error[E0308]: mismatched types
  --> $DIR/issue-57741-1.rs:14:9
   |
LL |     let y = match x {
   |                   - this match expression has type `std::boxed::Box<u32>`
LL |         S::A { a } | S::B { b: a } => a,
   |         ^^^^^^^^^^ expected struct `std::boxed::Box`, found enum `S`
   |
   = note: expected struct `std::boxed::Box<u32>`
                found enum `S`

error[E0308]: mismatched types
  --> $DIR/issue-57741-1.rs:14:22
   |
LL |     let y = match x {
   |                   - this match expression has type `std::boxed::Box<u32>`
LL |         S::A { a } | S::B { b: a } => a,
   |                      ^^^^^^^^^^^^^ expected struct `std::boxed::Box`, found enum `S`
   |
   = note: expected struct `std::boxed::Box<u32>`
                found enum `S`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0308`.