Rust Analyzer does not work in bzlmod

[purkhusid]

There seems to be a couple of issues with the Rust Analyzer project generator.

1. The workaround here:

   rules_rust/tools/rust_analyzer/main.rs

   Line 34 in 4136f6f

   let rules_rust_name = env!("ASPECT_REPOSITORY");

   does not work with bzlmod and AFAIK is no longer needed for bzlmod. If I just set the name to rules_rust it works and gets further into generating the project.
2. The generator uses the runfiles library and that library does not support bzlmod:

   rules_rust/tools/rust_analyzer/lib.rs

   Line 67 in 4136f6f

   let r = Runfiles::create()?;

Updating the Runfiles library to support is a bit bigger task since but there is prior art in e.g. rules_go/python/java/dotnet

[csmulhern]

The runfiles library needs to be updated to read _repo_mapping from the runfiles base directory to map repo names to the canonical name on disk. It's a simple file format (1 item per line, each line with 3 comma separated values, with no ambiguity as the values cannot contain commas).

More details are available here: https://github.com/bazelbuild/proposals/blob/main/designs/2022-07-21-locating-runfiles-with-bzlmod.md.

[cameron-martin]

After #2450, gen_rust_project works for me. Is there another issue here?

[csmulhern]

After #2450, gen_rust_project works for me. Is there another issue here?

I believe #2440 is also necessary.