Merge from rustc

1 files changed, 82 insertions, 11 deletions

diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index 1984cfeefc1..07a1bd49321 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -478,6 +478,7 @@ impl<T> Vec<T> {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     #[cfg_attr(not(test), rustc_diagnostic_item = "vec_with_capacity")]
+    #[track_caller]
     pub fn with_capacity(capacity: usize) -> Self {
         Self::with_capacity_in(capacity, Global)
     }
@@ -797,6 +798,7 @@ impl<T, A: Allocator> Vec<T, A> {
     #[cfg(not(no_global_oom_handling))]
     #[inline]
     #[unstable(feature = "allocator_api", issue = "32838")]
+    #[track_caller]
     pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
         Vec { buf: RawVec::with_capacity_in(capacity, alloc), len: 0 }
     }
@@ -1240,7 +1242,8 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn capacity(&self) -> usize {
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
+    pub const fn capacity(&self) -> usize {
         self.buf.capacity()
     }
 
@@ -1263,6 +1266,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[track_caller]
     pub fn reserve(&mut self, additional: usize) {
         self.buf.reserve(self.len, additional);
     }
@@ -1293,6 +1297,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[track_caller]
     pub fn reserve_exact(&mut self, additional: usize) {
         self.buf.reserve_exact(self.len, additional);
     }
@@ -1396,6 +1401,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[track_caller]
     #[inline]
     pub fn shrink_to_fit(&mut self) {
         // The capacity is never less than the length, and there's nothing to do when
@@ -1426,6 +1432,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[stable(feature = "shrink_to", since = "1.56.0")]
+    #[track_caller]
     pub fn shrink_to(&mut self, min_capacity: usize) {
         if self.capacity() > min_capacity {
             self.buf.shrink_to_fit(cmp::max(self.len, min_capacity));
@@ -1459,6 +1466,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[track_caller]
     pub fn into_boxed_slice(mut self) -> Box<[T], A> {
         unsafe {
             self.shrink_to_fit();
@@ -1548,8 +1556,22 @@ impl<T, A: Allocator> Vec<T, A> {
     #[inline]
     #[stable(feature = "vec_as_slice", since = "1.7.0")]
     #[cfg_attr(not(test), rustc_diagnostic_item = "vec_as_slice")]
-    pub fn as_slice(&self) -> &[T] {
-        self
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
+    pub const fn as_slice(&self) -> &[T] {
+        // SAFETY: `slice::from_raw_parts` requires pointee is a contiguous, aligned buffer of size
+        // `len` containing properly-initialized `T`s. Data must not be mutated for the returned
+        // lifetime. Further, `len * mem::size_of::<T>` <= `ISIZE::MAX`, and allocation does not
+        // "wrap" through overflowing memory addresses.
+        //
+        // * Vec API guarantees that self.buf:
+        //      * contains only properly-initialized items within 0..len
+        //      * is aligned, contiguous, and valid for `len` reads
+        //      * obeys size and address-wrapping constraints
+        //
+        // * We only construct `&mut` references to `self.buf` through `&mut self` methods; borrow-
+        //   check ensures that it is not possible to mutably alias `self.buf` within the
+        //   returned lifetime.
+        unsafe { slice::from_raw_parts(self.as_ptr(), self.len) }
     }
 
     /// Extracts a mutable slice of the entire vector.
@@ -1566,8 +1588,22 @@ impl<T, A: Allocator> Vec<T, A> {
     #[inline]
     #[stable(feature = "vec_as_slice", since = "1.7.0")]
     #[cfg_attr(not(test), rustc_diagnostic_item = "vec_as_mut_slice")]
-    pub fn as_mut_slice(&mut self) -> &mut [T] {
-        self
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
+    pub const fn as_mut_slice(&mut self) -> &mut [T] {
+        // SAFETY: `slice::from_raw_parts_mut` requires pointee is a contiguous, aligned buffer of
+        // size `len` containing properly-initialized `T`s. Data must not be accessed through any
+        // other pointer for the returned lifetime. Further, `len * mem::size_of::<T>` <=
+        // `ISIZE::MAX` and allocation does not "wrap" through overflowing memory addresses.
+        //
+        // * Vec API guarantees that self.buf:
+        //      * contains only properly-initialized items within 0..len
+        //      * is aligned, contiguous, and valid for `len` reads
+        //      * obeys size and address-wrapping constraints
+        //
+        // * We only construct references to `self.buf` through `&self` and `&mut self` methods;
+        //   borrow-check ensures that it is not possible to construct a reference to `self.buf`
+        //   within the returned lifetime.
+        unsafe { slice::from_raw_parts_mut(self.as_mut_ptr(), self.len) }
     }
 
