Crash on code mixing instances and type typed variables #20526
Description
Crash Report
INTERNAL ERROR
Traceback
mwe-mypy2.py:19: 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: 1.20.0+dev.56c33f251cb6b3791297fdaa57453d4afaa8c4dc
Traceback (most recent call last):
File "/home/.../.venv/bin/mypy", line 8, in <module>
sys.exit(console_entry())
File "/home/.../.venv/lib/python3.13/site-packages/mypy/__main__.py", line 15, in console_entry
main()
File "/home/.../.venv/lib/python3.13/site-packages/mypy/main.py", line 135, in main
res, messages, blockers = run_build(sources, options, fscache, t0, stdout, stderr)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/main.py", line 219, in run_build
res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/build.py", line 320, in build
result = build_inner(
File "/home/.../.venv/lib/python3.13/site-packages/mypy/build.py", line 417, in build_inner
graph = dispatch(sources, manager, stdout)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/build.py", line 3178, in dispatch
process_graph(graph, manager)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/build.py", line 3588, in process_graph
done, still_working, results = manager.wait_for_done(graph)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/build.py", line 1070, in wait_for_done
process_stale_scc(graph, next_scc, self)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/build.py", line 3752, in process_stale_scc
graph[id].type_check_first_pass()
File "/home/.../.venv/lib/python3.13/site-packages/mypy/build.py", line 2543, in type_check_first_pass
self.type_checker().check_first_pass()
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 530, in check_first_pass
self.accept(d)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 641, in accept
stmt.accept(self)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/nodes.py", line 1004, in accept
return visitor.visit_func_def(self)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 1198, in visit_func_def
self._visit_func_def(defn)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 1202, in _visit_func_def
self.check_func_item(defn, name=defn.name)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 1237, in check_func_item
self.check_func_def(defn, typ, name, allow_empty)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 1510, in check_func_def
self.accept(item.body)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 641, in accept
stmt.accept(self)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/nodes.py", line 1582, in accept
return visitor.visit_block(self)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 3159, in visit_block
self.accept(s)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 641, in accept
stmt.accept(self)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/nodes.py", line 1669, in accept
return visitor.visit_assignment_stmt(self)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 3212, in visit_assignment_stmt
self.check_assignment(s.lvalues[-1], s.rvalue, s.type is None, s.new_syntax)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 3387, in check_assignment
rvalue_type, lvalue_type = self.check_simple_assignment(
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checker.py", line 4668, in check_simple_assignment
rvalue_type = self.expr_checker.accept(
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checkexpr.py", line 6081, in accept
typ = self.accept_maybe_cache(node, type_context=type_context)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checkexpr.py", line 6116, in accept_maybe_cache
typ = node.accept(self)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/nodes.py", line 2298, in accept
return visitor.visit_call_expr(self)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checkexpr.py", line 508, in visit_call_expr
return self.visit_call_expr_inner(e, allow_none_return=allow_none_return)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checkexpr.py", line 645, in visit_call_expr_inner
ret_type = self.check_call_expr_with_callee_type(
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checkexpr.py", line 1495, in check_call_expr_with_callee_type
ret_type, callee_type = self.check_call(
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checkexpr.py", line 1588, in check_call
return self.check_callable_call(
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checkexpr.py", line 1799, in check_callable_call
arg_types = self.infer_arg_types_in_context(callee, args, arg_kinds, formal_to_actual)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checkexpr.py", line 1973, in infer_arg_types_in_context
res[ai] = self.accept(args[ai], arg_type)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checkexpr.py", line 6083, in accept
typ = node.accept(self) # r-value type, when interpreted as a value expression
File "/home/.../.venv/lib/python3.13/site-packages/mypy/nodes.py", line 2198, in accept
return visitor.visit_name_expr(self)
~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checkexpr.py", line 357, in visit_name_expr
narrowed = self.narrow_type_from_binder(e, result)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/checkexpr.py", line 6394, in narrow_type_from_binder
narrowed = narrow_declared_type(known_type, restriction)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/meet.py", line 141, in narrow_declared_type
narrow_declared_type(d, n)
~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/home/.../.venv/lib/python3.13/site-packages/mypy/meet.py", line 222, in narrow_declared_type
return meet_types(original_declared, original_narrowed)
File "/home/.../.venv/lib/python3.13/site-packages/mypy/meet.py", line 113, in meet_types
return t.accept(TypeMeetVisitor(s))
~~~~~~~~^^^^^^^^^^^^^^^^^^^^
File "/home/.../.venv/lib/python3.13/site-packages/mypy/types.py", line 2846, in accept
return visitor.visit_tuple_type(self)
~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/home/.../.venv/lib/python3.13/site-packages/mypy/meet.py", line 1079, in visit_tuple_type
return t.copy_modified(items=[meet_types(it, self.s.args[0]) for it in t.items])
~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^mwe-mypy2.py:19: : note: use --pdb to drop into pdb
File "/home/.../.venv/lib/python3.13/site-packages/mypy/meet.py", line 113, in meet_types
return t.accept(TypeMeetVisitor(s))
~~~~~~~~^^^^^^^^^^^^^^^^^^^^
File "/home/.../.venv/lib/python3.13/site-packages/mypy/types.py", line 3416, in accept
return visitor.visit_union_type(self)
~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/home/.../.venv/lib/python3.13/site-packages/mypy/meet.py", line 793, in visit_union_type
meets = [meet_types(x, self.s) for x in t.items]
~~~~~~~~~~^^^^^^^^^^^
File "/home/.../.venv/lib/python3.13/site-packages/mypy/meet.py", line 113, in meet_types
return t.accept(TypeMeetVisitor(s))
~~~~~~~~^^^^^^^^^^^^^^^^^^^^
File "/home/.../.venv/lib/python3.13/site-packages/mypy/types.py", line 1250, in accept
return visitor.visit_unpack_type(self)
~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/home/.../.venv/lib/python3.13/site-packages/mypy/meet.py", line 845, in visit_unpack_type
raise NotImplementedError
NotImplementedError: To Reproduce
from typing import Hashable, cast
type Key[K: Hashable] = K | type[K]
type TP[K: Hashable] = tuple[Key[K], ...]
type Value[V] = V | type[V] | None
type T[K: Hashable, V] = tuple[*TP[K], Value[V]]
def f[K, V](one: TP[K] | T[K, V], other: TP[K] | T[K, V]) -> TP[K] | T[K, V] | None:
if len(one) < len(other):
return None
if one[:len(other)] != other:
return None
return cast(TP[K] | T[K, V], one[len(other):])
def g[K, V](one: TP[K] | T[K, V], other: TP[K] | T[K, V]) -> int | None:
d: TP[K] | T[K, V] | None = f(one, other)
if d is None:
return None
n: int = len(d)
return nand then run mypy on it.
Your Environment
- Mypy version used: mypy 1.20.0+dev.56c33f251cb6b3791297fdaa57453d4afaa8c4dc (compiled: no)
- Mypy command-line flags:
--show-traceback - Mypy configuration options from
mypy.ini(and other config files): - Python version used: Python 3.13.5
- Operating system and version: 6.12.57+deb13-amd64
#1SMP PREEMPT_DYNAMIC Debian 6.12.57-1 (2025-11-05) x86_64 GNU/Linux