Rollup merge of rust-lang#148827 - GoldsteinE:stabilize-vec-into-raw-parts, r=Mark-Simulacrum

Stabilize vec_into_raw_parts

This stabilizes `Vec::into_raw_parts()` and `String::into_raw_parts()` per FCP in rust-lang#65816 (comment). While this _does not_ stabilize `Vec::into_parts()`, I fixed up the examples that said they were waiting for `vec_into_raw_parts`. As `Vec::from_parts()` and `Vec::into_parts()` are covered by the same feature `box_vec_non_null`, any doctest that uses `Vec::from_parts()` can also use `Vec::into_parts()` (and same for allocator-aware versions).

Closes rust-lang#65816

`@rustbot` modify labels: +T-libs-api

Author: Zalathar

library/alloc/src/string.rs

@@ -265,18 +265,11 @@ use crate::vec::{self, Vec};
 /// You can look at these with the [`as_ptr`], [`len`], and [`capacity`]
 /// methods:
 ///
-// FIXME Update this when vec_into_raw_parts is stabilized
 /// ```
-/// use std::mem;
-///
 /// let story = String::from("Once upon a time...");
 ///
-/// // Prevent automatically dropping the String's data
-/// let mut story = mem::ManuallyDrop::new(story);
-///
-/// let ptr = story.as_mut_ptr();
-/// let len = story.len();
-/// let capacity = story.capacity();
+/// // Deconstruct the String into parts.
+/// let (ptr, len, capacity) = story.into_raw_parts();
 ///
 /// // story has nineteen bytes
 /// assert_eq!(19, len);
@@ -932,7 +925,6 @@ impl String {
     /// # Examples
     ///
     /// ```
-    /// #![feature(vec_into_raw_parts)]
     /// let s = String::from("hello");
     ///
     /// let (ptr, len, cap) = s.into_raw_parts();
@@ -941,7 +933,7 @@ impl String {
     /// assert_eq!(rebuilt, "hello");
     /// ```
     #[must_use = "losing the pointer will leak memory"]
-    #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
+    #[stable(feature = "vec_into_raw_parts", since = "CURRENT_RUSTC_VERSION")]
     pub fn into_raw_parts(self) -> (*mut u8, usize, usize) {
         self.vec.into_raw_parts()
     }
@@ -970,19 +962,12 @@ impl String {
     ///
     /// # Examples
     ///
-    // FIXME Update this when vec_into_raw_parts is stabilized
     /// ```
-    /// use std::mem;
-    ///
     /// unsafe {
     ///     let s = String::from("hello");
     ///
-    ///     // Prevent automatically dropping the String's data
-    ///     let mut s = mem::ManuallyDrop::new(s);
-    ///
-    ///     let ptr = s.as_mut_ptr();
-    ///     let len = s.len();
-    ///     let capacity = s.capacity();
+    ///     // Deconstruct the String into parts.
+    ///     let (ptr, len, capacity) = s.into_raw_parts();
     ///
     ///     let s = String::from_raw_parts(ptr, len, capacity);
     ///

