`use` suggestions corrupted w/ nearby code when inside items

[durka]

This is... bizarre.

STR

fn main() {
    type Dict<K, V> = HashMap<K, V>;
}

Expected

help: possible candidates are found in other modules, you can import them into scope
  | use std::collections::HashMap;
  | use std::collections::hash_map::HashMap;

Actual

help: possible candidates are found in other modules, you can import them into scope
  | fn main() use std::collections::HashMap;
  | fn main() use std::collections::hash_map::HashMap;

The issue seems to arise from the erroneous code being inside another block. I originally encountered this with code generated by `lazy_static!`.

[oli-obk]

Duplicate of #42835

[durka]

Is it a duplicate? Issue here is the suggestion text is invalid.

[Mark-Simulacrum]

I don't think this is a duplicate of that issue; the diagnostic here needs to be enhanced to not be mangled with surrounding context, which isn't related to updating the message to note where to add the import.

cc @estebank, I seem to recall you doing something with this diagnostic recently that was potentially relevant, but I could be wrong.

[oli-obk]

It is 100% related. I changed the suggestion placement and screwed up. The suggestions are placed at the beginning of the current module/function, but that just doesn't work in the presence of desugarings. So the suggestion you see doesn't mangle with surrounding context, it is actually placed there!

[oli-obk]

Anyway, the original issue that's more related is #42548, but they are all caused by the same underlying problem

[estebank]

@Mark-Simulacrum I think the closest PRs I've worked on recently have been #42383 and #42904, but I doubt they affected the current issue given that I'm seeing the problem in the stable compiler as well. #42835 might be related (which sparked my urgency on completing #42904, so that it'd be more obvious when it happens).