Merge from rustc

17 files changed, 191 insertions, 418 deletions

diff --git a/library/alloc/src/borrow.rs b/library/alloc/src/borrow.rs
index f86face3f90..dbfd2e74abe 100644
--- a/library/alloc/src/borrow.rs
+++ b/library/alloc/src/borrow.rs
@@ -225,7 +225,6 @@ impl<B: ?Sized + ToOwned> Cow<'_, B> {
     /// assert!(!bull.is_borrowed());
     /// ```
     #[unstable(feature = "cow_is_borrowed", issue = "65143")]
-    #[rustc_const_unstable(feature = "const_cow_is_borrowed", issue = "65143")]
     pub const fn is_borrowed(&self) -> bool {
         match *self {
             Borrowed(_) => true,
@@ -248,7 +247,6 @@ impl<B: ?Sized + ToOwned> Cow<'_, B> {
     /// assert!(!bull.is_owned());
     /// ```
     #[unstable(feature = "cow_is_borrowed", issue = "65143")]
-    #[rustc_const_unstable(feature = "const_cow_is_borrowed", issue = "65143")]
     pub const fn is_owned(&self) -> bool {
         !self.is_borrowed()
     }
diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs
index b1759a486ac..54739c50d1d 100644
--- a/library/alloc/src/collections/vec_deque/mod.rs
+++ b/library/alloc/src/collections/vec_deque/mod.rs
@@ -103,6 +103,7 @@ pub struct VecDeque<
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Clone, A: Allocator + Clone> Clone for VecDeque<T, A> {
+    #[track_caller]
     fn clone(&self) -> Self {
         let mut deq = Self::with_capacity_in(self.len(), self.allocator().clone());
         deq.extend(self.iter().cloned());
@@ -113,6 +114,7 @@ impl<T: Clone, A: Allocator + Clone> Clone for VecDeque<T, A> {
     ///
     /// This method is preferred over simply assigning `source.clone()` to `self`,
     /// as it avoids reallocation if possible.
+    #[track_caller]
     fn clone_from(&mut self, source: &Self) {
         self.clear();
         self.extend(source.iter().cloned());
@@ -570,6 +572,7 @@ impl<T> VecDeque<T> {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
+    #[track_caller]
     pub fn with_capacity(capacity: usize) -> VecDeque<T> {
         Self::with_capacity_in(capacity, Global)
     }
@@ -625,6 +628,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// let deque: VecDeque<u32> = VecDeque::with_capacity(10);
     /// ```
     #[unstable(feature = "allocator_api", issue = "32838")]
+    #[track_caller]
     pub fn with_capacity_in(capacity: usize, alloc: A) -> VecDeque<T, A> {
         VecDeque { head: 0, len: 0, buf: RawVec::with_capacity_in(capacity, alloc) }
     }
@@ -789,6 +793,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     ///
     /// [`reserve`]: VecDeque::reserve
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[track_caller]
     pub fn reserve_exact(&mut self, additional: usize) {
         let new_cap = self.len.checked_add(additional).expect("capacity overflow");
         let old_cap = self.capacity();
@@ -818,6 +823,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert!(buf.capacity() >= 11);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[track_caller]
     pub fn reserve(&mut self, additional: usize) {
         let new_cap = self.len.checked_add(additional).expect("capacity overflow");
         let old_cap = self.capacity();
@@ -949,6 +955,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert!(buf.capacity() >= 4);
     /// ```
     #[stable(feature = "deque_extras_15", since = "1.5.0")]
+    #[track_caller]
     pub fn shrink_to_fit(&mut self) {
         self.shrink_to(0);
     }
@@ -974,6 +981,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert!(buf.capacity() >= 4);
     /// ```
     #[stable(feature = "shrink_to", since = "1.56.0")]
+    #[track_caller]
     pub fn shrink_to(&mut self, min_capacity: usize) {
         let target_cap = min_capacity.max(self.len);
 
@@ -1740,6 +1748,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert_eq!(d.front(), Some(&2));
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[track_caller]
     pub fn push_front(&mut self, value: T) {
         if self.is_full() {
             self.grow();
@@ -1767,6 +1776,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[rustc_confusables("push", "put", "append")]
+    #[track_caller]
     pub fn push_back(&mut self, value: T) {
         if self.is_full() {
             self.grow();
@@ -1876,6 +1886,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert_eq!(vec_deque, &['a', 'd', 'b', 'c']);
     /// ```
     #[stable(feature = "deque_extras_15", since = "1.5.0")]
+    #[track_caller]
     pub fn insert(&mut self, index: usize, value: T) {
         assert!(index <= self.len(), "index out of bounds");
         if self.is_full() {
@@ -1979,6 +1990,7 @@ impl<T, A: Allocator> VecDeque<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,
@@ -2045,6 +2057,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// ```
     #[inline]
     #[stable(feature = "append", since = "1.4.0")]
+    #[track_caller]
     pub fn append(&mut self, other: &mut Self) {
         if T::IS_ZST {
             self.len = self.len.checked_add(other.len).expect("capacity overflow");
@@ -2167,6 +2180,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     // be called in cold paths.
     // This may panic or abort
     #[inline(never)]
+    #[track_caller]
     fn grow(&mut self) {
         // Extend or possibly remove this assertion when valid use-cases for growing the
         // buffer without it being full emerge
@@ -2205,6 +2219,7 @@ impl<T, A: Allocator> VecDeque<T, A> {
     /// assert_eq!(buf, [5, 10, 101, 102, 103]);
     /// ```
     #[stable(feature = "vec_resize_with", since = "1.33.0")]
+    #[track_caller]
     pub fn resize_with(&mut self, new_len: usize, generator: impl FnMut() -> T) {
         let len = self.len;
 
