From 175afd76180d47b655377768a87a55f8581686f0 Mon Sep 17 00:00:00 2001
From: Thalia Archibald <thalia@archibald.dev>
Date: Mon, 21 Apr 2025 23:27:01 -0700
Subject: [PATCH 1/6] Stabilize `new_zeroed_alloc`

---
 compiler/rustc_index/src/bit_set.rs |  4 ++--
 compiler/rustc_index/src/lib.rs     |  2 +-
 library/alloc/src/boxed.rs          | 16 ++--------------
 library/alloc/src/rc.rs             | 16 ++--------------
 library/alloc/src/sync.rs           | 14 ++------------
 library/std/src/lib.rs              |  1 -
 6 files changed, 9 insertions(+), 44 deletions(-)

diff --git a/compiler/rustc_index/src/bit_set.rs b/compiler/rustc_index/src/bit_set.rs
index 645d95b1dba99..0b3bc8963a3bd 100644
--- a/compiler/rustc_index/src/bit_set.rs
+++ b/compiler/rustc_index/src/bit_set.rs
@@ -638,7 +638,7 @@ impl<T: Idx> ChunkedBitSet<T> {
                     };
                     #[cfg(not(feature = "nightly"))]
                     let mut words = {
-                        // FIXME: unconditionally use `Rc::new_zeroed` once it is stable (#63291).
+                        // FIXME: unconditionally use `Rc::new_zeroed` once it is stable (#129396).
                         let words = mem::MaybeUninit::<[Word; CHUNK_WORDS]>::zeroed();
                         // SAFETY: `words` can safely be all zeroes.
                         let words = unsafe { words.assume_init() };
@@ -704,7 +704,7 @@ impl<T: Idx> ChunkedBitSet<T> {
                     };
                     #[cfg(not(feature = "nightly"))]
                     let mut words = {
-                        // FIXME: unconditionally use `Rc::new_zeroed` once it is stable (#63291).
+                        // FIXME: unconditionally use `Rc::new_zeroed` once it is stable (#129396).
                         let words = mem::MaybeUninit::<[Word; CHUNK_WORDS]>::zeroed();
                         // SAFETY: `words` can safely be all zeroes.
                         let words = unsafe { words.assume_init() };
diff --git a/compiler/rustc_index/src/lib.rs b/compiler/rustc_index/src/lib.rs
index cc680838e7e7b..9d647209c6f89 100644
--- a/compiler/rustc_index/src/lib.rs
+++ b/compiler/rustc_index/src/lib.rs
@@ -1,9 +1,9 @@
 // tidy-alphabetical-start
 #![cfg_attr(all(feature = "nightly", test), feature(stmt_expr_attributes))]
+#![cfg_attr(bootstrap, feature(new_zeroed_alloc))]
 #![cfg_attr(feature = "nightly", allow(internal_features))]
 #![cfg_attr(feature = "nightly", feature(extend_one, step_trait, test))]
 #![cfg_attr(feature = "nightly", feature(new_range_api))]
-#![cfg_attr(feature = "nightly", feature(new_zeroed_alloc))]
 // tidy-alphabetical-end
 
