bug#70794: 30.0.50; Add Rust compilation regex

[Ergus via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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.