bug#52107: rust-analyzer shipped broken without rust-src

[Nicholas von Klitzing]

Hello Guix,

The rust-analyzer package depends on having a local copy of the rust compiler 
(rustc) source code available in order for it to function.
Currently, neither the rust-analyzer nor the rust package include rust-src, 
which means rust-analyzer is broken by default.

On non-guix systems the rustc source code is usually installed using `rustup 
component add rust-src`.

The workaround I'm currently using is to run `guix build --source rust` 
followed by adding `export 
RUST_SRC_PATH=/home/$user/rustc-$version-src/library` to ~/.profile following 
every rust upgrade.

rust-analyzer is a crucial tool for many rust developers, so this experience 
should definitely be improved or at least documented.

I am not very familiar with guix and therefore cannot recommend a good way to 
solve this.

What would possible solutions to this issue be?

Kind regards,
Nicholas