Fix callable instance variable support (python#10548)

Fixes python#708 and Fixes python#5485

Prevent handling as bounded method of callable members declared as instance variables.

Author: wyfo

mypy/checkmember.py

@@ -659,15 +659,23 @@ def instance_alias_type(alias: TypeAlias, named_type: Callable[[str], Instance])
     return expand_type_by_instance(tp, target)
 
 
-def analyze_var(
-    name: str,
-    var: Var,
-    itype: Instance,
-    info: TypeInfo,
-    mx: MemberContext,
-    *,
-    implicit: bool = False,
-) -> Type:
+def is_instance_var(var: Var, info: TypeInfo) -> bool:
+    """Return if var is an instance variable according to PEP 526."""
+    return (
+        # check the type_info node is the var (not a decorated function, etc.)
+        var.name in info.names and info.names[var.name].node is var
+        and not var.is_classvar
+        # variables without annotations are treated as classvar
+        and not var.is_inferred
+    )
+
+
+def analyze_var(name: str,
+                var: Var,
+                itype: Instance,
+                info: TypeInfo,
+                mx: MemberContext, *,
+                implicit: bool = False) -> Type:
     """Analyze access to an attribute via a Var node.
 
     This is conceptually part of analyze_member_access and the arguments are similar.
@@ -690,7 +698,12 @@ def analyze_var(
         t = get_proper_type(expand_type_by_instance(typ, itype))
         result: Type = t
         typ = get_proper_type(typ)
-        if var.is_initialized_in_class and isinstance(typ, FunctionLike) and not typ.is_type_obj():
+        if (
+            var.is_initialized_in_class
+            and not is_instance_var(var, info)
+            and isinstance(typ, FunctionLike)
+            and not typ.is_type_obj()
+        ):
             if mx.is_lvalue:
                 if var.is_property:
                     if not var.is_settable_property:

test-data/unit/check-dataclasses.test

@@ -1304,80 +1304,40 @@ reveal_type(A.__dataclass_fields__)  # N: Revealed type is "builtins.dict[builti
 
 [builtins fixtures/dict.pyi]
 
-[case testDataclassCallableProperty]
+[case testDataclassCallableFieldAccess]
 # flags: --python-version 3.7
 from dataclasses import dataclass
 from typing import Callable
 
 @dataclass
 class A:
-    foo: Callable[[int], int]
+    x: Callable[[int], int]
+    y: Callable[[int], int] = lambda i: i
 
-def my_foo(x: int) -> int:
-    return x
+a = A(lambda i:i)
+x: int = a.x(0)
+y: str = a.y(0) # E: Incompatible types in assignment (expression has type "int", variable has type "str")
+reveal_type(a.x)  # N: Revealed type is "def (builtins.int) -> builtins.int"
+reveal_type(a.y)  # N: Revealed type is "def (builtins.int) -> builtins.int"
+reveal_type(A.y)  # N: Revealed type is "def (builtins.int) -> builtins.int"
 
-a = A(foo=my_foo)
-a.foo(1)
-reveal_type(a.foo)  # N: Revealed type is "def (builtins.int) -> builtins.int"
-reveal_type(A.foo)  # N: Revealed type is "def (builtins.int) -> builtins.int"
-[typing fixtures/typing-medium.pyi]
-[builtins fixtures/dataclasses.pyi]
-
-[case testDataclassCallableAssignment]
-# flags: --python-version 3.7
-from dataclasses import dataclass
-from typing import Callable
-
-@dataclass
-class A:
-    foo: Callable[[int], int]
-
-def my_foo(x: int) -> int:
-    return x
-
-a = A(foo=my_foo)
-
-def another_foo(x: int) -> int:
-    return x
-
-a.foo = another_foo
-[builtins fixtures/dataclasses.pyi]
-
-[case testDataclassCallablePropertyWrongType]
+[case testDataclassCallableFieldAssignment]
 # flags: --python-version 3.7
 from dataclasses import dataclass
 from typing import Callable
 
 @dataclass
 class A:
-    foo: Callable[[int], int]
+    x: Callable[[int], int]
 
-def my_foo(x: int) -> str:
-    return "foo"
+def x(i: int) -> int:
+    return i
+def x2(s: str) -> str:
+    return s
 
