From ee065595767a7e024f1933e175dd52936f0f1b10 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Esteban=20K=C3=BCber?= <esteban@kuber.com.ar>
Date: Fri, 26 Jan 2018 16:38:07 -0800
Subject: [PATCH] Tweak presentation on lifetime trait mismatch

---
 src/librustc/infer/error_reporting/note.rs    | 10 ++++------
 .../mismatched_trait_impl.stderr              | 20 ++++++-------------
 2 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/src/librustc/infer/error_reporting/note.rs b/src/librustc/infer/error_reporting/note.rs
index e46613b3e4d..02ec9fe74c1 100644
--- a/src/librustc/infer/error_reporting/note.rs
+++ b/src/librustc/infer/error_reporting/note.rs
@@ -23,12 +23,10 @@ pub(super) fn note_region_origin(&self,
                 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
diff --git a/src/test/ui/in-band-lifetimes/mismatched_trait_impl.stderr b/src/test/ui/in-band-lifetimes/mismatched_trait_impl.stderr
index e96f7181a6d..e559405dbd8 100644
--- a/src/test/ui/in-band-lifetimes/mismatched_trait_impl.stderr
+++ b/src/test/ui/in-band-lifetimes/mismatched_trait_impl.stderr
@@ -13,13 +13,9 @@ 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
    |
@@ -27,13 +23,9 @@ note: but, the lifetime must be valid for the lifetime 'a as defined on the meth
 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