@@ -2751,6 +2766,7 @@ impl<T: Clone, A: Allocator> VecDeque<T, A> {
     /// assert_eq!(buf, [5, 10, 20, 20, 20]);
     /// ```
     #[stable(feature = "deque_extras", since = "1.16.0")]
+    #[track_caller]
     pub fn resize(&mut self, new_len: usize, value: T) {
         if new_len > self.len() {
             let extra = new_len - self.len();
@@ -2870,6 +2886,7 @@ impl<T, A: Allocator> IndexMut<usize> for VecDeque<T, A> {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> FromIterator<T> for VecDeque<T> {
+    #[track_caller]
     fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> VecDeque<T> {
         SpecFromIter::spec_from_iter(iter.into_iter())
     }
@@ -2909,16 +2926,19 @@ impl<'a, T, A: Allocator> IntoIterator for &'a mut VecDeque<T, A> {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T, A: Allocator> Extend<T> for VecDeque<T, A> {
+    #[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, elem: T) {
         self.push_back(elem);
     }
 
     #[inline]
+    #[track_caller]
     fn extend_reserve(&mut self, additional: usize) {
         self.reserve(additional);
     }
@@ -2934,16 +2954,19 @@ impl<T, A: Allocator> Extend<T> for VecDeque<T, A> {
 
 #[stable(feature = "extend_ref", since = "1.2.0")]
 impl<'a, T: 'a + Copy, A: Allocator> Extend<&'a T> for VecDeque<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, &elem: &'a T) {
         self.push_back(elem);
     }
 
     #[inline]
+    #[track_caller]
     fn extend_reserve(&mut self, additional: usize) {
         self.reserve(additional);
     }
@@ -3041,6 +3064,7 @@ impl<T, const N: usize> From<[T; N]> for VecDeque<T> {
     /// let deq2: VecDeque<_> = [1, 2, 3, 4].into();
     /// assert_eq!(deq1, deq2);
     /// ```
+    #[track_caller]
     fn from(arr: [T; N]) -> Self {
         let mut deq = VecDeque::with_capacity(N);
         let arr = ManuallyDrop::new(arr);
diff --git a/library/alloc/src/collections/vec_deque/spec_extend.rs b/library/alloc/src/collections/vec_deque/spec_extend.rs
index a9b0fd073b5..d246385ca84 100644
--- a/library/alloc/src/collections/vec_deque/spec_extend.rs
+++ b/library/alloc/src/collections/vec_deque/spec_extend.rs
@@ -7,6 +7,7 @@ use crate::vec;
 
 // Specialization trait used for VecDeque::extend
 pub(super) trait SpecExtend<T, I> {
+    #[track_caller]
     fn spec_extend(&mut self, iter: I);
 }
 
@@ -14,6 +15,7 @@ impl<T, I, A: Allocator> SpecExtend<T, I> for VecDeque<T, A>
 where
     I: Iterator<Item = T>,
 {
+    #[track_caller]
     default fn spec_extend(&mut self, mut iter: I) {
         // This function should be the moral equivalent of:
         //
@@ -44,6 +46,7 @@ impl<T, I, A: Allocator> SpecExtend<T, I> for VecDeque<T, A>
 where
     I: TrustedLen<Item = T>,
 {
+    #[track_caller]
     default fn spec_extend(&mut self, iter: I) {
         // This is the case for a TrustedLen iterator.
         let (low, high) = iter.size_hint();
@@ -76,6 +79,7 @@ where
 }
 
