error[E0271]: type mismatch resolving `<T as Pointee>::Metadata == ()`
  --> $DIR/pointee-tail-is-generic-errors.rs:13:5
   |
LL |     is_thin::<T>();
   |     ^^^^^^^^^^^^ expected `()`, found associated type
   |
   = note:    expected unit type `()`
           found associated type `<T as Pointee>::Metadata`
   = help: consider constraining the associated type `<T as Pointee>::Metadata` to `()`
   = note: for more information, visit https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
note: required by a bound in `is_thin`
  --> $DIR/pointee-tail-is-generic-errors.rs:20:33
   |
LL | fn is_thin<T: std::ptr::Pointee<Metadata = ()> + ?Sized>() {}
   |                                 ^^^^^^^^^^^^^ required by this bound in `is_thin`

error[E0271]: type mismatch resolving `<impl Debug + ?Sized as Pointee>::Metadata == ()`
  --> $DIR/pointee-tail-is-generic-errors.rs:16:5
   |
LL | type Opaque = impl std::fmt::Debug + ?Sized;
   |               ----------------------------- the found opaque type
...
LL |     is_thin::<Opaque>();
   |     ^^^^^^^^^^^^^^^^^ expected `()`, found associated type
   |
   = note:    expected unit type `()`
           found associated type `<impl Debug + ?Sized as Pointee>::Metadata`
note: required by a bound in `is_thin`
  --> $DIR/pointee-tail-is-generic-errors.rs:20:33
   |
LL | fn is_thin<T: std::ptr::Pointee<Metadata = ()> + ?Sized>() {}
   |                                 ^^^^^^^^^^^^^ required by this bound in `is_thin`
help: consider constraining the associated type `<impl Debug + ?Sized as Pointee>::Metadata` to `()`
   |
LL | type Opaque = impl std::fmt::Debug<Metadata = ()> + ?Sized;
   |                                   +++++++++++++++

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0271`.