error[E0716]: temporary value dropped while borrowed
  --> $DIR/regions-creating-enums.rs:33:17
   |
LL |         return &ast::num((*f)(x)); //~ ERROR borrowed value does not live long enough
   |                 ^^^^^^^^^^^^^^^^^- temporary value is freed at the end of this statement
   |                 |
   |                 creates a temporary which is freed while still in use
   |
note: borrowed value must be valid for the lifetime 'a as defined on the function body at 30:13...
  --> $DIR/regions-creating-enums.rs:30:13
   |
LL | fn map_nums<'a,'b, F>(x: &ast, f: &mut F) -> &'a ast<'b> where F: FnMut(usize) -> usize {
   |             ^^

error[E0716]: temporary value dropped while borrowed
  --> $DIR/regions-creating-enums.rs:38:17
   |
LL |         return &ast::add(m_x, m_y);  //~ ERROR borrowed value does not live long enough
   |                 ^^^^^^^^^^^^^^^^^^- temporary value is freed at the end of this statement
   |                 |
   |                 creates a temporary which is freed while still in use
   |
note: borrowed value must be valid for the lifetime 'a as defined on the function body at 30:13...
  --> $DIR/regions-creating-enums.rs:30:13
   |
LL | fn map_nums<'a,'b, F>(x: &ast, f: &mut F) -> &'a ast<'b> where F: FnMut(usize) -> usize {
   |             ^^

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0716`.