error: this function takes an immutable ref to return a mutable one
 --> $DIR/mut_from_ref.rs:9:39
  |
9 |     fn this_wont_hurt_a_bit(&self) -> &mut Foo {
  |                                       ^^^^^^^^
  |
note: lint level defined here
 --> $DIR/mut_from_ref.rs:4:9
  |
4 | #![deny(mut_from_ref)]
  |         ^^^^^^^^^^^^

error: this function takes an immutable ref to return a mutable one
  --> $DIR/mut_from_ref.rs:15:25
   |
15 |     fn ouch(x: &Foo) -> &mut Foo;
   |                         ^^^^^^^^

error: this function takes an immutable ref to return a mutable one
  --> $DIR/mut_from_ref.rs:24:21
   |
24 | fn fail(x: &u32) -> &mut u16 {
   |                     ^^^^^^^^

error: this function takes an immutable ref to return a mutable one
  --> $DIR/mut_from_ref.rs:28:50
   |
28 | fn fail_lifetime<'a>(x: &'a u32, y: &mut u32) -> &'a mut u32 {
   |                                                  ^^^^^^^^^^^

error: aborting due to 4 previous errors