New lint: calling `trim()` then `split_whitespace()`

What it does

Warns about calling str::trim (and variants) before str::split_whitespace (and variants). split_whitespace already ignores leading and trailing whitespace.

These two lines produce the same output:

    println!("{:?}", " A B C ".trim().split_whitespace().collect::<Vec<_>>());
    println!("{:?}", " A B C ".split_whitespace().collect::<Vec<_>>());

which is

["A", "B", "C"]
["A", "B", "C"]

playground

Lint Name

trim_split_whitespace

Category

pedantic

Advantage

• The trim call is needless
• The developer might not realize that split_whitespace works this way

Drawbacks

No response

Example

" A B C ".trim().split_whitespace()

Could be written as:

" A B C ".split_whitespace()