error[E0423]: expected function, tuple struct or tuple variant, found trait `Foo` --> $DIR/issue-58022.rs:14:9 | LL | Foo(Box::new(*slice)) | ^^^ not a function, tuple struct or tuple variant error[E0283]: type annotations needed --> $DIR/issue-58022.rs:4:25 | LL | fn new(slice: &[u8; Foo::SIZE]) -> Self; | ^^^^^^^^^ | | | cannot infer type | help: use the fully qualified path to an implementation: `::SIZE` | = note: cannot satisfy `_: Foo` = note: associated constants cannot be accessed directly on a `trait`, they can only be accessed through a specific `impl` error: aborting due to 2 previous errors Some errors have detailed explanations: E0283, E0423. For more information about an error, try `rustc --explain E0283`.