"remove this" suggestions should take spacing into account

[zackmdavis]

[sfackler]

I think this might make more sense over on https://github.com/rust-lang-nursery/rls-vscode or https://github.com/rust-lang-nursery/rls

[zackmdavis]

RLS is just plumbing through the suggestions we (the compiler) give it; any improvements would need to happen here.

[sfackler]

But it seems right at the diagnostic level that the mut span only covers that token, and not whitespace - it's the job of the library performing automated source transforms to do any stylistic cleanup.

[zackmdavis]

That's a good point; I guess the deeper issue is that the compiler's "replace this span with this text" concept of a "suggestion" is limited? (On the other hand, I'm not eager to try to teach external tools about the AST ...)

[oli-obk]

We do suggest inserting spaces, I don't see why we can't suggest removing them either.

Especially in the mut case, we always know that it's preceded and followed by a space

[estebank]

As a stop-gap measure we can use span_through_char instead of span_until_char in any suggestion that we know ends with a space separator to do the right thing on correctly formatted code, but the suggestion engine will need a revamp to be able to account for this kind of things on a more consistent and less ad-hoc manner so that it can handle, for example, multiple spaces between mut and the identifier.