Jan 11, 2025 · Jan 4, 2025 · Jan 4, 2025 · Jan 4, 2025 · Jan 4, 2025 · Jan 10, 2025
diff --git a/mypy/checker.py b/mypy/checker.py
                ok = is_subtype(first_sig, second_sig, ignore_pos_arg_names=True)
        elif first_type and second_type:
            if isinstance(first.node, Var):
                first_type = map_type_from_supertype(first_type, ctx, base1)
                first_type = expand_self_type(first.node, first_type, fill_typevars(ctx))
            if isinstance(second.node, Var):
                second_type = map_type_from_supertype(second_type, ctx, base2)
                second_type = expand_self_type(second.node, second_type, fill_typevars(ctx))
            ok = is_equivalent(first_type, second_type)
            if not ok:
diff --git a/test-data/unit/check-generic-subtyping.test b/test-data/unit/check-generic-subtyping.test

 class G(Generic[T]): ...
 class H(G[T_contra], Generic[T_contra]): ...  # E: Variance of TypeVar "T_contra" incompatible with variance in parent type

 [case testMultipleInheritanceCompatibleTypeVar]
 from typing import Generic, TypeVar

 T = TypeVar("T")
 U = TypeVar("U")

 class A(Generic[T]):
    x: T
    def fn(self, t: T) -> None: ...

 class A2(A[T]):
    y: str
    z: str

 class B(Generic[T]):
    x: T
    def fn(self, t: T) -> None: ...

 class C1(A2[str], B[str]): pass
 class C2(A2[str], B[int]): pass  # E: Definition of "x" in base class "A" is incompatible with definition in base class "B" \
                                 # E: Definition of "fn" in base class "A" is incompatible with definition in base class "B"
 class C3(A2[T], B[T]): pass
 class C4(A2[U], B[U]): pass
 class C5(A2[U], B[T]): pass  # E: Definition of "x" in base class "A" is incompatible with definition in base class "B" \
                             # E: Definition of "fn" in base class "A" is incompatible with definition in base class "B"

 class D1(A[str], B[str]): pass
 class D2(A[str], B[int]): pass  # E: Definition of "x" in base class "A" is incompatible with definition in base class "B" \
                                 # E: Definition of "fn" in base class "A" is incompatible with definition in base class "B"
 class D3(A[T], B[T]): pass
 class D4(A[U], B[U]): pass
 class D5(A[U], B[T]): pass  # E: Definition of "x" in base class "A" is incompatible with definition in base class "B" \
                             # E: Definition of "fn" in base class "A" is incompatible with definition in base class "B"

 [builtins fixtures/tuple.pyi]
Original file line number	Diff line number	Diff line change
Expand Up		@@ -2826,8 +2826,10 @@ class C(B, A[int]): ... # this is unsafe because...
		ok = is_subtype(first_sig, second_sig, ignore_pos_arg_names=True)
		elif first_type and second_type:
		if isinstance(first.node, Var):
		first_type = map_type_from_supertype(first_type, ctx, base1)
		first_type = expand_self_type(first.node, first_type, fill_typevars(ctx))
		if isinstance(second.node, Var):
		second_type = map_type_from_supertype(second_type, ctx, base2)
		second_type = expand_self_type(second.node, second_type, fill_typevars(ctx))
		ok = is_equivalent(first_type, second_type)
		if not ok:
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1065,3 +1065,39 @@ class F(E[T_co], Generic[T_co]): ... # E: Variance of TypeVar "T_co" incompatib

		class G(Generic[T]): ...
		class H(G[T_contra], Generic[T_contra]): ... # E: Variance of TypeVar "T_contra" incompatible with variance in parent type

		[case testMultipleInheritanceCompatibleTypeVar]
		from typing import Generic, TypeVar

		T = TypeVar("T")
		U = TypeVar("U")

		class A(Generic[T]):
		x: T
		def fn(self, t: T) -> None: ...

		class A2(A[T]):
		y: str
		z: str

		class B(Generic[T]):
		x: T
		def fn(self, t: T) -> None: ...

		class C1(A2[str], B[str]): pass
		class C2(A2[str], B[int]): pass # E: Definition of "x" in base class "A" is incompatible with definition in base class "B" \
		# E: Definition of "fn" in base class "A" is incompatible with definition in base class "B"
		class C3(A2[T], B[T]): pass
		class C4(A2[U], B[U]): pass
		class C5(A2[U], B[T]): pass # E: Definition of "x" in base class "A" is incompatible with definition in base class "B" \
		# E: Definition of "fn" in base class "A" is incompatible with definition in base class "B"

		class D1(A[str], B[str]): pass
		class D2(A[str], B[int]): pass # E: Definition of "x" in base class "A" is incompatible with definition in base class "B" \
		# E: Definition of "fn" in base class "A" is incompatible with definition in base class "B"
		class D3(A[T], B[T]): pass
		class D4(A[U], B[U]): pass
		class D5(A[U], B[T]): pass # E: Definition of "x" in base class "A" is incompatible with definition in base class "B" \
		# E: Definition of "fn" in base class "A" is incompatible with definition in base class "B"

		[builtins fixtures/tuple.pyi]