     /// Returns a raw pointer to the vector's buffer, or a dangling raw pointer
@@ -1624,9 +1660,10 @@ impl<T, A: Allocator> Vec<T, A> {
     /// [`as_ptr`]: Vec::as_ptr
     /// [`as_non_null`]: Vec::as_non_null
     #[stable(feature = "vec_as_ptr", since = "1.37.0")]
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
     #[rustc_never_returns_null_ptr]
     #[inline]
-    pub fn as_ptr(&self) -> *const T {
+    pub const fn as_ptr(&self) -> *const T {
         // We shadow the slice method of the same name to avoid going through
         // `deref`, which creates an intermediate reference.
         self.buf.ptr()
@@ -1685,9 +1722,10 @@ impl<T, A: Allocator> Vec<T, A> {
     /// [`as_ptr`]: Vec::as_ptr
     /// [`as_non_null`]: Vec::as_non_null
     #[stable(feature = "vec_as_ptr", since = "1.37.0")]
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
     #[rustc_never_returns_null_ptr]
     #[inline]
-    pub fn as_mut_ptr(&mut self) -> *mut T {
+    pub const fn as_mut_ptr(&mut self) -> *mut T {
         // We shadow the slice method of the same name to avoid going through
         // `deref_mut`, which creates an intermediate reference.
         self.buf.ptr()
@@ -1927,6 +1965,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// the insertion index is 0.
     #[cfg(not(no_global_oom_handling))]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[track_caller]
     pub fn insert(&mut self, index: usize, element: T) {
         #[cold]
         #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
@@ -2366,6 +2405,7 @@ impl<T, A: Allocator> Vec<T, A> {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_confusables("push_back", "put", "append")]
+    #[track_caller]
     pub fn push(&mut self, value: T) {
         // Inform codegen that the length does not change across grow_one().
         let len = self.len;
@@ -2507,6 +2547,7 @@ impl<T, A: Allocator> Vec<T, A> {
     #[cfg(not(no_global_oom_handling))]
     #[inline]
     #[stable(feature = "append", since = "1.4.0")]
+    #[track_caller]
     pub fn append(&mut self, other: &mut Self) {
         unsafe {
             self.append_elements(other.as_slice() as _);
@@ -2517,6 +2558,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// Appends elements to `self` from other buffer.
     #[cfg(not(no_global_oom_handling))]
     #[inline]
+    #[track_caller]
     unsafe fn append_elements(&mut self, other: *const [T]) {
         let count = unsafe { (*other).len() };
         self.reserve(count);
@@ -2628,8 +2670,9 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
     #[rustc_confusables("length", "size")]
-    pub fn len(&self) -> usize {
+    pub const fn len(&self) -> usize {
         self.len
     }
 
@@ -2646,7 +2689,8 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[cfg_attr(not(test), rustc_diagnostic_item = "vec_is_empty")]
-    pub fn is_empty(&self) -> bool {
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
+    pub const fn is_empty(&self) -> bool {
         self.len() == 0
     }
 
@@ -2678,6 +2722,7 @@ impl<T, A: Allocator> Vec<T, A> {
     #[inline]
     #[must_use = "use `.truncate()` if you don't need the other half"]
     #[stable(feature = "split_off", since = "1.4.0")]
+    #[track_caller]
     pub fn split_off(&mut self, at: usize) -> Self
     where
         A: Clone,
@@ -2735,6 +2780,7 @@ impl<T, A: Allocator> Vec<T, A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[stable(feature = "vec_resize_with", since = "1.33.0")]
+    #[track_caller]
     pub fn resize_with<F>(&mut self, new_len: usize, f: F)
     where
         F: FnMut() -> T,
@@ -2940,6 +2986,7 @@ impl<T: Clone, A: Allocator> Vec<T, A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[stable(feature = "vec_resize", since = "1.5.0")]
+    #[track_caller]
     pub fn resize(&mut self, new_len: usize, value: T) {
         let len = self.len();
 
