Amend failing test, use _cls again for error context and use appropriate code

Author: sterliakov

mypy/plugins/dataclasses.py

@@ -472,7 +472,8 @@ def _add_dunder_hash(self, is_hashable: bool) -> None:
                 self._api.fail(
                     "Incompatible override of '__hash__': dataclasses without"
                     " 'frozen' or 'unsafe_hash' have '__hash__' set to None",
-                    self._reason,
+                    self._cls,
+                    code=errorcodes.OVERRIDE,
                 )
             add_attribute_to_class(
                 self._api, self._cls, "__hash__", typ=NoneType(), is_classvar=True

test-data/unit/check-dataclasses.test

@@ -259,8 +259,9 @@ from dataclasses import dataclass
 class FrozenBase:
     pass
 
-@dataclass  # E: Incompatible override of '__hash__': dataclasses without 'frozen' or 'unsafe_hash' have '__hash__' set to None
-class BadNormalDerived(FrozenBase):  # E: Non-frozen dataclass cannot inherit from a frozen dataclass
+@dataclass
+class BadNormalDerived(FrozenBase):  # E: Incompatible override of '__hash__': dataclasses without 'frozen' or 'unsafe_hash' have '__hash__' set to None \
+                                     # E: Non-frozen dataclass cannot inherit from a frozen dataclass
     pass
 
 @dataclass
@@ -282,6 +283,11 @@ class BadFrozenDerived(NormalBase):  # E: Signature of "__hash__" incompatible w
 
 
 
+
+
+
+
+
 [builtins fixtures/dataclasses.pyi]
 
 [case testDataclassesFields]
@@ -2639,8 +2645,8 @@ class Good(Hashable):
 class AlsoGood(Hashable):
     a: int
 
-@dataclasses.dataclass()  # E: Incompatible override of '__hash__': dataclasses without 'frozen' or 'unsafe_hash' have '__hash__' set to None
-class Bad(Hashable):
+@dataclasses.dataclass()
+class Bad(Hashable):  # E: Incompatible override of '__hash__': dataclasses without 'frozen' or 'unsafe_hash' have '__hash__' set to None
     a: int
 
 Good(4)

test-data/unit/deps.test

@@ -1390,6 +1390,7 @@ class B(A):
 [out]
 <m.A.(abstract)> -> <m.B.__init__>, m
 <m.A.__dataclass_fields__> -> <m.B.__dataclass_fields__>
+<m.A.__hash__> -> <m.B.__hash__>
 <m.A.__init__> -> <m.B.__init__>, m.B.__init__
 <m.A.__mypy-replace> -> <m.B.__mypy-replace>, m, m.B.__mypy-replace
 <m.A.__new__> -> <m.B.__new__>
@@ -1422,6 +1423,7 @@ class B(A):
 [out]
 <m.A.(abstract)> -> <m.B.__init__>, m
 <m.A.__dataclass_fields__> -> <m.B.__dataclass_fields__>
+<m.A.__hash__> -> <m.B.__hash__>
 <m.A.__init__> -> <m.B.__init__>, m.B.__init__
 <m.A.__match_args__> -> <m.B.__match_args__>
 <m.A.__mypy-replace> -> <m.B.__mypy-replace>, m, m.B.__mypy-replace