False positive from cmp_owned?

[djc]

Lint name:

cmp_owned

I tried this code:

if OrderedFloat::from(dist) < OrderedFloat::from(val.0) {
    val.0 = dist;
}

I expected to see this happen: nothing.

Instead, this happened:

warning: this creates an owned instance just for comparison
  --> vectors/src/generator.rs:59:16
   |
59 |             if OrderedFloat::from(dist) < OrderedFloat::from(val.0) {
   |                ^^^^^^^^^^^^^^^^^^^^^^^^----------------------------
   |                |
   |                help: try: `OrderedFloat::from(val.0) == dist`
   |
   = note: `#[warn(clippy::cmp_owned)]` on by default
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#cmp_owned

First, it's weird that the comparison operator changes from < to ==. Second, the suggestion doesn't even work because OrderedFloat doesn't implement Ord with f32 itself. Third, since OrderedFloat is Copy clippy should probably not warn about creating an owned value of that type anyway.

Meta

• cargo clippy -V: e.g. clippy 0.1.53 (53cb7b09 2021-06-17)
• rustc -Vv:

rustc 1.53.0 (53cb7b09b 2021-06-17)
binary: rustc
commit-hash: 53cb7b09b00cbea8754ffb78e7e3cb521cb8af4b
commit-date: 2021-06-17
host: x86_64-apple-darwin
release: 1.53.0
LLVM version: 12.0.1