Use checkmember.py to check variable overrides

mypy/checkmember.py

@@ -93,11 +93,12 @@ def __init__(
         original_type: Type,
         context: Context,
         chk: mypy.checker.TypeChecker,
-        self_type: Type | None,
+        self_type: Type | None = None,
         module_symbol_table: SymbolTable | None = None,
         no_deferral: bool = False,
         is_self: bool = False,
         rvalue: Expression | None = None,
+        suppress_errors: bool = False,
     ) -> None:
         self.is_lvalue = is_lvalue
         self.is_super = is_super
@@ -113,13 +114,18 @@ def __init__(
         if rvalue is not None:
             assert is_lvalue
         self.rvalue = rvalue
+        self.suppress_errors = suppress_errors
 
     def named_type(self, name: str) -> Instance:
         return self.chk.named_type(name)
 
     def not_ready_callback(self, name: str, context: Context) -> None:
         self.chk.handle_cannot_determine_type(name, context)
 
+    def fail(self, msg: str) -> None:
+        if not self.suppress_errors:
+            self.msg.fail(msg, self.context)
+
     def copy_modified(
         self,
         *,
@@ -138,6 +144,7 @@ def copy_modified(
             module_symbol_table=self.module_symbol_table,
             no_deferral=self.no_deferral,
             rvalue=self.rvalue,
+            suppress_errors=self.suppress_errors,
         )
         if self_type is not None:
             mx.self_type = self_type
@@ -165,6 +172,7 @@ def analyze_member_access(
     no_deferral: bool = False,
     is_self: bool = False,
     rvalue: Expression | None = None,
+    suppress_errors: bool = False,
 ) -> Type:
     """Return the type of attribute 'name' of 'typ'.
 
@@ -191,6 +199,11 @@ def analyze_member_access(
 
     'rvalue' can be provided optionally to infer better setter type when is_lvalue is True,
     most notably this helps for descriptors with overloaded __set__() method.
+
+    'suppress_errors' will skip any logic that is only needed to generate error messages.
+    Note that this more of a performance optimization, one should not rely on this to not
+    show any messages, as some may be show e.g. by callbacks called here,
+    use msg.filter_errors(), if needed.
     """
     mx = MemberContext(
         is_lvalue=is_lvalue,
@@ -204,6 +217,7 @@ def analyze_member_access(
         no_deferral=no_deferral,
         is_self=is_self,
         rvalue=rvalue,
+        suppress_errors=suppress_errors,
     )
     result = _analyze_member_access(name, typ, mx, override_info)
     possible_literal = get_proper_type(result)
@@ -251,7 +265,8 @@ def _analyze_member_access(
             )
         return _analyze_member_access(name, typ.upper_bound, mx, override_info)
     elif isinstance(typ, DeletedType):
-        mx.msg.deleted_as_rvalue(typ, mx.context)
+        if not mx.suppress_errors:
+            mx.msg.deleted_as_rvalue(typ, mx.context)
         return AnyType(TypeOfAny.from_error)
     return report_missing_attribute(mx.original_type, typ, name, mx)
 
@@ -280,6 +295,8 @@ def report_missing_attribute(
     mx: MemberContext,
     override_info: TypeInfo | None = None,
 ) -> Type:
+    if mx.suppress_errors:
+        return AnyType(TypeOfAny.from_error)
     error_code = mx.msg.has_no_attr(original_type, typ, name, mx.context, mx.module_symbol_table)
     if not mx.msg.prefer_simple_messages():
         if may_be_awaitable_attribute(name, typ, mx, override_info):
@@ -297,7 +314,7 @@ def analyze_instance_member_access(
     if name == "__init__" and not mx.is_super:
         # Accessing __init__ in statically typed code would compromise
         # type safety unless used via super().
-        mx.msg.fail(message_registry.CANNOT_ACCESS_INIT, mx.context)
+        mx.fail(message_registry.CANNOT_ACCESS_INIT)
         return AnyType(TypeOfAny.from_error)
 
