review comments

14 files changed, 53 insertions, 33 deletions

diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
index e134a6c17cc..d0243dad700 100644
--- a/src/librustc/infer/error_reporting/mod.rs
+++ b/src/librustc/infer/error_reporting/mod.rs
@@ -1339,16 +1339,16 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                             err.span_label(
                                 *sp,
                                 format!(
-                                    "{}this is {}the {} {}{}",
+                                    "{}the {} {}{}{}",
+                                    if count > 1 { "one of " } else { "" },
+                                    target,
+                                    key,
+                                    pluralize!(count),
                                     if sp.is_desugaring(DesugaringKind::Async) {
-                                        "in the desugared `async fn`, "
+                                        " in the `Output` of this `async fn`"
                                     } else {
                                         ""
                                     },
-                                    if count > 1 { "one of" } else { "" },
-                                    target,
-                                    key,
-                                    pluralize!(count),
                                 ),
                             );
                         }
@@ -1364,18 +1364,24 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                     ty::Opaque(..) => "opaque type",
                     _ => "",
                 };
-                match t.kind {
-                    ty::Closure(def_id, _) | ty::Opaque(def_id, _) => {
-                        let span = self.tcx.def_span(def_id);
-                        debug!("note_type_err visit_ty {:?}", span.macro_backtrace());
-                        if !self.ignore_span.overlaps(span)
-                            && !self.expected.values().any(|exp| exp.iter().any(|sp| *sp == span))
-                        {
-                            let entry = self.types.entry(kind).or_default();
-                            entry.insert(span);
-                        }
+                if let ty::Closure(def_id, _) | ty::Opaque(def_id, _) = t.kind {
+                    let span = self.tcx.def_span(def_id);
+                    // Avoid cluttering the output when the "found" and error span overlap:
+                    //
+                    // error[E0308]: mismatched types
+                    //   --> $DIR/issue-20862.rs:2:5
+                    //    |
+                    // LL |     |y| x + y
+                    //    |     ^^^^^^^^^
+                    //    |     |
+                    //    |     the found closure
+                    //    |     expected `()`, found closure
+                    //    |
+                    //    = note: expected unit type `()`
+                    //                 found closure `[closure@$DIR/issue-20862.rs:2:5: 2:14 x:_]`
+                    if !self.ignore_span.overlaps(span) {
+                        self.types.entry(kind).or_default().insert(span);
                     }
-                    _ => {}
                 }
                 t.super_visit_with(self)
             }
diff --git a/src/test/ui/async-await/dont-suggest-missing-await.stderr b/src/test/ui/async-await/dont-suggest-missing-await.stderr
index 5bf10e00892..5c9b1d2c4d7 100644
--- a/src/test/ui/async-await/dont-suggest-missing-await.stderr
+++ b/src/test/ui/async-await/dont-suggest-missing-await.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/dont-suggest-missing-await.rs:14:18
    |
 LL | async fn make_u32() -> u32 {
-   |                        --- in the desugared `async fn`, this is the found opaque type
+   |                        --- the found opaque type in the `Output` of this `async fn`
 ...
 LL |         take_u32(x)
    |                  ^ expected `u32`, found opaque type
diff --git a/src/test/ui/async-await/suggest-missing-await-closure.stderr b/src/test/ui/async-await/suggest-missing-await-closure.stderr
index 43366e6bbbf..5926c8351ff 100644
--- a/src/test/ui/async-await/suggest-missing-await-closure.stderr
+++ b/src/test/ui/async-await/suggest-missing-await-closure.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/suggest-missing-await-closure.rs:16:18
    |
 LL | async fn make_u32() -> u32 {
-   |                        --- in the desugared `async fn`, this is the found opaque type
+   |                        --- the found opaque type in the `Output` of this `async fn`
 ...
 LL |         take_u32(x)
    |                  ^
diff --git a/src/test/ui/async-await/suggest-missing-await.stderr b/src/test/ui/async-await/suggest-missing-await.stderr
index c7fcbdd8138..c0dc32b83fb 100644
--- a/src/test/ui/async-await/suggest-missing-await.stderr
+++ b/src/test/ui/async-await/suggest-missing-await.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/suggest-missing-await.rs:13:14
    |
 LL | async fn make_u32() -> u32 {
-   |                        --- in the desugared `async fn`, this is the found opaque type
+   |                        --- the found opaque type in the `Output` of this `async fn`
 ...
