diff options
| -rw-r--r-- | library/core/src/ptr/mod.rs | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs index d7ed4edcc00..08d06cad55d 100644 --- a/library/core/src/ptr/mod.rs +++ b/library/core/src/ptr/mod.rs @@ -2277,6 +2277,14 @@ impl<F: FnPtr> fmt::Debug for F { /// `addr_of!(expr)` is equivalent to `&raw const expr`. The macro is *soft-deprecated*; /// use `&raw const` instead. /// +/// It is still an open question under which conditions writing through an `addr_of!`-created +/// pointer is permitted. If the place `expr` evaluates to is based on a raw pointer, then the +/// result of `addr_of!` inherits all permissions from that raw pointer. However, if the place is +/// based on a reference, local variable, or `static`, then until all details are decided, the same +/// rules as for shared references apply: it is UB to write through a pointer created with this +/// operation, except for bytes located inside an `UnsafeCell`. Use `&raw mut` (or [`addr_of_mut`]) +/// to create a raw pointer that definitely permits mutation. +/// /// Creating a reference with `&`/`&mut` is only allowed if the pointer is properly aligned /// and points to initialized data. For cases where those requirements do not hold, /// raw pointers should be used instead. However, `&expr as *const _` creates a reference |