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Rollup merge of #130061 - theemathas:box_vec_non_null, r=MarkSimulacrum,workingjubilee 

Add `NonNull` convenience methods to `Box` and `Vec`

Implements the ACP: https://github.com/rust-lang/libs-team/issues/418.

The docs for the added methods are mostly copied from the existing methods that use raw pointers instead of `NonNull`.

I'm new to this "contributing to rustc" thing, so I'm sorry if I did something wrong. In particular, I don't know what the process is for creating a new unstable feature. Please advise me if I should do something. Thank you.
This commit is contained in:
Stuart Cook 2024-09-15 12:14:55 +10:00 committed by GitHub
parent e02e6bf0e9 811ee38ff0
commit c11505f218
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7 changed files with 535 additions and 20 deletions
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223
library/alloc/src/boxed.rs
View File

@ -1060,6 +1060,59 @@ impl<T: ?Sized> Box<T> {
pub unsafe fn from_raw(raw: *mut T) -> Self {
unsafe { Self::from_raw_in(raw, Global) }
}
/// Constructs a box from a `NonNull` pointer.
///
/// After calling this function, the `NonNull` pointer is owned by
/// the resulting `Box`. Specifically, the `Box` destructor will call
/// the destructor of `T` and free the allocated memory. For this
/// to be safe, the memory must have been allocated in accordance
/// with the [memory layout] used by `Box` .
///
/// # Safety
///
/// This function is unsafe because improper use may lead to
/// memory problems. For example, a double-free may occur if the
/// function is called twice on the same `NonNull` pointer.
///
/// The safety conditions are described in the [memory layout] section.
///
/// # Examples
///
/// Recreate a `Box` which was previously converted to a `NonNull`
/// pointer using [`Box::into_non_null`]:
/// ```
/// #![feature(box_vec_non_null)]
///
/// let x = Box::new(5);
/// let non_null = Box::into_non_null(x);
/// let x = unsafe { Box::from_non_null(non_null) };
/// ```
/// Manually create a `Box` from scratch by using the global allocator:
/// ```
/// #![feature(box_vec_non_null)]
///
/// use std::alloc::{alloc, Layout};
/// use std::ptr::NonNull;
///
/// unsafe {
/// let non_null = NonNull::new(alloc(Layout::new::<i32>()).cast::<i32>())
/// .expect("allocation failed");
/// // In general .write is required to avoid attempting to destruct
/// // the (uninitialized) previous contents of `non_null`.
/// non_null.write(5);
/// let x = Box::from_non_null(non_null);
/// }
/// ```
///
/// [memory layout]: self#memory-layout
/// [`Layout`]: crate::Layout
#[unstable(feature = "box_vec_non_null", reason = "new API", issue = "130364")]
#[inline]
#[must_use = "call `drop(Box::from_non_null(ptr))` if you intend to drop the `Box`"]
pub unsafe fn from_non_null(ptr: NonNull<T>) -> Self {
unsafe { Self::from_raw(ptr.as_ptr()) }
}
}
impl<T: ?Sized, A: Allocator> Box<T, A> {
@ -1117,6 +1170,61 @@ impl<T: ?Sized, A: Allocator> Box<T, A> {
Box(unsafe { Unique::new_unchecked(raw) }, alloc)
}
/// Constructs a box from a `NonNull` pointer in the given allocator.
///
/// After calling this function, the `NonNull` pointer is owned by
/// the resulting `Box`. Specifically, the `Box` destructor will call
/// the destructor of `T` and free the allocated memory. For this
/// to be safe, the memory must have been allocated in accordance
/// with the [memory layout] used by `Box` .
///
/// # Safety
///
/// This function is unsafe because improper use may lead to
/// memory problems. For example, a double-free may occur if the
/// function is called twice on the same raw pointer.
///
///
/// # Examples
///
/// Recreate a `Box` which was previously converted to a `NonNull` pointer
/// using [`Box::into_non_null_with_allocator`]:
/// ```
/// #![feature(allocator_api, box_vec_non_null)]
///
/// use std::alloc::System;
///
/// let x = Box::new_in(5, System);
/// let (non_null, alloc) = Box::into_non_null_with_allocator(x);
/// let x = unsafe { Box::from_non_null_in(non_null, alloc) };
/// ```
/// Manually create a `Box` from scratch by using the system allocator:
/// ```
/// #![feature(allocator_api, box_vec_non_null, slice_ptr_get)]
///
/// use std::alloc::{Allocator, Layout, System};
///
/// unsafe {
/// let non_null = System.allocate(Layout::new::<i32>())?.cast::<i32>();
/// // In general .write is required to avoid attempting to destruct
/// // the (uninitialized) previous contents of `non_null`.
/// non_null.write(5);
/// let x = Box::from_non_null_in(non_null, System);
/// }
/// # Ok::<(), std::alloc::AllocError>(())
/// ```
///
/// [memory layout]: self#memory-layout
/// [`Layout`]: crate::Layout
#[unstable(feature = "allocator_api", issue = "32838")]
// #[unstable(feature = "box_vec_non_null", reason = "new API", issue = "130364")]
#[rustc_const_unstable(feature = "const_box", issue = "92521")]
#[inline]
