turn the is_notimplemented and erase_notimplemented into normal functions

Author: tyralla

mypy/checker.py

@@ -178,6 +178,7 @@
     coerce_to_literal,
     custom_special_method,
     erase_def_to_union_or_bound,
+    erase_notimplemented,
     erase_to_bound,
     erase_to_union_or_bound,
     false_only,
@@ -4894,21 +4895,6 @@ def infer_context_dependent(
         self.store_types(original_type_map)
         return typ
 
-    @staticmethod
-    def is_notimplemented(t: ProperType) -> bool:
-        return isinstance(t, Instance) and t.type.fullname == "builtins._NotImplementedType"
-
-    @classmethod
-    def erase_notimplemented(cls, t: Type) -> Type:
-        t = get_proper_type(t)
-        if cls.is_notimplemented(t):
-            return AnyType(TypeOfAny.special_form)
-        if isinstance(t, UnionType):
-            return UnionType.make_union(
-                [i for i in t.items if not cls.is_notimplemented(get_proper_type(i))]
-            )
-        return t
-
     def check_return_stmt(self, s: ReturnStmt) -> None:
 
         defn = self.scope.current_function()
@@ -4991,7 +4977,7 @@ def check_return_stmt(self, s: ReturnStmt) -> None:
                 else:
                     typ_: Type = typ
                     if defn.name in BINARY_MAGIC_METHODS or defn.name == "__subclasshook__":
-                        typ_ = self.erase_notimplemented(typ)
+                        typ_ = erase_notimplemented(typ)
                     self.check_subtype(
                         subtype_label="got",
                         subtype=typ_,

mypy/checkexpr.py

@@ -132,6 +132,7 @@
 from mypy.typeops import (
     callable_type,
     custom_special_method,
+    erase_notimplemented,
     erase_to_union_or_bound,
     false_only,
     fixup_partial_type,
@@ -3554,7 +3555,7 @@ def visit_op_expr(self, e: OpExpr) -> Type:
             else:
                 assert_never(use_reverse)
             e.method_type = method_type
-            return self.chk.erase_notimplemented(result)
+            return erase_notimplemented(result)
         else:
             raise RuntimeError(f"Unknown operator {e.op}")
 
@@ -3705,7 +3706,7 @@ def visit_comparison_expr(self, e: ComparisonExpr) -> Type:
                 result = join.join_types(result, sub_result)
 
         assert result is not None
-        return self.chk.erase_notimplemented(result)
+        return erase_notimplemented(result)
 
     def find_partial_type_ref_fast_path(self, expr: Expression) -> Type | None:
         """If expression has a partial generic type, return it without additional checks.
@@ -4228,7 +4229,7 @@ def check_op(
             # callable types.
             results_final = make_simplified_union(all_results)
             inferred_final = self.combine_function_signatures(get_proper_types(all_inferred))
-            return self.chk.erase_notimplemented(results_final), inferred_final
+            return erase_notimplemented(results_final), inferred_final
         else:
             result, inferred = self.check_method_call_by_name(
                 method=method,
@@ -4237,7 +4238,7 @@ def check_op(
                 arg_kinds=[ARG_POS],
                 context=context,
             )
-            return self.chk.erase_notimplemented(result), inferred
+            return erase_notimplemented(result), inferred
 
     def check_boolean_op(self, e: OpExpr) -> Type:
         """Type check a boolean operation ('and' or 'or')."""

mypy/typeops.py

@@ -999,6 +999,21 @@ def is_singleton_type(typ: Type) -> bool:
     return typ.is_singleton_type()
 
 
+def is_notimplemented(t: ProperType) -> bool:
+    return isinstance(t, Instance) and t.type.fullname == "builtins._NotImplementedType"
+
+
+def erase_notimplemented(t: Type) -> Type:
+    t = get_proper_type(t)
+    if is_notimplemented(t):
+        return AnyType(TypeOfAny.special_form)
+    if isinstance(t, UnionType):
+        return UnionType.make_union(
+            [i for i in t.items if not is_notimplemented(get_proper_type(i))]
+        )
+    return t
+
+
 def try_expanding_sum_type_to_union(typ: Type, target_fullname: str) -> Type:
     """Attempts to recursively expand any enum Instances with the given target_fullname
     into a Union of all of its component LiteralTypes.