Tweak presentation on lifetime trait mismatch

Author: estebank

src/librustc/infer/error_reporting/note.rs

@@ -23,12 +23,10 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                 if let Some((expected, found)) = self.values_str(&trace.values) {
                     let expected = expected.content();
                     let found = found.content();
-                    // FIXME: do we want a "the" here?
-                    err.span_note(trace.cause.span,
-                                  &format!("...so that {} (expected {}, found {})",
-                                           trace.cause.as_requirement_str(),
-                                           expected,
-                                           found));
+                    err.note(&format!("...so that the {}:\nexpected {}\n   found {}",
+                                      trace.cause.as_requirement_str(),
+                                      expected,
+                                      found));
                 } else {
                     // FIXME: this really should be handled at some earlier stage. Our
                     // handling of region checking when type errors are present is

src/test/ui/in-band-lifetimes/mismatched_trait_impl.stderr

@@ -13,27 +13,19 @@ note: first, the lifetime cannot outlive the anonymous lifetime #2 defined on th
 20 | |         x
 21 | |     }
    | |_____^
-note: ...so that method type is compatible with trait (expected fn(&i32, &'a u32, &u32) -> &'a u32, found fn(&i32, &u32, &u32) -> &u32)
-  --> $DIR/mismatched_trait_impl.rs:19:5
-   |
-19 | /     fn foo(&self, x: &u32, y: &'a u32) -> &'a u32 { //~ ERROR cannot infer
-20 | |         x
-21 | |     }
-   | |_____^
+   = note: ...so that the method type is compatible with trait:
+           expected fn(&i32, &'a u32, &u32) -> &'a u32
+              found fn(&i32, &u32, &u32) -> &u32
 note: but, the lifetime must be valid for the lifetime 'a as defined on the method body at 19:5...
   --> $DIR/mismatched_trait_impl.rs:19:5
    |
 19 | /     fn foo(&self, x: &u32, y: &'a u32) -> &'a u32 { //~ ERROR cannot infer
 20 | |         x
 21 | |     }
    | |_____^
-note: ...so that method type is compatible with trait (expected fn(&i32, &'a u32, &u32) -> &'a u32, found fn(&i32, &u32, &u32) -> &u32)
-  --> $DIR/mismatched_trait_impl.rs:19:5
-   |
-19 | /     fn foo(&self, x: &u32, y: &'a u32) -> &'a u32 { //~ ERROR cannot infer
-20 | |         x
-21 | |     }
-   | |_____^
+   = note: ...so that the method type is compatible with trait:
+           expected fn(&i32, &'a u32, &u32) -> &'a u32
+              found fn(&i32, &u32, &u32) -> &u32
 
 error: aborting due to previous error