error: lifetime may not live long enough
  --> $DIR/field-projection-mutating-context2.rs:8:25
   |
LL | fn foo<'a>(mut x: Foo<fn(&'a str)>, string: &'a str) {
   |        -- lifetime `'a` defined here
LL |     let Foo(ref mut y): Foo<fn(&'static str)> = x;
   |                         ^^^^^^^^^^^^^^^^^^^^^ type annotation requires that `'a` must outlive `'static`

error: aborting due to previous error