error[E0637]: invalid lifetime bound name: `'_`
  --> $DIR/E0637.rs:12:16
   |
12 | struct Foo<'a: '_>(&'a u8); //~ ERROR invalid lifetime bound name: `'_`
   |                ^^ `'_` is a reserved lifetime name

error[E0637]: invalid lifetime bound name: `'_`
  --> $DIR/E0637.rs:13:12
   |
13 | fn foo<'a: '_>(_: &'a u8) {} //~ ERROR invalid lifetime bound name: `'_`
   |            ^^ `'_` is a reserved lifetime name

error[E0637]: invalid lifetime bound name: `'_`
  --> $DIR/E0637.rs:16:10
   |
16 | impl<'a: '_> Bar<'a> { //~ ERROR invalid lifetime bound name: `'_`
   |          ^^ `'_` is a reserved lifetime name

error: aborting due to 3 previous errors