 pub mod bit_set;
diff --git a/library/alloc/src/boxed.rs b/library/alloc/src/boxed.rs
index 3db37f1d16f3d..173d0103c119b 100644
--- a/library/alloc/src/boxed.rs
+++ b/library/alloc/src/boxed.rs
@@ -290,8 +290,6 @@ impl<T> Box<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_zeroed_alloc)]
-    ///
     /// let zero = Box::<u32>::new_zeroed();
     /// let zero = unsafe { zero.assume_init() };
     ///
@@ -301,7 +299,7 @@ impl<T> Box<T> {
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
     #[inline]
-    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
+    #[stable(feature = "new_zeroed_alloc", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn new_zeroed() -> Box<mem::MaybeUninit<T>> {
         Self::new_zeroed_in(Global)
@@ -358,7 +356,6 @@ impl<T> Box<T> {
     /// # Ok::<(), std::alloc::AllocError>(())
     /// ```
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn try_new_uninit() -> Result<Box<mem::MaybeUninit<T>>, AllocError> {
         Box::try_new_uninit_in(Global)
@@ -384,7 +381,6 @@ impl<T> Box<T> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn try_new_zeroed() -> Result<Box<mem::MaybeUninit<T>>, AllocError> {
         Box::try_new_zeroed_in(Global)
@@ -463,7 +459,6 @@ impl<T, A: Allocator> Box<T, A> {
     #[unstable(feature = "allocator_api", issue = "32838")]
     #[cfg(not(no_global_oom_handling))]
     #[must_use]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn new_uninit_in(alloc: A) -> Box<mem::MaybeUninit<T>, A>
     where
         A: Allocator,
@@ -496,7 +491,6 @@ impl<T, A: Allocator> Box<T, A> {
     /// # Ok::<(), std::alloc::AllocError>(())
     /// ```
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn try_new_uninit_in(alloc: A) -> Result<Box<mem::MaybeUninit<T>, A>, AllocError>
     where
         A: Allocator,
@@ -532,7 +526,6 @@ impl<T, A: Allocator> Box<T, A> {
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[unstable(feature = "allocator_api", issue = "32838")]
     #[cfg(not(no_global_oom_handling))]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[must_use]
     pub fn new_zeroed_in(alloc: A) -> Box<mem::MaybeUninit<T>, A>
     where
@@ -570,7 +563,6 @@ impl<T, A: Allocator> Box<T, A> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn try_new_zeroed_in(alloc: A) -> Result<Box<mem::MaybeUninit<T>, A>, AllocError>
     where
         A: Allocator,
@@ -660,8 +652,6 @@ impl<T> Box<[T]> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_zeroed_alloc)]
-    ///
     /// let values = Box::<[u32]>::new_zeroed_slice(3);
     /// let values = unsafe { values.assume_init() };
     ///
@@ -670,7 +660,7 @@ impl<T> Box<[T]> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
+    #[stable(feature = "new_zeroed_alloc", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn new_zeroed_slice(len: usize) -> Box<[mem::MaybeUninit<T>]> {
         unsafe { RawVec::with_capacity_zeroed(len).into_box(len) }
@@ -785,7 +775,6 @@ impl<T, A: Allocator> Box<[T], A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[must_use]
     pub fn new_uninit_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A> {
         unsafe { RawVec::with_capacity_in(len, alloc).into_box(len) }
@@ -813,7 +802,6 @@ impl<T, A: Allocator> Box<[T], A> {
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[must_use]
     pub fn new_zeroed_slice_in(len: usize, alloc: A) -> Box<[mem::MaybeUninit<T>], A> {
         unsafe { RawVec::with_capacity_zeroed_in(len, alloc).into_box(len) }
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index 5018ff4ad71f3..0b5c9240db0f1 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -515,8 +515,6 @@ impl<T> Rc<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_zeroed_alloc)]
-    ///
     /// use std::rc::Rc;
     ///
     /// let zero = Rc::<u32>::new_zeroed();
@@ -527,7 +525,7 @@ impl<T> Rc<T> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
+    #[stable(feature = "new_zeroed_alloc", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn new_zeroed() -> Rc<mem::MaybeUninit<T>> {
         unsafe {
@@ -589,7 +587,6 @@ impl<T> Rc<T> {
     /// # Ok::<(), std::alloc::AllocError>(())
     /// ```
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn try_new_uninit() -> Result<Rc<mem::MaybeUninit<T>>, AllocError> {
         unsafe {
             Ok(Rc::from_ptr(Rc::try_allocate_for_layout(
@@ -622,7 +619,6 @@ impl<T> Rc<T> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[unstable(feature = "allocator_api", issue = "32838")]
-    //#[unstable(feature = "new_uninit", issue = "63291")]
     pub fn try_new_zeroed() -> Result<Rc<mem::MaybeUninit<T>>, AllocError> {
         unsafe {
             Ok(Rc::from_ptr(Rc::try_allocate_for_layout(
@@ -690,7 +686,6 @@ impl<T, A: Allocator> Rc<T, A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn new_uninit_in(alloc: A) -> Rc<mem::MaybeUninit<T>, A> {
         unsafe {
@@ -728,7 +723,6 @@ impl<T, A: Allocator> Rc<T, A> {
