On E0204 suggest missing type param bounds ``` error[E0204]: the trait `Copy` may not be implemented for this type --> f42.rs:9:17 | 9 | #[derive(Debug, Copy, Clone)] | ^^^^ 10 | pub struct AABB<K>{ 11 | pub loc: Vector2<K>, | ------------------- this field does not implement `Copy` 12 | pub size: Vector2<K> | -------------------- this field does not implement `Copy` | note: the `Copy` impl for `Vector2<K>` requires that `K: Debug` --> f42.rs:11:5 | 11 | pub loc: Vector2<K>, | ^^^^^^^^^^^^^^^^^^^ note: the `Copy` impl for `Vector2<K>` requires that `K: Debug` --> f42.rs:12:5 | 12 | pub size: Vector2<K> | ^^^^^^^^^^^^^^^^^^^^ = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info) help: consider restricting type parameter `K` | 10 | pub struct AABB<K: Debug>{ | +++++++ ``` Fix #89137.
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.