* On suggestions that include deletions, use a diff inspired output format
* When suggesting addition, use `+` as underline
* Color highlight modified span
Address the diagnostics part of #70844.
```
error[E0597]: `counter` does not live long enough
--> $DIR/issue-54556-niconii.rs:22:20
|
LL | if let Ok(_) = counter.lock() { }
| ^^^^^^^-------
| |
| borrowed value does not live long enough
| a temporary with access to the borrow is created here ...
...
LL | }
| -
| |
| `counter` dropped here while still borrowed
| ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `std::result::Result<MutexGuard<'_>, ()>`
|
help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
|
LL | if let Ok(_) = counter.lock() { };
| ^
```
(I opted to rely on compare-mode=nll rather than opt into
`#![feature(nll)]`, mostly to make it easy to observe the interesting
differences between the AST-borrwock diagnostic and the NLL one.)
