uv run fail to run pyw scripts on Mac (and probably Linux) with a confusing message

[ilyagr]

I tried reproducing the second example from https://docs.astral.sh/uv/guides/scripts/#using-gui-scripts on my Mac, and got a confusing error. I'm guessing uv tries to run a pythonw executable that doesn't exist on my system, or it's trying to run example_pyqt.pyw.py.

I think this should just work but, if not, the error message should be better.

$ uv run example_pyqt.pyw
error: Failed to spawn: `example_pyqt.pyw`
  Caused by: No such file or directory (os error 2)
$ uname -a
Darwin macaw.local 23.6.0 Darwin Kernel Version 23.6.0: Thu Sep 12 23:36:12 PDT 2024; root:xnu-10063.141.1.701.1~1/RELEASE_ARM64_T6020 arm64 arm Darwin
$ uv --version
uv 0.5.7 (Homebrew 2024-12-06)

After renaming the file to .py, everything worked (it's an impressive demo!).

[zanieb]

Ah pyw is "Windows only", we can improve the error message here. Or.. just invoke the python interpreter (which I think could be correct?)

[ilyagr]

Thanks! I think either approach could work.

I also wonder whether there are other cases where uv will deceptively report "Failed to spawn x: No such file or directory" when x actually exists.