error[E0277]: the trait bound `(): ~const Tr` is not satisfied in `fn(()) -> i32 {<() as Tr>::a}`
  --> $DIR/const-closure-trait-method-fail.rs:16:42
   |
LL | const _: () = assert!(need_const_closure(Tr::a) == 42);
   |                       ------------------ ^^^^^ within `fn(()) -> i32 {<() as Tr>::a}`, the trait `~const Tr` is not implemented for `()`
   |                       |
   |                       required by a bound introduced by this call
   |
note: the trait `Tr` is implemented for `()`, but that implementation is not `const`
  --> $DIR/const-closure-trait-method-fail.rs:16:42
   |
LL | const _: () = assert!(need_const_closure(Tr::a) == 42);
   |                                          ^^^^^
   = note: required because it appears within the type `fn(()) -> i32 {<() as Tr>::a}`
note: required by a bound in `need_const_closure`
  --> $DIR/const-closure-trait-method-fail.rs:12:32
   |
LL | const fn need_const_closure<T: ~const FnOnce(()) -> i32>(x: T) -> i32 {
   |                                ^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `need_const_closure`

error: aborting due to previous error

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