error[E0015]: cannot call non-const fn `<Vec<usize> as Default>::default` in constant functions --> $DIR/std-impl-gate.rs:13:5 | LL | Default::default() | ^^^^^^^^^^^^^^^^^^ | = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants = help: add `#![feature(const_trait_impl)]` to the crate attributes to enable error: aborting due to previous error For more information about this error, try `rustc --explain E0015`.