Limit expensive decorator function

[cdce8p]

Description

Modeled after the idea here, replace the deprecate_default_argument_values decorator with a default one if DeprecationWarnings aren't enabled. I.e. these will still show during Pytest runs or if a user chooses to enable warnings (with -Wd or similar).

Github Actions isn't the most reliable / reproducible, but I think it's about a 10-30% improvement.

@DanielNoord You did the initial performance analysis in #1157 (comment). Would you be able to check again with these changes? Just a heads up, I don't know if the profiler enables DeprecationWarnings. Just for testing, you could add a simple print inside the if block to make sure.

https://docs.python.org/3/library/warnings.html#default-warning-filter
https://docs.python.org/3/using/cmdline.html#cmdoption-W

Closes #1383

[Pierre-Sassoulas]

LGTM, nice way to keep the deprecation warning when it matters.

But it means when deprecation warnings are activated in user code astroid will still be slow right ? Maybe we should add a warning about that in the changelog ?

[DanielNoord]

@DanielNoord You did the initial performance analysis in #1157 (comment). Would you be able to check again with these changes? Just a heads up, I don't know if the profiler enables DeprecationWarnings. Just for testing, you could add a simple print inside the if block to make sure.

FYI, I checked and with python -m cProfile the profiler does not enable DeprectationWarnings. I'm obviously unsure if there are specifics about other ways of invoking the profiler.

This is indeed much better! I did a rough profile and on a successive run over pylint itself I went from 64 to 53 seconds. I'm always unsure how to calculate this but 53/64 = 0,82. So I guess you could say almost a 20% performance increase?
Of course this is all very basic evidence, but this definitely solves the underlying issue. Thanks for looking into this @cdce8p!

[cdce8p]

But it means when deprecation warnings are activated in user code astroid will still be slow right ? Maybe we should add a warning about that in the changelog ?

I've already mentioned it in the Changelog message.

Only run expensive decorator functions when
non-default Deprecation warnings are enabled, eg. during a Pytest run.

The change itself doesn't make astroid slower than it's already. It just is an improvement if Deprecation warnings are disabled.