chore: refactor backtrace style in panic

[Konippi]

Refactor get_backtrace_style for better readability and potential performance improvements

This PR aims to improve the readability and maintainability of the set_backtrace_style and get_backtrace_style function.

[rustbot]

r? @tgross35

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[tgross35]

Hey, thanks for the PR. Unfortunately I have to disagree that nesting combinators with extra indentation is more clear than what already existed.

If you want to improve something, you could flatten the let format = ... to a match. Along the lines of:

let format = match crate::env::var_os("RUST_BACKTRACE") {
    Some(x) if &x == "0" => BacktraceStyle::Off,
    Some(x) if &x == "full" /* ... */
    // ...
    None if /* ... */
    // ...
}

[tgross35]

Note that this isn't equivalent to the equality &x == "0" checks that were there before. PartialEq for OsStr is usually just a byte for byte comparison, but calling to_str incurs the cost of validating it is UTF-8.

Unlikely to make much of a difference here, but also no reason to change away from ==.

[Konippi]

thanks for accurate reviewing!
I didn't take account into the cost of validating it's UTF-8 by using to_str.

[tgross35]

@rustbot author

[joboet]

@bors r=@tgross35

[bors]

📌 Commit a798e0f has been approved by tgross35

It is now in the queue for this repository.