TypeGuard should not appear here

[dfroger]

Crash Report

Get a crash with RuntimeError: TypeGuard should not appear here. A source code to reproduce it is included bellow.

Traceback

$ mypy --show-traceback foo.py 
foo.py:26: 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: 0.910+dev.9d92fbaab4d1c18991d71517a9981900ae60db25
Traceback (most recent call last):
  File "/home/david/mypy-master/bin/mypy", line 8, in <module>
    sys.exit(console_entry())
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/__main__.py", line 11, in console_entry
    main(None, sys.stdout, sys.stderr)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/main.py", line 103, in main
    res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/build.py", line 180, in build
    sources, options, alt_lib_path, flush_errors, fscache, stdout, stderr, extra_plugins
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/build.py", line 254, in _build
    graph = dispatch(sources, manager, stdout)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/build.py", line 2696, in dispatch
    process_graph(graph, manager)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/build.py", line 3020, in process_graph
    process_stale_scc(graph, scc, manager)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/build.py", line 3118, in process_stale_scc
    graph[id].type_check_first_pass()
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/build.py", line 2165, in type_check_first_pass
    self.type_checker().check_first_pass()
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checker.py", line 294, in check_first_pass
    self.accept(d)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checker.py", line 401, in accept
    stmt.accept(self)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/nodes.py", line 689, in accept
    return visitor.visit_func_def(self)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checker.py", line 726, in visit_func_def
    self._visit_func_def(defn)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checker.py", line 730, in _visit_func_def
    self.check_func_item(defn, name=defn.name)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checker.py", line 792, in check_func_item
    self.check_func_def(defn, typ, name)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checker.py", line 975, in check_func_def
    self.accept(item.body)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checker.py", line 401, in accept
    stmt.accept(self)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/nodes.py", line 1017, in accept
    return visitor.visit_block(self)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checker.py", line 1984, in visit_block
    self.accept(s)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checker.py", line 401, in accept
    stmt.accept(self)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/nodes.py", line 1153, in accept
    return visitor.visit_return_stmt(self)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checker.py", line 3169, in visit_return_stmt
    self.check_return_stmt(s)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checker.py", line 3202, in check_return_stmt
    s.expr, return_type, allow_none_return=allow_none_func_call))
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checkexpr.py", line 3903, in accept
    typ = node.accept(self)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/nodes.py", line 1961, in accept
    return visitor.visit_list_comprehension(self)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checkexpr.py", line 3719, in visit_list_comprehension
    e.generator, 'builtins.list', '<list-comprehension>')
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checkexpr.py", line 3761, in check_generator_or_comprehension
    [gen.left_expr], [nodes.ARG_POS], gen)[0]
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checkexpr.py", line 920, in check_call
    object_type)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checkexpr.py", line 1016, in check_callable_call
    messages=arg_messages, object_type=object_type)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checkexpr.py", line 1485, in check_argument_types
    actual + 1, i + 1, callee, object_type, args[actual], context, messages)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/checkexpr.py", line 1513, in check_arg
    elif not is_subtype(caller_type, callee_type):
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/subtypes.py", line 97, in is_subtype
    ignore_promotions=ignore_promotions)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/subtypes.py", line 151, in _is_subtype
    ignore_promotions=ignore_promotions))
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/types.py", line 1790, in accept
    return visitor.visit_union_type(self)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/subtypes.py", line 476, in visit_union_type
    return all(self._is_subtype(item, self.orig_right) for item in left.items)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/subtypes.py", line 476, in <genexpr>
    return all(self._is_subtype(item, self.orig_right) for item in left.items)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/subtypes.py", line 209, in _is_subtype
    ignore_promotions=self.ignore_promotions)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/subtypes.py", line 97, in is_subtype
    ignore_promotions=ignore_promotions)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/subtypes.py", line 151, in _is_subtype
    ignore_promotions=ignore_promotions))
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/types.py", line 290, in accept
    return visitor.visit_type_guard_type(self)
  File "/home/david/mypy-master/lib/python3.7/site-packages/mypy/subtypes.py", line 479, in visit_type_guard_type
    raise RuntimeError("TypeGuard should not appear here")
RuntimeError: TypeGuard should not appear here
foo.py:26: : note: use --pdb to drop into pdb

To Reproduce

from typing import Any, List
from typing_extensions import TypeGuard


class Base:
    ...


class Foo(Base):
    ...


class Bar(Base):
    ...


def is_foo(item: Any) -> TypeGuard[Foo]:
    return isinstance(item, Foo)


def is_bar(item: Any) -> TypeGuard[Bar]:
    return isinstance(item, Bar)


def foobar(items: List[Any]) -> List[Base]:
    return [x for x in items if is_foo(x) or is_bar(x)]

Your Environment

• Mypy version used: 0.910+dev.9d92fbaab4d1c18991d71517a9981900ae60db25
• Mypy command-line flags: mypy --show-traceback foo.py
• Mypy configuration options from mypy.ini (and other config files): no config file
• Python version used: 3.7.10
• Operating system and version: Linux Mint 20.1 Ulyssa

[hauntsaninja]

cc @JelleZijlstra