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Description
Bug Report
When a class derives from a base class marked withdataclass_transform and the derived class has no fields, mypy incorrectly infers that the derived class does not provide its own constructor. This issue does not happen if the derived class has any fields.
Pyright infers the correct constructor signature here.
To Reproduce
fromtypingimportdataclass_transform,reveal_type@dataclass_transform()classBase:def__init__(self,a:int )->None:passclassDerivedNoFields(Base ):passclassDerivedWithFields(Base ):b:strreveal_type(DerivedNoFields.__init__ )reveal_type(DerivedWithFields.__init__ )
Expected Behavior
main.py:14: note: Revealed type is "def (self: __main__.DerivedNoFields)"main.py:15: note: Revealed type is "def (self: __main__.DerivedWithFields, b: builtins.str)"Actual Behavior
main.py:14: note: Revealed type is "def (self: __main__.Base, a: builtins.int)"main.py:15: note: Revealed type is "def (self: __main__.DerivedWithFields, b: builtins.str)"Your Environment
- Mypy version used: 3.16.1
- Python version used: 3.13
- No command-line flags or configuration options