Use more precise span for E0282 in cast expressions

[FabianWolff]

This pull request fixes #85586. The example code given there:

fn main() {
    let a = [1, 2, 3].iter().sum();
    let b = (a + 1) as usize;
}

currently produces

error[E0282]: type annotations needed
 --> issue-85586.rs:3:13
  |
3 |     let b = (a + 1) as usize;
  |             ^^^^^^^^^^^^^^^^ cannot infer type
  |
  = note: type must be known at this point

error: aborting due to previous error

even though the type of the entire cast expression quite clearly should be usize. The error is in the cast's left-hand side, which is made explicit by the changes in this PR:

error[E0282]: type annotations needed
 --> issue-85586.rs:3:13
  |
3 |     let b = (a + 1) as usize;
  |             ^^^^^^^ cannot infer type
  |
  = note: type must be known at this point

error: aborting due to previous error

[rust-highfive]

r? @matthewjasper

(rust-highfive has picked a reviewer for you, use r? to override)

[Aaron1011]

You should be able to remove the new Span parameter, and just use self.expr.span inside of CastCheck

[FabianWolff]

You are right; it seems that I got confused with e.span and expr.span. Thanks for pointing this out, I have fixed it now.

[camelid]

r? @davidtwco

[davidtwco]

@bors r+

[bors]

📌 Commit 74d1bd2 has been approved by davidtwco

[bors]

⌛ Testing commit 74d1bd2 with merge f3f8e75...

[bors]

☀️ Test successful - checks-actions
Approved by: davidtwco
Pushing f3f8e75 to master...