 impl<T, A: Allocator> SpecExtend<T, vec::IntoIter<T>> for VecDeque<T, A> {
+    #[track_caller]
     fn spec_extend(&mut self, mut iterator: vec::IntoIter<T>) {
         let slice = iterator.as_slice();
         self.reserve(slice.len());
@@ -93,6 +97,7 @@ where
     I: Iterator<Item = &'a T>,
     T: Copy,
 {
+    #[track_caller]
     default fn spec_extend(&mut self, iterator: I) {
         self.spec_extend(iterator.copied())
     }
@@ -102,6 +107,7 @@ impl<'a, T: 'a, A: Allocator> SpecExtend<&'a T, slice::Iter<'a, T>> for VecDeque
 where
     T: Copy,
 {
+    #[track_caller]
     fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) {
         let slice = iterator.as_slice();
         self.reserve(slice.len());
diff --git a/library/alloc/src/collections/vec_deque/spec_from_iter.rs b/library/alloc/src/collections/vec_deque/spec_from_iter.rs
index 2708c7fe102..1efe84d6d7d 100644
--- a/library/alloc/src/collections/vec_deque/spec_from_iter.rs
+++ b/library/alloc/src/collections/vec_deque/spec_from_iter.rs
@@ -9,6 +9,7 @@ impl<T, I> SpecFromIter<T, I> for VecDeque<T>
 where
     I: Iterator<Item = T>,
 {
+    #[track_caller]
     default fn spec_from_iter(iterator: I) -> Self {
         // Since converting is O(1) now, just re-use the `Vec` logic for
         // anything where we can't do something extra-special for `VecDeque`,
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index ff5ddd16e07..50bf385d671 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -108,13 +108,12 @@
 #![feature(coerce_unsized)]
 #![feature(const_align_of_val)]
 #![feature(const_box)]
-#![feature(const_cow_is_borrowed)]
 #![feature(const_eval_select)]
 #![feature(const_heap)]
 #![feature(const_maybe_uninit_write)]
-#![feature(const_option)]
 #![feature(const_pin)]
 #![feature(const_size_of_val)]
+#![feature(const_vec_string_slice)]
 #![feature(core_intrinsics)]
 #![feature(deprecated_suggestion)]
 #![feature(deref_pure_trait)]
@@ -172,7 +171,6 @@
 #![feature(allow_internal_unstable)]
 #![feature(cfg_sanitize)]
 #![feature(const_precise_live_drops)]
-#![feature(const_ptr_write)]
 #![feature(const_try)]
 #![feature(decl_macro)]
 #![feature(dropck_eyepatch)]
diff --git a/library/alloc/src/raw_vec.rs b/library/alloc/src/raw_vec.rs
index 436e0596e3d..45de0617f33 100644
--- a/library/alloc/src/raw_vec.rs
+++ b/library/alloc/src/raw_vec.rs
@@ -20,6 +20,7 @@ mod tests;
 // only one location which panics rather than a bunch throughout the module.
 #[cfg(not(no_global_oom_handling))]
 #[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
+#[track_caller]
 fn capacity_overflow() -> ! {
     panic!("capacity overflow");
 }
@@ -125,6 +126,7 @@ impl<T> RawVec<T, Global> {
     #[cfg(not(any(no_global_oom_handling, test)))]
     #[must_use]
     #[inline]
+    #[track_caller]
     pub fn with_capacity(capacity: usize) -> Self {
         Self { inner: RawVecInner::with_capacity(capacity, T::LAYOUT), _marker: PhantomData }
     }
@@ -133,6 +135,7 @@ impl<T> RawVec<T, Global> {
     #[cfg(not(any(no_global_oom_handling, test)))]
     #[must_use]
     #[inline]
+    #[track_caller]
     pub fn with_capacity_zeroed(capacity: usize) -> Self {
         Self {
             inner: RawVecInner::with_capacity_zeroed_in(capacity, Global, T::LAYOUT),
@@ -145,6 +148,7 @@ impl RawVecInner<Global> {
     #[cfg(not(any(no_global_oom_handling, test)))]
     #[must_use]
     #[inline]
+    #[track_caller]
     fn with_capacity(capacity: usize, elem_layout: Layout) -> Self {
         match Self::try_allocate_in(capacity, AllocInit::Uninitialized, Global, elem_layout) {
             Ok(res) => res,
@@ -184,6 +188,7 @@ impl<T, A: Allocator> RawVec<T, A> {
     /// allocator for the returned `RawVec`.
     #[cfg(not(no_global_oom_handling))]
     #[inline]
+    #[track_caller]
     pub fn with_capacity_in(capacity: usize, alloc: A) -> Self {
         Self {
             inner: RawVecInner::with_capacity_in(capacity, alloc, T::LAYOUT),
@@ -205,6 +210,7 @@ impl<T, A: Allocator> RawVec<T, A> {
     /// of allocator for the returned `RawVec`.
     #[cfg(not(no_global_oom_handling))]
     #[inline]
+    #[track_caller]
     pub fn with_capacity_zeroed_in(capacity: usize, alloc: A) -> Self {
         Self {
             inner: RawVecInner::with_capacity_zeroed_in(capacity, alloc, T::LAYOUT),
@@ -280,7 +286,7 @@ impl<T, A: Allocator> RawVec<T, A> {
     /// `Unique::dangling()` if `capacity == 0` or `T` is zero-sized. In the former case, you must
     /// be careful.
     #[inline]
-    pub fn ptr(&self) -> *mut T {
+    pub const fn ptr(&self) -> *mut T {
         self.inner.ptr()
     }
 
@@ -293,7 +299,7 @@ impl<T, A: Allocator> RawVec<T, A> {
     ///
     /// This will always be `usize::MAX` if `T` is zero-sized.
     #[inline]
-    pub fn capacity(&self) -> usize {
+    pub const fn capacity(&self) -> usize {
         self.inner.capacity(size_of::<T>())
     }
 
@@ -324,6 +330,7 @@ impl<T, A: Allocator> RawVec<T, A> {
     /// Aborts on OOM.
     #[cfg(not(no_global_oom_handling))]
     #[inline]
+    #[track_caller]
     pub fn reserve(&mut self, len: usize, additional: usize) {
         self.inner.reserve(len, additional, T::LAYOUT)
     }
@@ -332,6 +339,7 @@ impl<T, A: Allocator> RawVec<T, A> {
     /// caller to ensure `len == self.capacity()`.
     #[cfg(not(no_global_oom_handling))]
     #[inline(never)]
+    #[track_caller]
     pub fn grow_one(&mut self) {
         self.inner.grow_one(T::LAYOUT)
     }
@@ -359,6 +367,7 @@ impl<T, A: Allocator> RawVec<T, A> {
     ///
     /// Aborts on OOM.
     #[cfg(not(no_global_oom_handling))]
+    #[track_caller]
     pub fn reserve_exact(&mut self, len: usize, additional: usize) {
         self.inner.reserve_exact(len, additional, T::LAYOUT)
     }
@@ -383,6 +392,7 @@ impl<T, A: Allocator> RawVec<T, A> {
     ///
     /// Aborts on OOM.
     #[cfg(not(no_global_oom_handling))]
+    #[track_caller]
     #[inline]
     pub fn shrink_to_fit(&mut self, cap: usize) {
         self.inner.shrink_to_fit(cap, T::LAYOUT)
@@ -408,6 +418,7 @@ impl<A: Allocator> RawVecInner<A> {
 
