Suggest dereferncing when possible in E0277, fix #87437

src/test/ui/traits/suggest-deferences/issue-39029.stderr

@@ -5,7 +5,7 @@ LL |     let _errors = TcpListener::bind(&bad);
    |                   ----------------- ^^^^
    |                   |                 |
    |                   |                 the trait `ToSocketAddrs` is not implemented for `NoToSocketAddrs`
-   |                   |                 help: consider adding dereference here: `&*bad`
+   |                   |                 help: consider dereferencing here: `&*bad`
    |                   required by a bound introduced by this call
    |
    = note: required because of the requirements on the impl of `ToSocketAddrs` for `&NoToSocketAddrs`

src/test/ui/traits/suggest-deferences/issue-62530.stderr

@@ -5,7 +5,7 @@ LL |     takes_type_parameter(&string);  // Error
    |     -------------------- ^^^^^^^
    |     |                    |
    |     |                    the trait `SomeTrait` is not implemented for `&String`
-   |     |                    help: consider adding dereference here: `&*string`
+   |     |                    help: consider dereferencing here: `&*string`
    |     required by a bound introduced by this call
    |
 note: required by a bound in `takes_type_parameter`

src/test/ui/traits/suggest-deferences/multiple-0.stderr

@@ -5,7 +5,7 @@ LL |     foo(&baz);
    |     --- ^^^^
    |     |   |
    |     |   the trait `Happy` is not implemented for `&Baz`
-   |     |   help: consider adding dereference here: `&***baz`
+   |     |   help: consider dereferencing here: `&***baz`
    |     required by a bound introduced by this call
    |
 note: required by a bound in `foo`

src/test/ui/traits/suggest-deferences/root-obligation.fixed

@@ -0,0 +1,14 @@
+// run-rustfix
+
+fn get_vowel_count(string: &str) -> usize {
+    string
+        .chars()
+        .filter(|c| "aeiou".contains(*c))
+        //~^ ERROR expected a `Fn<(char,)>` closure, found `char`
+        .count()
+}
+
+fn main() {
+    let _ = get_vowel_count("asdf");
+}
+

src/test/ui/traits/suggest-deferences/root-obligation.rs

@@ -0,0 +1,14 @@
+// run-rustfix
+
+fn get_vowel_count(string: &str) -> usize {
+    string
+        .chars()
+        .filter(|c| "aeiou".contains(c))
+        //~^ ERROR expected a `Fn<(char,)>` closure, found `char`
+        .count()
+}
+
+fn main() {
+    let _ = get_vowel_count("asdf");
+}
+

src/test/ui/traits/suggest-deferences/root-obligation.stderr

@@ -0,0 +1,24 @@
+error[E0277]: expected a `Fn<(char,)>` closure, found `char`
+  --> $DIR/root-obligation.rs:6:38
+   |
+LL |         .filter(|c| "aeiou".contains(c))
+   |                             -------- ^ expected an `Fn<(char,)>` closure, found `char`
+   |                             |
+   |                             required by a bound introduced by this call
+   |
+   = help: the trait `Fn<(char,)>` is not implemented for `char`
+   = note: required because of the requirements on the impl of `FnOnce<(char,)>` for `&char`
+   = note: required because of the requirements on the impl of `Pattern<'_>` for `&char`
+note: required by a bound in `core::str::<impl str>::contains`
+  --> $SRC_DIR/core/src/str/mod.rs:LL:COL
+   |
+LL |     pub fn contains<'a, P: Pattern<'a>>(&'a self, pat: P) -> bool {
+   |                            ^^^^^^^^^^^ required by this bound in `core::str::<impl str>::contains`
+help: consider dereferencing here
+   |
+LL |         .filter(|c| "aeiou".contains(*c))
+   |                                      +
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.