error[E0503]: cannot use `e` because it was mutably borrowed
  --> $DIR/match-on-borrowed.rs:47:11
   |
LL |         E::V(ref mut x, _) => x,
   |              --------- `e.0` is borrowed here
...
LL |     match e { // Don't know that E uses a tag for its discriminant
   |           ^ use of borrowed `e.0`
...
LL |     x;
   |     - borrow later used here

error[E0503]: cannot use `*f` because it was mutably borrowed
  --> $DIR/match-on-borrowed.rs:61:11
   |
LL |         E::V(ref mut x, _) => x,
   |              --------- `f.0` is borrowed here
...
LL |     match f { // Don't know that E uses a tag for its discriminant
   |           ^ use of borrowed `f.0`
...
LL |     x;
   |     - borrow later used here

error[E0503]: cannot use `t` because it was mutably borrowed
  --> $DIR/match-on-borrowed.rs:81:5
   |
LL |     let x = &mut t;
   |             ------ `t` is borrowed here
LL |     match t {
   |     ^^^^^^^ use of borrowed `t`
...
LL |     x;
   |     - borrow later used here

error[E0381]: used binding `n` isn't initialized
  --> $DIR/match-on-borrowed.rs:93:11
   |
LL |     let n: Never;
   |         - binding declared here but left uninitialized
LL |     match n {}
   |           ^ `n` used here but it isn't initialized
   |
help: consider assigning a value
   |
LL |     let n: Never = todo!();
   |                  +++++++++

error: aborting due to 4 previous errors

Some errors have detailed explanations: E0381, E0503.
For more information about an error, try `rustc --explain E0381`.