     # The base object has an instance type.
@@ -310,13 +327,14 @@ def analyze_instance_member_access(
         state.find_occurrences
         and info.name == state.find_occurrences[0]
         and name == state.find_occurrences[1]
+        and not mx.suppress_errors
     ):
         mx.msg.note("Occurrence of '{}.{}'".format(*state.find_occurrences), mx.context)
 
     # Look up the member. First look up the method dictionary.
     method = info.get_method(name)
     if method and not isinstance(method, Decorator):
-        if mx.is_super:
+        if mx.is_super and not mx.suppress_errors:
             validate_super_call(method, mx)
 
         if method.is_property:
@@ -327,7 +345,7 @@ def analyze_instance_member_access(
                 mx.chk.warn_deprecated(items[1], mx.context)
             return analyze_var(name, getter.var, typ, mx)
 
-        if mx.is_lvalue:
+        if mx.is_lvalue and not mx.suppress_errors:
             mx.msg.cant_assign_to_method(mx.context)
         if not isinstance(method, OverloadedFuncDef):
             signature = function_type(method, mx.named_type("builtins.function"))
@@ -361,7 +379,6 @@ def validate_super_call(node: FuncBase, mx: MemberContext) -> None:
     unsafe_super = False
     if isinstance(node, FuncDef) and node.is_trivial_body:
         unsafe_super = True
-        impl = node
     elif isinstance(node, OverloadedFuncDef):
         if node.impl:
             impl = node.impl if isinstance(node.impl, FuncDef) else node.impl.func
@@ -505,7 +522,7 @@ def analyze_member_var_access(
     if isinstance(vv, Decorator):
         # The associated Var node of a decorator contains the type.
         v = vv.var
-        if mx.is_super:
+        if mx.is_super and not mx.suppress_errors:
             validate_super_call(vv.func, mx)
 
     if isinstance(vv, TypeInfo):
@@ -603,7 +620,7 @@ def analyze_member_var_access(
         if not itype.extra_attrs.mod_name:
             return itype.extra_attrs.attrs[name]
 
-    if mx.is_super:
+    if mx.is_super and not mx.suppress_errors:
         mx.msg.undefined_in_superclass(name, mx.context)
         return AnyType(TypeOfAny.from_error)
     else:
@@ -669,11 +686,10 @@ def analyze_descriptor_access(descriptor_type: Type, mx: MemberContext) -> Type:
 
     dunder_get = descriptor_type.type.get_method("__get__")
     if dunder_get is None:
-        mx.msg.fail(
+        mx.fail(
             message_registry.DESCRIPTOR_GET_NOT_CALLABLE.format(
                 descriptor_type.str_with_options(mx.msg.options)
-            ),
-            mx.context,
+            )
         )
         return AnyType(TypeOfAny.from_error)
 
@@ -732,11 +748,10 @@ def analyze_descriptor_access(descriptor_type: Type, mx: MemberContext) -> Type:
         return inferred_dunder_get_type
 
     if not isinstance(inferred_dunder_get_type, CallableType):
-        mx.msg.fail(
+        mx.fail(
             message_registry.DESCRIPTOR_GET_NOT_CALLABLE.format(
                 descriptor_type.str_with_options(mx.msg.options)
-            ),
-            mx.context,
+            )
         )
         return AnyType(TypeOfAny.from_error)
 
@@ -747,11 +762,10 @@ def analyze_descriptor_assign(descriptor_type: Instance, mx: MemberContext) -> T
     instance_type = get_proper_type(mx.self_type)
     dunder_set = descriptor_type.type.get_method("__set__")
     if dunder_set is None:
-        mx.chk.fail(
+        mx.fail(
             message_registry.DESCRIPTOR_SET_NOT_CALLABLE.format(
                 descriptor_type.str_with_options(mx.msg.options)
-            ),
-            mx.context,
+            ).value
         )
         return AnyType(TypeOfAny.from_error)
 