pub const unsafe fn from_non_null_in(raw: NonNull<T>, alloc: A) -> Self {
// SAFETY: guaranteed by the caller.
unsafe { Box::from_raw_in(raw.as_ptr(), alloc) }
}
/// Consumes the `Box`, returning a wrapped raw pointer.
///
/// The pointer will be properly aligned and non-null.
@ -1172,6 +1280,66 @@ impl<T: ?Sized, A: Allocator> Box<T, A> {
unsafe { addr_of_mut!(*&mut *Self::into_raw_with_allocator(b).0) }
}
/// Consumes the `Box`, returning a wrapped `NonNull` pointer.
///
/// The pointer will be properly aligned.
///
/// After calling this function, the caller is responsible for the
/// memory previously managed by the `Box`. In particular, the
/// caller should properly destroy `T` and release the memory, taking
/// into account the [memory layout] used by `Box`. The easiest way to
/// do this is to convert the `NonNull` pointer back into a `Box` with the
/// [`Box::from_non_null`] function, allowing the `Box` destructor to
/// perform the cleanup.
///
/// Note: this is an associated function, which means that you have
/// to call it as `Box::into_non_null(b)` instead of `b.into_non_null()`.
/// This is so that there is no conflict with a method on the inner type.
///
/// # Examples
/// Converting the `NonNull` pointer back into a `Box` with [`Box::from_non_null`]
/// for automatic cleanup:
/// ```
/// #![feature(box_vec_non_null)]
///
/// let x = Box::new(String::from("Hello"));
/// let non_null = Box::into_non_null(x);
/// let x = unsafe { Box::from_non_null(non_null) };
/// ```
/// Manual cleanup by explicitly running the destructor and deallocating
/// the memory:
/// ```
/// #![feature(box_vec_non_null)]
///
/// use std::alloc::{dealloc, Layout};
///
/// let x = Box::new(String::from("Hello"));
/// let non_null = Box::into_non_null(x);
/// unsafe {
/// non_null.drop_in_place();
/// dealloc(non_null.as_ptr().cast::<u8>(), Layout::new::<String>());
/// }
/// ```
/// Note: This is equivalent to the following:
/// ```
/// #![feature(box_vec_non_null)]
///
/// let x = Box::new(String::from("Hello"));
/// let non_null = Box::into_non_null(x);
/// unsafe {
/// drop(Box::from_non_null(non_null));
/// }
/// ```
///
/// [memory layout]: self#memory-layout
#[must_use = "losing the pointer will leak memory"]
#[unstable(feature = "box_vec_non_null", reason = "new API", issue = "130364")]
#[inline]
pub fn into_non_null(b: Self) -> NonNull<T> {
// SAFETY: `Box` is guaranteed to be non-null.
unsafe { NonNull::new_unchecked(Self::into_raw(b)) }
}
/// Consumes the `Box`, returning a wrapped raw pointer and the allocator.
///
/// The pointer will be properly aligned and non-null.
@ -1233,6 +1401,61 @@ impl<T: ?Sized, A: Allocator> Box<T, A> {
(ptr, alloc)
}
/// Consumes the `Box`, returning a wrapped `NonNull` pointer and the allocator.
///
/// The pointer will be properly aligned.
///
/// After calling this function, the caller is responsible for the
/// memory previously managed by the `Box`. In particular, the
/// caller should properly destroy `T` and release the memory, taking
/// into account the [memory layout] used by `Box`. The easiest way to
/// do this is to convert the `NonNull` pointer back into a `Box` with the
/// [`Box::from_non_null_in`] function, allowing the `Box` destructor to
/// perform the cleanup.
///
/// Note: this is an associated function, which means that you have
/// to call it as `Box::into_non_null_with_allocator(b)` instead of
/// `b.into_non_null_with_allocator()`. This is so that there is no
/// conflict with a method on the inner type.
///
/// # Examples
/// Converting the `NonNull` pointer back into a `Box` with
/// [`Box::from_non_null_in`] for automatic cleanup:
/// ```
/// #![feature(allocator_api, box_vec_non_null)]
///
/// use std::alloc::System;
///
/// let x = Box::new_in(String::from("Hello"), System);
/// let (non_null, alloc) = Box::into_non_null_with_allocator(x);
/// let x = unsafe { Box::from_non_null_in(non_null, alloc) };
/// ```
/// Manual cleanup by explicitly running the destructor and deallocating
/// the memory:
/// ```
/// #![feature(allocator_api, box_vec_non_null)]
///
/// use std::alloc::{Allocator, Layout, System};
///
/// let x = Box::new_in(String::from("Hello"), System);
/// let (non_null, alloc) = Box::into_non_null_with_allocator(x);
/// unsafe {
/// non_null.drop_in_place();
/// alloc.deallocate(non_null.cast::<u8>(), Layout::new::<String>());
/// }
/// ```
///
/// [memory layout]: self#memory-layout
#[must_use = "losing the pointer will leak memory"]
#[unstable(feature = "allocator_api", issue = "32838")]
// #[unstable(feature = "box_vec_non_null", reason = "new API", issue = "130364")]
#[inline]
pub fn into_non_null_with_allocator(b: Self) -> (NonNull<T>, A) {
let (ptr, alloc) = Box::into_raw_with_allocator(b);
// SAFETY: `Box` is guaranteed to be non-null.
unsafe { (NonNull::new_unchecked(ptr), alloc) }
}
#[unstable(
feature = "ptr_internals",
issue = "none",

