1 error[E0106]: missing lifetime specifier
2 --> $DIR/issue-19707.rs:3:28
4 LL | type Foo = fn(&u8, &u8) -> &u8;
5 | --- --- ^ expected named lifetime parameter
7 = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from argument 1 or argument 2
8 = note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html
9 help: consider making the type lifetime-generic with a new `'a` lifetime
11 LL | type Foo = for<'a> fn(&'a u8, &'a u8) -> &'a u8;
12 | ^^^^^^^ ^^^^^^ ^^^^^^ ^^^
13 help: consider introducing a named lifetime parameter
15 LL | type Foo<'a> = fn(&'a u8, &'a u8) -> &'a u8;
16 | ^^^^ ^^^^^^ ^^^^^^ ^^^
18 error[E0106]: missing lifetime specifier
19 --> $DIR/issue-19707.rs:5:27
21 LL | fn bar<F: Fn(&u8, &u8) -> &u8>(f: &F) {}
22 | --- --- ^ expected named lifetime parameter
24 = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from argument 1 or argument 2
25 = note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html
26 help: consider making the bound lifetime-generic with a new `'a` lifetime
28 LL | fn bar<F: for<'a> Fn(&'a u8, &'a u8) -> &'a u8>(f: &F) {}
29 | ^^^^^^^ ^^^^^^ ^^^^^^ ^^^
30 help: consider introducing a named lifetime parameter
32 LL | fn bar<'a, F: Fn(&'a u8, &'a u8) -> &'a u8>(f: &F) {}
33 | ^^^ ^^^^^^ ^^^^^^ ^^^
35 error: aborting due to 2 previous errors
37 For more information about this error, try `rustc --explain E0106`.