@@ -851,11 +865,11 @@ def analyze_var(
     if typ:
         if isinstance(typ, PartialType):
             return mx.chk.handle_partial_var_type(typ, mx.is_lvalue, var, mx.context)
-        if mx.is_lvalue and var.is_property and not var.is_settable_property:
-            # TODO allow setting attributes in subclass (although it is probably an error)
-            mx.msg.read_only_property(name, itype.type, mx.context)
-        if mx.is_lvalue and var.is_classvar:
-            mx.msg.cant_assign_to_classvar(name, mx.context)
+        if mx.is_lvalue and not mx.suppress_errors:
+            if var.is_property and not var.is_settable_property:
+                mx.msg.read_only_property(name, itype.type, mx.context)
+            if var.is_classvar:
+                mx.msg.cant_assign_to_classvar(name, mx.context)
         t = freshen_all_functions_type_vars(typ)
         t = expand_self_type_if_needed(t, mx, var, original_itype)
         t = expand_type_by_instance(t, itype)
@@ -875,11 +889,10 @@ def analyze_var(
                 call_type = typ
 
         if isinstance(call_type, FunctionLike) and not call_type.is_type_obj():
-            if mx.is_lvalue:
-                if var.is_property:
-                    if not var.is_settable_property:
-                        mx.msg.read_only_property(name, itype.type, mx.context)
-                else:
+            if mx.is_lvalue and not mx.suppress_errors:
+                if var.is_property and not var.is_settable_property:
+                    mx.msg.read_only_property(name, itype.type, mx.context)
+                elif not var.is_property:
                     mx.msg.cant_assign_to_method(mx.context)
 
             if not var.is_staticmethod:
@@ -1073,22 +1086,20 @@ def analyze_class_attribute_access(
 
     is_decorated = isinstance(node.node, Decorator)
     is_method = is_decorated or isinstance(node.node, FuncBase)
-    if mx.is_lvalue:
+    if mx.is_lvalue and not mx.suppress_errors:
         if is_method:
             mx.msg.cant_assign_to_method(mx.context)
         if isinstance(node.node, TypeInfo):
-            mx.msg.fail(message_registry.CANNOT_ASSIGN_TO_TYPE, mx.context)
+            mx.fail(message_registry.CANNOT_ASSIGN_TO_TYPE)
 
     # Refuse class attribute access if slot defined
     if info.slots and name in info.slots:
-        mx.msg.fail(message_registry.CLASS_VAR_CONFLICTS_SLOTS.format(name), mx.context)
+        mx.fail(message_registry.CLASS_VAR_CONFLICTS_SLOTS.format(name))
 
     # If a final attribute was declared on `self` in `__init__`, then it
     # can't be accessed on the class object.
     if node.implicit and isinstance(node.node, Var) and node.node.is_final:
-        mx.msg.fail(
-            message_registry.CANNOT_ACCESS_FINAL_INSTANCE_ATTR.format(node.node.name), mx.context
-        )
+        mx.fail(message_registry.CANNOT_ACCESS_FINAL_INSTANCE_ATTR.format(node.node.name))
 
     # An assignment to final attribute on class object is also always an error,
     # independently of types.
@@ -1146,7 +1157,7 @@ def analyze_class_attribute_access(
                         message = message_registry.GENERIC_CLASS_VAR_ACCESS
                     else:
                         message = message_registry.GENERIC_INSTANCE_VAR_CLASS_ACCESS
-                    mx.msg.fail(message, mx.context)
+                    mx.fail(message)
             t = expand_self_type_if_needed(t, mx, node.node, itype, is_class=True)
             # Erase non-mapped variables, but keep mapped ones, even if there is an error.
             # In the above example this means that we infer following types:
@@ -1176,9 +1187,7 @@ def analyze_class_attribute_access(
         return AnyType(TypeOfAny.special_form)
 
     if isinstance(node.node, TypeVarExpr):
-        mx.msg.fail(
-            message_registry.CANNOT_USE_TYPEVAR_AS_EXPRESSION.format(info.name, name), mx.context
-        )
+        mx.fail(message_registry.CANNOT_USE_TYPEVAR_AS_EXPRESSION.format(info.name, name))
         return AnyType(TypeOfAny.from_error)
 