@@ -2971,6 +3018,7 @@ impl<T: Clone, A: Allocator> Vec<T, A> {
     /// [`extend`]: Vec::extend
     #[cfg(not(no_global_oom_handling))]
     #[stable(feature = "vec_extend_from_slice", since = "1.6.0")]
+    #[track_caller]
     pub fn extend_from_slice(&mut self, other: &[T]) {
         self.spec_extend(other.iter())
     }
@@ -2998,6 +3046,7 @@ impl<T: Clone, A: Allocator> Vec<T, A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[stable(feature = "vec_extend_from_within", since = "1.53.0")]
+    #[track_caller]
     pub fn extend_from_within<R>(&mut self, src: R)
     where
         R: RangeBounds<usize>,
@@ -3058,6 +3107,7 @@ impl<T, A: Allocator, const N: usize> Vec<[T; N], A> {
 
 impl<T: Clone, A: Allocator> Vec<T, A> {
     #[cfg(not(no_global_oom_handling))]
+    #[track_caller]
     /// Extend the vector by `n` clones of value.
     fn extend_with(&mut self, n: usize, value: T) {
         self.reserve(n);
@@ -3118,6 +3168,7 @@ impl<T: PartialEq, A: Allocator> Vec<T, A> {
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[cfg_attr(not(test), rustc_diagnostic_item = "vec_from_elem")]
+#[track_caller]
 pub fn from_elem<T: Clone>(elem: T, n: usize) -> Vec<T> {
     <T as SpecFromElem>::from_elem(elem, n, Global)
 }
@@ -3125,6 +3176,7 @@ pub fn from_elem<T: Clone>(elem: T, n: usize) -> Vec<T> {
 #[doc(hidden)]
 #[cfg(not(no_global_oom_handling))]
 #[unstable(feature = "allocator_api", issue = "32838")]
+#[track_caller]
 pub fn from_elem_in<T: Clone, A: Allocator>(elem: T, n: usize, alloc: A) -> Vec<T, A> {
     <T as SpecFromElem>::from_elem(elem, n, alloc)
 }
@@ -3197,7 +3249,7 @@ impl<T, A: Allocator> ops::Deref for Vec<T, A> {
 
     #[inline]
     fn deref(&self) -> &[T] {
-        unsafe { slice::from_raw_parts(self.as_ptr(), self.len) }
+        self.as_slice()
     }
 }
 
@@ -3205,7 +3257,7 @@ impl<T, A: Allocator> ops::Deref for Vec<T, A> {
 impl<T, A: Allocator> ops::DerefMut for Vec<T, A> {
     #[inline]
     fn deref_mut(&mut self) -> &mut [T] {
-        unsafe { slice::from_raw_parts_mut(self.as_mut_ptr(), self.len) }
+        self.as_mut_slice()
     }
 }
 
@@ -3216,6 +3268,7 @@ unsafe impl<T, A: Allocator> ops::DerefPure for Vec<T, A> {}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Clone, A: Allocator + Clone> Clone for Vec<T, A> {
     #[cfg(not(test))]
+    #[track_caller]
     fn clone(&self) -> Self {
         let alloc = self.allocator().clone();
         <[T]>::to_vec_in(&**self, alloc)
@@ -3253,6 +3306,7 @@ impl<T: Clone, A: Allocator + Clone> Clone for Vec<T, A> {
     /// // And no reallocation occurred
     /// assert_eq!(yp, y.as_ptr());
     /// ```
+    #[track_caller]
     fn clone_from(&mut self, source: &Self) {
         crate::slice::SpecCloneIntoVec::clone_into(source.as_slice(), self);
     }
@@ -3351,6 +3405,7 @@ impl<T, I: SliceIndex<[T]>, A: Allocator> IndexMut<I> for Vec<T, A> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> FromIterator<T> for Vec<T> {
     #[inline]
+    #[track_caller]
     fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Vec<T> {
         <Self as SpecFromIter<T, I::IntoIter>>::from_iter(iter.into_iter())
     }
@@ -3419,16 +3474,19 @@ impl<'a, T, A: Allocator> IntoIterator for &'a mut Vec<T, A> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T, A: Allocator> Extend<T> for Vec<T, A> {
     #[inline]
+    #[track_caller]
     fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
         <Self as SpecExtend<T, I::IntoIter>>::spec_extend(self, iter.into_iter())
     }
 
     #[inline]
+    #[track_caller]
     fn extend_one(&mut self, item: T) {
         self.push(item);
     }
 