2
library/alloc/src/vec/in_place_collect.rs
View File

@ -328,7 +328,7 @@ where
mem::forget(dst_guard);
let vec = unsafe { Vec::from_nonnull(dst_buf, len, dst_cap) };
let vec = unsafe { Vec::from_parts(dst_buf, len, dst_cap) };
vec
}

320
library/alloc/src/vec/mod.rs
View File

@ -603,15 +603,116 @@ impl<T> Vec<T> {
unsafe { Self::from_raw_parts_in(ptr, length, capacity, Global) }
}
/// A convenience method for hoisting the non-null precondition out of [`Vec::from_raw_parts`].
#[doc(alias = "from_non_null_parts")]
/// Creates a `Vec<T>` directly from a `NonNull` pointer, a length, and a capacity.
///
/// # Safety
///
/// See [`Vec::from_raw_parts`].
/// This is highly unsafe, due to the number of invariants that aren't
/// checked:
///
/// * `ptr` must have been allocated using the global allocator, such as via
/// the [`alloc::alloc`] function.
/// * `T` needs to have the same alignment as what `ptr` was allocated with.
/// (`T` having a less strict alignment is not sufficient, the alignment really
/// needs to be equal to satisfy the [`dealloc`] requirement that memory must be
/// allocated and deallocated with the same layout.)
/// * The size of `T` times the `capacity` (ie. the allocated size in bytes) needs
/// to be the same size as the pointer was allocated with. (Because similar to
/// alignment, [`dealloc`] must be called with the same layout `size`.)
/// * `length` needs to be less than or equal to `capacity`.
/// * The first `length` values must be properly initialized values of type `T`.
/// * `capacity` needs to be the capacity that the pointer was allocated with.
/// * The allocated size in bytes must be no larger than `isize::MAX`.
/// See the safety documentation of [`pointer::offset`].
///
/// These requirements are always upheld by any `ptr` that has been allocated
/// via `Vec<T>`. Other allocation sources are allowed if the invariants are
/// upheld.
///
/// Violating these may cause problems like corrupting the allocator's
/// internal data structures. For example it is normally **not** safe
/// to build a `Vec<u8>` from a pointer to a C `char` array with length
/// `size_t`, doing so is only safe if the array was initially allocated by
/// a `Vec` or `String`.
/// It's also not safe to build one from a `Vec<u16>` and its length, because
/// the allocator cares about the alignment, and these two types have different
/// alignments. The buffer was allocated with alignment 2 (for `u16`), but after
/// turning it into a `Vec<u8>` it'll be deallocated with alignment 1. To avoid
/// these issues, it is often preferable to do casting/transmuting using
/// [`NonNull::slice_from_raw_parts`] instead.
///
/// The ownership of `ptr` is effectively transferred to the
/// `Vec<T>` which may then deallocate, reallocate or change the
/// contents of memory pointed to by the pointer at will. Ensure
/// that nothing else uses the pointer after calling this
/// function.
///
/// [`String`]: crate::string::String
/// [`alloc::alloc`]: crate::alloc::alloc
/// [`dealloc`]: crate::alloc::GlobalAlloc::dealloc
///
/// # Examples
///
/// ```
/// #![feature(box_vec_non_null)]
///
/// use std::ptr::NonNull;
/// use std::mem;
///
/// let v = vec![1, 2, 3];
///
// FIXME Update this when vec_into_raw_parts is stabilized
/// // Prevent running `v`'s destructor so we are in complete control
/// // of the allocation.
/// let mut v = mem::ManuallyDrop::new(v);