     # TODO: some logic below duplicates analyze_ref_expr in checkexpr.py
@@ -1267,7 +1276,7 @@ def analyze_typeddict_access(
                 typ, mx.context.index, setitem=True
             )
             assigned_readonly_keys = typ.readonly_keys & key_names
-            if assigned_readonly_keys:
+            if assigned_readonly_keys and not mx.suppress_errors:
                 mx.msg.readonly_keys_mutated(assigned_readonly_keys, context=mx.context)
         else:
             # It can also be `a.__setitem__(...)` direct call.

test-data/unit/check-classes.test

@@ -145,7 +145,7 @@ class Base:
         pass
 
 class Derived(Base):
-    __hash__ = 1  # E: Incompatible types in assignment (expression has type "int", base class "Base" defined the type as "Callable[[Base], int]")
+    __hash__ = 1  # E: Incompatible types in assignment (expression has type "int", base class "Base" defined the type as "Callable[[], int]")
 
 [case testOverridePartialAttributeWithMethod]
 # This was crashing: https://github.com/python/mypy/issues/11686.
@@ -4453,7 +4453,7 @@ class A:
     def a(self) -> None: pass
     b = 1
 class B(A):
-    a = 1  # E: Incompatible types in assignment (expression has type "int", base class "A" defined the type as "Callable[[A], None]")
+    a = 1  # E: Incompatible types in assignment (expression has type "int", base class "A" defined the type as "Callable[[], None]")
     def b(self) -> None: pass  # E: Signature of "b" incompatible with supertype "A" \
                                # N:      Superclass: \
                                # N:          int \
@@ -4546,20 +4546,20 @@ main:7: error: Incompatible types in assignment (expression has type "Callable[[
 [case testClassSpec]
 from typing import Callable
 class A():
-    b = None  # type: Callable[[A, int], int]
+    b = None  # type: Callable[[int], int]
 class B(A):
     def c(self, a: int) -> int: pass
     b = c
+reveal_type(A().b)  # N: Revealed type is "def (builtins.int) -> builtins.int"
+reveal_type(B().b)  # N: Revealed type is "def (a: builtins.int) -> builtins.int"
 
 [case testClassSpecError]
 from typing import Callable
 class A():
-    b = None  # type: Callable[[A, int], int]
+    b = None  # type: Callable[[int], int]
 class B(A):
     def c(self, a: str) -> int: pass
-    b = c
-[out]
-main:6: error: Incompatible types in assignment (expression has type "Callable[[str], int]", base class "A" defined the type as "Callable[[int], int]")
+    b = c  # E: Incompatible types in assignment (expression has type "Callable[[str], int]", base class "A" defined the type as "Callable[[int], int]")
 
 [case testClassStaticMethod]
 class A():
@@ -4581,10 +4581,11 @@ class A():
 class B(A):
     @staticmethod
     def b(a: str) -> None: pass
-    c = b
+    c = b  # E: Incompatible types in assignment (expression has type "Callable[[str], None]", base class "A" defined the type as "Callable[[int], None]")
+a: A
+reveal_type(a.a)  # N: Revealed type is "def (a: builtins.int)"
+reveal_type(a.c)  # N: Revealed type is "def (a: builtins.int)"
 [builtins fixtures/staticmethod.pyi]
-[out]
-main:8: error: Incompatible types in assignment (expression has type "Callable[[str], None]", base class "A" defined the type as "Callable[[int], None]")
 
 [case testClassStaticMethodSubclassing]
 class A:
@@ -4649,31 +4650,28 @@ class B(A):
 class A:
     x = 1
 class B(A):
-    x = "a"
+    x = "a"  # E: Incompatible types in assignment (expression has type "str", base class "A" defined the type as "int")
 class C(B):
-    x = object()
-[out]
-main:4: error: Incompatible types in assignment (expression has type "str", base class "A" defined the type as "int")
-main:6: error: Incompatible types in assignment (expression has type "object", base class "A" defined the type as "int")
+    x = object()  # E: Incompatible types in assignment (expression has type "object", base class "B" defined the type as "str")
 
