No module named librt under PyPy

[jaraco]

Bug Report

As discovered in jaraco/skeleton#188, attempting to run mypy under PyPy fails with "no module named 'librt'".

To Reproduce

Install latest mypy and PyPy.

pypy -m mypy {some codebase}

Expected Behavior

Should run as it did a few weeks ago.

Actual Behavior

 tempora main 🐚 .tox/pypy/bin/mypy .
Traceback (most recent call last):
  File "/Users/jaraco/code/jaraco/tempora/.tox/pypy/bin/mypy", line 5, in <module>
    from mypy.__main__ import console_entry
  File "/Users/jaraco/code/jaraco/tempora/.tox/pypy/lib/pypy3.10/site-packages/mypy/__main__.py", line 9, in <module>
    from mypy.main import main, process_options
  File "/Users/jaraco/code/jaraco/tempora/.tox/pypy/lib/pypy3.10/site-packages/mypy/main.py", line 17, in <module>
    from mypy import build, defaults, state, util
  File "<frozen importlib._bootstrap>", line 1078, in _handle_fromlist
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/Users/jaraco/code/jaraco/tempora/.tox/pypy/lib/pypy3.10/site-packages/mypy/build.py", line 31, in <module>
    from librt.internal import cache_version
ModuleNotFoundError: No module named 'librt'

Your Environment

• Mypy version used: 1.19.1
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: Python 3.10.14 (39dc8d3c85a7, Nov 09 2024, 22:49:03) [PyPy 7.3.17 with GCC Apple LLVM 16.0.0 (clang-1600.0.26.4)]

[jaraco]

Attempting to install mypy 1.19.0 fails to compile librt.

[jaraco]

Pinning to mypy<1.19 on PyPy seems to work around the issue.

[hauntsaninja]

Yeah, librt doesn't support PyPy.

See also #20329 (comment) and mypyc/librt#16 (comment)

[A5rocks]

Wait librt starting building? Sorry, missed the difference in 1.19.1 vs 1.19.0.

[HeWeMel]

I think I have the same problem (https://github.com/HeWeMel/nographs/actions/runs/20466071430/job/58810049765#step:6:23).

Is it likely that it will be resolved in a few days, or would you recommend implementing the above solution with the pinning so that the CI pipeline is up and running again quickly?

(And thanks to everyone working on mypy for this great tool.)

[ilevkivskyi]

Hm, I thought with my recent PR it should fail more gracefully. Btw what is the reason to run mypy using PyPy? Most likely it will be slower than CPython (with compiled binaries) and type-checking results will be identical with CPython.

[ilevkivskyi]

It should now fail with a more helpful error message. The PyPy support itself will be tracked in #20329