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authorRalf Jung <post@ralfj.de>2019-07-03 20:13:42 +0200
committerRalf Jung <post@ralfj.de>2019-07-03 20:14:59 +0200
commit6225607e67d9934bcb8ddd0ab74abe4ea974f178 (patch)
tree5d18095ef7f8bc2c53aa1ac7dd6f109039af5e7f /src
parent8c6fb028ca887dff9ec2fe0a90398b6d5bf5fb45 (diff)
downloadrust-6225607e67d9934bcb8ddd0ab74abe4ea974f178.tar.gz
rust-6225607e67d9934bcb8ddd0ab74abe4ea974f178.zip
remove bogus example from drop_in_place
Diffstat (limited to 'src')
-rw-r--r--src/libcore/ptr/mod.rs32
1 files changed, 5 insertions, 27 deletions
diff --git a/src/libcore/ptr/mod.rs b/src/libcore/ptr/mod.rs
index fccb00d768c..da781d7e9fe 100644
--- a/src/libcore/ptr/mod.rs
+++ b/src/libcore/ptr/mod.rs
@@ -100,7 +100,11 @@ pub use unique::Unique;
 ///   as the compiler doesn't need to prove that it's sound to elide the
 ///   copy.
 ///
+/// Unaligned values cannot be dropped in place, they must be copied to an aligned
+/// location first using [`ptr::read_unaligned`].
+///
 /// [`ptr::read`]: ../ptr/fn.read.html
+/// [`ptr::read_unaligned`]: ../ptr/fn.read_unaligned.html
 ///
 /// # Safety
 ///
@@ -108,8 +112,7 @@ pub use unique::Unique;
 ///
 /// * `to_drop` must be [valid] for reads.
 ///
-/// * `to_drop` must be properly aligned. See the example below for how to drop
-///   an unaligned pointer.
+/// * `to_drop` must be properly aligned.
 ///
 /// Additionally, if `T` is not [`Copy`], using the pointed-to value after
 /// calling `drop_in_place` can cause undefined behavior. Note that `*to_drop =
@@ -153,31 +156,6 @@ pub use unique::Unique;
 /// assert!(weak.upgrade().is_none());
 /// ```
 ///
-/// Unaligned values cannot be dropped in place, they must be copied to an aligned
-/// location first:
-/// ```
-/// use std::ptr;
-/// use std::mem::{self, MaybeUninit};
-///
-/// unsafe fn drop_after_copy<T>(to_drop: *mut T) {
-///     let mut copy: MaybeUninit<T> = MaybeUninit::uninit();
-///     ptr::copy(to_drop, copy.as_mut_ptr(), 1);
-///     drop(copy.assume_init());
-/// }
-///
-/// #[repr(packed, C)]
-/// struct Packed {
-///     _padding: u8,
-///     unaligned: Vec<i32>,
-/// }
-///
-/// let mut p = Packed { _padding: 0, unaligned: vec![42] };
-/// unsafe {
-///     drop_after_copy(&mut p.unaligned as *mut _);
-///     mem::forget(p);
-/// }
-/// ```
-///
 /// Notice that the compiler performs this copy automatically when dropping packed structs,
 /// i.e., you do not usually have to worry about such issues unless you call `drop_in_place`
 /// manually.