-a = A(foo=my_foo)  # E: Argument "foo" to "A" has incompatible type "Callable[[int], str]"; expected "Callable[[int], int]"
-[typing fixtures/typing-medium.pyi]
-[builtins fixtures/dataclasses.pyi]
-
-[case testDataclassCallablePropertyWrongTypeAssignment]
-# flags: --python-version 3.7
-from dataclasses import dataclass
-from typing import Callable
-
-@dataclass
-class A:
-    foo: Callable[[int], int]
-
-def my_foo(x: int) -> int:
-    return x
-
-a = A(foo=my_foo)
-
-def another_foo(x: int) -> str:
-    return "foo"
-
-a.foo = another_foo  # E: Incompatible types in assignment (expression has type "Callable[[int], str]", variable has type "Callable[[int], int]")
-[typing fixtures/typing-medium.pyi]
+a = A(lambda i:i)
+a.x = x
+a.x = x2 # E: Incompatible types in assignment (expression has type "Callable[[str], str]", variable has type "Callable[[int], int]")
 [builtins fixtures/dataclasses.pyi]
 
 [case testDataclassFieldDoesNotFailOnKwargsUnpacking]

test-data/unit/check-functions.test

@@ -571,39 +571,51 @@ A().f('') # E: Argument 1 to "f" of "A" has incompatible type "str"; expected "i
 
 
 [case testMethodAsDataAttribute]
-from typing import Any, Callable
+from typing import Any, Callable, ClassVar
 class B: pass
 x = None # type: Any
 class A:
-    f = x # type: Callable[[A], None]
-    g = x # type: Callable[[A, B], None]
+    f = x # type: ClassVar[Callable[[A], None]]
+    g = x # type: ClassVar[Callable[[A, B], None]]
 a = None # type: A
 a.f()
 a.g(B())
 a.f(a) # E: Too many arguments
 a.g()  # E: Too few arguments
 
 [case testMethodWithInvalidMethodAsDataAttribute]
-from typing import Any, Callable
+from typing import Any, Callable, ClassVar
 class B: pass
 x = None # type: Any
 class A:
-    f = x # type: Callable[[], None]
-    g = x # type: Callable[[B], None]
+    f = x # type: ClassVar[Callable[[], None]]
+    g = x # type: ClassVar[Callable[[B], None]]
 a = None # type: A
 a.f() # E: Attribute function "f" with type "Callable[[], None]" does not accept self argument
 a.g() # E: Invalid self argument "A" to attribute function "g" with type "Callable[[B], None]"
 
 [case testMethodWithDynamicallyTypedMethodAsDataAttribute]
-from typing import Any, Callable
+from typing import Any, Callable, ClassVar
 class B: pass
 x = None # type: Any
 class A:
-    f = x # type: Callable[[Any], Any]
+    f = x # type: ClassVar[Callable[[Any], Any]]
 a = None # type: A
 a.f()
 a.f(a) # E: Too many arguments
 
+[case testMethodWithInferredMethodAsDataAttribute]
+from typing import Any
+def m(self: "A") -> int: ...
+
+class A:
+    n = m
+
+a = A()
+reveal_type(a.n())  # N: Revealed type is "builtins.int"
+reveal_type(A.n(a))  # N: Revealed type is "builtins.int"
+A.n()  # E: Too few arguments
+
 [case testOverloadedMethodAsDataAttribute]
 from foo import *
 [file foo.pyi]
@@ -645,35 +657,35 @@ a.g(B())
 a.g(a)   # E: Argument 1 has incompatible type "A[B]"; expected "B"
 
 [case testInvalidMethodAsDataAttributeInGenericClass]
-from typing import Any, TypeVar, Generic, Callable
+from typing import Any, TypeVar, Generic, Callable, ClassVar
 t = TypeVar('t')
 class B: pass
 class C: pass
 x = None # type: Any
 class A(Generic[t]):
-    f = x # type: Callable[[A[B]], None]
+    f = x # type: ClassVar[Callable[[A[B]], None]]
 ab = None # type: A[B]
 ac = None # type: A[C]
 ab.f()
 ac.f()   # E: Invalid self argument "A[C]" to attribute function "f" with type "Callable[[A[B]], None]"
 