 [case testClassOneErrorPerLine]
 class A:
-  x = 1
+    x = 1
 class B(A):
-  x = ""
-  x = 1.0
-[out]
-main:4: error: Incompatible types in assignment (expression has type "str", base class "A" defined the type as "int")
-main:5: error: Incompatible types in assignment (expression has type "float", base class "A" defined the type as "int")
+    x: str = ""  # E: Incompatible types in assignment (expression has type "str", base class "A" defined the type as "int")
+    x = 1.0  # E: Incompatible types in assignment (expression has type "float", variable has type "str")
+class BInfer(A):
+    x = ""  # E: Incompatible types in assignment (expression has type "str", base class "A" defined the type as "int")
+    x = 1.0  # E: Incompatible types in assignment (expression has type "float", variable has type "str") \
+             # E: Incompatible types in assignment (expression has type "float", base class "A" defined the type as "int")
 
 [case testClassIgnoreType_RedefinedAttributeAndGrandparentAttributeTypesNotIgnored]
 class A:
     x = 0
 class B(A):
     x = ''  # type: ignore
 class C(B):
-    x = ''  # E: Incompatible types in assignment (expression has type "str", base class "A" defined the type as "int")
-[out]
+    x = ''
 
 [case testClassIgnoreType_RedefinedAttributeTypeIgnoredInChildren]
 class A:
@@ -4682,7 +4680,6 @@ class B(A):
     x = ''  # type: ignore
 class C(B):
     x = ''  # type: ignore
-[out]
 
 [case testInvalidMetaclassStructure]
 class X(type): pass
@@ -8586,3 +8583,68 @@ class Wrapper(Generic[T, R]):
     def __call__(self, s: T) -> list[R]: ...
 def deco_instance(fn: Callable[[T, int], R]) -> Wrapper[T, R]: ...
 [builtins fixtures/property.pyi]
+
+[case testOverridePropertyWithDescriptor]
+from typing import Any
+
+class StrProperty:
+    def __get__(self, instance: Any, owner: Any) -> str: ...
+
+class Base:
+    @property
+    def id(self) -> str: ...
+
+class BadBase:
+    @property
+    def id(self) -> int: ...
+
+class Derived(Base):
+    id = StrProperty()
+
+class BadDerived(BadBase):
+    id = StrProperty()  # E: Incompatible types in assignment (expression has type "str", base class "BadBase" defined the type as "int")
+[builtins fixtures/property.pyi]
+
+[case testLambdaInOverrideInference]
+class B:
+    def f(self, x: int) -> int: ...
+class C(B):
+    f = lambda s, x: x
+
+reveal_type(C().f)  # N: Revealed type is "def (x: builtins.int) -> builtins.int"
+
+[case testGenericDecoratorInOverrideInference]
+from typing import Any, Callable, TypeVar
+from typing_extensions import ParamSpec, Concatenate
+
+P = ParamSpec("P")
+T = TypeVar("T")
+def wrap(f: Callable[Concatenate[Any, P], T]) -> Callable[Concatenate[Any, P], T]: ...
+
+class Base:
+    def g(self, a: int) -> int:
+        return a + 1
+
+class Derived(Base):
+    def _g(self, a: int) -> int:
+        return a + 2
+    g = wrap(_g)
+
+reveal_type(Derived().g)  # N: Revealed type is "def (a: builtins.int) -> builtins.int"
+[builtins fixtures/paramspec.pyi]
+
+[case testClassVarOverrideWithSubclass]
+class A: ...
+class B(A): ...
+class AA:
+    cls = A
+class BB(AA):
+    cls = B
+
+[case testSelfReferenceWithinMethodFunction]
+class B:
+    x: str
+class C(B):
+    def meth(self) -> None:
+        def cb() -> None:
+            self.x: int = 1  # E: Incompatible types in assignment (expression has type "int", base class "B" defined the type as "str")

test-data/unit/check-functions.test

@@ -3528,8 +3528,8 @@ class Parent:
     def method_with(self, param: str) -> "Parent": ...
 
