices)s)')
+ try:
+ closest_choice = _difflib.get_close_matches(value, action.choices, 1)
+ except TypeError:
+ closest_choice = []
+
+ args ={
+ 'value': value,
+ 'choices': ', '.join(map(repr, action.choices)),
+ }
+ if closest_choice:
+ closest_choice = closest_choice[0]
+ args['closest'] = closest_choice
+ msg = _('invalid choice: %(value)r, maybe you meant %(closest)r? '
+ '(choose from %(choices)s)')
+ else:
+ msg = _('invalid choice: %(value)r (choose from %(choices)s)')
+
  raise ArgumentError(action, msg % args)
 
  # =======================

Lib/test/test_argparse.py

@@ -2193,9 +2193,9 @@ def test_wrong_argument_subparsers_no_destination_error(self):
  subparsers.add_parser('bar')
  with self.assertRaises(ArgumentParserError) as excinfo:
  parser.parse_args(('baz',))
- self.assertRegex(
+ self.assertIn(
+ "error: argument{foo,bar}: invalid choice: 'baz', maybe you meant 'bar'? (choose from 'foo', 'bar')",
  excinfo.exception.stderr,
- r"error: argument{foo,bar}: invalid choice: 'baz' \(choose from 'foo', 'bar'\)\n$"
  )
 
  def test_optional_subparsers(self):

Misc/NEWS.d/next/Core and Builtins/2022-11-25-12-23-56.gh-issue-99749.-S_guS.rst

@@ -0,0 +1 @@
+Add closest choice if exists in Argparser if wrong choice picked.