     #[cfg(not(no_global_oom_handling))]
     #[inline]
+    #[track_caller]
     fn with_capacity_in(capacity: usize, alloc: A, elem_layout: Layout) -> Self {
         match Self::try_allocate_in(capacity, AllocInit::Uninitialized, alloc, elem_layout) {
             Ok(this) => {
@@ -432,6 +443,7 @@ impl<A: Allocator> RawVecInner<A> {
 
     #[cfg(not(no_global_oom_handling))]
     #[inline]
+    #[track_caller]
     fn with_capacity_zeroed_in(capacity: usize, alloc: A, elem_layout: Layout) -> Self {
         match Self::try_allocate_in(capacity, AllocInit::Zeroed, alloc, elem_layout) {
             Ok(res) => res,
@@ -488,17 +500,17 @@ impl<A: Allocator> RawVecInner<A> {
     }
 
     #[inline]
-    fn ptr<T>(&self) -> *mut T {
+    const fn ptr<T>(&self) -> *mut T {
         self.non_null::<T>().as_ptr()
     }
 
     #[inline]
-    fn non_null<T>(&self) -> NonNull<T> {
-        self.ptr.cast().into()
+    const fn non_null<T>(&self) -> NonNull<T> {
+        self.ptr.cast().as_non_null_ptr()
     }
 
     #[inline]
-    fn capacity(&self, elem_size: usize) -> usize {
+    const fn capacity(&self, elem_size: usize) -> usize {
         if elem_size == 0 { usize::MAX } else { self.cap.0 }
     }
 
@@ -526,6 +538,7 @@ impl<A: Allocator> RawVecInner<A> {
 
     #[cfg(not(no_global_oom_handling))]
     #[inline]
+    #[track_caller]
     fn reserve(&mut self, len: usize, additional: usize, elem_layout: Layout) {
         // Callers expect this function to be very cheap when there is already sufficient capacity.
         // Therefore, we move all the resizing and error-handling logic from grow_amortized and
@@ -550,6 +563,7 @@ impl<A: Allocator> RawVecInner<A> {
 
     #[cfg(not(no_global_oom_handling))]
     #[inline]
+    #[track_caller]
     fn grow_one(&mut self, elem_layout: Layout) {
         if let Err(err) = self.grow_amortized(self.cap.0, 1, elem_layout) {
             handle_error(err);
@@ -573,6 +587,7 @@ impl<A: Allocator> RawVecInner<A> {
     }
 
     #[cfg(not(no_global_oom_handling))]
+    #[track_caller]
     fn reserve_exact(&mut self, len: usize, additional: usize, elem_layout: Layout) {
         if let Err(err) = self.try_reserve_exact(len, additional, elem_layout) {
             handle_error(err);
@@ -597,6 +612,7 @@ impl<A: Allocator> RawVecInner<A> {
 
     #[cfg(not(no_global_oom_handling))]
     #[inline]
+    #[track_caller]
     fn shrink_to_fit(&mut self, cap: usize, elem_layout: Layout) {
         if let Err(err) = self.shrink(cap, elem_layout) {
             handle_error(err);
@@ -770,6 +786,7 @@ where
 #[cfg(not(no_global_oom_handling))]
 #[cold]
 #[optimize(size)]
+#[track_caller]
 fn handle_error(e: TryReserveError) -> ! {
     match e.kind() {
         CapacityOverflow => capacity_overflow(),
diff --git a/library/alloc/src/slice.rs b/library/alloc/src/slice.rs
index a92d22b1c30..e3c7835f1d1 100644
--- a/library/alloc/src/slice.rs
+++ b/library/alloc/src/slice.rs
@@ -19,20 +19,6 @@ use core::cmp::Ordering::{self, Less};
 use core::mem::{self, MaybeUninit};
 #[cfg(not(no_global_oom_handling))]
 use core::ptr;
-#[cfg(not(no_global_oom_handling))]
-use core::slice::sort;
-
-use crate::alloc::Allocator;
-#[cfg(not(no_global_oom_handling))]
-use crate::alloc::Global;
-#[cfg(not(no_global_oom_handling))]
-use crate::borrow::ToOwned;
-use crate::boxed::Box;
-use crate::vec::Vec;
-
-#[cfg(test)]
-mod tests;
-
 #[unstable(feature = "array_chunks", issue = "74985")]
 pub use core::slice::ArrayChunks;
 #[unstable(feature = "array_chunks", issue = "74985")]
@@ -43,6 +29,8 @@ pub use core::slice::ArrayWindows;
 pub use core::slice::EscapeAscii;
 #[stable(feature = "slice_get_slice", since = "1.28.0")]
 pub use core::slice::SliceIndex;
+#[cfg(not(no_global_oom_handling))]
+use core::slice::sort;
 #[stable(feature = "slice_group_by", since = "1.77.0")]
 pub use core::slice::{ChunkBy, ChunkByMut};
 #[stable(feature = "rust1", since = "1.0.0")]
@@ -83,6 +71,14 @@ pub use hack::into_vec;
 #[cfg(test)]
 pub use hack::to_vec;
 