 class Child(Parent):
-    method_without: Callable[["Child"], "Child"]
-    method_with: Callable[["Child", str], "Child"]  # E: Incompatible types in assignment (expression has type "Callable[[str], Child]", base class "Parent" defined the type as "Callable[[Arg(str, 'param')], Parent]")
+    method_without: Callable[[], "Child"]
+    method_with: Callable[[str], "Child"]  # E: Incompatible types in assignment (expression has type "Callable[[str], Child]", base class "Parent" defined the type as "Callable[[Arg(str, 'param')], Parent]")
 [builtins fixtures/tuple.pyi]
 
 [case testDistinctFormattingUnion]

test-data/unit/check-incremental.test

@@ -5235,11 +5235,7 @@ class Sub(Base):
 
 [builtins fixtures/property.pyi]
 [out]
-tmp/a.py:3: error: Cannot determine type of "foo"
-tmp/a.py:4: error: Cannot determine type of "foo"
 [out2]
-tmp/a.py:3: error: Cannot determine type of "foo"
-tmp/a.py:4: error: Cannot determine type of "foo"
 
 [case testRedefinitionClass]
 import b

test-data/unit/check-namedtuple.test

@@ -548,7 +548,7 @@ b = B._make([''])  # type: B
 [case testNamedTupleIncompatibleRedefinition]
 from typing import NamedTuple
 class Crash(NamedTuple):
-    count: int  # E: Incompatible types in assignment (expression has type "int", base class "tuple" defined the type as "Callable[[Tuple[int, ...], object], int]")
+    count: int  # E: Incompatible types in assignment (expression has type "int", base class "tuple" defined the type as "Callable[[object], int]")
 [builtins fixtures/tuple.pyi]
 
 [case testNamedTupleInClassNamespace]

test-data/unit/check-protocols.test

@@ -332,7 +332,7 @@ class MyHashable(Protocol):
 
 class C(MyHashable):
     __my_hash__ = None  # E: Incompatible types in assignment \
-(expression has type "None", base class "MyHashable" defined the type as "Callable[[MyHashable], int]")
+(expression has type "None", base class "MyHashable" defined the type as "Callable[[], int]")
 
 [case testProtocolsWithNoneAndStrictOptional]
 from typing import Protocol

test-data/unit/check-selftype.test

@@ -1803,7 +1803,7 @@ class C:
     def bar(self) -> Self: ...
     foo: Callable[[S, Self], Tuple[Self, S]]
 
-reveal_type(C().foo)  # N: Revealed type is "def [S] (S`1, __main__.C) -> Tuple[__main__.C, S`1]"
+reveal_type(C().foo)  # N: Revealed type is "def [S] (S`2, __main__.C) -> Tuple[__main__.C, S`2]"
 reveal_type(C().foo(42, C()))  # N: Revealed type is "Tuple[__main__.C, builtins.int]"
 class This: ...
 [builtins fixtures/tuple.pyi]
@@ -1899,7 +1899,7 @@ class C:
 
 class D(C): ...
 
-reveal_type(D.f)  # N: Revealed type is "def [T] (T`1) -> T`1"
+reveal_type(D.f)  # N: Revealed type is "def [T] (T`3) -> T`3"
 reveal_type(D().f)  # N: Revealed type is "def () -> __main__.D"
 
 [case testTypingSelfOnSuperTypeVarValues]

test-data/unit/fine-grained.test

@@ -4520,9 +4520,9 @@ x = 0
 x = ''
 [builtins fixtures/tuple.pyi]
 [out]
-b.py:5: error: Incompatible types in assignment (expression has type "int", base class "tuple" defined the type as "Callable[[Tuple[int, ...], object], int]")
+b.py:5: error: Incompatible types in assignment (expression has type "int", base class "tuple" defined the type as "Callable[[object], int]")
 ==
-b.py:5: error: Incompatible types in assignment (expression has type "int", base class "tuple" defined the type as "Callable[[Tuple[int, ...], object], int]")
+b.py:5: error: Incompatible types in assignment (expression has type "int", base class "tuple" defined the type as "Callable[[object], int]")
 
 [case testReprocessEllipses1]
 import a