Building internal PEXes for built-in tools with `[pex].emit_warnings` shows warnings that seem useless

[huonw]

Describe the bug

In 2.20.x, we're introduced the [pex].emit_warnings option (https://www.pantsbuild.org/2.20/reference/subsystems/pex#emit_warnings) to be able to surface more warnings from PEX, but building internal PEXes for builtin tools can show the warnings. Users can't do anything about them. This option is thus off by default.

For instance:

cd $(mktemp -d)

cat > pants.toml <<EOF
[GLOBAL]
pants_version = "2.22.0.dev1"

backend_packages = []

[pex]
emit_warnings = true
EOF

touch BUILD

pants update-build-files ::

Running that shows:

11:59:12.71 [INFO] waiting for pantsd to start...
11:59:13.23 [INFO] pantsd started
11:59:13.54 [INFO] Initializing scheduler...
11:59:13.92 [INFO] Scheduler initialized.
11:59:16.88 [WARN] /Users/huon/.cache/pants/named_caches/pex_root/installed_wheels/8d43c1ed16877f3d2ed39e5ef3e92aa8885d4427cd7d9ce62683c922a5c0cd07/pex-2.3.1-py2.py3-none-any.whl/pex/bin/pex.py:947: PEXWarning: Could not calculate a targeted shebang for:
cp310-cp310-macosx_14_0_arm64 interpreter at /Users/huon/.pyenv/versions/3.10.1/bin/python3.10
cp310-cp310-macosx_14_0_arm64 interpreter at /Users/huon/.pyenv/versions/3.10.4/bin/python3.10
cp310-cp310-macosx_14_0_arm64 interpreter at /opt/homebrew/Cellar/[email protected]/3.10.12_1/Frameworks/Python.framework/Versions/3.10/bin/python3.10
cp311-cp311-macosx_14_0_arm64 interpreter at /Users/huon/.pyenv/versions/3.11.0/bin/python3.11
cp311-cp311-macosx_14_0_arm64 interpreter at /opt/homebrew/Cellar/[email protected]/3.11.9/Frameworks/Python.framework/Versions/3.11/bin/python3.11
cp312-cp312-macosx_14_0_arm64 interpreter at /Users/huon/.pyenv/versions/3.12.0/bin/python3.12
cp312-cp312-macosx_14_0_arm64 interpreter at /opt/homebrew/Cellar/[email protected]/3.12.2_1/Frameworks/Python.framework/Versions/3.12/bin/python3.12
cp37-cp37m-macosx_14_0_arm64 interpreter at /Users/huon/.pyenv/versions/3.7.13/bin/python3.7
cp38-cp38-macosx_14_0_arm64 interpreter at /Users/huon/.pyenv/versions/3.8.7/bin/python3.8
cp38-cp38-macosx_14_0_arm64 interpreter at /opt/homebrew/Cellar/[email protected]/3.8.19/Frameworks/Python.framework/Versions/3.8/bin/python3.8
cp39-cp39-macosx_14_0_arm64 interpreter at /Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.9/bin/python3.9
cp39-cp39-macosx_14_0_arm64 interpreter at /Users/huon/.pyenv/versions/3.9.1/bin/python3.9
cp39-cp39-macosx_14_0_arm64 interpreter at /Users/huon/.pyenv/versions/3.9.10/bin/python3.9
cp39-cp39-macosx_14_0_arm64 interpreter at /Users/huon/.pyenv/versions/3.9.17/bin/python3.9
cp39-cp39-macosx_14_0_arm64 interpreter at /Users/huon/.pyenv/versions/3.9.7/bin/python3.9

Using shebang: #!/usr/bin/env python3.7
If this is not appropriate, you can specify a custom shebang using the --python-shebang option.
  pex_warnings.warn(

11:59:16.95 [INFO] Starting: Building black.pex from resource://pants.backend.python.lint.black/black.lock
11:59:18.13 [INFO] Completed: Building black.pex from resource://pants.backend.python.lint.black/black.lock
11:59:18.54 [INFO] No required changes to BUILD files found. However, there may still be deprecations that `update-build-files` doesn't know how to fix. See https://www.pantsbuild.org/2.22/docs/releases/upgrade-tips for upgrade tips.

There's a big chunk of PEX warnings, that I don't think I as a normal user can do anything to silence as they seem to be about some PEXes that pants is building internally. (I could change the interpreters I have installed, but that doesn't seem appropriate.)

Pants version

2.20, 2.21, 2.22

This was previously shown by default, which was a regression between that and 2.20.0.dev7 likely related to #20480.

• https://github.com/pantsbuild/pants/releases/tag/release_2.20.0a0
• https://github.com/pantsbuild/pants/compare/release_2.20.0.dev7...release_2.20.0a0

We turned down the default level in #20590.

OS macOS

Additional info N/A

[huonw]

Heya @cburroughs, thanks for exposing the warnings. Do you have thoughts on this consequence of it?

[cburroughs]

In general this is surfacing the type of issues like #19514 that users run into which would be good to have dogfooded answer for.

In this case, I'm confused by how we got there though. Shouldn't Pants be using the bundled version of PBS from scie-pants?

[huonw]

Removing this from the 2.20.x milestone, since we landed #20593 as a stop-gap to reduce severity in 2.20.0

[cburroughs]

Is there something actionable/blocking for 2.21 here? (I'd like to change the default, but I think that's a new feature at this point.)

[huonw]

Ah, yes, thanks, I think this is now fully covered by #20586. The stopgap from #20590 is still around in 2.21 (and 2.22 etc.): https://github.com/pantsbuild/pants/blob/2.21.x/src/python/pants/backend/python/util_rules/pex_environment.py#L85

[huonw]

Oh, wait, hm, no, #20586 covers tests related to Pants' dependencies. The warnings are there for built-in tools. I'll reframe this one.

[huonw]

And indeed, not blocking for 2.21 👍