///
/// // Pull out the various important pieces of information about `v`
/// let p = unsafe { NonNull::new_unchecked(v.as_mut_ptr()) };
/// let len = v.len();
/// let cap = v.capacity();
///
/// unsafe {
/// // Overwrite memory with 4, 5, 6
/// for i in 0..len {
/// p.add(i).write(4 + i);
/// }
///
/// // Put everything back together into a Vec
/// let rebuilt = Vec::from_parts(p, len, cap);
/// assert_eq!(rebuilt, [4, 5, 6]);
/// }
/// ```
///
/// Using memory that was allocated elsewhere:
///
/// ```rust
/// #![feature(box_vec_non_null)]
///
/// use std::alloc::{alloc, Layout};
/// use std::ptr::NonNull;
///
/// fn main() {
/// let layout = Layout::array::<u32>(16).expect("overflow cannot happen");
///
/// let vec = unsafe {
/// let Some(mem) = NonNull::new(alloc(layout).cast::<u32>()) else {
/// return;
/// };
///
/// mem.write(1_000_000);
///
/// Vec::from_parts(mem, 1, 16)
/// };
///
/// assert_eq!(vec, &[1_000_000]);
/// assert_eq!(vec.capacity(), 16);
/// }
/// ```
#[inline]
#[cfg(not(no_global_oom_handling))] // required by tests/run-make/alloc-no-oom-handling
pub(crate) unsafe fn from_nonnull(ptr: NonNull<T>, length: usize, capacity: usize) -> Self {
unsafe { Self::from_nonnull_in(ptr, length, capacity, Global) }
#[unstable(feature = "box_vec_non_null", reason = "new API", issue = "130364")]
pub unsafe fn from_parts(ptr: NonNull<T>, length: usize, capacity: usize) -> Self {
unsafe { Self::from_parts_in(ptr, length, capacity, Global) }
}
}
@ -830,19 +931,119 @@ impl<T, A: Allocator> Vec<T, A> {
unsafe { Vec { buf: RawVec::from_raw_parts_in(ptr, capacity, alloc), len: length } }
}
/// A convenience method for hoisting the non-null precondition out of [`Vec::from_raw_parts_in`].
#[doc(alias = "from_non_null_parts_in")]
/// Creates a `Vec<T, A>` directly from a `NonNull` pointer, a length, a capacity,
/// and an allocator.
///
/// # Safety
///
/// See [`Vec::from_raw_parts_in`].
/// This is highly unsafe, due to the number of invariants that aren't
/// checked:
///
/// * `ptr` must be [*currently allocated*] via the given allocator `alloc`.
/// * `T` needs to have the same alignment as what `ptr` was allocated with.
/// (`T` having a less strict alignment is not sufficient, the alignment really
/// needs to be equal to satisfy the [`dealloc`] requirement that memory must be
/// allocated and deallocated with the same layout.)
/// * The size of `T` times the `capacity` (ie. the allocated size in bytes) needs
/// to be the same size as the pointer was allocated with. (Because similar to
/// alignment, [`dealloc`] must be called with the same layout `size`.)
/// * `length` needs to be less than or equal to `capacity`.
/// * The first `length` values must be properly initialized values of type `T`.
/// * `capacity` needs to [*fit*] the layout size that the pointer was allocated with.
/// * The allocated size in bytes must be no larger than `isize::MAX`.
/// See the safety documentation of [`pointer::offset`].
///
/// These requirements are always upheld by any `ptr` that has been allocated
/// via `Vec<T, A>`. Other allocation sources are allowed if the invariants are
/// upheld.
///
/// Violating these may cause problems like corrupting the allocator's
/// internal data structures. For example it is **not** safe
/// to build a `Vec<u8>` from a pointer to a C `char` array with length `size_t`.
