Use multispan suggestions more often

* Use more accurate span for `async move` suggestion
* Use more accurate span for deref suggestion
* Use `multipart_suggestion` more often

2 files changed, 41 insertions, 33 deletions

diff --git a/src/test/ui/impl-trait/does-not-live-long-enough.stderr b/src/test/ui/impl-trait/does-not-live-long-enough.stderr
index 468c2f36629..73fd5e8ded3 100644
--- a/src/test/ui/impl-trait/does-not-live-long-enough.stderr
+++ b/src/test/ui/impl-trait/does-not-live-long-enough.stderr
@@ -14,7 +14,7 @@ LL |     fn started_with<'a>(&'a self, prefix: &'a str) -> impl Iterator<Item=&'
 help: to force the closure to take ownership of `prefix` (and any other referenced variables), use the `move` keyword
    |
 LL |         self.data.iter().filter(move |s| s.starts_with(prefix)).map(|s| s.as_ref())
-   |                                 ^^^^^^^^
+   |                                 ^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr b/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr
index 00145d10ed7..0ecec5eea36 100644
--- a/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr
+++ b/src/test/ui/impl-trait/dyn-trait-return-should-be-impl-trait.stderr
@@ -140,14 +140,15 @@ LL | fn bam() -> Box<dyn Trait> {
    |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
 LL |     if true {
 LL |         return Struct;
-   |                ^^^^^^
-   |                |
-   |                expected struct `Box`, found struct `Struct`
-   |                help: store this in the heap by calling `Box::new`: `Box::new(Struct)`
+   |                ^^^^^^ expected struct `Box`, found struct `Struct`
    |
    = note: expected struct `Box<(dyn Trait + 'static)>`
               found struct `Struct`
    = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
+help: store this in the heap by calling `Box::new`
+   |
+LL |         return Box::new(Struct);
+   |                ^^^^^^^^^      ^
 
 error[E0308]: mismatched types
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:36:5
@@ -156,14 +157,15 @@ LL | fn bam() -> Box<dyn Trait> {
    |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
 ...
 LL |     42
-   |     ^^
-   |     |
-   |     expected struct `Box`, found integer
-   |     help: store this in the heap by calling `Box::new`: `Box::new(42)`
+   |     ^^ expected struct `Box`, found integer
    |
    = note: expected struct `Box<(dyn Trait + 'static)>`
                 found type `{integer}`
    = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
+help: store this in the heap by calling `Box::new`
+   |
+LL |     Box::new(42)
+   |     ^^^^^^^^^  ^
 
 error[E0308]: mismatched types
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:40:16
@@ -172,14 +174,15 @@ LL | fn baq() -> Box<dyn Trait> {
    |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
 LL |     if true {
 LL |         return 0;
-   |                ^
-   |                |
-   |                expected struct `Box`, found integer
-   |                help: store this in the heap by calling `Box::new`: `Box::new(0)`
+   |                ^ expected struct `Box`, found integer
    |
    = note: expected struct `Box<(dyn Trait + 'static)>`
                 found type `{integer}`
    = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
+help: store this in the heap by calling `Box::new`
+   |
+LL |         return Box::new(0);
+   |                ^^^^^^^^^ ^
 
 error[E0308]: mismatched types
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:42:5
@@ -188,14 +191,15 @@ LL | fn baq() -> Box<dyn Trait> {
    |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
 ...
 LL |     42
-   |     ^^
-   |     |
-   |     expected struct `Box`, found integer
-   |     help: store this in the heap by calling `Box::new`: `Box::new(42)`
+   |     ^^ expected struct `Box`, found integer
    |
    = note: expected struct `Box<(dyn Trait + 'static)>`
                 found type `{integer}`
    = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
+help: store this in the heap by calling `Box::new`
+   |
+LL |     Box::new(42)
+   |     ^^^^^^^^^  ^
 
 error[E0308]: mismatched types
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:46:9
@@ -204,14 +208,15 @@ LL | fn baz() -> Box<dyn Trait> {
    |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
 LL |     if true {
 LL |         Struct
-   |         ^^^^^^
-   |         |
-   |         expected struct `Box`, found struct `Struct`
-   |         help: store this in the heap by calling `Box::new`: `Box::new(Struct)`
+   |         ^^^^^^ expected struct `Box`, found struct `Struct`
    |
    = note: expected struct `Box<(dyn Trait + 'static)>`
               found struct `Struct`
    = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
+help: store this in the heap by calling `Box::new`
+   |
+LL |         Box::new(Struct)
+   |         ^^^^^^^^^      ^
 
 error[E0308]: mismatched types
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:48:9
@@ -220,14 +225,15 @@ LL | fn baz() -> Box<dyn Trait> {
    |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
 ...
 LL |         42
-   |         ^^
-   |         |
-   |         expected struct `Box`, found integer
-   |         help: store this in the heap by calling `Box::new`: `Box::new(42)`
+   |         ^^ expected struct `Box`, found integer
    |
    = note: expected struct `Box<(dyn Trait + 'static)>`
                 found type `{integer}`
    = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
+help: store this in the heap by calling `Box::new`
+   |
+LL |         Box::new(42)
+   |         ^^^^^^^^^  ^
 
 error[E0308]: mismatched types
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:53:9
@@ -236,14 +242,15 @@ LL | fn baw() -> Box<dyn Trait> {
    |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
 LL |     if true {
 LL |         0
-   |         ^
-   |         |
-   |         expected struct `Box`, found integer
-   |         help: store this in the heap by calling `Box::new`: `Box::new(0)`
+   |         ^ expected struct `Box`, found integer
    |
    = note: expected struct `Box<(dyn Trait + 'static)>`
                 found type `{integer}`
    = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
+help: store this in the heap by calling `Box::new`
+   |
+LL |         Box::new(0)
+   |         ^^^^^^^^^ ^
 
 error[E0308]: mismatched types
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:55:9
@@ -252,14 +259,15 @@ LL | fn baw() -> Box<dyn Trait> {
    |             -------------- expected `Box<(dyn Trait + 'static)>` because of return type
 ...
 LL |         42
-   |         ^^
-   |         |
-   |         expected struct `Box`, found integer
-   |         help: store this in the heap by calling `Box::new`: `Box::new(42)`
+   |         ^^ expected struct `Box`, found integer
    |
    = note: expected struct `Box<(dyn Trait + 'static)>`
                 found type `{integer}`
    = note: for more on the distinction between the stack and the heap, read https://doc.rust-lang.org/book/ch15-01-box.html, https://doc.rust-lang.org/rust-by-example/std/box.html, and https://doc.rust-lang.org/std/boxed/index.html
+help: store this in the heap by calling `Box::new`
+   |
+LL |         Box::new(42)
+   |         ^^^^^^^^^  ^
 
 error[E0746]: return type cannot have an unboxed trait object
   --> $DIR/dyn-trait-return-should-be-impl-trait.rs:60:13