bug#70794: 30.0.50; Add Rust compilation regex

[Eli Zaretskii]

> Date: Wed, 15 May 2024 15:10:02 +0200
> From: Ergus <spacibba@aol.com>
> Cc: 70794@debbugs.gnu.org
> 
> On Sat, May 11, 2024 at 11:51:04AM GMT, Eli Zaretskii wrote:
> >
> >Thanks, but could you please also send the examples of Rust messages,
> >because we need to add them to etc/compilation.txt?
> 
> Hi Eli:
> 
> Typically they look like this:
> 
> ```
> error[E0425]: cannot find function `ruun` in module `broot::cli`
>    --> src/main.rs:6:23
>     |
> 6  |     match broot::cli::ruun() {
>     |                       ^^^^ help: a function with a similar name exists: 
> `run`
>     |
>    ::: /tmp/broot/src/cli/mod.rs:49:1
>     |
> 49 | pub fn run() -> Result<Option<Launchable>, ProgramError> {
>     | -------------------------------------------------------- similarly
>     named function `run` defined here
> ```
> 
> or
> 
> ```
> error: cannot find macro `deebug` in this scope
>     --> src/main.rs:5:5
>      |
> 5   |     deebug!("env::args(): {:#?}", 
> std::env::args().collect::<Vec<String>>());
>      |     ^^^^^^ help: a macro with a similar name exists: `debug`
>      |
>     ::: 
> /home/ergo/.cargo/registry/src/index.crates.io-6f17d22bba15001f/log-0.4.21/src/macros.rs:154:1
>      |
> 154 | macro_rules! debug {
>      | ------------------ similarly named macro `debug` defined here
> ```
> 
> ```
> warning: crate-level attribute should be an inner attribute: add an 
> exclamation mark: `#![foo]`
>   --> src/main.rs:3:1
>    |
> 3 | #[feature(proc_macro_diagnostic)]
>    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>    |
>    = note: `#[warn(unused_attributes)]` on by default
> ```
> 
> Two details:
> 
> 1. As you can see the [] is optional
> 2. The path is always relative to project's root

Thanks, installed on master, and closing the bug.