+use crate::alloc::Allocator;
+#[cfg(not(no_global_oom_handling))]
+use crate::alloc::Global;
+#[cfg(not(no_global_oom_handling))]
+use crate::borrow::ToOwned;
+use crate::boxed::Box;
+use crate::vec::Vec;
+
 // HACK(japaric): With cfg(test) `impl [T]` is not available, these three
 // functions are actually methods that are in `impl [T]` but not in
 // `core::slice::SliceExt` - we need to supply these functions for the
diff --git a/library/alloc/src/slice/tests.rs b/library/alloc/src/slice/tests.rs
deleted file mode 100644
index 786704caeb0..00000000000
--- a/library/alloc/src/slice/tests.rs
+++ /dev/null
@@ -1,369 +0,0 @@
-use core::cell::Cell;
-use core::cmp::Ordering::{self, Equal, Greater, Less};
-use core::convert::identity;
-use core::sync::atomic::AtomicUsize;
-use core::sync::atomic::Ordering::Relaxed;
-use core::{fmt, mem};
-use std::panic;
-
-use rand::distributions::Standard;
-use rand::prelude::*;
-use rand::{Rng, RngCore};
-
-use crate::borrow::ToOwned;
-use crate::rc::Rc;
-use crate::string::ToString;
-use crate::test_helpers::test_rng;
-use crate::vec::Vec;
-
-macro_rules! do_test {
-    ($input:ident, $func:ident) => {
-        let len = $input.len();
-
-        // Work out the total number of comparisons required to sort
-        // this array...
-        let mut count = 0usize;
-        $input.to_owned().$func(|a, b| {
-            count += 1;
-            a.cmp(b)
-        });
-
-        // ... and then panic on each and every single one.
-        for panic_countdown in 0..count {
-            // Refresh the counters.
-            VERSIONS.store(0, Relaxed);
-            for i in 0..len {
-                DROP_COUNTS[i].store(0, Relaxed);
-            }
-
-            let v = $input.to_owned();
-            let _ = panic::catch_unwind(move || {
-                let mut v = v;
-                let mut panic_countdown = panic_countdown;
-                v.$func(|a, b| {
-                    if panic_countdown == 0 {
-                        SILENCE_PANIC.with(|s| s.set(true));
-                        panic!();
-                    }
-                    panic_countdown -= 1;
-                    a.cmp(b)
-                })
-            });
-
-            // Check that the number of things dropped is exactly
-            // what we expect (i.e., the contents of `v`).
-            for (i, c) in DROP_COUNTS.iter().enumerate().take(len) {
-                let count = c.load(Relaxed);
-                assert!(count == 1, "found drop count == {} for i == {}, len == {}", count, i, len);
-            }
-
-            // Check that the most recent versions of values were dropped.
-            assert_eq!(VERSIONS.load(Relaxed), 0);
-        }
-    };
-}
-
-const MAX_LEN: usize = 80;
-
-static DROP_COUNTS: [AtomicUsize; MAX_LEN] = [
-    // FIXME(RFC 1109): AtomicUsize is not Copy.
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-    AtomicUsize::new(0),
-];
-
-static VERSIONS: AtomicUsize = AtomicUsize::new(0);
-
-#[derive(Clone, Eq)]
-struct DropCounter {
-    x: u32,
-    id: usize,
-    version: Cell<usize>,
-}
-
-impl PartialEq for DropCounter {
-    fn eq(&self, other: &Self) -> bool {
-        self.partial_cmp(other) == Some(Ordering::Equal)
-    }
-}
-
-impl PartialOrd for DropCounter {
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        self.version.set(self.version.get() + 1);
-        other.version.set(other.version.get() + 1);
-        VERSIONS.fetch_add(2, Relaxed);
-        self.x.partial_cmp(&other.x)
-    }
-}
-
-impl Ord for DropCounter {
-    fn cmp(&self, other: &Self) -> Ordering {
-        self.partial_cmp(other).unwrap()
-    }
-}
-
-impl Drop for DropCounter {
-    fn drop(&mut self) {
-        DROP_COUNTS[self.id].fetch_add(1, Relaxed);
-        VERSIONS.fetch_sub(self.version.get(), Relaxed);
-    }
-}
-
-std::thread_local!(static SILENCE_PANIC: Cell<bool> = Cell::new(false));
-
-#[test]
-#[cfg_attr(target_os = "emscripten", ignore)] // no threads
-#[cfg_attr(not(panic = "unwind"), ignore = "test requires unwinding support")]
-fn panic_safe() {
-    panic::update_hook(move |prev, info| {
-        if !SILENCE_PANIC.with(|s| s.get()) {
-            prev(info);
-        }
-    });
-
-    let mut rng = test_rng();
-
-    // Miri is too slow (but still need to `chain` to make the types match)
-    let lens = if cfg!(miri) { (1..10).chain(0..0) } else { (1..20).chain(70..MAX_LEN) };
-    let moduli: &[u32] = if cfg!(miri) { &[5] } else { &[5, 20, 50] };
-
-    for len in lens {
-        for &modulus in moduli {
-            for &has_runs in &[false, true] {
-                let mut input = (0..len)
-                    .map(|id| DropCounter {
-                        x: rng.next_u32() % modulus,
-                        id: id,
-                        version: Cell::new(0),
-                    })
-                    .collect::<Vec<_>>();
-
-                if has_runs {
-                    for c in &mut input {
-                        c.x = c.id as u32;
-                    }
-
-                    for _ in 0..5 {
-                        let a = rng.gen::<usize>() % len;
-                        let b = rng.gen::<usize>() % len;
-                        if a < b {
-                            input[a..b].reverse();
