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Implement Copy and Clone for UnsafeCell<T> #55207

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Implement Copy and Clone for UnsafeCell<T> #55207

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d8951ee
Implement Copy and Clone for UnsafeCell<T>
Oct 19, 2018
4676b10
Modify stability attributes so CI can build, only impl Clone if T is …
Nov 1, 2018
67bcac6
Remove call to clone, and explain why
Nov 1, 2018
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13 changes: 13 additions & 0 deletions src/libcore/cell.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1512,6 +1512,19 @@ impl<T: ?Sized> UnsafeCell<T> {
}
}

#[stable(feature = "unsafe_cell_copy_clone_conservative", since = "1.31.0")]
impl<T: Clone + Copy> Clone for UnsafeCell<T> {
fn clone(&self) -> UnsafeCell<T> {
// NOTE: we are explicitly not calling `.clone()` here, to enforce the
// use of Copy, rather than relying on what could be a custom impl
// of Clone
UnsafeCell::new(self.value)
}
}

#[stable(feature = "unsafe_cell_copy_clone_conservative", since = "1.31.0")]
impl<T: Copy> Copy for UnsafeCell<T> {}

#[stable(feature = "unsafe_cell_default", since = "1.10.0")]
impl<T: Default> Default for UnsafeCell<T> {
/// Creates an `UnsafeCell`, with the `Default` value for T.
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