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn new_zeroed_in(alloc: A) -> Rc<mem::MaybeUninit<T>, A> {
         unsafe {
@@ -873,7 +867,6 @@ impl<T, A: Allocator> Rc<T, A> {
     /// # Ok::<(), std::alloc::AllocError>(())
     /// ```
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn try_new_uninit_in(alloc: A) -> Result<Rc<mem::MaybeUninit<T>, A>, AllocError> {
         unsafe {
@@ -912,7 +905,6 @@ impl<T, A: Allocator> Rc<T, A> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[unstable(feature = "allocator_api", issue = "32838")]
-    //#[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn try_new_zeroed_in(alloc: A) -> Result<Rc<mem::MaybeUninit<T>, A>, AllocError> {
         unsafe {
@@ -1054,8 +1046,6 @@ impl<T> Rc<[T]> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_zeroed_alloc)]
-    ///
     /// use std::rc::Rc;
     ///
     /// let values = Rc::<[u32]>::new_zeroed_slice(3);
@@ -1066,7 +1056,7 @@ impl<T> Rc<[T]> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
-    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
+    #[stable(feature = "new_zeroed_alloc", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn new_zeroed_slice(len: usize) -> Rc<[mem::MaybeUninit<T>]> {
         unsafe {
@@ -1129,7 +1119,6 @@ impl<T, A: Allocator> Rc<[T], A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn new_uninit_slice_in(len: usize, alloc: A) -> Rc<[mem::MaybeUninit<T>], A> {
         unsafe { Rc::from_ptr_in(Rc::allocate_for_slice_in(len, &alloc), alloc) }
@@ -1158,7 +1147,6 @@ impl<T, A: Allocator> Rc<[T], A> {
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn new_zeroed_slice_in(len: usize, alloc: A) -> Rc<[mem::MaybeUninit<T>], A> {
         unsafe {
diff --git a/library/alloc/src/sync.rs b/library/alloc/src/sync.rs
index b8925f4544f44..4090a04f21a9f 100644
--- a/library/alloc/src/sync.rs
+++ b/library/alloc/src/sync.rs
@@ -516,8 +516,6 @@ impl<T> Arc<T> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_zeroed_alloc)]
-    ///
     /// use std::sync::Arc;
     ///
     /// let zero = Arc::<u32>::new_zeroed();
@@ -529,7 +527,7 @@ impl<T> Arc<T> {
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
     #[inline]
-    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
+    #[stable(feature = "new_zeroed_alloc", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn new_zeroed() -> Arc<mem::MaybeUninit<T>> {
         unsafe {
@@ -603,7 +601,6 @@ impl<T> Arc<T> {
     /// # Ok::<(), std::alloc::AllocError>(())
     /// ```
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn try_new_uninit() -> Result<Arc<mem::MaybeUninit<T>>, AllocError> {
         unsafe {
             Ok(Arc::from_ptr(Arc::try_allocate_for_layout(
@@ -636,7 +633,6 @@ impl<T> Arc<T> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     pub fn try_new_zeroed() -> Result<Arc<mem::MaybeUninit<T>>, AllocError> {
         unsafe {
             Ok(Arc::from_ptr(Arc::try_allocate_for_layout(
@@ -703,7 +699,6 @@ impl<T, A: Allocator> Arc<T, A> {
     /// ```
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn new_uninit_in(alloc: A) -> Arc<mem::MaybeUninit<T>, A> {
         unsafe {
@@ -741,7 +736,6 @@ impl<T, A: Allocator> Arc<T, A> {
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn new_zeroed_in(alloc: A) -> Arc<mem::MaybeUninit<T>, A> {
         unsafe {
@@ -927,7 +921,6 @@ impl<T, A: Allocator> Arc<T, A> {
     /// # Ok::<(), std::alloc::AllocError>(())
     /// ```
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn try_new_uninit_in(alloc: A) -> Result<Arc<mem::MaybeUninit<T>, A>, AllocError> {
         unsafe {
@@ -966,7 +959,6 @@ impl<T, A: Allocator> Arc<T, A> {
     ///
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[unstable(feature = "allocator_api", issue = "32838")]
-    // #[unstable(feature = "new_uninit", issue = "63291")]
     #[inline]
     pub fn try_new_zeroed_in(alloc: A) -> Result<Arc<mem::MaybeUninit<T>, A>, AllocError> {
         unsafe {
@@ -1197,8 +1189,6 @@ impl<T> Arc<[T]> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(new_zeroed_alloc)]
-    ///
     /// use std::sync::Arc;
     ///
     /// let values = Arc::<[u32]>::new_zeroed_slice(3);
@@ -1210,7 +1200,7 @@ impl<T> Arc<[T]> {
     /// [zeroed]: mem::MaybeUninit::zeroed
     #[cfg(not(no_global_oom_handling))]
     #[inline]
-    #[unstable(feature = "new_zeroed_alloc", issue = "129396")]
+    #[stable(feature = "new_zeroed_alloc", since = "CURRENT_RUSTC_VERSION")]
     #[must_use]
     pub fn new_zeroed_slice(len: usize) -> Arc<[mem::MaybeUninit<T>]> {
         unsafe {
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index 311b2cb932392..2c0061dc40320 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -376,7 +376,6 @@
 #![feature(allocator_api)]
 #![feature(get_mut_unchecked)]
 #![feature(map_try_insert)]
-#![feature(new_zeroed_alloc)]
 #![feature(slice_concat_trait)]
 #![feature(thin_box)]
 #![feature(try_reserve_kind)]

