Have nametuple __replace__ return self

Author: max-muoto

mypy/semanal_namedtuple.py

@@ -57,6 +57,7 @@
     TYPED_NAMEDTUPLE_NAMES,
     AnyType,
     CallableType,
+    Instance,
     LiteralType,
     TupleType,
     Type,
@@ -633,7 +634,7 @@ def add_method(
         if self.options.python_version >= (3, 13):
             add_method(
                 "__replace__",
-                ret=None,
+                ret=Instance(info, []),
                 args=[Argument(var, var.type, EllipsisExpr(), ARG_NAMED_OPT) for var in vars],
             )
 

test-data/unit/check-namedtuple.test

@@ -1407,9 +1407,12 @@ from typing import NamedTuple
 class A(NamedTuple):
     x: int
 
-A(x=0).__replace__(x=1)
+replaced = A(x=0).__replace__(x=1)
+reveal_type(replaced)  # N: Revealed type is "Tuple[builtins.int, fallback=__main__.A]"
+
 A(x=0).__replace__(x="asdf")  # E: Argument "x" to "__replace__" of "A" has incompatible type "str"; expected "int"
 A(x=0).__replace__(y=1)  # E: Unexpected keyword argument "y" for "__replace__" of "A"
+
 [builtins fixtures/tuple.pyi]
 [typing fixtures/typing-namedtuple.pyi]