IDE Assist for &str -> String

[gleich]

Hello, rust analyzer maintainers! It would be awesome to have an IDE assist feature in which a user could convert a &str to a String by essentially just wrapping it in String::from() (or .to_string(), whatever would be best). I would be interested in adding myself if it ends up getting accepted by the RA team.

[Veykril]

An assist for a trivial(and very specific task) like this seems unlikely to be of much value. This sounds more like the task for a custom completion snippet:

    "rust-analyzer.completion.snippets": {
        "String::from": {
            "postfix": "strfrom",
            "body": "String::from(${receiver})",
            "scope": "expr",
        },
    },

On the other hand, we should already show a to_string completion for you when putting a . after a &str variable.

[flodiebold]

An assist for a trivial(and very specific task) like this seems unlikely to be of much value

Slightly disagree, once we have a diagnostic saying "this expects a String, but got a &str", then it makes sense to give a quickfix for that.

[Veykril]

Yes of course, I was solely thinking of assists, not diagnostic quickfixes. Having a diagnostic quickfix here certainly makes sense.

[flodiebold]

This is doable now that we have the type-mismatch diagnostic.
Quickfixes are defined here:
https://github.com/rust-analyzer/rust-analyzer/blob/9da9418661c2a357b291d6adf11ea296d9dd924a/crates/ide_diagnostics/src/handlers/type_mismatch.rs#L32-L44

[harpsword]

2022-04-28.20.57.18.mov

I found out that this feature already exists.

[flodiebold]

That's a quickfix coming from rustc, not rust-analyzer.

[Rustin170506]

@rustbot claim
I'll try to fix it.