Fix Literal mixing enum values and strings failing to parse

CHANGELOG.rst

@@ -19,17 +19,19 @@ Added
 ^^^^^
 - Support for Python 3.13 (`#554
   <https://github.com/omni-us/jsonargparse/pull/554>`__).
-- Support for `NotRequired` and `Required` annotations for `TypedDict` keys
-  (`#571 <https://github.com/omni-us/jsonargparse/pull/571>`__).
+- Support for ``NotRequired`` and ``Required`` annotations for ``TypedDict``
+  keys (`#571 <https://github.com/omni-us/jsonargparse/pull/571>`__).
 
 Fixed
 ^^^^^
 - Callable type with subclass return not showing the ``--*.help`` option (`#567
   <https://github.com/omni-us/jsonargparse/pull/567>`__).
-- Forward referenced types not compatible with `Type` typehint (`#576
+- Forward referenced types not compatible with ``Type`` typehint (`#576
   <https://github.com/omni-us/jsonargparse/pull/576/>`__).
 - Subclass nested in ``Iterable`` makes help fail (`#578
   <https://github.com/omni-us/jsonargparse/pull/578>`__).
+- ``Literal`` mixing enum values and strings failing to parse (`#580
+  <https://github.com/omni-us/jsonargparse/pull/580/>`__).
 
 Changed
 ^^^^^^^

jsonargparse/_typehints.py

@@ -760,7 +760,7 @@ def adapt_typehints(
     # Literal
     elif typehint_origin in literal_types:
         if val not in subtypehints and isinstance(val, str):
-            subtypes = Union[tuple({type(v) for v in subtypehints})]
+            subtypes = Union[tuple({type(v) for v in subtypehints if type(v) is not str})]
             val = adapt_typehints(val, subtypes, **adapt_kwargs)
         if val not in subtypehints:
             raise_unexpected_value(f"Expected a {typehint}", val)

jsonargparse_tests/test_typehints.py

@@ -248,6 +248,16 @@ def test_enum_str_optional(parser):
     assert None is parser.parse_args(["--enum=null"]).enum
 
 
+@pytest.mark.skipif(not Literal, reason="Literal introduced in python 3.8 or backported in typing_extensions")
+def test_literal_enum_values(parser):
+    parser.add_argument("--enum", type=Literal[EnumABC.A, EnumABC.C, "X"])
+    assert EnumABC.A == parser.parse_args(["--enum=A"]).enum
+    assert EnumABC.C == parser.parse_args(["--enum=C"]).enum
+    assert "X" == parser.parse_args(["--enum=X"]).enum
+    with pytest.raises(ArgumentError, match="Expected a typing.*.Literal"):
+        parser.parse_args(["--enum=B"])
+
+
 # set tests