Fix __eq__ note

Author: ilevkivskyi

mypy/checker.py

@@ -130,6 +130,7 @@
     WhileStmt,
     WithStmt,
     YieldExpr,
+    get_func_def,
     is_final_node,
 )
 from mypy.operators import flip_ops, int_op_to_method, neg_ops
@@ -2507,8 +2508,9 @@ def check_override(
 
                 override_ids = override.type_var_ids()
                 type_name = None
-                if isinstance(override.definition, FuncDef):
-                    type_name = override.definition.info.name
+                definition = get_func_def(override)
+                if isinstance(definition, FuncDef):
+                    type_name = definition.info.name
 
                 def erase_override(t: Type) -> Type:
                     return erase_typevars(t, ids_to_erase=override_ids)

mypy/messages.py

@@ -44,7 +44,6 @@
     CallExpr,
     ClassDef,
     Context,
-    Decorator,
     Expression,
     FuncDef,
     IndexExpr,
@@ -56,6 +55,7 @@
     SymbolTable,
     TypeInfo,
     Var,
+    get_func_def,
     reverse_builtin_aliases,
 )
 from mypy.operators import op_methods, op_methods_to_symbols
@@ -2939,9 +2939,7 @@ def format_single(arg: Type) -> str:
 
 def pretty_class_or_static_decorator(tp: CallableType) -> str | None:
     """Return @classmethod or @staticmethod, if any, for the given callable type."""
-    definition = tp.definition
-    if isinstance(definition, Decorator):
-        definition = definition.func
+    definition = get_func_def(tp)
     if definition is not None and isinstance(definition, SYMBOL_FUNCBASE_TYPES):
         if definition.is_class:
             return "@classmethod"
@@ -2995,9 +2993,7 @@ def [T <: int] f(self, x: int, y: T) -> None
             slash = True
 
     # If we got a "special arg" (i.e: self, cls, etc...), prepend it to the arg list
-    definition = tp.definition
-    if isinstance(definition, Decorator):
-        definition = definition.func
+    definition = get_func_def(tp)
     if (
         isinstance(definition, FuncDef)
         and hasattr(definition, "arguments")
@@ -3058,9 +3054,7 @@ def [T <: int] f(self, x: int, y: T) -> None
 
 
 def get_first_arg(tp: CallableType) -> str | None:
-    definition = tp.definition
-    if isinstance(definition, Decorator):
-        definition = definition.func
+    definition = get_func_def(tp)
     if not isinstance(definition, FuncDef) or not definition.info or definition.is_static:
         return None
     return definition.original_first_arg

mypy/nodes.py

@@ -4380,6 +4380,13 @@ def is_final_node(node: SymbolNode | None) -> bool:
     return isinstance(node, (Var, FuncDef, OverloadedFuncDef, Decorator)) and node.is_final
 
 
+def get_func_def(typ: mypy.types.CallableType) -> SymbolNode | None:
+    definition = typ.definition
+    if isinstance(definition, Decorator):
+        definition = definition.func
+    return definition
+
+
 def local_definitions(
     names: SymbolTable, name_prefix: str, info: TypeInfo | None = None
 ) -> Iterator[Definition]:

test-data/unit/check-classes.test

@@ -9241,3 +9241,20 @@ C().prop = "no"  # E: Invalid self argument "C" to attribute function "prop" wit
 reveal_type(C().prop_t)  # N: Revealed type is "__main__.C"
 C().prop_t = 1  # E: Incompatible types in assignment (expression has type "int", variable has type "list[C]")
 [builtins fixtures/property.pyi]
+
+[case testClassEqDecoratedAbstractNote]
+from abc import abstractmethod
+
+class C:
+    @abstractmethod
+    def __eq__(self, other: C) -> bool: ...
+[builtins fixtures/plugin_attrs.pyi]
+[out]
+main:5: error: Argument 1 of "__eq__" is incompatible with supertype "builtins.object"; supertype defines the argument type as "object"
+main:5: note: This violates the Liskov substitution principle
+main:5: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
+main:5: note: It is recommended for "__eq__" to work with arbitrary objects, for example:
+main:5: note:     def __eq__(self, other: object) -> bool:
+main:5: note:         if not isinstance(other, C):
+main:5: note:             return NotImplemented
+main:5: note:         return <logic to compare two C instances>