Add new manual_ilog10 perf lint

[GuillaumeGomez]

There is already an existing manual_ilog2, so maybe instead of creating this new lint, we should deprecate manual_ilog2 and create a more global manual_ilog_n?

Anyway, ilog10 is more performant than ilog(10) (as indicated in the docs), so if possible, we should always use it instead (same for ilog2/ilog(2)).

changelog: Add new manual_ilog10

r? @samueltardieu

[samueltardieu]

You should at least rename the manual_ilog2.rs file into manual_ilog_n.rs, put both lints inside the file and share the code. Otherwise at some point both implementations will differ and turn into a technical debt.

View changes since this review

[samueltardieu]

@rustbot label lint-nominated

[rustbot]

This lint has been nominated for inclusion.

A FCP topic has been created on Zulip.

[GuillaumeGomez]

You should at least rename the manual_ilog2.rs file into manual_ilog_n.rs, put both lints inside the file and share the code. Otherwise at some point both implementations will differ and turn into a technical debt.

View changes since this review

Is there a process when a lint is renamed? Because I'd like to not have two lints for the kinda same thing.

[samueltardieu]

I'm proposing to rename the file, not to rename the lint.

If you want to propose renaming the lint, please discuss this in the FCP Zulip thread. If this is the accepted solution, then cargo dev rename_lint would definitely be helpful.

[rustbot]

☔ The latest upstream changes (possibly #17329) made this pull request unmergeable. Please resolve the merge conflicts.