From 764d163099c6b5299efe7551de1180603f0c8367 Mon Sep 17 00:00:00 2001
From: Michal 'vorner' Vaner <vorner@vorner.cz>
Date: Sat, 1 Jun 2019 11:55:25 +0200
Subject: [PATCH] docs: Use String in Rc::into_raw examples

It is unclear if accessing an integer after `drop_in_place` has been
called on it is undefined behaviour or not, as demonstrated by the
discussion in
https://github.com/rust-lang/rust/pull/60766#pullrequestreview-243414222.

Avoid these uncertainties by using String which frees memory in its
`drop_in_place` to make sure this is undefined behaviour. The message in
the docs should be to watch out and not access the data after that, not
discussing when one maybe could get away with it O:-).
---
 src/liballoc/rc.rs   | 14 +++++++-------
 src/liballoc/sync.rs | 14 +++++++-------
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index 1f357a719bb43..b3b67a80e1063 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -1274,17 +1274,17 @@ impl<T> Weak<T> {
     /// use std::rc::{Rc, Weak};
     /// use std::ptr;
     ///
-    /// let strong = Rc::new(42);
+    /// let strong = Rc::new("hello".to_owned());
     /// let weak = Rc::downgrade(&strong);
     /// // Both point to the same object
     /// assert!(ptr::eq(&*strong, Weak::as_raw(&weak)));
     /// // The strong here keeps it alive, so we can still access the object.
-    /// assert_eq!(42, unsafe { *Weak::as_raw(&weak) });
+    /// assert_eq!("hello", unsafe { &*Weak::as_raw(&weak) });
     ///
     /// drop(strong);
     /// // But not any more. We can do Weak::as_raw(&weak), but accessing the pointer would lead to
     /// // undefined behaviour.
-    /// // assert_eq!(42, unsafe { *Weak::as_raw(&weak) });
+    /// // assert_eq!("hello", unsafe { &*Weak::as_raw(&weak) });
     /// ```
     ///
     /// [`null`]: ../../std/ptr/fn.null.html
@@ -1319,12 +1319,12 @@ impl<T> Weak<T> {
     ///
     /// use std::rc::{Rc, Weak};
     ///
-    /// let strong = Rc::new(42);
+    /// let strong = Rc::new("hello".to_owned());
     /// let weak = Rc::downgrade(&strong);
     /// let raw = Weak::into_raw(weak);
     ///
     /// assert_eq!(1, Rc::weak_count(&strong));
-    /// assert_eq!(42, unsafe { *raw });
+    /// assert_eq!("hello", unsafe { &*raw });
     ///
     /// drop(unsafe { Weak::from_raw(raw) });
     /// assert_eq!(0, Rc::weak_count(&strong));
@@ -1360,14 +1360,14 @@ impl<T> Weak<T> {
     ///
     /// use std::rc::{Rc, Weak};
     ///
-    /// let strong = Rc::new(42);
+    /// let strong = Rc::new("hello".to_owned());
     ///
     /// let raw_1 = Weak::into_raw(Rc::downgrade(&strong));
     /// let raw_2 = Weak::into_raw(Rc::downgrade(&strong));
     ///
     /// assert_eq!(2, Rc::weak_count(&strong));
     ///
-    /// assert_eq!(42, *Weak::upgrade(&unsafe { Weak::from_raw(raw_1) }).unwrap());
+    /// assert_eq!("hello", &*Weak::upgrade(&unsafe { Weak::from_raw(raw_1) }).unwrap());
     /// assert_eq!(1, Rc::weak_count(&strong));
     ///
     /// drop(strong);
diff --git a/src/liballoc/sync.rs b/src/liballoc/sync.rs
index 70865656c510e..38f2d1a14dcee 100644
--- a/src/liballoc/sync.rs
+++ b/src/liballoc/sync.rs
@@ -1083,17 +1083,17 @@ impl<T> Weak<T> {
     /// use std::sync::{Arc, Weak};
     /// use std::ptr;
     ///
-    /// let strong = Arc::new(42);
+    /// let strong = Arc::new("hello".to_owned());
     /// let weak = Arc::downgrade(&strong);
     /// // Both point to the same object
     /// assert!(ptr::eq(&*strong, Weak::as_raw(&weak)));
     /// // The strong here keeps it alive, so we can still access the object.
-    /// assert_eq!(42, unsafe { *Weak::as_raw(&weak) });
+    /// assert_eq!("hello", unsafe { &*Weak::as_raw(&weak) });
     ///
     /// drop(strong);
     /// // But not any more. We can do Weak::as_raw(&weak), but accessing the pointer would lead to
     /// // undefined behaviour.
-    /// // assert_eq!(42, unsafe { *Weak::as_raw(&weak) });
+    /// // assert_eq!("hello", unsafe { &*Weak::as_raw(&weak) });
     /// ```
     ///
     /// [`null`]: ../../std/ptr/fn.null.html
@@ -1128,12 +1128,12 @@ impl<T> Weak<T> {
     ///
     /// use std::sync::{Arc, Weak};
     ///
-    /// let strong = Arc::new(42);
+    /// let strong = Arc::new("hello".to_owned());
     /// let weak = Arc::downgrade(&strong);
     /// let raw = Weak::into_raw(weak);
     ///
     /// assert_eq!(1, Arc::weak_count(&strong));
-    /// assert_eq!(42, unsafe { *raw });
+    /// assert_eq!("hello", unsafe { &*raw });
     ///
     /// drop(unsafe { Weak::from_raw(raw) });
     /// assert_eq!(0, Arc::weak_count(&strong));
@@ -1170,14 +1170,14 @@ impl<T> Weak<T> {
     ///
     /// use std::sync::{Arc, Weak};
     ///
-    /// let strong = Arc::new(42);
+    /// let strong = Arc::new("hello".to_owned());
     ///
     /// let raw_1 = Weak::into_raw(Arc::downgrade(&strong));
     /// let raw_2 = Weak::into_raw(Arc::downgrade(&strong));
     ///
     /// assert_eq!(2, Arc::weak_count(&strong));
     ///
-    /// assert_eq!(42, *Weak::upgrade(&unsafe { Weak::from_raw(raw_1) }).unwrap());
+    /// assert_eq!("hello", &*Weak::upgrade(&unsafe { Weak::from_raw(raw_1) }).unwrap());
     /// assert_eq!(1, Arc::weak_count(&strong));
     ///
     /// drop(strong);