library/alloc/src/vec/mod.rs

@@ -592,21 +592,13 @@ impl<T> Vec<T> {
     ///
     /// # Examples
     ///
-    // FIXME Update this when vec_into_raw_parts is stabilized
     /// ```
     /// use std::ptr;
-    /// use std::mem;
     ///
     /// let v = vec![1, 2, 3];
     ///
-    /// // 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 = v.as_mut_ptr();
-    /// let len = v.len();
-    /// let cap = v.capacity();
+    /// // Deconstruct the vector into parts.
+    /// let (p, len, cap) = v.into_raw_parts();
     ///
     /// unsafe {
     ///     // Overwrite memory with 4, 5, 6
@@ -700,23 +692,13 @@ impl<T> Vec<T> {
     ///
     /// # Examples
     ///
-    // FIXME Update this when vec_into_raw_parts is stabilized
     /// ```
     /// #![feature(box_vec_non_null)]
     ///
-    /// use std::ptr::NonNull;
-    /// use std::mem;
-    ///
     /// let v = vec![1, 2, 3];
     ///
-    /// // 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();
+    /// // Deconstruct the vector into parts.
+    /// let (p, len, cap) = v.into_parts();
     ///
     /// unsafe {
     ///     // Overwrite memory with 4, 5, 6
@@ -783,7 +765,6 @@ impl<T> Vec<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(vec_into_raw_parts)]
     /// let v: Vec<i32> = vec![-1, 0, 1];
     ///
     /// let (ptr, len, cap) = v.into_raw_parts();
@@ -798,7 +779,7 @@ impl<T> Vec<T> {
     /// assert_eq!(rebuilt, [4294967295, 0, 1]);
     /// ```
     #[must_use = "losing the pointer will leak memory"]
-    #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
+    #[stable(feature = "vec_into_raw_parts", since = "CURRENT_RUSTC_VERSION")]
     pub fn into_raw_parts(self) -> (*mut T, usize, usize) {
         let mut me = ManuallyDrop::new(self);
         (me.as_mut_ptr(), me.len(), me.capacity())
@@ -823,7 +804,7 @@ impl<T> Vec<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(vec_into_raw_parts, box_vec_non_null)]
+    /// #![feature(box_vec_non_null)]
     ///
     /// let v: Vec<i32> = vec![-1, 0, 1];
     ///
@@ -840,7 +821,6 @@ impl<T> Vec<T> {
     /// ```
     #[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.
@@ -996,29 +976,20 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// # Examples
     ///
-    // FIXME Update this when vec_into_raw_parts is stabilized
     /// ```
     /// #![feature(allocator_api)]
     ///
     /// use std::alloc::System;
     ///
     /// use std::ptr;
-    /// use std::mem;
     ///
     /// let mut v = Vec::with_capacity_in(3, System);
     /// v.push(1);
     /// v.push(2);
     /// v.push(3);
     ///
-    /// // 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 = v.as_mut_ptr();
-    /// let len = v.len();
-    /// let cap = v.capacity();
-    /// let alloc = v.allocator();
+    /// // Deconstruct the vector into parts.
+    /// let (p, len, cap, alloc) = v.into_raw_parts_with_alloc();
     ///
     /// unsafe {
     ///     // Overwrite memory with 4, 5, 6
@@ -1116,29 +1087,18 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// # Examples
     ///
-    // FIXME Update this when vec_into_raw_parts is stabilized
     /// ```
     /// #![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);
     ///
-    /// // 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();
+    /// // Deconstruct the vector into parts.
+    /// let (p, len, cap, alloc) = v.into_parts_with_alloc();
     ///
     /// unsafe {
     ///     // Overwrite memory with 4, 5, 6
@@ -1206,7 +1166,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, vec_into_raw_parts)]
+    /// #![feature(allocator_api)]
     ///
     /// use std::alloc::System;
     ///
@@ -1228,7 +1188,6 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[must_use = "losing the pointer will leak memory"]
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "vec_into_raw_parts", reason = "new API", issue = "65816")]
     pub fn into_raw_parts_with_alloc(self) -> (*mut T, usize, usize, A) {
         let mut me = ManuallyDrop::new(self);
         let len = me.len();
@@ -1256,7 +1215,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(allocator_api, vec_into_raw_parts, box_vec_non_null)]
+    /// #![feature(allocator_api, box_vec_non_null)]
     ///
     /// use std::alloc::System;
     ///
@@ -1279,7 +1238,6 @@ impl<T, A: Allocator> Vec<T, A> {
     #[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.

library/core/src/intrinsics/mod.rs

@@ -769,13 +769,9 @@ pub const fn forget<T: ?Sized>(_: T);
 /// // in terms of converting the original inner type (`&i32`) to the new one (`Option<&i32>`),
 /// // this has all the same caveats. Besides the information provided above, also consult the
 /// // [`from_raw_parts`] documentation.
+/// let (ptr, len, capacity) = v_clone.into_raw_parts();
 /// let v_from_raw = unsafe {
-// FIXME Update this when vec_into_raw_parts is stabilized
-///     // Ensure the original vector is not dropped.
-///     let mut v_clone = std::mem::ManuallyDrop::new(v_clone);
-///     Vec::from_raw_parts(v_clone.as_mut_ptr() as *mut Option<&i32>,
-///                         v_clone.len(),
-///                         v_clone.capacity())
+///     Vec::from_raw_parts(ptr.cast::<*mut Option<&i32>>(), len, capacity)
 /// };
 /// ```
 ///

library/std/src/lib.rs

@@ -382,7 +382,6 @@
 #![feature(try_reserve_kind)]
 #![feature(try_with_capacity)]
 #![feature(unique_rc_arc)]
-#![feature(vec_into_raw_parts)]
 #![feature(wtf8_internals)]
 // tidy-alphabetical-end
 //