Crash on complicated ParamSpec usage

[bersbersbers]

Crash Report

mypy crashes.

Traceback

(project_3.11) C:\Code>mypy mypy_1.5_crash.py --show-traceback
mypy_1.5_crash.py:6: error: Missing return statement  [empty-body]
mypy_1.5_crash.py:12: error: Missing return statement  [empty-body]
mypy_1.5_crash.py:11: error: INTERNAL ERROR -- Please try using mypy master on GitHub: 
https://mypy.readthedocs.io/en/stable/common_issues.html#using-a-development-mypy-build
Please report a bug at https://github.com/python/mypy/issues
version: 1.6.0+dev.5617cdd03d12ff73622c8d4b496979e0377b1675
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Scripts\mypy.exe\__main__.py", line 7, in <module>
    sys.exit(console_entry())
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\__main__.py", line 15, in console_entry       
    main()
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\main.py", line 94, in main
    res, messages, blockers = run_build(sources, options, fscache, t0, stdout, stderr)
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\main.py", line 173, in run_build
    res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\build.py", line 195, in build
    result = _build(
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\build.py", line 268, in _build
    graph = dispatch(sources, manager, stdout)
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\build.py", line 2927, in dispatch
    process_graph(graph, manager)
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\build.py", line 3325, in process_graph        
    process_stale_scc(graph, scc, manager)
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\build.py", line 3426, in process_stale_scc    
    graph[id].type_check_first_pass()
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\build.py", line 2312, in type_check_first_pass
    self.type_checker().check_first_pass()
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\checker.py", line 475, in check_first_pass    
    self.accept(d)
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\checker.py", line 585, in accept
    stmt.accept(self)
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\nodes.py", line 898, in accept
    return visitor.visit_decorator(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\checker.py", line 4776, in visit_decorator    
    sig, t2 = self.expr_checker.check_call(
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\checkexpr.py", line 1437, in check_call
    return self.check_callable_call(
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\checkexpr.py", line 1628, in check_callable_call
    self.check_argument_types(
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\checkexpr.py", line 2324, in check_argument_types
    check_arg(
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\checkexpr.py", line 2360, in check_arg
    elif not is_subtype(caller_type, callee_type, options=self.chk.options):
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\subtypes.py", line 177, in is_subtype
    return _is_subtype(left, right, subtype_context, proper_subtype=False)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\subtypes.py", line 332, in _is_subtype
    return left.accept(SubtypeVisitor(orig_right, subtype_context, proper_subtype))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\types.py", line 1923, in accept
    return visitor.visit_callable_type(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\subtypes.py", line 692, in visit_callable_type
    return is_callable_compatible(
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\subtypes.py", line 1418, in is_callable_compatible
    unified = unify_generic_callable(left, right, ignore_return=ignore_return)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\subtypes.py", line 1725, in unify_generic_callable
    applied = mypy.applytype.apply_generic_arguments(
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\applytype.py", line 170, in apply_generic_arguments
    arg_types=[expand_type(at, id_to_type) for at in callable.arg_types]
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\applytype.py", line 170, in <listcomp>
    arg_types=[expand_type(at, id_to_type) for at in callable.arg_types]
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\expandtype.py", line 72, in expand_type
    return typ.accept(ExpandTypeVisitor(env))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\types.py", line 1923, in accept
    return visitor.visit_callable_type(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\expandtype.py", line 435, in visit_callable_type
    arg_types = self.expand_types(t.arg_types)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\expandtype.py", line 542, in expand_types
    a.append(t.accept(self))
             ^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\types.py", line 1923, in accept
    return visitor.visit_callable_type(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\expandtype.py", line 435, in visit_callable_type
    arg_types = self.expand_types(t.arg_types)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\expandtype.py", line 542, in expand_types
    a.append(t.accept(self))
             ^^^^^^^^^^^^^^
  File "C:\Users\bers\.pyenv-win-venv\envs\project_3.11\Lib\site-packages\mypy\types.py", line 1923, in accept
    return visitor.visit_callable_type(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

(last three entries repeat)

To Reproduce

Trying to investigate #15594. Code is possibly nonsense.

from typing import Callable, Concatenate, ParamSpec, TypeVar

T = TypeVar("T")
P = ParamSpec("P")

def decorator(
    caller_: Callable[Concatenate[Callable[P, T], P], T]
) -> Callable[[Callable[P, T]], Callable[P, T]]:
    ...

@decorator
def caller(callable: Callable[P, T], *args: P.args, **kwargs: P.kwargs) -> T:
    ...

Your Environment

• Mypy version used: mypy-1.6.0+dev.5617cdd03d12ff73622c8d4b496979e0377b1675, possibly also 1.4.1
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.11.4
• Operating system and version: Windows

[bersbersbers]

This was briefly fixed by #15272 (until that PR was reverted). It may be a duplicate of #15388 and #15073.

[bersbersbers]

582a4de from #15837 also fixes this.

[ilevkivskyi]

The crash was fixed by #15837 (note the original example only works correctly with --new-type-inference).