-                        } else {
-                            input.swap(a, b);
-                        }
-                    }
-                }
-
-                do_test!(input, sort_by);
-                do_test!(input, sort_unstable_by);
-            }
-        }
-    }
-
-    // Set default panic hook again.
-    drop(panic::take_hook());
-}
-
-#[test]
-#[cfg_attr(miri, ignore)] // Miri is too slow
-#[cfg_attr(not(panic = "unwind"), ignore = "test requires unwinding support")]
-fn test_sort() {
-    let mut rng = test_rng();
-
-    for len in (2..25).chain(500..510) {
-        for &modulus in &[5, 10, 100, 1000] {
-            for _ in 0..10 {
-                let orig: Vec<_> = (&mut rng)
-                    .sample_iter::<i32, _>(&Standard)
-                    .map(|x| x % modulus)
-                    .take(len)
-                    .collect();
-
-                // Sort in default order.
-                let mut v = orig.clone();
-                v.sort();
-                assert!(v.windows(2).all(|w| w[0] <= w[1]));
-
-                // Sort in ascending order.
-                let mut v = orig.clone();
-                v.sort_by(|a, b| a.cmp(b));
-                assert!(v.windows(2).all(|w| w[0] <= w[1]));
-
-                // Sort in descending order.
-                let mut v = orig.clone();
-                v.sort_by(|a, b| b.cmp(a));
-                assert!(v.windows(2).all(|w| w[0] >= w[1]));
-
-                // Sort in lexicographic order.
-                let mut v1 = orig.clone();
-                let mut v2 = orig.clone();
-                v1.sort_by_key(|x| x.to_string());
-                v2.sort_by_cached_key(|x| x.to_string());
-                assert!(v1.windows(2).all(|w| w[0].to_string() <= w[1].to_string()));
-                assert!(v1 == v2);
-
-                // Sort with many pre-sorted runs.
-                let mut v = orig.clone();
-                v.sort();
-                v.reverse();
-                for _ in 0..5 {
-                    let a = rng.gen::<usize>() % len;
-                    let b = rng.gen::<usize>() % len;
-                    if a < b {
-                        v[a..b].reverse();
-                    } else {
-                        v.swap(a, b);
-                    }
-                }
-                v.sort();
-                assert!(v.windows(2).all(|w| w[0] <= w[1]));
-            }
-        }
-    }
-
-    const ORD_VIOLATION_MAX_LEN: usize = 500;
-    let mut v = [0; ORD_VIOLATION_MAX_LEN];
-    for i in 0..ORD_VIOLATION_MAX_LEN {
-        v[i] = i as i32;
-    }
-
-    // Sort using a completely random comparison function. This will reorder the elements *somehow*,
-    // it may panic but the original elements must still be present.
-    let _ = panic::catch_unwind(move || {
-        v.sort_by(|_, _| *[Less, Equal, Greater].choose(&mut rng).unwrap());
-    });
-
-    v.sort();
-    for i in 0..ORD_VIOLATION_MAX_LEN {
-        assert_eq!(v[i], i as i32);
-    }
-
-    // Should not panic.
-    [0i32; 0].sort();
-    [(); 10].sort();
-    [(); 100].sort();
-
-    let mut v = [0xDEADBEEFu64];
-    v.sort();
-    assert!(v == [0xDEADBEEF]);
-}
-
-#[test]
-fn test_sort_stability() {
-    // Miri is too slow
-    let large_range = if cfg!(miri) { 0..0 } else { 500..510 };
-    let rounds = if cfg!(miri) { 1 } else { 10 };
-
-    let mut rng = test_rng();
-    for len in (2..25).chain(large_range) {
-        for _ in 0..rounds {
-            let mut counts = [0; 10];
-
-            // create a vector like [(6, 1), (5, 1), (6, 2), ...],
-            // where the first item of each tuple is random, but
-            // the second item represents which occurrence of that
-            // number this element is, i.e., the second elements
-            // will occur in sorted order.
-            let orig: Vec<_> = (0..len)
-                .map(|_| {
-                    let n = rng.gen::<usize>() % 10;
-                    counts[n] += 1;
-                    (n, counts[n])
-                })
-                .collect();
-
-            let mut v = orig.clone();
-            // Only sort on the first element, so an unstable sort
-            // may mix up the counts.
-            v.sort_by(|&(a, _), &(b, _)| a.cmp(&b));
-
-            // This comparison includes the count (the second item
-            // of the tuple), so elements with equal first items
-            // will need to be ordered with increasing
-            // counts... i.e., exactly asserting that this sort is
-            // stable.
-            assert!(v.windows(2).all(|w| w[0] <= w[1]));
-
-            let mut v = orig.clone();
-            v.sort_by_cached_key(|&(x, _)| x);
-            assert!(v.windows(2).all(|w| w[0] <= w[1]));
-        }
-    }
-}
diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index ee878e879e9..82dbf030608 100644
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -1059,7 +1059,8 @@ impl String {
     #[inline]
     #[must_use = "`self` will be dropped if the result is not used"]
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn into_bytes(self) -> Vec<u8> {
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
+    pub const fn into_bytes(self) -> Vec<u8> {
         self.vec
     }
 
