error: const `impl` for trait `A` which is not marked with `#[const_trait]` --> $DIR/const-impl-requires-const-trait.rs:6:12 | LL | impl const A for () {} | ^ this trait is not `const` | = note: marking a trait with `#[const_trait]` ensures all default method bodies are `const` = note: adding a non-const method body in the future would be a breaking change help: mark `A` as `#[const_trait]` to allow it to have `const` implementations | LL | #[const_trait] pub trait A {} | ++++++++++++++ error: aborting due to 1 previous error