Generic of TypeVar causes SCC singleton as inherently stale, when used with match syntax #13213
Description
Crash Report
I am trying to write a generic type to hold the type of a column, as parsed from a text-based table format. I want to have a type of "column type" that holds the underlying python type.
Traceback
LOG: Mypy Version: 0.971
LOG: Config File: setup.cfg
LOG: Configured Executable: /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/bin/python
LOG: Current Executable: /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/bin/python
LOG: Cache Dir: .mypy_cache
LOG: Compiled: True
LOG: Exclude: ['(dxp_scripts)']
LOG: Found source: BuildSource(path='bug.py', module='bug', has_text=False, base_dir='/home/yakov/orion/repo')
LOG: Could not load cache for bug: bug.meta.json
LOG: Metadata not found for bug
LOG: Parsing bug.py (bug)
LOG: Metadata fresh for typing: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/typing.pyi
LOG: Metadata fresh for builtins: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/builtins.pyi
LOG: Metadata fresh for collections: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/collections/__init__.pyi
LOG: Metadata fresh for sys: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/sys.pyi
LOG: Metadata fresh for _typeshed: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/_typeshed/__init__.pyi
LOG: Metadata fresh for abc: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/abc.pyi
LOG: Metadata fresh for types: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/types.pyi
LOG: Metadata fresh for typing_extensions: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/typing_extensions.pyi
LOG: Metadata fresh for _ast: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/_ast.pyi
LOG: Metadata fresh for _collections_abc: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/_collections_abc.pyi
LOG: Metadata fresh for collections.abc: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/collections/abc.pyi
LOG: Metadata fresh for io: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/io.pyi
LOG: Metadata fresh for importlib.abc: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/importlib/abc.pyi
LOG: Metadata fresh for importlib.machinery: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/importlib/machinery.pyi
LOG: Metadata fresh for array: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/array.pyi
LOG: Metadata fresh for ctypes: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/ctypes/__init__.pyi
LOG: Metadata fresh for mmap: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/mmap.pyi
LOG: Metadata fresh for pickle: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/pickle.pyi
LOG: Metadata fresh for os: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/os/__init__.pyi
LOG: Metadata fresh for codecs: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/codecs.pyi
LOG: Metadata fresh for importlib: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/importlib/__init__.pyi
LOG: Metadata fresh for importlib.metadata: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/importlib/metadata/__init__.pyi
LOG: Metadata fresh for os.path: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/os/path.pyi
LOG: Metadata fresh for contextlib: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/contextlib.pyi
LOG: Metadata fresh for subprocess: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/subprocess.pyi
LOG: Metadata fresh for _codecs: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/_codecs.pyi
LOG: Metadata fresh for pathlib: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/pathlib.pyi
LOG: Metadata fresh for email.message: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/email/message.pyi
LOG: Metadata fresh for importlib.metadata._meta: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/importlib/metadata/_meta.pyi
LOG: Metadata fresh for posixpath: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/posixpath.pyi
LOG: Metadata fresh for email: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/email/__init__.pyi
LOG: Metadata fresh for email.charset: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/email/charset.pyi
LOG: Metadata fresh for email.contentmanager: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/email/contentmanager.pyi
LOG: Metadata fresh for email.errors: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/email/errors.pyi
LOG: Metadata fresh for email.policy: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/email/policy.pyi
LOG: Metadata fresh for genericpath: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/genericpath.pyi
LOG: Metadata fresh for email.header: file /home/yakov/.cache/pypoetry/virtualenvs/repo-0gsef-ws-py3.10/lib/python3.10/site-packages/mypy/typeshed/stdlib/email/header.pyi
LOG: Loaded graph with 38 nodes (0.019 sec)
LOG: Found 2 SCCs; largest has 37 nodes
LOG: Processing 1 queued fresh SCCs
LOG: Processing SCC singleton (bug) as inherently stale
bug.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: 0.971
bug.py:11: : note: use --pdb to drop into pdb
LOG: Build finished in 0.163 seconds with 38 modules, and 0 errors
Traceback (most recent call last):
File "mypy/checker.py", line 435, in accept
File "mypy/nodes.py", line 758, in accept
File "mypy/checker.py", line 786, in visit_func_def
File "mypy/checker.py", line 790, in _visit_func_def
File "mypy/checker.py", line 852, in check_func_item
File "mypy/checker.py", line 872, in check_func_def
File "mypy/checker.py", line 1492, in expand_typevars
File "mypy/checker.py", line 6133, in expand_func
File "mypy/nodes.py", line 758, in accept
File "mypy/treetransform.py", line 115, in visit_func_def
File "mypy/treetransform.py", line 580, in block
File "mypy/treetransform.py", line 194, in visit_block
File "mypy/treetransform.py", line 591, in statements
File "mypy/treetransform.py", line 564, in stmt
TypeError: mypy.nodes.Node object expected; got None
To Reproduce
# bug.py
from typing import Generic, Type, TypeVar
ColumnType = TypeVar("ColumnType", str, bool)
class ValueType(Generic[ColumnType]):
"""The type of values that exist in a column."""
