Add raw identifier in a typo suggestion

[linyihai]

Fixes #68962

[rustbot]

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[fmease]

Thanks for working on this. I have a couple of suggestions.

[fmease]

Actually, nvm. I don't know what I wrote there 🤦 It was early.

[fmease]

Looks good, thanks! However, could you check if the other occurrences of suggestion.candidate in this crate should be updated to use to_ident_string(), too? And add regression tests if applicable?

[linyihai]

Looks good, thanks! However, could you check if the other occurrences of suggestion.candidate in this crate should be updated to use to_ident_string(), too? And add regression tests if applicable?

I can't find anything that needs to be fixed, and the other two places that show error messages don't seem to need fixing.

https://github.com/rust-lang/rust/blob/master/compiler/rustc_resolve/src/diagnostics.rs#L1597-L1606
This is already covered by my test case：

LL | fn r#fn() {}
   | --------- similarly named function `r#fn` defined here

(btw, I didn't find the way they called to_ident_string but they did show the raw identifier)

https://github.com/rust-lang/rust/blob/master/compiler/rustc_resolve/src/diagnostics.rs#L1609-L1618
This is about correcting variables that start with underscores. Variables that start with underscores do not require a raw identifier. And the to_ident_string will only append raw identifier for keyword and reserverd word.

[fmease]

@bors r+ rollup

[bors]

📌 Commit 589c2fe has been approved by fmease

It is now in the queue for this repository.

[fmease]

(btw, I didn't find the way they called to_ident_string but they did show the raw identifier)

I had to look myself because I didn't know this either until a moment ago:

The reason why the Symbol gets properly escaped is because the Symbol suggestion.candidate gets passed to a “diagnostic struct” (e.g., errors::DefinedHere::SimilarlyNamed), i.e., a struct that derives Diagnostic which allows the struct to get turned into a Diag which gets formatted in the end and said derive macro calls IntoDiagArg::into_diag_arg for each normal field. Finally, the IntoDiagArg impl for Symbol calls to_ident_string under the hood: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_errors/trait.IntoDiagArg.html#impl-IntoDiagArg-for-Symbol