1 error: unsatisfied lifetime constraints
2 --> $DIR/regions-return-ref-to-upvar-issue-17403.rs:17:24
4 LL | let mut f = || &mut x; //~ ERROR cannot infer
5 | -- ^^^^^^ returning this value requires that `'1` must outlive `'2`
7 | |return type of closure is &'2 mut i32
8 | lifetime `'1` represents this closure's body
10 = note: closure implements `FnMut`, so references to captured variables can't escape the closure
12 error: aborting due to previous error