Spans for view items are fairly inaccurate

[brson]

In this test case:

// xfail-stage0                                                                                                                                                               
// error-pattern:'swap' is glob-imported from multiple different modules                                                                                                      
// issue #482                                                                                                                                                                 

use std;
// expecting swap to be defined in vec                                                                                                                                        
import std::vec::*;
import alternate_supplier::*;

mod alternate_supplier {
  fn swap() {}
}

fn main() { swap() }

I get this error:

../src/test/compile-fail/cross-crate-glob-collision.rs:7:10:8:6: note: 'swap' is imported here
../src/test/compile-fail/cross-crate-glob-collision.rs:8:25:10:3: note: 'swap' is imported here
../src/test/compile-fail/cross-crate-glob-collision.rs:14:12:14:17: error: 'swap' is glob-imported from multiple different modules.

The spans for the two imports, while in the general ballpark, are not very exact. I suspect that all types of view items have similar problems with their spans.

[catamorphism]

I fixed this one, but I'm not sure how to add a regression test when the right error message involves having a certain span. If anyone has suggestions, let me know.

[brson]

Maybe you could formulate a test where the span is minimally likely to change. Or you could put comments in the test indicated that you're specifically testing for the correct span, so whoever messes with it feels more inclined to update the test. Or you could just skip the test; sometimes that's easiest.

[catamorphism]

Yeah, I'm skipping it for now. But the code example is right here in case anyone wants to add it as a test ;-)