 [case testPartiallyTypedSelfInMethodDataAttribute]
-from typing import Any, TypeVar, Generic, Callable
+from typing import Any, TypeVar, Generic, Callable, ClassVar
 t = TypeVar('t')
 class B: pass
 class C: pass
 x = None # type: Any
 class A(Generic[t]):
-    f = x # type: Callable[[A], None]
+    f = x # type: ClassVar[Callable[[A], None]]
 ab = None # type: A[B]
 ac = None # type: A[C]
 ab.f()
 ac.f()
 
 [case testCallableDataAttribute]
-from typing import Callable
+from typing import Callable, ClassVar
 class A:
-    g = None # type: Callable[[A], None]
+    g = None # type: ClassVar[Callable[[A], None]]
     def __init__(self, f: Callable[[], None]) -> None:
         self.f = f
 a = A(None)

test-data/unit/check-functools.test

@@ -25,12 +25,12 @@ Ord() >= 1  # E: Unsupported operand types for >= ("Ord" and "int")
 
 [case testTotalOrderingLambda]
 from functools import total_ordering
-from typing import Any, Callable
+from typing import Any, Callable, ClassVar
 
 @total_ordering
 class Ord:
-    __eq__: Callable[[Any, object], bool] = lambda self, other: False
-    __lt__: Callable[[Any, "Ord"], bool] = lambda self, other: False
+    __eq__: ClassVar[Callable[[Any, object], bool]] = lambda self, other: False
+    __lt__: ClassVar[Callable[[Any, "Ord"], bool]] = lambda self, other: False
 
 reveal_type(Ord() < Ord())  # N: Revealed type is "builtins.bool"
 reveal_type(Ord() <= Ord())  # N: Revealed type is "builtins.bool"

test-data/unit/check-selftype.test

@@ -366,16 +366,16 @@ reveal_type(x.f)  # N: Revealed type is "builtins.int"
 [builtins fixtures/property.pyi]
 
 [case testSelfTypeProperSupertypeAttribute]
-from typing import Callable, TypeVar
+from typing import Callable, TypeVar, ClassVar
 class K: pass
 T = TypeVar('T', bound=K)
 class A(K):
     @property
     def g(self: K) -> int: return 0
     @property
     def gt(self: T) -> T: return self
-    f: Callable[[object], int]
-    ft: Callable[[T], T]
+    f: ClassVar[Callable[[object], int]]
+    ft: ClassVar[Callable[[T], T]]
 
 class B(A):
     pass
@@ -392,15 +392,15 @@ reveal_type(B().ft())  # N: Revealed type is "__main__.B"
 [builtins fixtures/property.pyi]
 
 [case testSelfTypeProperSupertypeAttributeTuple]
-from typing import Callable, TypeVar, Tuple
+from typing import Callable, TypeVar, Tuple, ClassVar
 T = TypeVar('T')
 class A(Tuple[int, int]):
     @property
     def g(self: object) -> int: return 0
     @property
     def gt(self: T) -> T: return self
-    f: Callable[[object], int]
-    ft: Callable[[T], T]
+    f: ClassVar[Callable[[object], int]]
+    ft: ClassVar[Callable[[T], T]]
 
 class B(A):
     pass
@@ -450,7 +450,7 @@ reveal_type(X1.ft())  # N: Revealed type is "Type[__main__.X]"
 [builtins fixtures/property.pyi]
 
 [case testSelfTypeProperSupertypeAttributeGeneric]
-from typing import Callable, TypeVar, Generic
+from typing import Callable, TypeVar, Generic, ClassVar
 Q = TypeVar('Q', covariant=True)
 class K(Generic[Q]):
     q: Q
@@ -460,8 +460,8 @@ class A(K[Q]):
     def g(self: K[object]) -> int: return 0
     @property
     def gt(self: K[T]) -> T: return self.q
-    f: Callable[[object], int]
-    ft: Callable[[T], T]
+    f: ClassVar[Callable[[object], int]]
+    ft: ClassVar[Callable[[T], T]]
 
 class B(A[Q]):
     pass