Fix terminal size detection

[Secrus]

Closes: python-poetry/poetry#7184

This fixes the issue, where in Python <3.11 shutil.get_terminal_size() would return (0, 0) size in non-TTY terminals.

[TheKevJames]

I don't believe this solves the problem, see sample CI run here.

Note that python3 -c 'import shutil; print(shutil.get_terminal_size(fallback=(80, 24)))' still returns os.terminal_size(columns=0, lines=0).

Using the fallback when the original answer is zero only occurs in Python 3.11+:

Changed in version 3.11: The fallback values are also used if os.get_terminal_size() returns zeroes.

Source: https://docs.python.org/3/library/shutil.html#shutil.get_terminal_size

[Secrus]

I don't believe this solves the problem, see sample CI run here.

Note that python3 -c 'import shutil; print(shutil.get_terminal_size(fallback=(80, 24)))' still returns os.terminal_size(columns=0, lines=0).

Using the fallback when the original answer is zero only occurs in Python 3.11+:

Changed in version 3.11: The fallback values are also used if os.get_terminal_size() returns zeroes.

Source: https://docs.python.org/3/library/shutil.html#shutil.get_terminal_size

@TheKevJames

I have tested it with Docker. Non-tty terminals are handled correctly when passing the fallback value.

the exact commands I used:

docker run --rm python:3.11-slim python3 -c "import shutil; print(shutil.get_terminal_size(fallback=(80,24)))"

docker run --rm -t python:3.11-slim python3 -c "import shutil; print(shutil.get_terminal_size(fallback=(80,24)))"

docker run --rm python:3.10-slim python3 -c "import shutil; print(shutil.get_terminal_size(fallback=(80,24)))"

docker run --rm -t python:3.10-slim python3 -c "import shutil; print(shutil.get_terminal_size(fallback=(80,24)))"

And as you see on the screen, in no case, it returns (0, 0). We are currently working on designing a proper unit testing approach to detect it.

[TheKevJames]

Ah, interesting! Ok, then I think there has been a miscommunication:

The original issue reported to poetry was that poetry was breaking in CircleCI. After our investigation in python-poetry/poetry#7184, we ultimately determined the root cause was the columns value being 0.

@neersighted proposed here that it may be possible to reproduce this error by running in docker without a tty, but that was meant to be a reproduction case rather than actually being the central issue.

Given your results show that your change here fixes the issue in docker, but my results here show that CircleCI continues to receive columns=0 even when a fallback value is provided, I think we've successfully proven that using docker without -t does not reproduce the original issue.

EDIT: I guess this implies the original issue in CircleCI is not definitely related to the existence/non-existence of an attached tty.

[Secrus]

Interesting... Seems like a Circle CI thing (online-judge-tools/oj#611, aws/aws-cdk#2355)

[neersighted]

It appears that they do allocate a TTY with a (reported) size of zero, which is fascinating and going to break other tools... e.g. bash provides variables for this that just report the value of TIOCGWINSZ.

[istankovic]

Is there any blocker for this fix?