error[E0277]: the trait bound `(): ~const Tr` is not satisfied in `fn(()) -> i32 {<() as Tr>::a}` --> $DIR/const-closure-trait-method-fail.rs:16:23 | 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:16:23 | 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`.