Unexpected '...' for homogeneous tuples using builtin tuple (PEP 585)

[antonagestam]

Bug Report

When using builtin tuple to create a type alias, mypy reports an error.

To Reproduce

t = tuple[str, ...]

Expected Behavior

No error.

Actual Behavior

$ mypy <(echo 't = tuple[str, ...]')
/dev/fd/63:1: error: Unexpected '...'  [misc]
    t = tuple[str, ...]
    ^
Found 1 error in 1 file (checked 1 source file)

Your Environment

• Mypy version used: 0.800

• Mypy command-line flags:

• Mypy configuration options from mypy.ini (and other config files):

  [mypy]
  python_version = 3.9
  show_error_codes = True
  pretty = True
  files = .
  
  ignore_missing_imports = False
  no_implicit_reexport = True
  no_implicit_optional = True
  strict_equality = True
  strict_optional = True
  check_untyped_defs = True
  disallow_incomplete_defs = True
  disallow_untyped_defs = True
  disallow_untyped_calls = True
  disallow_untyped_decorators = True
  disallow_subclassing_any = True
  
  warn_unused_configs = True
  warn_redundant_casts = True
  warn_unused_ignores = True
  warn_return_any = True
  warn_unreachable = True
  

• Python version used: 3.9.0

• Operating system and version: Macos 11.1

[srittau]

This seems to affect more than just type aliases. When I tried to change the tuples in typeshed's stdlib/random.pyi, it complained with the same error message. (Using mypy 0.820+dev.9cbf4c0da8f83efd0ba82a91e180b6e96dd15f69 and Python 3.8.3.):

def foo(self) -> tuple[int, ...]: ...  # error: Unexpected '...'
def bar(self, x: tuple[int, ...]) -> None: ...  # error: Unexpected '...'

[Akuli]

mypy/mypy/checker.py

Line 951 in 4827f3a

# builtins.tuple[T] is typing.Tuple[T, ...]

Maybe this is the problem?

[antonagestam]

@srittau Interesting, I noticed it works in some places of our codebase, when I tried isolating them with e.g. mypy <(echo 'ordering: tuple[str, ...] = ("-pk",)' it fails. Might be something else going on that is shadowing those definitions I guess.

That's why I thought this was only happening for type aliases. I'll rename the issue.

[posita]

Is this a dup of #10242? Also, are you still seeing these errors?

def foo(self) -> tuple[int, ...]: ...  # error: Unexpected '...'
def bar(self, x: tuple[int, ...]) -> None: ...  # error: Unexpected '...'

☝️ Those don't appear for me in 0.901, but these do: 👇

% cat -n test.py
     1  from __future__ import annotations
     2
     3  from collections.abc import Callable
     4
     5  _T = tuple[int, ...]  # <- spurious `Unexpected "..."` message
     6  f: Callable[[_T], None] = lambda t: print("{}".format(t))
     7  f((1, 2, 3))
     8  f([1, 2, 3])  # <- still validly caught, apparently
% mypy test.py
test.py:5: error: Unexpected "..."
test.py:8: error: Argument 1 has incompatible type "List[int]"; expected "Tuple[int, ...]"
Found 2 errors in 1 file (checked 1 source file)
% python --version
Python 3.9.5
% mypy --version
mypy 0.901

[sg495]

This is still happening to me on 0.910. Here is a snippet:

T = tuple[int, ...]

Here are the mypy version check and output:

>mypy --version
mypy 0.910
>mypy test.py
test.py:1: error: Unexpected "..."
Found 1 error in 1 file (checked 1 source file)

[posita]

I think the fix was landed after 0.910 was released. @JukkaL, can you confirm whether it will make it into the next one?

[MatthieuDartiailh]

@JukkaL any update on when this will be released ?

[ergoithz]

@JukkaL any update on when this will be released ?

Furthermore, any plans on releasing this fix before Python 4?

[hauntsaninja]

You can follow #11158 for the release. I can promise you that this will be released before Python 4 :D