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| author | Mazdak Farrokhzad <twingoow@gmail.com> | 2019-07-04 01:39:04 +0200 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2019-07-04 01:39:04 +0200 |
| commit | 6363a58e9af1b00669ebf1e343a67e3d1815f463 (patch) | |
| tree | 124c3531ddc1815ad1586b3c78373f9e9117ce3c | |
| parent | 144ed029c5aa190d16475d19495f170051ec7d46 (diff) | |
| parent | 6225607e67d9934bcb8ddd0ab74abe4ea974f178 (diff) | |
| download | rust-6363a58e9af1b00669ebf1e343a67e3d1815f463.tar.gz rust-6363a58e9af1b00669ebf1e343a67e3d1815f463.zip | |
Rollup merge of #62351 - RalfJung:drop-in-place, r=cramertj
remove bogus example from drop_in_place Fixes https://github.com/rust-lang/rust/issues/62313
| -rw-r--r-- | src/libcore/ptr/mod.rs | 32 |
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. |