From 46727f4cb06c3496a541ee8517a24ef5cb77627c Mon Sep 17 00:00:00 2001
From: Alice Ryhl <aliceryhl@google.com>
Date: Wed, 20 Aug 2025 15:04:34 +0000
Subject: [PATCH 2/6] Stabilize file_as_c_str

---
 library/core/src/panic/location.rs                            | 3 ++-
 tests/ui/rfcs/rfc-2091-track-caller/file-is-nul-terminated.rs | 1 -
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/library/core/src/panic/location.rs b/library/core/src/panic/location.rs
index 7a68d393906cb..5935849344475 100644
--- a/library/core/src/panic/location.rs
+++ b/library/core/src/panic/location.rs
@@ -193,8 +193,9 @@ impl<'a> Location<'a> {
     /// This is useful for interop with APIs that expect C/C++ `__FILE__` or
     /// `std::source_location::file_name`, both of which return a nul-terminated `const char*`.
     #[must_use]
-    #[unstable(feature = "file_with_nul", issue = "141727")]
     #[inline]
+    #[stable(feature = "file_with_nul", since = "CURRENT_RUSTC_VERSION")]
+    #[rustc_const_stable(feature = "file_with_nul", since = "CURRENT_RUSTC_VERSION")]
     pub const fn file_as_c_str(&self) -> &'a CStr {
         let filename = self.filename.as_ptr();
 
diff --git a/tests/ui/rfcs/rfc-2091-track-caller/file-is-nul-terminated.rs b/tests/ui/rfcs/rfc-2091-track-caller/file-is-nul-terminated.rs
index 7902f40b09bdb..698492966adf3 100644
--- a/tests/ui/rfcs/rfc-2091-track-caller/file-is-nul-terminated.rs
+++ b/tests/ui/rfcs/rfc-2091-track-caller/file-is-nul-terminated.rs
@@ -1,5 +1,4 @@
 //@ run-pass
-#![feature(file_with_nul)]
 
 #[track_caller]
 const fn assert_file_has_trailing_zero() {

From 7ce81d145359aa230f8fc2d7de12650091508329 Mon Sep 17 00:00:00 2001
From: beepster4096 <19316085+beepster4096@users.noreply.github.com>
Date: Tue, 26 Aug 2025 01:12:20 -0700
Subject: [PATCH 3/6] deref related cleanups in ref_prop

---
 compiler/rustc_mir_transform/src/ref_prop.rs | 33 ++++++++------------
 1 file changed, 13 insertions(+), 20 deletions(-)

diff --git a/compiler/rustc_mir_transform/src/ref_prop.rs b/compiler/rustc_mir_transform/src/ref_prop.rs
index 6f61215cee2d6..b9d6e74ecae89 100644
--- a/compiler/rustc_mir_transform/src/ref_prop.rs
+++ b/compiler/rustc_mir_transform/src/ref_prop.rs
@@ -195,10 +195,10 @@ fn compute_replacement<'tcx>(
     //   including DEF. This violates the DEF dominates USE condition, and so is impossible.
     let is_constant_place = |place: Place<'_>| {
         // We only allow `Deref` as the first projection, to avoid surprises.
-        if place.projection.first() == Some(&PlaceElem::Deref) {
+        if let Some((&PlaceElem::Deref, rest)) = place.projection.split_first() {
             // `place == (*some_local).xxx`, it is constant only if `some_local` is constant.
             // We approximate constness using SSAness.
-            ssa.is_ssa(place.local) && place.projection[1..].iter().all(PlaceElem::is_stable_offset)
+            ssa.is_ssa(place.local) && rest.iter().all(PlaceElem::is_stable_offset)
         } else {
             storage_live.has_single_storage(place.local)
                 && place.projection[..].iter().all(PlaceElem::is_stable_offset)
@@ -206,7 +206,7 @@ fn compute_replacement<'tcx>(
     };
 
