Crash when unpacking non TypeVarTuple in args list to `Callable` alias

[hamdanal]

Crash Report

Traceback

main.py:3: error: Name "TypeVarTuple" is not defined  [name-defined]
main.py:4: error: Variable "__main__.Ts" is not valid as a type  [valid-type]
main.py:4: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#variables-vs-type-aliases
main.py:5: error: Bad number of arguments for type alias, expected 0, given 1  [type-arg]
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/__main__.py", line 37, in <module>
    console_entry()
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/__main__.py", line 15, in console_entry
    main()
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/main.py", line 100, in main
    res, messages, blockers = run_build(sources, options, fscache, t0, stdout, stderr)
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/main.py", line 182, in run_build
    res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/build.py", line 192, in build
    result = _build(
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/build.py", line 266, in _build
    graph = dispatch(sources, manager, stdout)
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/build.py", line 2942, in dispatch
    process_graph(graph, manager)
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/build.py", line 3340, in process_graph
    process_stale_scc(graph, scc, manager)
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/build.py", line 3435, in process_stale_scc
    mypy.semanal_main.semantic_analysis_for_scc(graph, scc, manager.errors)
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/semanal_main.py", line 93, in semantic_analysis_for_scc
    process_top_levels(graph, scc, patches)
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/semanal_main.py", line 220, in process_top_levels
    deferred, incomplete, progress = semantic_analyze_target(
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/semanal_main.py", line 349, in semantic_analyze_target
    analyzer.refresh_partial(
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/semanal.py", line 599, in refresh_partial
    self.refresh_top_level(node)
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/semanal.py", line 610, in refresh_top_level
    self.accept(d)
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/semanal.py", line 6588, in accept
    node.accept(self)
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/nodes.py", line 1310, in accept
    return visitor.visit_assignment_stmt(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/semanal.py", line 2919, in visit_assignment_stmt
    self.process_type_annotation(s)
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/semanal.py", line 3435, in process_type_annotation
    if analyzed is None or has_placeholder(analyzed):
                           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/semanal_shared.py", line 372, in has_placeholder
    return typ.accept(HasPlaceholders())
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/types.py", line 410, in accept
    return visitor.visit_type_alias_type(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/type_visitor.py", line 550, in visit_type_alias_type
    return get_proper_type(t).accept(self)
           ^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/types.py", line 3085, in get_proper_type
    typ = typ._expand_once()
          ^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/types.py", line 352, in _expand_once
    new_tp = self.alias.target.accept(InstantiateAliasVisitor(mapping))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/types.py", line 1979, in accept
    return visitor.visit_callable_type(self)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/expandtype.py", line 380, in visit_callable_type
    arg_types = self.interpolate_args_for_unpack(t, var_arg.typ)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/layers/google.python.pip/pip/lib/python3.12/site-packages/mypy/expandtype.py", line 329, in interpolate_args_for_unpack
    assert isinstance(var_arg_type, TypeVarTupleType), type(var_arg_type)
AssertionError: <class 'mypy.types.UnboundType'>
main.py:5: 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: 1.10.0+dev.790e8a73d8671a41cae419b4ea07579bfb2bc292
main.py:5: : note: use --pdb to drop into pdb

To Reproduce

https://mypy-play.net/?mypy=master&python=3.12&gist=744b559e656f6f35cd5762bddf979038

# This crashes
from typing import Callable
Ts = TypeVarTuple("Ts")  # <- oops forgot to import TypeVarTuple
Alias = Callable[[*Ts], int]
x: Alias[int]
reveal_type(x)

And this

from typing import Callable, TypeVar
T = TypeVar("T")
Alias = Callable[[*T], int]
x: Alias[int]
reveal_type(x)

And this

from typing import Any, Callable
unknown: Any
Alias = Callable[[*unknown], int]
x: Alias[int]
# reveal_type(x)

Your Environment

• Mypy version used: 1.8.0 and from the master branch
• Mypy command-line flags: N/A
• Mypy configuration options from mypy.ini (and other config files): N/A
• Python version used: 3.12
• Operating system and version: Linux