warning: the feature `deref_patterns` is incomplete and may not be safe to use and/or cause compiler crashes
  --> $DIR/ref-mut.rs:1:12
   |
LL | #![feature(deref_patterns)]
   |            ^^^^^^^^^^^^^^
   |
   = note: see issue #87121 <https://github.com/rust-lang/rust/issues/87121> for more information
   = note: `#[warn(incomplete_features)]` on by default

error[E0277]: the trait bound `Rc<{integer}>: DerefMut` is not satisfied
  --> $DIR/ref-mut.rs:13:9
   |
LL |         deref!(x) => {}
   |         ^^^^^^^^^ the trait `DerefMut` is not implemented for `Rc<{integer}>`
   |
   = note: this error originates in the macro `deref` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 1 previous error; 1 warning emitted

For more information about this error, try `rustc --explain E0277`.