added missing implementation hint

src/test/ui/binary-op-on-double-ref.stderr

@@ -4,8 +4,7 @@ error[E0369]: binary operation `%` cannot be applied to type `&&{integer}`
 LL |         x % 2 == 0
    |         ^^^^^
    |
-   = note: this is a reference to a type that `%` can be applied to; you need to dereference this variable once for this operation to work
-   = note: an implementation of `std::ops::Rem` might be missing for `&&{integer}`
+   = help: `%` can be used on '{integer}', you can dereference `x`: `*x`
 
 error: aborting due to previous error
 

src/test/ui/codemap_tests/issue-28308.stderr

@@ -2,7 +2,7 @@ error[E0600]: cannot apply unary operator `!` to type `&'static str`
   --> $DIR/issue-28308.rs:12:5
    |
 LL |     assert!("foo");
-   |     ^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^ cannot apply unary operator `!`
 
 error: aborting due to previous error
 

src/test/ui/error-codes/E0067.stderr

@@ -5,6 +5,8 @@ LL |     LinkedList::new() += 1; //~ ERROR E0368
    |     -----------------^^^^^
    |     |
    |     cannot use `+=` on type `std::collections::LinkedList<_>`
+   |
+   = note: an implementation of `std::ops::AddAssign` might be missing for `std::collections::LinkedList<_>`
 
 error[E0067]: invalid left-hand side expression
   --> $DIR/E0067.rs:14:5

src/test/ui/error-codes/E0600.stderr

@@ -2,7 +2,7 @@ error[E0600]: cannot apply unary operator `!` to type `&'static str`
   --> $DIR/E0600.rs:12:5
    |
 LL |     !"a"; //~ ERROR E0600
-   |     ^^^^
+   |     ^^^^ cannot apply unary operator `!`
 
 error: aborting due to previous error
 

src/test/ui/error-festival.stderr

@@ -17,6 +17,8 @@ LL |     x += 2;
    |     -^^^^^
    |     |
    |     cannot use `+=` on type `&str`
+   |
+   = note: an implementation of `std::ops::AddAssign` might be missing for `&str`
 
 error[E0599]: no method named `z` found for type `&str` in the current scope
   --> $DIR/error-festival.rs:26:7
@@ -28,7 +30,9 @@ error[E0600]: cannot apply unary operator `!` to type `Question`
   --> $DIR/error-festival.rs:29:5
    |
 LL |     !Question::Yes;
-   |     ^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^ cannot apply unary operator `!`
+   |
+   = note: an implementation of `std::ops::Not` might be missing for `Question`
 
 error[E0604]: only `u8` can be cast as `char`, not `u32`
   --> $DIR/error-festival.rs:35:5

src/test/ui/feature-gate-negate-unsigned.stderr

@@ -2,13 +2,17 @@ error[E0600]: cannot apply unary operator `-` to type `usize`
   --> $DIR/feature-gate-negate-unsigned.rs:20:23
    |
 LL |     let _max: usize = -1;
-   |                       ^^
+   |                       ^^ cannot apply unary operator `-`
+   |
+   = note: unsigned values cannot be negated
 
 error[E0600]: cannot apply unary operator `-` to type `u8`
   --> $DIR/feature-gate-negate-unsigned.rs:24:14
    |
 LL |     let _y = -x;
-   |              ^^
+   |              ^^ cannot apply unary operator `-`
+   |
+   = note: unsigned values cannot be negated
 
 error: aborting due to 2 previous errors
 

src/test/ui/issue-5239-1.stderr

@@ -5,6 +5,8 @@ LL |     let x = |ref x: isize| { x += 1; };
    |                              -^^^^^
    |                              |
    |                              cannot use `+=` on type `&isize`
+   |
+   = help: `+=` can be used on 'isize', you can dereference `x`: `*x`
 
 error: aborting due to previous error
 

src/test/ui/reachable/expr_unary.stderr

@@ -2,7 +2,7 @@ error[E0600]: cannot apply unary operator `!` to type `!`
   --> $DIR/expr_unary.rs:17:16
    |
 LL |     let x: ! = ! { return; }; //~ ERROR unreachable
-   |                ^^^^^^^^^^^^^
+   |                ^^^^^^^^^^^^^ cannot apply unary operator `!`
 
 error: unreachable expression
   --> $DIR/expr_unary.rs:17:16

src/test/ui/type-check/missing_trait_impl.rs

@@ -14,3 +14,7 @@ fn main() {
 fn foo<T>(x: T, y: T) {
     let z = x + y; //~ ERROR binary operation `+` cannot be applied to type `T`
 }
+
+fn bar<T>(x: T) {
+    x += x; //~ ERROR binary assignment operation `+=` cannot be applied to type `T`
+}

src/test/ui/type-check/missing_trait_impl.stderr

@@ -6,6 +6,17 @@ LL |     let z = x + y; //~ ERROR binary operation `+` cannot be applied to type
    |
    = note: `T` might need a bound for `std::ops::Add`
 
-error: aborting due to previous error
+error[E0368]: binary assignment operation `+=` cannot be applied to type `T`
+  --> $DIR/missing_trait_impl.rs:19:5
+   |
+LL |     x += x; //~ ERROR binary assignment operation `+=` cannot be applied to type `T`
+   |     -^^^^^
+   |     |
+   |     cannot use `+=` on type `T`
+   |
+   = note: `T` might need a bound for `std::ops::AddAssign`
+
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0369`.
+Some errors occurred: E0368, E0369.
+For more information about an error, try `rustc --explain E0368`.