error[E0038]: the trait `Trait` is not dyn compatible
  --> $DIR/not-dyn-compatible.rs:27:30
   |
LL |         let dyn_object: &dyn Trait = &Struct(64);
   |                              ^^^^^ `Trait` is not dyn compatible
   |
note: for a trait to be dyn compatible it needs to allow building a vtable
      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
  --> $DIR/not-dyn-compatible.rs:14:26
   |
LL | trait Trait {
   |       ----- this trait is not dyn compatible...
...
LL |     unsafe extern "C" fn dyn_method_ref(&self, mut ap: ...) -> u64 {
   |                          ^^^^^^^^^^^^^^ ...because method `dyn_method_ref` is C-variadic
   = help: consider moving `dyn_method_ref` to another trait
   = help: only type `Struct` implements `Trait`; consider using it directly instead.

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0038`.