`PYTHON_LLTRACE`/`PYTHON_OPT_DEBUG` only reads first character of environment variable

[StepfenShawn]

Feature or enhancement

Proposal:

The PYTHON_LLTRACE and PYTHON_OPT_DEBUG environment variables are currently parsed by only reading the first character:

lltrace = *python_lltrace - '0';  // '10' becomes 1

This means values like PYTHON_LLTRACE=10 are interpreted as 1 instead of 10.

PR: #148636

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

Linked PRs

• gh-148638: Parse PYTHON_LLTRACE/PYTHON_OPT_DEBUG as integer #148636

[Fidget-Spinner]

I think we should just remove the TODO comments. There's no need to parse them anyways, these values never exceed 5.

[StepfenShawn]

The code currently checks if (lltrace >= 5) in multiple places (ceval.h, ceval_macros.h, bytecodes.c), which explicitly handles values of 5 and above. For example:

// ceval.h:304-306
if (lltrace >= 5) {
    lltrace_resume_frame(frame);
}

My thought is: While today's levels only go up to 5, the >= comparison itself signals that higher values are semantically valid and may be used for even more verbose tracing in the future🤔?

[Fidget-Spinner]

The env var is used for internal development purposes. I really hope we dont exceed 9 levels.