From 8f13f8752f925e376b26cb32382fe25acd2a8241 Mon Sep 17 00:00:00 2001
From: Corey Farwell <coreyf@rwell.org>
Date: Tue, 16 Feb 2016 21:43:49 -0500
Subject: [PATCH] Improve 'std::mem::transmute_copy' doc example.

Prior to this commit, it was a trivial example that did not demonstrate
the effects of using the function.

Fixes https://github.com/rust-lang/rust/issues/31094
---
 src/libcore/mem.rs | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs
index a521700b84bd8..c36ad592ad3b5 100644
--- a/src/libcore/mem.rs
+++ b/src/libcore/mem.rs
@@ -571,9 +571,25 @@ pub const POST_DROP_USIZE: usize = POST_DROP_U64 as usize;
 /// ```
 /// use std::mem;
 ///
-/// let one = unsafe { mem::transmute_copy(&1) };
+/// #[repr(packed)]
+/// struct Foo {
+///     bar: u8,
+/// }
+///
+/// let foo_slice = [10u8];
+///
+/// unsafe {
+///     // Copy the data from 'foo_slice' and treat it as a 'Foo'
+///     let mut foo_struct: Foo = mem::transmute_copy(&foo_slice);
+///     assert_eq!(foo_struct.bar, 10);
+///
+///     // Modify the copied data
+///     foo_struct.bar = 20;
+///     assert_eq!(foo_struct.bar, 20);
+/// }
 ///
-/// assert_eq!(1, one);
+/// // The contents of 'foo_slice' should not have changed
+/// assert_eq!(foo_slice, [10]);
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]