/// It's also not safe to build one from a `Vec<u16>` and its length, because
/// the allocator cares about the alignment, and these two types have different
/// alignments. The buffer was allocated with alignment 2 (for `u16`), but after
/// turning it into a `Vec<u8>` it'll be deallocated with alignment 1.
///
/// The ownership of `ptr` is effectively transferred to the
/// `Vec<T>` which may then deallocate, reallocate or change the
/// contents of memory pointed to by the pointer at will. Ensure
/// that nothing else uses the pointer after calling this
/// function.
///
/// [`String`]: crate::string::String
/// [`dealloc`]: crate::alloc::GlobalAlloc::dealloc
/// [*currently allocated*]: crate::alloc::Allocator#currently-allocated-memory
/// [*fit*]: crate::alloc::Allocator#memory-fitting
///
/// # Examples
///
/// ```
/// #![feature(allocator_api, box_vec_non_null)]
///
/// use std::alloc::System;
///
/// use std::ptr::NonNull;
/// use std::mem;
///
/// let mut v = Vec::with_capacity_in(3, System);
/// v.push(1);
/// v.push(2);
/// v.push(3);
///
// FIXME Update this when vec_into_raw_parts is stabilized
/// // Prevent running `v`'s destructor so we are in complete control
/// // of the allocation.
/// let mut v = mem::ManuallyDrop::new(v);
///
/// // Pull out the various important pieces of information about `v`
/// let p = unsafe { NonNull::new_unchecked(v.as_mut_ptr()) };
/// let len = v.len();
/// let cap = v.capacity();
/// let alloc = v.allocator();
///
/// unsafe {
/// // Overwrite memory with 4, 5, 6
/// for i in 0..len {
/// p.add(i).write(4 + i);
/// }
///
/// // Put everything back together into a Vec
/// let rebuilt = Vec::from_parts_in(p, len, cap, alloc.clone());
/// assert_eq!(rebuilt, [4, 5, 6]);
/// }
/// ```
///
/// Using memory that was allocated elsewhere:
///
/// ```rust
/// #![feature(allocator_api, box_vec_non_null)]
///
/// use std::alloc::{AllocError, Allocator, Global, Layout};
///
/// fn main() {
/// let layout = Layout::array::<u32>(16).expect("overflow cannot happen");
///
/// let vec = unsafe {
/// let mem = match Global.allocate(layout) {
/// Ok(mem) => mem.cast::<u32>(),
/// Err(AllocError) => return,
/// };
///
/// mem.write(1_000_000);
///
/// Vec::from_parts_in(mem, 1, 16, Global)
/// };
///
/// assert_eq!(vec, &[1_000_000]);
/// assert_eq!(vec.capacity(), 16);
/// }
/// ```
#[inline]
#[cfg(not(no_global_oom_handling))] // required by tests/run-make/alloc-no-oom-handling
pub(crate) unsafe fn from_nonnull_in(
ptr: NonNull<T>,
length: usize,
capacity: usize,
alloc: A,
) -> Self {
#[unstable(feature = "allocator_api", reason = "new API", issue = "32838")]
// #[unstable(feature = "box_vec_non_null", issue = "130364")]
pub unsafe fn from_parts_in(ptr: NonNull<T>, length: usize, capacity: usize, alloc: A) -> Self {
unsafe { Vec { buf: RawVec::from_nonnull_in(ptr, capacity, alloc), len: length } }
}
@ -885,6 +1086,49 @@ impl<T, A: Allocator> Vec<T, A> {
(me.as_mut_ptr(), me.len(), me.capacity())
}
#[doc(alias = "into_non_null_parts")]
/// Decomposes a `Vec<T>` into its raw components: `(NonNull pointer, length, capacity)`.
///
/// Returns the `NonNull` pointer to the underlying data, the length of
/// the vector (in elements), and the allocated capacity of the
/// data (in elements). These are the same arguments in the same
/// order as the arguments to [`from_parts`].
///
/// After calling this function, the caller is responsible for the
