error[E0277]: the trait bound `(): ~const Tr` is not satisfied in `fn(()) -> i32 {<() as Tr>::a}`
  --> $DIR/const-closure-trait-method-fail.rs:18:23
   |
LL | const _: () = assert!(need_const_closure(Tr::a) == 42);
   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^ within `fn(()) -> i32 {<() as Tr>::a}`, the trait `~const Tr` is not implemented for `()`
   |
note: the trait `Tr` is implemented for `()`, but that implementation is not `const`
  --> $DIR/const-closure-trait-method-fail.rs:18:23
   |
LL | const _: () = assert!(need_const_closure(Tr::a) == 42);
   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^
   = note: required because it appears within the type `fn(()) -> i32 {<() as Tr>::a}`

error: aborting due to previous error

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