Some errors cause ridiculously long highlighted spans in the IDE

[johnw42]

Situation:

I'm using duplicate to test some hairy code involving From/TryFrom trait implementations. When I run into an error, I frequently get an error highlight in the IDE that covers everything from the substitution table up to the point where the actual error occurred. It's very distracting.

Reproduction:

I'm about to create a PR with a unit test that demonstrates the problem, plus changes to fix it.

Expected Behavior:

Ideally I'd like to see an error on the line in the substitution table that triggered the problem, plus a separate error where the problem was detected, but the second error is more important.

Affected Versions:

Found in 2.0.1

[Emoun]

Thank you for identifying this issue and suggesting af fix.

For completeness, this is a minimal repreducable example:

#[duplicate::duplicate_item(
  SomeType;
  [i8];
)]
fn some_fn() {
  SomeType::MIN
}

The error span covers from line 3 ("i8]..") to line 6 ("..::MIN"):

We can discuss the fix in the PR.