New lint: collapsible_str_replace

[camsteffen]

What it does

Checks for consecutive calls to str::replace (2 or more) that can be collapsed into a single call.

Categories (optional)

• Kind: perf

What is the advantage of the recommended code over the original code

Faster since the string is only scanned once. Also less repetitive code.

Drawbacks

None.

Example

"hesuo worpd"
    .replace('s', "l")
    .replace("u", "l")
    .replace('p', "l")

Could be written as:

"hesuo worpd".replace(|c| matches!(c, 's' | 'u' | 'p'), "l")

Using matches! is potentially faster than a slice of chars (replace(&['s', 'u', 'p'], "l")). But if any of the chars are variables, the lint can fall back to suggesting a slice of chars.

[nahuakang]

This actually looks really fun. I'd like to move on to this issue 🙌

[xFrednet]

@nahuakang could you maybe assign your self by commenting @rustbot claim? This makes it easier to see that someone is working on this issue. You can unassign yourself at anytime if you want to stop working on this 🙃. It's nice to see you around, keep up the good work 👍

[nahuakang]

@rustbot claim