python · serhiy-storchaka · Feb 5, 2024 · Feb 5, 2024
diff --git a/Lib/argparse.py b/Lib/argparse.py
@@ -2488,7 +2488,7 @@ def parse_known_intermixed_args(self, args=None, namespace=None):
    # ========================
    def _get_values(self, action, arg_strings):
        # for everything but PARSER, REMAINDER args, strip out first '--'
-        if action.nargs not in [PARSER, REMAINDER]:
+        if not action.option_strings and action.nargs not in [PARSER, REMAINDER]:
            try:
                arg_strings.remove('--')
            except ValueError:

diff --git a/Lib/test/test_argparse.py b/Lib/test/test_argparse.py
@@ -5332,6 +5332,22 @@ def test_zero_or_more_optional(self):
        args = parser.parse_args([])
        self.assertEqual(NS(x=[]), args)

+    def test_double_dash(self):
+        parser = argparse.ArgumentParser()
+        parser.add_argument('-f', '--foo', nargs='*')
+        parser.add_argument('bar', nargs='*')
+
+        args = parser.parse_args(['--foo=--'])
+        self.assertEqual(NS(foo=['--'], bar=[]), args)
+        args = parser.parse_args(['--foo', '--'])
+        self.assertEqual(NS(foo=[], bar=[]), args)
+        args = parser.parse_args(['-f--'])
+        self.assertEqual(NS(foo=['--'], bar=[]), args)
+        args = parser.parse_args(['-f', '--'])
+        self.assertEqual(NS(foo=[], bar=[]), args)
+        args = parser.parse_args(['--foo', 'a', 'b', '--', 'c', 'd'])
+        self.assertEqual(NS(foo=['a', 'b'], bar=['c', 'd']), args)
+

 # ===========================
 # parse_intermixed_args tests

diff --git a/Misc/NEWS.d/next/Library/2024-01-31-20-07-11.gh-issue-109475.lmTb9S.rst b/Misc/NEWS.d/next/Library/2024-01-31-20-07-11.gh-issue-109475.lmTb9S.rst
@@ -0,0 +1,2 @@
+Fix support of explicit option value "--" in :mod:`argparse` (e.g.
+``--option=--``).
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Fix support of explicit option value "--" in :mod:`argparse` (e.g.
		``--option=--``).