--edition should tell what the default edition is

[matthiaskrgr]

rustc --edition: error: Argument to option 'edition' missing

rustc --edition=help: error: argument for `--edition` must be one of: 2015|2018|2021|2024. (instead was `help`)

rustc --help

        --edition 2015|2018|2021|2024
                        Specify which edition of the compiler to use when
                        compiling code.

The default is not mentioned anywhere. I assume it is 2015?

[fmease]

The default is indeed 2015. It should probably not only mention the default (2015) but also the latest stable edition (2021).

[jyn514]

Mentoring instructions: modify

rust/compiler/rustc_session/src/config.rs

Line 1345 in 65a6e22

"Specify which edition of the compiler to use when compiling code.",

to include DEFAULT_EDITION and LATEST_STABLE_EDITION somewhere.

[sigaloid]

@rustbot claim

[sigaloid]

What is the best way to insert the values for DEFAULT_EDITION and LATEST_STABLE_EDITION into the string? opt::opt_s only takes &'static str's and I don't see an easy way to create one while inlining those variables. Neither concat! nor format! works - former only accepts literals rather than the static variable, and the latter would create a &str, but then drop a temporary variable.

I don't believe it would be a good idea to simply write the value of these variables into the string, so I'm wondering what other options I have. However, if that's the way forward, I can do so.

[jyn514]

opt::opt_s only takes &'static str's

Where does that requirement come from? Seems fine to loosen it.

[jyn514]

ah I see, the string ends up stored in RustcOptGroup.

Honestly, given that this is only used once and the string is tiny, using Box::leak seems fine.