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Fix swapped errors for frozen/non-frozen dataclass inheritance #18918

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Merged
merged 2 commits into from
Apr 14, 2025
Merged

Fix swapped errors for frozen/non-frozen dataclass inheritance #18918

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eaec7a2
Fix swapped error messages for frozen/non-frozen dataclass inheritance
nawrazi Apr 13, 2025
34f64aa
Rephrase error messages
nawrazi Apr 13, 2025
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4 changes: 2 additions & 2 deletions mypy/plugins/dataclasses.py
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Original file line number Diff line number Diff line change
Expand Up @@ -359,12 +359,12 @@ def transform(self) -> bool:

if decorator_arguments["frozen"]:
if any(not parent["frozen"] for parent in parent_decorator_arguments):
self._api.fail("Cannot inherit frozen dataclass from a non-frozen one", info)
self._api.fail("Frozen dataclass cannot inherit from a non-frozen dataclass", info)
self._propertize_callables(attributes, settable=False)
self._freeze(attributes)
else:
if any(parent["frozen"] for parent in parent_decorator_arguments):
self._api.fail("Cannot inherit non-frozen dataclass from a frozen one", info)
self._api.fail("Non-frozen dataclass cannot inherit from a frozen dataclass", info)
self._propertize_callables(attributes)

if decorator_arguments["slots"]:
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4 changes: 2 additions & 2 deletions test-data/unit/check-dataclasses.test
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Expand Up @@ -260,15 +260,15 @@ class FrozenBase:
pass

@dataclass
class BadNormalDerived(FrozenBase): # E: Cannot inherit non-frozen dataclass from a frozen one
class BadNormalDerived(FrozenBase): # E: Non-frozen dataclass cannot inherit from a frozen dataclass
pass

@dataclass
class NormalBase:
pass

@dataclass(frozen=True)
class BadFrozenDerived(NormalBase): # E: Cannot inherit frozen dataclass from a non-frozen one
class BadFrozenDerived(NormalBase): # E: Frozen dataclass cannot inherit from a non-frozen dataclass
pass

[builtins fixtures/dataclasses.pyi]
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