A decorator with a dotted name fails at runtime:

class C:
    def deco(self, f):
        return f

c = C()

@c.deco
def f():
    pass

On main (444ae5e):

NameError: "name 'c.deco' is not defined"

CPython 3.4 runs it. The parser turns the dotted name into one Name whose Id is the whole string, where CPython builds a Name plus one Attribute per component (ast_for_dotted_name in Python/ast.c). test_dotted in vm/tests/decorators.py is commented out because of it.

Go 1.27.1, darwin/arm64.