@@ -1076,8 +1077,11 @@ impl String {
     #[must_use]
     #[stable(feature = "string_as_str", since = "1.7.0")]
     #[cfg_attr(not(test), rustc_diagnostic_item = "string_as_str")]
-    pub fn as_str(&self) -> &str {
-        self
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
+    pub const fn as_str(&self) -> &str {
+        // SAFETY: String contents are stipulated to be valid UTF-8, invalid contents are an error
+        // at construction.
+        unsafe { str::from_utf8_unchecked(self.vec.as_slice()) }
     }
 
     /// Converts a `String` into a mutable string slice.
@@ -1096,8 +1100,11 @@ impl String {
     #[must_use]
     #[stable(feature = "string_as_str", since = "1.7.0")]
     #[cfg_attr(not(test), rustc_diagnostic_item = "string_as_mut_str")]
-    pub fn as_mut_str(&mut self) -> &mut str {
-        self
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
+    pub const fn as_mut_str(&mut self) -> &mut str {
+        // SAFETY: String contents are stipulated to be valid UTF-8, invalid contents are an error
+        // at construction.
+        unsafe { str::from_utf8_unchecked_mut(self.vec.as_mut_slice()) }
     }
 
     /// Appends a given string slice onto the end of this `String`.
@@ -1168,7 +1175,8 @@ impl String {
     #[inline]
     #[must_use]
     #[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.vec.capacity()
     }
 
@@ -1431,8 +1439,9 @@ impl String {
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn as_bytes(&self) -> &[u8] {
-        &self.vec
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
+    pub const fn as_bytes(&self) -> &[u8] {
+        self.vec.as_slice()
     }
 
     /// Shortens this `String` to the specified length.
@@ -1784,7 +1793,8 @@ impl String {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub unsafe fn as_mut_vec(&mut self) -> &mut Vec<u8> {
+    #[rustc_const_unstable(feature = "const_vec_string_slice", issue = "129041")]
+    pub const unsafe fn as_mut_vec(&mut self) -> &mut Vec<u8> {
         &mut self.vec
     }
 
@@ -1805,8 +1815,9 @@ impl String {
     #[inline]
     #[must_use]
     #[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.vec.len()
     }
 
@@ -1824,7 +1835,8 @@ impl String {
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
-    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
     }
 
@@ -2589,7 +2601,7 @@ impl ops::Deref for String {
 
     #[inline]
     fn deref(&self) -> &str {
-        unsafe { str::from_utf8_unchecked(&self.vec) }
+        self.as_str()
     }
 }
 
@@ -2600,7 +2612,7 @@ unsafe impl ops::DerefPure for String {}
 impl ops::DerefMut for String {
     #[inline]
     fn deref_mut(&mut self) -> &mut str {
-        unsafe { str::from_utf8_unchecked_mut(&mut *self.vec) }
+        self.as_mut_str()
     }
 }
 
diff --git a/library/alloc/src/vec/cow.rs b/library/alloc/src/vec/cow.rs
index c18091705a6..4deb35efffc 100644
--- a/library/alloc/src/vec/cow.rs
+++ b/library/alloc/src/vec/cow.rs
@@ -58,6 +58,7 @@ impl<'a, T> FromIterator<T> for Cow<'a, [T]>
 where
     T: Clone,
 {
+    #[track_caller]
     fn from_iter<I: IntoIterator<Item = T>>(it: I) -> Cow<'a, [T]> {
         Cow::Owned(FromIterator::from_iter(it))
     }
diff --git a/library/alloc/src/vec/in_place_collect.rs b/library/alloc/src/vec/in_place_collect.rs
index fd94bbbdeb1..a7dba16944e 100644
--- a/library/alloc/src/vec/in_place_collect.rs
+++ b/library/alloc/src/vec/in_place_collect.rs
@@ -229,6 +229,7 @@ where
     I: Iterator<Item = T> + InPlaceCollect,
     <I as SourceIter>::Source: AsVecIntoIter,
 {
+    #[track_caller]
     default fn from_iter(iterator: I) -> Self {
         // Select the implementation in const eval to avoid codegen of the dead branch to improve compile times.
         let fun: fn(I) -> Vec<T> = const {
@@ -246,6 +247,7 @@ where
     }
 }
 
+#[track_caller]
 fn from_iter_in_place<I, T>(mut iterator: I) -> Vec<T>
 where
     I: Iterator<Item = T> + InPlaceCollect,
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())
     }
diff --git a/library/alloc/src/vec/spec_extend.rs b/library/alloc/src/vec/spec_extend.rs
index 7085bceef5b..b98db669059 100644
--- a/library/alloc/src/vec/spec_extend.rs
+++ b/library/alloc/src/vec/spec_extend.rs
@@ -6,6 +6,7 @@ use crate::alloc::Allocator;
 
 // Specialization trait used for Vec::extend
 pub(super) trait SpecExtend<T, I> {
+    #[track_caller]
     fn spec_extend(&mut self, iter: I);
 }
 
