Mypy crashes on async tuple to tuple assignment #19920
Description
Crash Report
We got a tuple to tuple assignment with asyncio.gather, which crashes mypy, it looks like this:
tab_content: PriceCombinedDBAccessTabContentDto
price_region_stats: PriceRegionStats
( # < Error points to this line, this is line 70
price_data,
tab_content,
all_price_regions,
all_prof_role_groups,
price_region_stats,
has_civ_service,
) = await asyncio.gather(
get_price_data(handler, TabName.COMBINED_DBACCESS, price_description, backoffice_employer_id, session),
get_price_tab_content(http_client, config, TabName.COMBINED_DBACCESS, backoffice_employer_id),
get_all_price_regions(handler),
get_all_prof_role_groups(handler),
get_price_regions_stats(http_client, config),
check_employer_has_service_no_handler(
http_client, config, employer_id_or_backoffice_employer_id, ProductItemCode.ContactsView
),
)Traceback
xhh/pages/price/combined_dbaccess.py:70: 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: 1.19.0+dev.354bea6352ee7a38b05e2f42c874e7d1f7bf557a
Traceback (most recent call last):
File "/Users/gooverdian/Projects/xhh/.venv/bin/mypy", line 8, in <module>
sys.exit(console_entry())
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/__main__.py", line 15, in console_entry
main()
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/main.py", line 127, in main
res, messages, blockers = run_build(sources, options, fscache, t0, stdout, stderr)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/main.py", line 211, in run_build
res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/build.py", line 196, in build
result = _build(
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/build.py", line 272, in _build
graph = dispatch(sources, manager, stdout)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/build.py", line 2946, in dispatch
process_graph(graph, manager)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/build.py", line 3346, in process_graph
process_stale_scc(graph, scc, manager)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/build.py", line 3447, in process_stale_scc
graph[id].type_check_first_pass()
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/build.py", line 2325, in type_check_first_pass
self.type_checker().check_first_pass()
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 524, in check_first_pass
self.accept(d)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 635, in accept
stmt.accept(self)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/nodes.py", line 1127, in accept
return visitor.visit_decorator(self)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 5412, in visit_decorator
self.visit_decorator_inner(e)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 5419, in visit_decorator_inner
self.check_func_item(e.func, name=e.func.name, allow_empty=allow_empty)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 1231, in check_func_item
self.check_func_def(defn, typ, name, allow_empty)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 1504, in check_func_def
self.accept(item.body)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 635, in accept
stmt.accept(self)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/nodes.py", line 1542, in accept
return visitor.visit_block(self)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 3126, in visit_block
self.accept(s)
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 635, in accept
stmt.accept(self)
~~~~~~~~~~~^^^^^^
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/nodes.py", line 1629, in accept
return visitor.visit_assignment_stmt(self)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 3177, in visit_assignment_stmt
self.check_assignment(s.lvalues[-1], s.rvalue, s.type is None, s.new_syntax)
~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 3233, in check_assignment
self.check_assignment_to_multiple_lvalues(
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
lvalue.items, rvalue, rvalue, infer_lvalue_type
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 3984, in check_assignment_to_multiple_lvalues
self.check_multi_assignment(lvalues, rvalue, context, infer_lvalue_type)
~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 4062, in check_multi_assignment
self.check_multi_assignment_from_tuple(
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
lvalues, rvalue, rvalue_type, context, undefined_rvalue, infer_lvalue_type
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "/Users/gooverdian/Projects/xhh/.venv/lib/python3.13/site-packages/mypy/checker.py", line 4202, in check_multi_assignment_from_tuple
assert isinstance(reinferred_rvalue_type, TupleType)
~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: To Reproduce
This file is not new, so the diff, which lead to that error is adding types to some members of a left tuple before the assignment:
+ tab_content: PriceCombinedDBAccessTabContentDto
+ price_region_stats: PriceRegionStats
(
price_data,
tab_content,
all_price_regions,
all_prof_role_groups,
price_region_stats,
has_civ_service,
) = await asyncio.gather(
get_price_data(handler, TabName.COMBINED_DBACCESS, price_description, backoffice_employer_id, session),
get_price_tab_content(http_client, config, TabName.COMBINED_DBACCESS, backoffice_employer_id),
get_all_price_regions(handler),
get_all_prof_role_groups(handler),
get_price_regions_stats(http_client, config),
check_employer_has_service_no_handler(
http_client, config, employer_id_or_backoffice_employer_id, ProductItemCode.ContactsView
),
)UPD: Found a way to reproduce it in playground https://mypy-play.net/?mypy=latest&python=3.13&gist=ca818b7f434ca646dd6373b26f5b58f6, seems like there would be an error if it wouldn't crash.
Your Environment
- Mypy version used: 1.15.0, 1.18.2, git master
- Mypy command-line flags: --config-file (path to config), --show-traceback, (path to file)
- Mypy configuration options from
mypy.ini(and other config files):[tool.mypy] warn_redundant_casts = true warn_unused_ignores = true warn_unused_configs = true show_error_codes = true ignore_missing_imports = true follow_imports = "silent" follow_untyped_imports = true disallow_untyped_calls = false disallow_incomplete_defs = true disallow_untyped_decorators = true check_untyped_defs = true strict = true disallow_untyped_defs = true disallow_any_generics = true disallow_subclassing_any = true warn_return_any = true enable_error_code = [ "deprecated", "ignore-without-code", ] python_version = "3.13" exclude = [ "xhh/pages/employer/documents-management", "xhh/pages/employer/financial-documents", "xhh/pages/employer/reviews-settings", "xhh/page.py", ] - Python version used: 3.13
- Operating system and version: mac sequoia 15.6.1, alpine ubuntu (docker)