string = "String"
boolean = "Bool"
def astype(self) -> Type[ColumnType]:
"""Interpret the text type as a python type.
Returns:
the python type that this value type represents.
"""
match self:
case ValueType.string:
return str
case ValueType.boolean:
return bool
Your Environment
- Mypy version used: 0.971
- Mypy command-line flags:
mypy bug.py --ignore-missing-imports --strict --show-error-code --show-traceback -v > mypy.log 2>&1 - Mypy configuration options from
mypy.ini(and other config files):
[mypy]
follow_imports = silent
strict_optional = True
warn_redundant_casts = True
warn_unused_ignores = True
disallow_any_generics = True
check_untyped_defs = True
no_implicit_reexport = True
disallow_untyped_defs = True
ignore_missing_imports = True
enable_error_code = ignore-without-code
strict = True
exclude = (dxp_scripts)
- Python version used: 3.10
- Operating system and version:
$ uname -a
Linux LT-YPECHERSKY 5.10.102.1-microsoft-standard-WSL2 #1 SMP Wed Mar 2 00:30:59 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
$ pip list
Package Version
-------------------- ---------
arrow 1.2.2
attrs 21.4.0
binaryornot 0.4.4
black 22.6.0
certifi 2022.6.15
cfgv 3.3.1
chardet 5.0.0
charset-normalizer 2.1.0
click 8.1.3
click-default-group 1.2.2
cookiecutter 1.7.3
coverage 5.5
cruft 2.10.2
darglint 1.8.1
distlib 0.3.5
filelock 3.7.1
flake8 4.0.1
flake8-docstrings 1.6.0
gitdb 4.0.9
GitPython 3.1.27
identify 2.5.2
idna 3.3
importlib-resources 5.8.0
incremental 21.3.0
iniconfig 1.1.1
isort 5.10.1
Jinja2 3.1.2
jinja2-time 0.2.0
MarkupSafe 2.1.1
mccabe 0.6.1
mypy 0.971
mypy-extensions 0.4.3
nodeenv 1.7.0
packaging 21.3
parsy 1.4.0
pathspec 0.9.0
pip 22.1.2
platformdirs 2.5.2
pluggy 1.0.0
poetry-core 1.0.8
poyo 0.5.0
pre-commit 2.20.0
py 1.11.0
pycodestyle 2.8.0
pydocstyle 6.1.1
pyflakes 2.4.0
pyparsing 3.0.9
pytest 6.2.5
pytest-cov 3.0.0
pytest-mock 3.8.2
python-dateutil 2.8.2
python-slugify 6.1.2
PyYAML 6.0
requests 2.28.1
setuptools 62.6.0
six 1.16.0
smmap 5.0.0
snowballstemmer 2.2.0
text-unidecode 1.3
tl-spotfire 0.1.0
toml 0.10.2
tomli 2.0.1
towncrier 21.9.0
tox 3.25.1
tox-gh-actions 2.9.1
tox-poetry-installer 0.8.4
typer 0.4.2
typing_extensions 4.3.0
urllib3 1.26.10
virtualenv 20.15.1
wheel 0.37.1
xdoctest 0.15.10
There is a related attempt that does not have the INTERNAL ERROR, which still indicates to me that something might be wrong:
from typing import Generic, Type, TypeVar
ColumnType = TypeVar("ColumnType", str, bool)
class ValueType(Generic[ColumnType]):
"""The type of values that exist in a column."""
string = "String"
boolean = "Bool"
def astype(self) -> Type[ColumnType]:
"""Interpret the text type as a python type.
Returns:
the python type that this value type represents.
"""
if self == ValueType.string:
return str
return bool
$ mypy bug.py --ignore-missing-imports --strict --show-error-code --show-traceback
bug.py:40: error: Incompatible return value type (got "Type[str]", expected "Type[bool]") [return-value]
bug.py:41: error: Incompatible return value type (got "Type[bool]", expected "Type[str]") [return-value]