clarify safety documentation of ptr::swap and ptr::copy

2 files changed, 6 insertions, 0 deletions

diff --git a/library/core/src/intrinsics.rs b/library/core/src/intrinsics.rs
index 9ef2c7cde02..84b9a3bba88 100644
--- a/library/core/src/intrinsics.rs
+++ b/library/core/src/intrinsics.rs
@@ -2709,6 +2709,9 @@ pub const unsafe fn copy_nonoverlapping<T>(src: *const T, dst: *mut T, count: us
 ///
 /// * `dst` must be [valid] for writes of `count * size_of::<T>()` bytes.
 ///
+/// * `src` must remain valid for reads even after `dst` is written, and vice versa.
+///   (In other words, there cannot be aliasing restrictions on the use of these pointers.)
+///
 /// * Both `src` and `dst` must be properly aligned.
 ///
 /// Like [`read`], `copy` creates a bitwise copy of `T`, regardless of
diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
index 5f094ac4e7e..f8badc4130d 100644
--- a/library/core/src/ptr/mod.rs
+++ b/library/core/src/ptr/mod.rs
@@ -797,6 +797,9 @@ pub const fn slice_from_raw_parts_mut<T>(data: *mut T, len: usize) -> *mut [T] {
 ///
 /// * Both `x` and `y` must be [valid] for both reads and writes.
 ///
+/// * `x` must remain valid for reads and writes even after `y` is read/written, and vice versa.
+///   (In other words, there cannot be aliasing restrictions on the use of these pointers.)
+///
 /// * Both `x` and `y` must be properly aligned.
 ///
 /// Note that even if `T` has size `0`, the pointers must be non-null and properly aligned.