bug#70794: 30.0.50; Add Rust compilation regex

[Ergus]

On Tue, Jun 04, 2024 at 06:06:16PM GMT, Stefan Kangas wrote:
> Mattias Engdeg�rd <mattias.engdegard@gmail.com> writes:
>
> > Even with the obvious fixes, the pattern would still be incomplete and not even 
> > match parts of the examples given. I'm happy to work with Rust users or package 
> > maintainers to work out details but I don't want to do a rush job now, nor 
> > delay Emacs 30.
>
> BTW, shouldn't stuff like this be happier if it was in something like
> `rust-mode`?
>
> It seems like the maintainers of major modes are in a better position to
> add and maintain support for the compilers and tools of their respective
> languages than we are.

Hi Stefan:

Actually I opened the initial issue because there is a rust-ts-mode now
in vanilla and in my opinion it is a bit incoherent to have a native
mode to support rust, but don't support compiling rust.

Specially considering that adding such support seems extremely simple,
it only requires to improve the regex to be a bit more strict. And the
one I provided is buggy mainly due to the "too free" wildcard I used to
match anything including the new line...

Just improving the [^\0]+?--> in the regex; I thing everything will work
properly.