/// memory previously managed by the `Vec`. The only way to do
/// this is to convert the `NonNull` pointer, length, and capacity back
/// into a `Vec` with the [`from_parts`] function, allowing
/// the destructor to perform the cleanup.
///
/// [`from_parts`]: Vec::from_parts
///
/// # Examples
///
/// ```
/// #![feature(vec_into_raw_parts, box_vec_non_null)]
///
/// let v: Vec<i32> = vec![-1, 0, 1];
///
/// let (ptr, len, cap) = v.into_parts();
///
/// let rebuilt = unsafe {
/// // We can now make changes to the components, such as
/// // transmuting the raw pointer to a compatible type.
/// let ptr = ptr.cast::<u32>();
///
/// Vec::from_parts(ptr, len, cap)
/// };
/// assert_eq!(rebuilt, [4294967295, 0, 1]);
/// ```
#[must_use = "losing the pointer will leak memory"]
#[unstable(feature = "box_vec_non_null", reason = "new API", issue = "130364")]
// #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
pub fn into_parts(self) -> (NonNull<T>, usize, usize) {
let (ptr, len, capacity) = self.into_raw_parts();
// SAFETY: A `Vec` always has a non-null pointer.
(unsafe { NonNull::new_unchecked(ptr) }, len, capacity)
}
/// Decomposes a `Vec<T>` into its raw components: `(pointer, length, capacity, allocator)`.
///
/// Returns the raw pointer to the underlying data, the length of the vector (in elements),
@ -934,6 +1178,54 @@ impl<T, A: Allocator> Vec<T, A> {
(ptr, len, capacity, alloc)
}
#[doc(alias = "into_non_null_parts_with_alloc")]
/// Decomposes a `Vec<T>` into its raw components: `(NonNull pointer, length, capacity, allocator)`.
///
/// Returns the `NonNull` pointer to the underlying data, the length of the vector (in elements),
/// the allocated capacity of the data (in elements), and the allocator. These are the same
/// arguments in the same order as the arguments to [`from_parts_in`].
///
/// After calling this function, the caller is responsible for the
/// memory previously managed by the `Vec`. The only way to do
/// this is to convert the `NonNull` pointer, length, and capacity back
/// into a `Vec` with the [`from_parts_in`] function, allowing
/// the destructor to perform the cleanup.
///
/// [`from_parts_in`]: Vec::from_parts_in
///
/// # Examples
///
/// ```
/// #![feature(allocator_api, vec_into_raw_parts, box_vec_non_null)]
///
/// use std::alloc::System;
///
/// let mut v: Vec<i32, System> = Vec::new_in(System);
/// v.push(-1);
/// v.push(0);
/// v.push(1);
///
/// let (ptr, len, cap, alloc) = v.into_parts_with_alloc();
///
/// let rebuilt = unsafe {
/// // We can now make changes to the components, such as
/// // transmuting the raw pointer to a compatible type.
/// let ptr = ptr.cast::<u32>();
///
/// Vec::from_parts_in(ptr, len, cap, alloc)
/// };
/// assert_eq!(rebuilt, [4294967295, 0, 1]);
/// ```
#[must_use = "losing the pointer will leak memory"]
#[unstable(feature = "allocator_api", issue = "32838")]
// #[unstable(feature = "box_vec_non_null", reason = "new API", issue = "130364")]
// #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
pub fn into_parts_with_alloc(self) -> (NonNull<T>, usize, usize, A) {
let (ptr, len, capacity, alloc) = self.into_raw_parts_with_alloc();
// SAFETY: A `Vec` always has a non-null pointer.
(unsafe { NonNull::new_unchecked(ptr) }, len, capacity, alloc)
}
/// Returns the total number of elements the vector can hold without
/// reallocating.
///

