warning: the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
  --> $DIR/no-unsize-coerce-dyn-trait.rs:1:12
   |
LL | #![feature(dyn_star, trait_upcasting)]
   |            ^^^^^^^^
   |
   = note: see issue #102425 <https://github.com/rust-lang/rust/issues/102425> for more information
   = note: `#[warn(incomplete_features)]` on by default

error[E0308]: mismatched types
  --> $DIR/no-unsize-coerce-dyn-trait.rs:11:26
   |
LL |     let y: Box<dyn* B> = x;
   |            -----------   ^ expected trait `B`, found trait `A`
   |            |
   |            expected due to this
   |
   = note: expected struct `Box<dyn* B>`
              found struct `Box<dyn* A>`

error: aborting due to previous error; 1 warning emitted

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