diff options
| -rw-r--r-- | library/core/src/marker.rs | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs index 56dddee7b77..9326aaf5684 100644 --- a/library/core/src/marker.rs +++ b/library/core/src/marker.rs @@ -291,6 +291,7 @@ pub trait StructuralEq { /// /// ``` /// # #[allow(dead_code)] +/// #[derive(Copy, Clone)] /// struct Point { /// x: i32, /// y: i32, @@ -315,6 +316,20 @@ pub trait StructuralEq { /// the trait `Copy` may not be implemented for this type; field `points` does not implement `Copy` /// ``` /// +/// Shared references (`&T`) are also `Copy`, so a type can be `Copy`, even when it holds +/// shared references of types `T` that are *not* `Copy`. Consider the following struct, +/// which can implement `Copy`, because it only holds a *shared reference* to our non-`Copy` +/// type `PointList` from above: +/// +/// ``` +/// # #![allow(dead_code)] +/// # struct PointList; +/// #[derive(Copy, Clone)] +/// struct PointListWrapper<'a> { +/// point_list_ref: &'a PointList, +/// } +/// ``` +/// /// ## When *can't* my type be `Copy`? /// /// Some types can't be copied safely. For example, copying `&mut T` would create an aliased |