2
library/alloc/src/vec/spec_from_iter.rs
View File

@ -51,7 +51,7 @@ impl<T> SpecFromIter<T, IntoIter<T>> for Vec<T> {
if has_advanced {
ptr::copy(it.ptr.as_ptr(), it.buf.as_ptr(), it.len());
}
return Vec::from_nonnull(it.buf, it.len(), it.cap);
return Vec::from_parts(it.buf, it.len(), it.cap);
}
}

4
tests/ui/privacy/suggest-box-new.stderr
View File

@ -44,7 +44,7 @@ LL | wtf: Some(Box::new_zeroed()),
| ~~~~~~~~~~~~~~
LL | wtf: Some(Box::new_in(_, _)),
| ~~~~~~~~~~~~~~
and 10 other candidates
and 12 other candidates
help: consider using the `Default` trait
|
LL | wtf: Some(<Box as std::default::Default>::default()),
@ -89,7 +89,7 @@ LL | let _ = Box::new_zeroed();
| ~~~~~~~~~~~~~~
LL | let _ = Box::new_in(_, _);
| ~~~~~~~~~~~~~~
and 10 other candidates
and 12 other candidates
help: consider using the `Default` trait
|
LL | let _ = <Box as std::default::Default>::default();

2
tests/ui/suggestions/deref-path-method.stderr
View File

@ -9,7 +9,7 @@ note: if you're trying to build a new `Vec<_, _>` consider using one of the foll
Vec::<T>::with_capacity
Vec::<T>::try_with_capacity
Vec::<T>::from_raw_parts
and 4 others
and 6 others
--> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
help: the function `contains` is implemented on `[_]`
|

2
tests/ui/ufcs/bad-builder.stderr
View File

@ -9,7 +9,7 @@ note: if you're trying to build a new `Vec<Q>` consider using one of the followi
Vec::<T>::with_capacity
Vec::<T>::try_with_capacity
Vec::<T>::from_raw_parts
and 4 others
and 6 others
--> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
help: there is an associated function `new` with a similar name
|