     let mut can_perform_opt = |target: Place<'tcx>, loc: Location| {
-        if target.projection.first() == Some(&PlaceElem::Deref) {
+        if target.is_indirect_first_projection() {
             // We are creating a reborrow. As `place.local` is a reference, removing the storage
             // statements should not make it much harder for LLVM to optimize.
             storage_to_remove.insert(target.local);
@@ -266,7 +266,7 @@ fn compute_replacement<'tcx>(
             Rvalue::Ref(_, _, place) | Rvalue::RawPtr(_, place) => {
                 let mut place = *place;
                 // Try to see through `place` in order to collapse reborrow chains.
-                if place.projection.first() == Some(&PlaceElem::Deref)
+                if let Some((&PlaceElem::Deref, rest)) = place.projection.split_first()
                     && let Value::Pointer(target, inner_needs_unique) = targets[place.local]
                     // Only see through immutable reference and pointers, as we do not know yet if
                     // mutable references are fully replaced.
@@ -274,7 +274,7 @@ fn compute_replacement<'tcx>(
                     // Only collapse chain if the pointee is definitely live.
                     && can_perform_opt(target, location)
                 {
-                    place = target.project_deeper(&place.projection[1..], tcx);
+                    place = target.project_deeper(rest, tcx);
                 }
                 assert_ne!(place.local, local);
                 if is_constant_place(place) {
@@ -323,7 +323,7 @@ fn compute_replacement<'tcx>(
                 return;
             }
 
-            if place.projection.first() != Some(&PlaceElem::Deref) {
+            if !place.is_indirect_first_projection() {
                 // This is not a dereference, nothing to do.
                 return;
             }
@@ -392,20 +392,15 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'tcx> {
     }
 
     fn visit_var_debug_info(&mut self, debuginfo: &mut VarDebugInfo<'tcx>) {
-        // If the debuginfo is a pointer to another place:
-        // - if it's a reborrow, see through it;
-        // - if it's a direct borrow, increase `debuginfo.references`.
+        // If the debuginfo is a pointer to another place
+        // and it's a reborrow: see through it
         while let VarDebugInfoContents::Place(ref mut place) = debuginfo.value
             && place.projection.is_empty()
             && let Value::Pointer(target, _) = self.targets[place.local]
-            && target.projection.iter().all(|p| p.can_use_in_debuginfo())
+            && let &[PlaceElem::Deref] = &target.projection[..]
         {
-            if let Some((&PlaceElem::Deref, rest)) = target.projection.split_last() {
-                *place = Place::from(target.local).project_deeper(rest, self.tcx);
-                self.any_replacement = true;
-            } else {
-                break;
-            }
+            *place = Place::from(target.local);
+            self.any_replacement = true;
         }
 
         // Simplify eventual projections left inside `debuginfo`.
@@ -414,9 +409,7 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'tcx> {
 
     fn visit_place(&mut self, place: &mut Place<'tcx>, ctxt: PlaceContext, loc: Location) {
         loop {
-            if place.projection.first() != Some(&PlaceElem::Deref) {
-                return;
-            }
+            let Some((&PlaceElem::Deref, rest)) = place.projection.split_first() else { return };
 
             let Value::Pointer(target, _) = self.targets[place.local] else { return };
 
@@ -432,7 +425,7 @@ impl<'tcx> MutVisitor<'tcx> for Replacer<'tcx> {
                 return;
             }
 
-            *place = target.project_deeper(&place.projection[1..], self.tcx);
+            *place = target.project_deeper(rest, self.tcx);
             self.any_replacement = true;
         }
     }

From b27942853efdb2fde2b6f73023c38ebfec3fcb8f Mon Sep 17 00:00:00 2001
From: Folkert de Vries <folkert@folkertdev.nl>
Date: Fri, 19 Sep 2025 21:53:06 +0200
Subject: [PATCH 4/6] naked_asm: emit a label starting with `func_end`

