Rollup merge of #37658 - GuillaumeGomez:ref_suggestion, r=nikomatsakis,eddyb

Ref suggestion

src/test/ui/span/coerce-suggestions.rs

@@ -32,7 +32,6 @@ fn main() {
     //~| NOTE types differ in mutability
     //~| NOTE expected type `&mut std::string::String`
     //~| NOTE found type `&std::string::String`
-    //~| HELP try with `&mut y`
     test2(&y);
     //~^ ERROR E0308
     //~| NOTE types differ in mutability

src/test/ui/span/coerce-suggestions.stderr

@@ -18,11 +18,7 @@ error[E0308]: mismatched types
    |
    = note: expected type `&str`
               found type `std::string::String`
-   = help: here are some functions which might fulfill your needs:
-           - .as_str()
-           - .trim()
-           - .trim_left()
-           - .trim_right()
+   = help: try with `&String::new()`
 
 error[E0308]: mismatched types
   --> $DIR/coerce-suggestions.rs:30:10
@@ -34,18 +30,18 @@ error[E0308]: mismatched types
               found type `&std::string::String`
 
 error[E0308]: mismatched types
-  --> $DIR/coerce-suggestions.rs:36:11
+  --> $DIR/coerce-suggestions.rs:35:11
    |
-36 |     test2(&y);
+35 |     test2(&y);
    |           ^^ types differ in mutability
    |
    = note: expected type `&mut i32`
               found type `&std::string::String`
 
 error[E0308]: mismatched types
-  --> $DIR/coerce-suggestions.rs:42:9
+  --> $DIR/coerce-suggestions.rs:41:9
    |
-42 |     f = box f;
+41 |     f = box f;
    |         ^^^^^ cyclic type of infinite size
    |
    = note: expected type `_`