Skip to content

Avoid allocations and copying in Vec::leak #89337

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 4 commits into from
Oct 15, 2021
Merged

Avoid allocations and copying in Vec::leak #89337

Changes from 2 commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
58b1a12
Avoid allocations and copying in Vec::leak
mbrubeck Sep 28, 2021
1fca2ce
Additional docs about Vec::leak behavior
mbrubeck Sep 28, 2021
129af04
Mention Rust version in Vec::leak docs.
m-ou-se Oct 12, 2021
df15b28
Remove potentially unsound note on reconstructing a leaked Vec.
m-ou-se Oct 12, 2021
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 7 additions & 3 deletions library/alloc/src/vec/mod.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1952,8 +1952,11 @@ impl<T, A: Allocator> Vec<T, A> {
/// `'a`. If the type has only static references, or none at all, then this
/// may be chosen to be `'static`.
///
/// This function is similar to the [`leak`][Box::leak] function on [`Box`]
/// except that there is no way to recover the leaked memory.
/// This method does not reallocate or shrink the `Vec`, so the leaked
/// allocation may include unused capacity that is not part of the returned
/// slice. Unsafe code that later reconstructs or deallocates the `Vec`
/// (for example, by calling [`Vec::from_raw_parts`]) must keep track of the
/// original capacity.
///
/// This function is mainly useful for data that lives for the remainder of
/// the program's life. Dropping the returned reference will cause a memory
Expand All @@ -1976,7 +1979,8 @@ impl<T, A: Allocator> Vec<T, A> {
where
A: 'a,
{
Box::leak(self.into_boxed_slice())
let mut me = ManuallyDrop::new(self);
unsafe { slice::from_raw_parts_mut(me.as_mut_ptr(), me.len) }
}

/// Returns the remaining spare capacity of the vector as a slice of
Expand Down