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Make RawVec private to alloc #90542

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Nov 13, 2021
Merged

Make RawVec private to alloc #90542

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3 changes: 2 additions & 1 deletion library/alloc/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -173,6 +173,8 @@ extern crate test;
#[macro_use]
mod macros;

mod raw_vec;

// Heaps provided for low-level allocation strategies

pub mod alloc;
Expand All @@ -191,7 +193,6 @@ mod boxed {
pub mod borrow;
pub mod collections;
pub mod fmt;
pub mod raw_vec;
pub mod rc;
pub mod slice;
pub mod str;
Expand Down
61 changes: 4 additions & 57 deletions library/alloc/src/raw_vec.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,4 @@
#![unstable(feature = "raw_vec_internals", reason = "implementation detail", issue = "none")]
#![doc(hidden)]
#![unstable(feature = "raw_vec_internals", reason = "unstable const warnings", issue = "none")]
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Can this be removed since it is no longer exported?

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I tried that but got

error: const-stable function cannot use `#[feature(const_fn_trait_bound)]`
   --> library/alloc/src/raw_vec.rs:104:9
    |
104 | impl<T, A: Allocator> RawVec<T, A> {
    |         ^
    |
help: if it is not part of the public API, make this function unstably const
    |
121 |     #[rustc_const_unstable(feature = "...", issue = "...")]
    |
help: otherwise `#[rustc_allow_const_fn_unstable]` can be used to bypass stability checks
    |
121 |     #[rustc_allow_const_fn_unstable(const_fn_trait_bound)]
    |

error: `Unique::<T>::dangling` is not yet stable as a const fn
   --> library/alloc/src/raw_vec.rs:123:21
    |
123 |         Self { ptr: Unique::dangling(), cap: 0, alloc }
    |                     ^^^^^^^^^^^^^^^^^^
    |
    = help: const-stable functions can only call other const-stable functions

Adding rustc_allow_const_fn_unstable solves the former but not the latter.


use core::alloc::LayoutError;
use core::cmp;
Expand Down Expand Up @@ -50,7 +49,7 @@ enum AllocInit {
/// `usize::MAX`. This means that you need to be careful when round-tripping this type with a
/// `Box<[T]>`, since `capacity()` won't yield the length.
#[allow(missing_debug_implementations)]
pub struct RawVec<T, A: Allocator = Global> {
pub(crate) struct RawVec<T, A: Allocator = Global> {
ptr: Unique<T>,
cap: usize,
alloc: A,
Expand Down Expand Up @@ -87,33 +86,20 @@ impl<T> RawVec<T, Global> {
/// # Aborts
///
/// Aborts on OOM.
#[cfg(not(no_global_oom_handling))]
#[cfg(not(any(no_global_oom_handling, test)))]
#[must_use]
#[inline]
pub fn with_capacity(capacity: usize) -> Self {
Self::with_capacity_in(capacity, Global)
}

/// Like `with_capacity`, but guarantees the buffer is zeroed.
#[cfg(not(no_global_oom_handling))]
#[cfg(not(any(no_global_oom_handling, test)))]
#[must_use]
#[inline]
pub fn with_capacity_zeroed(capacity: usize) -> Self {
Self::with_capacity_zeroed_in(capacity, Global)
}

/// Reconstitutes a `RawVec` from a pointer and capacity.
///
/// # Safety
///
/// The `ptr` must be allocated (on the system heap), and with the given `capacity`.
/// The `capacity` cannot exceed `isize::MAX` for sized types. (only a concern on 32-bit
/// systems). ZST vectors may have a capacity up to `usize::MAX`.
/// If the `ptr` and `capacity` come from a `RawVec`, then this is guaranteed.
#[inline]
pub unsafe fn from_raw_parts(ptr: *mut T, capacity: usize) -> Self {
unsafe { Self::from_raw_parts_in(ptr, capacity, Global) }
}
}

impl<T, A: Allocator> RawVec<T, A> {
Expand Down Expand Up @@ -154,14 +140,6 @@ impl<T, A: Allocator> RawVec<T, A> {
Self::allocate_in(capacity, AllocInit::Zeroed, alloc)
}

/// Converts a `Box<[T]>` into a `RawVec<T>`.
pub fn from_box(slice: Box<[T], A>) -> Self {
unsafe {
let (slice, alloc) = Box::into_raw_with_allocator(slice);
RawVec::from_raw_parts_in(slice.as_mut_ptr(), slice.len(), alloc)
}
}

/// Converts the entire buffer into `Box<[MaybeUninit<T>]>` with the specified `len`.
///
/// Note that this will correctly reconstitute any `cap` changes
Expand Down Expand Up @@ -290,37 +268,6 @@ impl<T, A: Allocator> RawVec<T, A> {
/// # Aborts
///
/// Aborts on OOM.
///
/// # Examples
///
/// ```
/// # #![feature(raw_vec_internals)]
/// # extern crate alloc;
/// # use std::ptr;
/// # use alloc::raw_vec::RawVec;
/// struct MyVec<T> {
/// buf: RawVec<T>,
/// len: usize,
/// }
///
/// impl<T: Clone> MyVec<T> {
/// pub fn push_all(&mut self, elems: &[T]) {
/// self.buf.reserve(self.len, elems.len());
/// // reserve would have aborted or panicked if the len exceeded
/// // `isize::MAX` so this is safe to do unchecked now.
/// for x in elems {
/// unsafe {
/// ptr::write(self.buf.ptr().add(self.len), x.clone());
/// }
/// self.len += 1;
/// }
/// }
/// }
/// # fn main() {
/// # let mut vector = MyVec { buf: RawVec::new(), len: 0 };
/// # vector.push_all(&[1, 3, 5, 7, 9]);
/// # }
/// ```
#[cfg(not(no_global_oom_handling))]
#[inline]
pub fn reserve(&mut self, len: usize, additional: usize) {
Expand Down