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Fix misleading error message for invalid value for Literal strings #790

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Merged
merged 1 commit into from
Oct 21, 2025
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Fix misleading error message for invalid value for Literal strings #790

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2 changes: 2 additions & 0 deletions CHANGELOG.rst
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Expand Up @@ -22,6 +22,8 @@ Fixed
<https://github.com/omni-us/jsonargparse/pull/787>`__).
- ``Union`` with path type and non-path value incorrectly dumped as string
(`#789 <https://github.com/omni-us/jsonargparse/pull/789>`__).
- Misleading error message for invalid value for ``Literal`` strings (`#790
<https://github.com/omni-us/jsonargparse/pull/790>`__).


v4.42.0 (2025-10-14)
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5 changes: 3 additions & 2 deletions jsonargparse/_typehints.py
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Expand Up @@ -781,8 +781,9 @@ 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 if type(v) is not str))]
val = adapt_typehints(val, subtypes, **adapt_kwargs)
subtypes = tuple((type(v) for v in subtypehints if type(v) is not str))
if subtypes:
val = adapt_typehints(val, Union[subtypes], **adapt_kwargs)
if val not in subtypehints:
raise_unexpected_value(f"Expected a {typehint}", val)

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2 changes: 2 additions & 0 deletions jsonargparse_tests/test_typehints.py
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Expand Up @@ -183,6 +183,8 @@ def test_union_of_literals(parser):
parser.add_argument("--literal", type=Union[Literal[1, 2], Literal["a", "b"]])
assert "a" == parser.parse_args(["--literal=a"]).literal
assert 2 == parser.parse_args(["--literal=2"]).literal
with pytest.raises(ArgumentError, match=r"Expected a typing.Literal\['a', 'b']"):
parser.parse_args(["--literal=x"])


@parser_modes
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