Exclude private attributes from override checks

mypy/checker.py

@@ -1879,6 +1879,7 @@ def check_explicit_override_decorator(
             found_method_base_classes
             and not defn.is_explicit_override
             and defn.name not in ("__init__", "__new__")
+            and not is_private(defn.name)
         ):
             self.msg.explicit_override_decorator_missing(
                 defn.name, found_method_base_classes[0].fullname, context or defn
@@ -1921,7 +1922,7 @@ def check_method_or_accessor_override_for_base(
             base_attr = base.names.get(name)
             if base_attr:
                 # First, check if we override a final (always an error, even with Any types).
-                if is_final_node(base_attr.node):
+                if is_final_node(base_attr.node) and not is_private(name):
                     self.msg.cant_override_final(name, base.name, defn)
                 # Second, final can't override anything writeable independently of types.
                 if defn.is_final:
@@ -2680,7 +2681,7 @@ class C(B, A[int]): ...  # this is unsafe because...
             ok = True
         # Final attributes can never be overridden, but can override
         # non-final read-only attributes.
-        if is_final_node(second.node):
+        if is_final_node(second.node) and not is_private(name):
             self.msg.cant_override_final(name, base2.name, ctx)
         if is_final_node(first.node):
             self.check_if_final_var_override_writable(name, second.node, ctx)
@@ -3308,6 +3309,8 @@ def check_compatibility_final_super(
         """
         if not isinstance(base_node, (Var, FuncBase, Decorator)):
             return True
+        if is_private(node.name):
+            return True
         if base_node.is_final and (node.is_final or not isinstance(base_node, Var)):
             # Give this error only for explicit override attempt with `Final`, or
             # if we are overriding a final method with variable.

test-data/unit/check-dataclasses.test

@@ -2531,3 +2531,16 @@ class Foo:
 
     c: int  # E: Name "c" already defined on line 5
 [builtins fixtures/dataclasses.pyi]
+
+[case testDataclassInheritanceWorksWithExplicitOverrides]
+# flags: --enable-error-code explicit-override
+from dataclasses  import dataclass
+
+@dataclass
+class Base:
+    x: int
+
+@dataclass
+class Child(Base):
+    y: int
+[builtins fixtures/dataclasses.pyi]

test-data/unit/check-final.test

@@ -1117,3 +1117,16 @@ from typing import Final
 class MyClass:
     a: None
     a: Final[int] = 1  # E: Cannot redefine an existing name as final  # E: Name "a" already defined on line 5
+
+[case testFinalOverrideAllowedForPrivate]
+from typing import Final, final
+
+class Parent:
+    __foo: Final[int] = 0
+    @final
+    def __bar(self) -> None: ...
+
+class Child(Parent):
+    __foo: Final[int] = 1
+    @final
+    def __bar(self) -> None: ...

test-data/unit/check-functions.test

@@ -3159,6 +3159,16 @@ class D(A, B):
     def f(self, z: int) -> str: pass  # E: Method "f" is not using @override but is overriding a method in class "__main__.A"
 [typing fixtures/typing-override.pyi]
 
+[case testExplicitOverrideAllowedForPrivate]
+# flags: --enable-error-code explicit-override --python-version 3.12
+
+class B:
+    def __f(self, y: int) -> str: pass
+
+class C(B):
+    def __f(self, y: int) -> str: pass  # OK
+[typing fixtures/typing-override.pyi]
+
 [case testCallableProperty]
 from typing import Callable
 

test-data/unit/fine-grained-dataclass-transform.test

@@ -86,9 +86,9 @@ class A(Dataclass):
 
 [out]
 main:7: error: Unexpected keyword argument "x" for "B"
-builtins.pyi:13: note: "B" defined here
+builtins.pyi:14: note: "B" defined here
 main:7: error: Unexpected keyword argument "y" for "B"
-builtins.pyi:13: note: "B" defined here
+builtins.pyi:14: note: "B" defined here
 ==
 
 [case frozenInheritanceViaDefault]

test-data/unit/fixtures/dataclasses.pyi

@@ -3,6 +3,7 @@ from typing import (
     Generic, Iterator, Iterable, Mapping, Optional, Sequence, Tuple,
     TypeVar, Union, overload,
 )
+from typing_extensions import override
 
 _T = TypeVar('_T')
 _U = TypeVar('_U')
@@ -29,8 +30,10 @@ class dict(Mapping[KT, VT]):
     def __init__(self, **kwargs: VT) -> None: pass
     @overload
     def __init__(self, arg: Iterable[Tuple[KT, VT]], **kwargs: VT) -> None: pass
+    @override
     def __getitem__(self, key: KT) -> VT: pass
     def __setitem__(self, k: KT, v: VT) -> None: pass
+    @override
     def __iter__(self) -> Iterator[KT]: pass
     def __contains__(self, item: object) -> int: pass
     def update(self, a: Mapping[KT, VT]) -> None: pass
@@ -42,7 +45,9 @@ class dict(Mapping[KT, VT]):
 
 class list(Generic[_T], Sequence[_T]):
     def __contains__(self, item: object) -> int: pass
+    @override
     def __getitem__(self, key: int) -> _T: pass
+    @override
     def __iter__(self) -> Iterator[_T]: pass
 
 class function: pass