 LL |     take_u32(x)
    |              ^
@@ -16,6 +16,9 @@ LL |     take_u32(x)
 error[E0308]: mismatched types
   --> $DIR/suggest-missing-await.rs:23:5
    |
+LL | async fn dummy() {}
+   |                  - the found opaque type in the `Output` of this `async fn`
+...
 LL |     dummy()
    |     ^^^^^^^ expected `()`, found opaque type
    |
diff --git a/src/test/ui/closures/closure-reform-bad.stderr b/src/test/ui/closures/closure-reform-bad.stderr
index 16727b58e1f..3c4ae450764 100644
--- a/src/test/ui/closures/closure-reform-bad.stderr
+++ b/src/test/ui/closures/closure-reform-bad.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/closure-reform-bad.rs:11:15
    |
 LL |     let f = |s: &str| println!("{}{}", s, string);
-   |             ------------------------------------- this is the found closure
+   |             ------------------------------------- the found closure
 LL |     call_bare(f)
    |               ^ expected fn pointer, found closure
    |
diff --git a/src/test/ui/extern/extern-types-distinct-types.stderr b/src/test/ui/extern/extern-types-distinct-types.stderr
index 2e258d687d3..32b45ee10ad 100644
--- a/src/test/ui/extern/extern-types-distinct-types.stderr
+++ b/src/test/ui/extern/extern-types-distinct-types.stderr
@@ -1,6 +1,11 @@
 error[E0308]: mismatched types
   --> $DIR/extern-types-distinct-types.rs:9:5
    |
+LL |     type A;
+   |     ------- the found foreign type
+LL |     type B;
+   |     ------- the expected foreign type
+...
 LL |     r
    |     ^ expected extern type `B`, found extern type `A`
    |
diff --git a/src/test/ui/impl-trait/equality2.stderr b/src/test/ui/impl-trait/equality2.stderr
index 4e1880f31dc..b882514f616 100644
--- a/src/test/ui/impl-trait/equality2.stderr
+++ b/src/test/ui/impl-trait/equality2.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/equality2.rs:25:18
    |
 LL | fn hide<T: Foo>(x: T) -> impl Foo {
-   |                          -------- this is the found opaque type
+   |                          -------- the found opaque type
 ...
 LL |     let _: u32 = hide(0_u32);
    |            ---   ^^^^^^^^^^^ expected `u32`, found opaque type
@@ -16,7 +16,7 @@ error[E0308]: mismatched types
   --> $DIR/equality2.rs:31:18
    |
 LL | fn hide<T: Foo>(x: T) -> impl Foo {
-   |                          -------- this is the found opaque type
+   |                          -------- the found opaque type
 ...
 LL |     let _: i32 = Leak::leak(hide(0_i32));
    |            ---   ^^^^^^^^^^^^^^^^^^^^^^^ expected `i32`, found associated type
@@ -32,7 +32,10 @@ error[E0308]: mismatched types
   --> $DIR/equality2.rs:38:10
    |
 LL | fn hide<T: Foo>(x: T) -> impl Foo {
-   |                          -------- this is the expected opaque type
+   |                          --------
+   |                          |
+   |                          the expected opaque type
+   |                          the found opaque type
 ...
 LL |     x = (x.1,
    |          ^^^ expected `u32`, found `i32`
@@ -44,7 +47,10 @@ error[E0308]: mismatched types
   --> $DIR/equality2.rs:41:10
    |
 LL | fn hide<T: Foo>(x: T) -> impl Foo {
-   |                          -------- this is the expected opaque type
+   |                          --------
+   |                          |
+   |                          the expected opaque type
+   |                          the found opaque type
 ...
