feat: add `manual_max` and `manual_min` lints by sylvestre · Pull Request #17206 · rust-lang/rust-clippy

sylvestre · 2026-06-10T19:53:22Z

Add two complexity lints that detect a single-sided clamp written as an if/else (or a guarding if) and suggest Ord::max / Ord::min:

let _ = if a < b { b } else { a };  // -> a.max(b)
if cores < b { cores = b; }         // -> cores = cores.max(b);

This is the sound, generalizable form of the manual clamp simplified by hand in uutils/coreutils#12753 (nproc). Unlike manual_clamp, which only fires when both a lower and an upper bound are applied, these catch the common single-bound floor/ceiling case.

Restricted to Ord types so float NaN semantics are not changed, and emitted as MaybeIncorrect since the branching form re-evaluates the selected operand.

changelog: add manual_max and manual_min lints

rustbot · 2026-06-10T19:53:27Z

r? @llogiq

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github-actions · 2026-06-10T20:03:45Z

Lintcheck changes for 4992d2c

Lint	Added	Removed	Changed
`clippy::manual_max`	17	0	0
`clippy::manual_min`	8	0	0

This comment will be updated if you push new changes

oech3 · 2026-06-11T04:48:45Z

nproc did not compare cores - limit with 1. So this is slightly different with this lint.

samueltardieu · 2026-06-11T12:29:22Z

You'll have to guard this with a MSRV check (1.21).

sylvestre · 2026-06-13T09:19:36Z

@samueltardieu done, merci!

sylvestre · 2026-06-17T06:36:14Z

@rustbot ready

sylvestre · 2026-07-05T21:59:29Z

Lintcheck - 4 hits on default set (27 crates), 51 hits (22 min + 29 max) on extended set (499 crates), no ICEs.

Add two `complexity` lints that detect a single-sided clamp written as an `if`/`else` (or a guarding `if`) and suggest `Ord::max` / `Ord::min`: let _ = if a < b { b } else { a }; // -> a.max(b) if cores < b { cores = b; } // -> cores = cores.max(b); This is the sound, generalizable form of a manual clamp that is often simplified by hand in real code (for example in the `nproc` utility of uutils/coreutils). Unlike `manual_clamp`, which only fires when both a lower and an upper bound are applied, these catch the common single-bound floor/ceiling case. Restricted to `Ord` types so float `NaN` semantics are not changed, and emitted as `MaybeIncorrect` since the branching form re-evaluates the selected operand.

rustbot · 2026-08-03T21:14:22Z

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

rustbot · 2026-08-04T05:47:41Z

This lint has been nominated for inclusion.

A FCP topic has been created on Zulip.

rustbot · 2026-08-12T14:34:29Z

☔ The latest upstream changes (possibly #17552) made this pull request unmergeable. Please resolve the merge conflicts.

rustbot assigned llogiq Jun 10, 2026

rustbot added needs-fcp PRs that add, remove, or rename lints and need an FCP S-waiting-on-review Status: Awaiting review from the assignee but also interested parties labels Jun 10, 2026