The `cargo asm` tool pattern matches on such labels to figure out where functions end: normal functions generated by LLVM always do have such a label. We don't guarantee that naked functions emit such a label, but having `cargo asm` work is convenient
---
 compiler/rustc_codegen_ssa/src/mir/naked_asm.rs | 6 ++++++
 tests/assembly-llvm/naked-functions/wasm32.rs   | 1 +
 2 files changed, 7 insertions(+)

diff --git a/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs b/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs
index 31784cabf4af3..e7239ebfecf63 100644
--- a/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/naked_asm.rs
@@ -228,6 +228,9 @@ fn prefix_and_suffix<'tcx>(
             writeln!(begin, "{asm_name}:").unwrap();
 
             writeln!(end).unwrap();
+            // emit a label starting with `func_end` for `cargo asm` and other tooling that might
+            // pattern match on assembly generated by LLVM.
+            writeln!(end, ".Lfunc_end_{asm_name}:").unwrap();
             writeln!(end, ".size {asm_name}, . - {asm_name}").unwrap();
             writeln!(end, ".popsection").unwrap();
             if !arch_suffix.is_empty() {
@@ -246,6 +249,7 @@ fn prefix_and_suffix<'tcx>(
             writeln!(begin, "{asm_name}:").unwrap();
 
             writeln!(end).unwrap();
+            writeln!(end, ".Lfunc_end_{asm_name}:").unwrap();
             writeln!(end, ".popsection").unwrap();
             if !arch_suffix.is_empty() {
                 writeln!(end, "{}", arch_suffix).unwrap();
@@ -263,6 +267,7 @@ fn prefix_and_suffix<'tcx>(
             writeln!(begin, "{asm_name}:").unwrap();
 
             writeln!(end).unwrap();
+            writeln!(end, ".Lfunc_end_{asm_name}:").unwrap();
             writeln!(end, ".popsection").unwrap();
             if !arch_suffix.is_empty() {
                 writeln!(end, "{}", arch_suffix).unwrap();
@@ -287,6 +292,7 @@ fn prefix_and_suffix<'tcx>(
             writeln!(end).unwrap();
             // .size is ignored for function symbols, so we can skip it
             writeln!(end, "end_function").unwrap();
+            writeln!(end, ".Lfunc_end_{asm_name}:").unwrap();
         }
         BinaryFormat::Xcoff => {
             // the LLVM XCOFFAsmParser is extremely incomplete and does not implement many of the
diff --git a/tests/assembly-llvm/naked-functions/wasm32.rs b/tests/assembly-llvm/naked-functions/wasm32.rs
index 77547e82041fe..4bf04dd392341 100644
--- a/tests/assembly-llvm/naked-functions/wasm32.rs
+++ b/tests/assembly-llvm/naked-functions/wasm32.rs
@@ -21,6 +21,7 @@ use minicore::*;
 // CHECK: .functype nop () -> ()
 // CHECK-NOT: .size
 // CHECK: end_function
+// CHECK-LABEL: .Lfunc_end_nop:
 #[no_mangle]
 #[unsafe(naked)]
 extern "C" fn nop() {

From ac3c480388d27ee9ebeb23d308bd37289d37bc41 Mon Sep 17 00:00:00 2001
From: tk <49250442+tkr-sh@users.noreply.github.com>
Date: Wed, 14 May 2025 00:54:47 +0200
Subject: [PATCH 5/6] docs: improve doc of some methods w/ ranges