     #[inline]
+    #[track_caller]
     fn extend_reserve(&mut self, additional: usize) {
         self.reserve(additional);
     }
@@ -3448,6 +3506,7 @@ impl<T, A: Allocator> Vec<T, A> {
     // leaf method to which various SpecFrom/SpecExtend implementations delegate when
     // they have no further optimizations to apply
     #[cfg(not(no_global_oom_handling))]
+    #[track_caller]
     fn extend_desugared<I: Iterator<Item = T>>(&mut self, mut iterator: I) {
         // This is the case for a general iterator.
         //
@@ -3475,6 +3534,7 @@ impl<T, A: Allocator> Vec<T, A> {
     // specific extend for `TrustedLen` iterators, called both by the specializations
     // and internal places where resolving specialization makes compilation slower
     #[cfg(not(no_global_oom_handling))]
+    #[track_caller]
     fn extend_trusted(&mut self, iterator: impl iter::TrustedLen<Item = T>) {
         let (low, high) = iterator.size_hint();
         if let Some(additional) = high {
@@ -3625,16 +3685,19 @@ impl<T, A: Allocator> Vec<T, A> {
 #[cfg(not(no_global_oom_handling))]
 #[stable(feature = "extend_ref", since = "1.2.0")]
 impl<'a, T: Copy + 'a, A: Allocator> Extend<&'a T> for Vec<T, A> {
+    #[track_caller]
     fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I) {
         self.spec_extend(iter.into_iter())
     }
 
     #[inline]
+    #[track_caller]
     fn extend_one(&mut self, &item: &'a T) {
         self.push(item);
     }
 
     #[inline]
+    #[track_caller]
     fn extend_reserve(&mut self, additional: usize) {
         self.reserve(additional);
     }
@@ -3745,6 +3808,7 @@ impl<T: Clone> From<&[T]> for Vec<T> {
     /// assert_eq!(Vec::from(&[1, 2, 3][..]), vec![1, 2, 3]);
     /// ```
     #[cfg(not(test))]
+    #[track_caller]
     fn from(s: &[T]) -> Vec<T> {
         s.to_vec()
     }
@@ -3765,6 +3829,7 @@ impl<T: Clone> From<&mut [T]> for Vec<T> {
     /// assert_eq!(Vec::from(&mut [1, 2, 3][..]), vec![1, 2, 3]);
     /// ```
     #[cfg(not(test))]
+    #[track_caller]
     fn from(s: &mut [T]) -> Vec<T> {
         s.to_vec()
     }
@@ -3784,6 +3849,7 @@ impl<T: Clone, const N: usize> From<&[T; N]> for Vec<T> {
     /// ```
     /// assert_eq!(Vec::from(&[1, 2, 3]), vec![1, 2, 3]);
     /// ```
+    #[track_caller]
     fn from(s: &[T; N]) -> Vec<T> {
         Self::from(s.as_slice())
     }
@@ -3799,6 +3865,7 @@ impl<T: Clone, const N: usize> From<&mut [T; N]> for Vec<T> {
     /// ```
     /// assert_eq!(Vec::from(&mut [1, 2, 3]), vec![1, 2, 3]);
     /// ```
+    #[track_caller]
     fn from(s: &mut [T; N]) -> Vec<T> {
         Self::from(s.as_mut_slice())
     }
@@ -3815,6 +3882,7 @@ impl<T, const N: usize> From<[T; N]> for Vec<T> {
     /// assert_eq!(Vec::from([1, 2, 3]), vec![1, 2, 3]);
     /// ```
     #[cfg(not(test))]
+    #[track_caller]
     fn from(s: [T; N]) -> Vec<T> {
         <[T]>::into_vec(Box::new(s))
     }
@@ -3844,6 +3912,7 @@ where
     /// let b: Cow<'_, [i32]> = Cow::Borrowed(&[1, 2, 3]);
     /// assert_eq!(Vec::from(o), Vec::from(b));
     /// ```
+    #[track_caller]
     fn from(s: Cow<'a, [T]>) -> Vec<T> {
         s.into_owned()
     }
@@ -3892,6 +3961,7 @@ impl<T, A: Allocator> From<Vec<T, A>> for Box<[T], A> {
     ///
     /// assert_eq!(Box::from(vec), vec![1, 2, 3].into_boxed_slice());
     /// ```
+    #[track_caller]
     fn from(v: Vec<T, A>) -> Self {
         v.into_boxed_slice()
     }
@@ -3907,6 +3977,7 @@ impl From<&str> for Vec<u8> {
     /// ```
     /// assert_eq!(Vec::from("123"), vec![b'1', b'2', b'3']);
     /// ```
+    #[track_caller]
     fn from(s: &str) -> Vec<u8> {
         From::from(s.as_bytes())
     }