@typing.no_type_check_decorator is nonfunctional

[lunixbochs]

from typing import no_type_check, no_type_check_decorator

@no_type_check_decorator
def test(fn):
    return fn

@test
def blah(x: {'x': 1}):
    pass

@no_type_check
def blah2(x: {'x': 1}):
    pass

$ mypy notypecheck.py 
notypecheck.py:1: error: Module 'typing' has no attribute 'no_type_check_decorator'
notypecheck.py:8: error: Invalid type comment or annotation

I think this firstly needs a typeshed stub, but I think it won't work without special case support in mypy as well.

Related: python/typeshed#2884

[gvanrossum]

Also related: #607. I propose that we should reserve #607 for the issue that @no_type_check doesn't work for classes, and use this (new) issue for the "meta" decorator @no_type_check_decorator.

[lunixbochs]

There's now a typeshed stub: python/typeshed#3460 (comment)

[lunixbochs]

Can someone advise on how to track within mypy that a function acts as no_type_check? The current no_type_check appears to be handled via the hardcoded path in a few places.

[ilevkivskyi]

Can someone advise on how to track within mypy that a function acts as no_type_check? The current no_type_check appears to be handled via the hardcoded path in a few places.

Although in general we don't like adding new flags to "important" nodes, it looks like in this case this is the only way (because the other way I see is keeping a global state, which is even worse). You can add a flag to FuncDef indicating whether this function can act as a no_type_check decorator, then check this flag on looked up node for every decorator that is a RefExpr.

[AlexWaygood]

no_type_check_decorator has now been deprecated in Python 3.13, with removal scheduled for Python 3.15: python/cpython#106309.