error[E0502]: cannot borrow `u` (via `u.y`) as immutable because it is also borrowed as mutable (via `u.x`)
  --> $DIR/union-borrow-move-parent-sibling.rs:56:13
   |
LL |     let a = &mut (*u.x).0;
   |                    --- mutable borrow occurs here (via `u.x`)
LL |     let b = &u.y;
   |             ^^^^ immutable borrow of `u.y` -- which overlaps with `u.x` -- occurs here
LL |     use_borrow(a);
   |                - mutable borrow later used here
   |
   = note: `u.y` is a field of the union `U`, so it overlaps the field `u.x`

error[E0507]: cannot move out of dereference of `ManuallyDrop<((MockVec<u8>, MockVec<u8>), MockVec<u8>)>`
  --> $DIR/union-borrow-move-parent-sibling.rs:62:13
   |
LL |     let a = u.x.0;
   |             ^^^^^
   |             |
   |             move occurs because value has type `(MockVec<u8>, MockVec<u8>)`, which does not implement the `Copy` trait
   |             help: consider borrowing here: `&u.x.0`

error[E0382]: use of moved value: `u`
  --> $DIR/union-borrow-move-parent-sibling.rs:64:13
   |
LL |     let u = U { x: ManuallyDrop::new(((MockVec::new(), MockVec::new()), MockVec::new())) };
   |         - move occurs because `u` has type `U`, which does not implement the `Copy` trait
LL |     let a = u.x.0;
LL |     let a = u.x;
   |             --- value moved here
LL |     let b = u.y;
   |             ^^^ value used here after move

error[E0502]: cannot borrow `u` (via `u.y`) as immutable because it is also borrowed as mutable (via `u.x`)
  --> $DIR/union-borrow-move-parent-sibling.rs:70:13
   |
LL |     let a = &mut ((*u.x).0).0;
   |                     --- mutable borrow occurs here (via `u.x`)
LL |     let b = &u.y;
   |             ^^^^ immutable borrow of `u.y` -- which overlaps with `u.x` -- occurs here
LL |     use_borrow(a);
   |                - mutable borrow later used here
   |
   = note: `u.y` is a field of the union `U`, so it overlaps the field `u.x`

error[E0507]: cannot move out of dereference of `ManuallyDrop<((MockVec<u8>, MockVec<u8>), MockVec<u8>)>`
  --> $DIR/union-borrow-move-parent-sibling.rs:76:13
   |
LL |     let a = (u.x.0).0;
   |             ^^^^^^^^^
   |             |
   |             move occurs because value has type `MockVec<u8>`, which does not implement the `Copy` trait
   |             help: consider borrowing here: `&(u.x.0).0`

error[E0382]: use of moved value: `u`
  --> $DIR/union-borrow-move-parent-sibling.rs:78:13
   |
LL |     let u = U { x: ManuallyDrop::new(((MockVec::new(), MockVec::new()), MockVec::new())) };
   |         - move occurs because `u` has type `U`, which does not implement the `Copy` trait
LL |     let a = (u.x.0).0;
LL |     let a = u.x;
   |             --- value moved here
LL |     let b = u.y;
   |             ^^^ value used here after move

error[E0502]: cannot borrow `u` (via `u.x`) as immutable because it is also borrowed as mutable (via `u.y`)
  --> $DIR/union-borrow-move-parent-sibling.rs:84:13
   |
LL |     let a = &mut *u.y;
   |                   --- mutable borrow occurs here (via `u.y`)
LL |     let b = &u.x;
   |             ^^^^ immutable borrow of `u.x` -- which overlaps with `u.y` -- occurs here
LL |     use_borrow(a);
   |                - mutable borrow later used here
   |
   = note: `u.x` is a field of the union `U`, so it overlaps the field `u.y`

error: aborting due to 7 previous errors

Some errors have detailed explanations: E0382, E0502, E0507.
For more information about an error, try `rustc --explain E0382`.