mypy --install-types segfaults

[aphedges]

Bug Report

When running mypy --install-types, mypy segfaults instead of completing successfully.

To Reproduce

1. Install the following requirements with pip:

mypy==0.900
mypy-extensions==0.4.3
pip==21.1.2
PyYAML==5.4.1
setuptools==57.0.0
toml==0.10.2
typed-ast==1.4.3
typing-extensions==3.10.0.0

2. Put the following code in test.py:

import yaml

3. Run mypy test.py, which will display the following output:

test.py:1: error: Library stubs not installed for "yaml" (or incompatible with Python 3.7)
test.py:1: note: Hint: "python3 -m pip install types-PyYAML"
test.py:1: note: (or run "mypy --install-types" to install all missing stub packages)
test.py:1: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
Found 1 error in 1 file (checked 1 source file)

4. Run mypy --install-types

Actual Behavior

mypy outputs the following:

Installing missing stub packages:
Segmentation fault: 11

When running python -X dev -m mypy --install-types, I get the following, more verbose output:

Installing missing stub packages:
Fatal Python error: Segmentation fault

Current thread 0x000000010e30cdc0 (most recent call first):
  File "/Users/ahedges/.pyenv/versions/mypy2/lib/python3.7/site-packages/mypy/__main__.py", line 11 in console_entry
  File "/Users/ahedges/.pyenv/versions/mypy2/lib/python3.7/site-packages/mypy/__main__.py", line 23 in <module>
  File "/Users/ahedges/.pyenv/versions/3.7.10/lib/python3.7/runpy.py", line 85 in _run_code
  File "/Users/ahedges/.pyenv/versions/3.7.10/lib/python3.7/runpy.py", line 193 in _run_module_as_main
Segmentation fault: 11

Your Environment

• Mypy version used: 0.900
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.7.10
• Operating system and version: macOS 10.15.7 (19H1030)

[JukkaL]

This seem to be a problem with the binary wheels. As a workaround, you can uninstall mypy and reinstall without the binaries:

python3 -m pip install --no-binary :all: mypy

EDIT: See comment below for a better way to do it (replace :all: with mypy).

However, this results in much worse performance. We'll need a 0.901 hotfix release.

[emmatyping]

Note that most people probably want --no-binary=mypy because they do want typed_ast, lxml, and others to use pre-compiled binaries. So I'd recommend

python3 -m pip install --no-binary=mypy mypy

[JukkaL]

I just released mypy 0.901 that includes a fix to this issue.

[aphedges]

@JukkaL, I can confirm this solves my problem. Thank you so much for the quick fix!