@@ -13,6 +14,7 @@ impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
 where
     I: Iterator<Item = T>,
 {
+    #[track_caller]
     default fn spec_extend(&mut self, iter: I) {
         self.extend_desugared(iter)
     }
@@ -22,12 +24,14 @@ impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
 where
     I: TrustedLen<Item = T>,
 {
+    #[track_caller]
     default fn spec_extend(&mut self, iterator: I) {
         self.extend_trusted(iterator)
     }
 }
 
 impl<T, A: Allocator> SpecExtend<T, IntoIter<T>> for Vec<T, A> {
+    #[track_caller]
     fn spec_extend(&mut self, mut iterator: IntoIter<T>) {
         unsafe {
             self.append_elements(iterator.as_slice() as _);
@@ -41,6 +45,7 @@ where
     I: Iterator<Item = &'a T>,
     T: Clone,
 {
+    #[track_caller]
     default fn spec_extend(&mut self, iterator: I) {
         self.spec_extend(iterator.cloned())
     }
@@ -50,6 +55,7 @@ impl<'a, T: 'a, A: Allocator> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A
 where
     T: Copy,
 {
+    #[track_caller]
     fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) {
         let slice = iterator.as_slice();
         unsafe { self.append_elements(slice) };
diff --git a/library/alloc/src/vec/spec_from_elem.rs b/library/alloc/src/vec/spec_from_elem.rs
index 96d701e15d4..6c7b4d89f2d 100644
--- a/library/alloc/src/vec/spec_from_elem.rs
+++ b/library/alloc/src/vec/spec_from_elem.rs
@@ -10,6 +10,7 @@ pub(super) trait SpecFromElem: Sized {
 }
 
 impl<T: Clone> SpecFromElem for T {
+    #[track_caller]
     default fn from_elem<A: Allocator>(elem: Self, n: usize, alloc: A) -> Vec<Self, A> {
         let mut v = Vec::with_capacity_in(n, alloc);
         v.extend_with(n, elem);
@@ -19,6 +20,7 @@ impl<T: Clone> SpecFromElem for T {
 
 impl<T: Clone + IsZero> SpecFromElem for T {
     #[inline]
+    #[track_caller]
     default fn from_elem<A: Allocator>(elem: T, n: usize, alloc: A) -> Vec<T, A> {
         if elem.is_zero() {
             return Vec { buf: RawVec::with_capacity_zeroed_in(n, alloc), len: n };
@@ -31,6 +33,7 @@ impl<T: Clone + IsZero> SpecFromElem for T {
 
 impl SpecFromElem for i8 {
     #[inline]
+    #[track_caller]
     fn from_elem<A: Allocator>(elem: i8, n: usize, alloc: A) -> Vec<i8, A> {
         if elem == 0 {
             return Vec { buf: RawVec::with_capacity_zeroed_in(n, alloc), len: n };
@@ -46,6 +49,7 @@ impl SpecFromElem for i8 {
 
 impl SpecFromElem for u8 {
     #[inline]
+    #[track_caller]
     fn from_elem<A: Allocator>(elem: u8, n: usize, alloc: A) -> Vec<u8, A> {
         if elem == 0 {
             return Vec { buf: RawVec::with_capacity_zeroed_in(n, alloc), len: n };
diff --git a/library/alloc/src/vec/spec_from_iter.rs b/library/alloc/src/vec/spec_from_iter.rs
index e1f0b639bdf..ad7688e1c59 100644
--- a/library/alloc/src/vec/spec_from_iter.rs
+++ b/library/alloc/src/vec/spec_from_iter.rs
@@ -29,12 +29,14 @@ impl<T, I> SpecFromIter<T, I> for Vec<T>
 where
     I: Iterator<Item = T>,
 {
+    #[track_caller]
     default fn from_iter(iterator: I) -> Self {
         SpecFromIterNested::from_iter(iterator)
     }
 }
 
 impl<T> SpecFromIter<T, IntoIter<T>> for Vec<T> {
+    #[track_caller]
     fn from_iter(iterator: IntoIter<T>) -> Self {
         // A common case is passing a vector into a function which immediately
         // re-collects into a vector. We can short circuit this if the IntoIter
diff --git a/library/alloc/src/vec/spec_from_iter_nested.rs b/library/alloc/src/vec/spec_from_iter_nested.rs
index 77f7761d22f..22eed238798 100644
--- a/library/alloc/src/vec/spec_from_iter_nested.rs
+++ b/library/alloc/src/vec/spec_from_iter_nested.rs
@@ -15,6 +15,7 @@ impl<T, I> SpecFromIterNested<T, I> for Vec<T>
 where
     I: Iterator<Item = T>,
 {
+    #[track_caller]
     default fn from_iter(mut iterator: I) -> Self {
         // Unroll the first iteration, as the vector is going to be
         // expanded on this iteration in every case when the iterable is not
@@ -47,6 +48,7 @@ impl<T, I> SpecFromIterNested<T, I> for Vec<T>
 where
     I: TrustedLen<Item = T>,
 {
+    #[track_caller]
     fn from_iter(iterator: I) -> Self {
         let mut vector = match iterator.size_hint() {
             (_, Some(upper)) => Vec::with_capacity(upper),
diff --git a/library/alloc/src/vec/splice.rs b/library/alloc/src/vec/splice.rs
index 9e36377c148..ca5cb17f8bf 100644
--- a/library/alloc/src/vec/splice.rs
+++ b/library/alloc/src/vec/splice.rs
@@ -52,6 +52,7 @@ impl<I: Iterator, A: Allocator> ExactSizeIterator for Splice<'_, I, A> {}
 
 #[stable(feature = "vec_splice", since = "1.21.0")]
 impl<I: Iterator, A: Allocator> Drop for Splice<'_, I, A> {
+    #[track_caller]
     fn drop(&mut self) {
         self.drain.by_ref().for_each(drop);
         // At this point draining is done and the only remaining tasks are splicing
@@ -123,6 +124,7 @@ impl<T, A: Allocator> Drain<'_, T, A> {
     }
 
     /// Makes room for inserting more elements before the tail.
+    #[track_caller]
     unsafe fn move_tail(&mut self, additional: usize) {
         let vec = unsafe { self.vec.as_mut() };
         let len = self.tail_start + self.tail_len;