From 40df8fd0fad99db880bee40fce7c855922e7f0f9 Mon Sep 17 00:00:00 2001 From: aticu <15schnic@gmail.com> Date: Mon, 20 Jul 2020 20:39:17 +0200 Subject: [PATCH] Apply #66379 to `*mut T` `as_ref` --- src/libcore/ptr/mut_ptr.rs | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/src/libcore/ptr/mut_ptr.rs b/src/libcore/ptr/mut_ptr.rs index 96856e7512cab..915dc3e45f644 100644 --- a/src/libcore/ptr/mut_ptr.rs +++ b/src/libcore/ptr/mut_ptr.rs @@ -47,17 +47,22 @@ impl *mut T { /// operation because the returned value could be pointing to invalid /// memory. /// - /// When calling this method, you have to ensure that if the pointer is - /// non-NULL, then it is properly aligned, dereferenceable (for the whole - /// size of `T`) and points to an initialized instance of `T`. This applies - /// even if the result of this method is unused! + /// When calling this method, you have to ensure that *either* the pointer is NULL *or* + /// all of the following is true: + /// - it is properly aligned + /// - it must point to an initialized instance of T; in particular, the pointer must be + /// "dereferencable" in the sense defined [here]. + /// + /// This applies even if the result of this method is unused! /// (The part about being initialized is not yet fully decided, but until /// it is, the only safe approach is to ensure that they are indeed initialized.) /// /// Additionally, the lifetime `'a` returned is arbitrarily chosen and does - /// not necessarily reflect the actual lifetime of the data. It is up to the - /// caller to ensure that for the duration of this lifetime, the memory this - /// pointer points to does not get written to outside of `UnsafeCell`. + /// not necessarily reflect the actual lifetime of the data. *You* must enforce + /// Rust's aliasing rules. In particular, for the duration of this lifetime, + /// the memory the pointer points to must not get mutated (except inside `UnsafeCell`). + /// + /// [here]: crate::ptr#safety /// /// # Examples ///