 LL |          x.0);
    |          ^^^ expected `i32`, found `u32`
diff --git a/src/test/ui/issues/issue-24036.stderr b/src/test/ui/issues/issue-24036.stderr
index 670bf57067b..036c05fc848 100644
--- a/src/test/ui/issues/issue-24036.stderr
+++ b/src/test/ui/issues/issue-24036.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/issue-24036.rs:3:9
    |
 LL |     let mut x = |c| c + 1;
-   |                 --------- this is the expected closure
+   |                 --------- the expected closure
 LL |     x = |c| c + 1;
    |         ^^^^^^^^^ expected closure, found a different closure
    |
diff --git a/src/test/ui/suggestions/fn-or-tuple-struct-without-args.stderr b/src/test/ui/suggestions/fn-or-tuple-struct-without-args.stderr
index 5b18c239b6e..232e54b5d37 100644
--- a/src/test/ui/suggestions/fn-or-tuple-struct-without-args.stderr
+++ b/src/test/ui/suggestions/fn-or-tuple-struct-without-args.stderr
@@ -236,7 +236,7 @@ error[E0308]: mismatched types
   --> $DIR/fn-or-tuple-struct-without-args.rs:46:20
    |
 LL |     let closure = || 42;
-   |                   ----- this is the found closure
+   |                   ----- the found closure
 LL |     let _: usize = closure;
    |            -----   ^^^^^^^
    |            |       |
diff --git a/src/test/ui/suggestions/opaque-type-error.stderr b/src/test/ui/suggestions/opaque-type-error.stderr
index 3a7ea2bcdd2..167d61bdf7c 100644
--- a/src/test/ui/suggestions/opaque-type-error.stderr
+++ b/src/test/ui/suggestions/opaque-type-error.stderr
@@ -2,7 +2,7 @@ error[E0308]: `if` and `else` have incompatible types
   --> $DIR/opaque-type-error.rs:20:9
    |
 LL |   fn thing_two() -> impl Future<Output = Result<(), ()>> {
-   |                     ------------------------------------ this is the found opaque type
+   |                     ------------------------------------ the found opaque type
 ...
 LL | /     if true {
 LL | |         thing_one()
diff --git a/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.nll.stderr b/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.nll.stderr
index 182a3c7e81e..9549074d4bf 100644
--- a/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.nll.stderr
+++ b/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.nll.stderr
@@ -13,7 +13,7 @@ LL |     let z: i32 = x;
    |            expected due to this
 ...
 LL | type WrongGeneric<T> = impl 'static;
-   | ------------------------------------ this is the found opaque type
+   | ------------------------------------ the found opaque type
    |
    = note:     expected type `i32`
            found opaque type `WrongGeneric::<&{integer}>`
diff --git a/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.stderr b/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.stderr
index b061ec3fff8..5a7f9d74eba 100644
--- a/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.stderr
+++ b/src/test/ui/type-alias-impl-trait/generic_type_does_not_live_long_enough.stderr
@@ -13,7 +13,7 @@ LL |     let z: i32 = x;
    |            expected due to this
 ...
 LL | type WrongGeneric<T> = impl 'static;
-   | ------------------------------------ this is the found opaque type
+   | ------------------------------------ the found opaque type
    |
    = note:     expected type `i32`
            found opaque type `WrongGeneric::<&{integer}>`
diff --git a/src/test/ui/type-alias-impl-trait/never_reveal_concrete_type.stderr b/src/test/ui/type-alias-impl-trait/never_reveal_concrete_type.stderr
index 415ac4bbdcb..70c99c944d6 100644
--- a/src/test/ui/type-alias-impl-trait/never_reveal_concrete_type.stderr
+++ b/src/test/ui/type-alias-impl-trait/never_reveal_concrete_type.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/never_reveal_concrete_type.rs:13:27
    |
 LL | type NoReveal = impl std::fmt::Debug;
-   | ------------------------------------- this is the found opaque type
+   | ------------------------------------- the found opaque type
 ...
 LL |     let _: &'static str = x;
    |            ------------   ^ expected `&str`, found opaque type
diff --git a/src/test/ui/type-alias-impl-trait/no_revealing_outside_defining_module.stderr b/src/test/ui/type-alias-impl-trait/no_revealing_outside_defining_module.stderr
index 3e67dc90dcb..375c0bc7fe2 100644
--- a/src/test/ui/type-alias-impl-trait/no_revealing_outside_defining_module.stderr
+++ b/src/test/ui/type-alias-impl-trait/no_revealing_outside_defining_module.stderr
@@ -2,7 +2,7 @@ error[E0308]: mismatched types
   --> $DIR/no_revealing_outside_defining_module.rs:15:19
    |
 LL |     pub type Boo = impl ::std::fmt::Debug;
-   |     -------------------------------------- this is the found opaque type
+   |     -------------------------------------- the found opaque type
 ...
 LL |     let _: &str = bomp();
    |            ----   ^^^^^^ expected `&str`, found opaque type
@@ -16,7 +16,7 @@ error[E0308]: mismatched types
   --> $DIR/no_revealing_outside_defining_module.rs:19:5
    |
 LL |     pub type Boo = impl ::std::fmt::Debug;
-   |     -------------------------------------- this is the expected opaque type
+   |     -------------------------------------- the expected opaque type
 ...
 LL | fn bomp() -> boo::Boo {
    |              -------- expected `Boo` because of return type