---
 library/alloc/src/collections/vec_deque/mod.rs | 12 ++++++------
 library/alloc/src/string.rs                    | 12 ++++++------
 library/alloc/src/vec/mod.rs                   |  8 ++++----
 3 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/library/alloc/src/collections/vec_deque/mod.rs b/library/alloc/src/collections/vec_deque/mod.rs
index 2fce5c3e737e4..d589860524b82 100644
--- a/library/alloc/src/collections/vec_deque/mod.rs
+++ b/library/alloc/src/collections/vec_deque/mod.rs
@@ -1486,8 +1486,8 @@ impl<T, A: Allocator> VecDeque<T, A> {
     ///
     /// # Panics
     ///
-    /// Panics if the starting point is greater than the end point or if
-    /// the end point is greater than the length of the deque.
+    /// Panics if the range has `start_bound > end_bound`, or, if the range is
+    /// bounded on either end and past the length of the deque.
     ///
     /// # Examples
     ///
@@ -1522,8 +1522,8 @@ impl<T, A: Allocator> VecDeque<T, A> {
     ///
     /// # Panics
     ///
-    /// Panics if the starting point is greater than the end point or if
-    /// the end point is greater than the length of the deque.
+    /// Panics if the range has `start_bound > end_bound`, or, if the range is
+    /// bounded on either end and past the length of the deque.
     ///
     /// # Examples
     ///
@@ -1568,8 +1568,8 @@ impl<T, A: Allocator> VecDeque<T, A> {
     ///
     /// # Panics
     ///
-    /// Panics if the starting point is greater than the end point or if
-    /// the end point is greater than the length of the deque.
+    /// Panics if the range has `start_bound > end_bound`, or, if the range is
+    /// bounded on either end and past the length of the deque.
     ///
     /// # Leaking
     ///
diff --git a/library/alloc/src/string.rs b/library/alloc/src/string.rs
index 1d0dd4be1b66a..e669c4708ad09 100644
--- a/library/alloc/src/string.rs
+++ b/library/alloc/src/string.rs
@@ -1117,8 +1117,8 @@ impl String {
     ///
     /// # Panics
     ///
-    /// Panics if the starting point or end point do not lie on a [`char`]
-    /// boundary, or if they're out of bounds.
+    /// Panics if the range has `start_bound > end_bound`, or, if the range is
+    /// bounded on either end and does not lie on a [`char`] boundary.
     ///
     /// # Examples
     ///
@@ -1939,8 +1939,8 @@ impl String {
     ///
     /// # Panics
     ///
-    /// Panics if the starting point or end point do not lie on a [`char`]
-    /// boundary, or if they're out of bounds.
+    /// Panics if the range has `start_bound > end_bound`, or, if the range is
+    /// bounded on either end and does not lie on a [`char`] boundary.
     ///
     /// # Leaking
     ///
@@ -2050,8 +2050,8 @@ impl String {
     ///
     /// # Panics
     ///
-    /// Panics if the starting point or end point do not lie on a [`char`]
-    /// boundary, or if they're out of bounds.
+    /// Panics if the range has `start_bound > end_bound`, or, if the range is
+    /// bounded on either end and does not lie on a [`char`] boundary.
     ///
     /// # Examples
     ///
diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index 1b80b43abc357..10c7ee4f6c89d 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -2796,8 +2796,8 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// # Panics
     ///
-    /// Panics if the starting point is greater than the end point or if
-    /// the end point is greater than the length of the vector.
+    /// Panics if the range has `start_bound > end_bound`, or, if the range is
+    /// bounded on either end and past the length of the vector.
     ///
     /// # Leaking
     ///
@@ -3860,8 +3860,8 @@ impl<T, A: Allocator> Vec<T, A> {
     ///
     /// # Panics
     ///
-    /// Panics if the starting point is greater than the end point or if
-    /// the end point is greater than the length of the vector.
+    /// Panics if the range has `start_bound > end_bound`, or, if the range is
+    /// bounded on either end and past the length of the vector.
     ///
     /// # Examples
     ///

From 5c0cb3af59e03b4248ae58ca4e65f14307320195 Mon Sep 17 00:00:00 2001
From: Ben Kimock <kimockb@gmail.com>
Date: Sat, 20 Sep 2025 18:27:33 -0400
Subject: [PATCH 6/6] Fix old typo in lang_start_internal comment

---
 library/std/src/rt.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/std/src/rt.rs b/library/std/src/rt.rs
index b3f3b301e3db6..8d95cc1fb5747 100644
--- a/library/std/src/rt.rs
+++ b/library/std/src/rt.rs
@@ -161,7 +161,7 @@ fn lang_start_internal(
     // mechanism itself.
     //
     // There are a couple of instances where unwinding can begin. First is inside of the
-    // `rt::init`, `rt::cleanup` and similar functions controlled by bstd. In those instances a
+    // `rt::init`, `rt::cleanup` and similar functions controlled by std. In those instances a
     // panic is a std implementation bug. A quite likely one too, as there isn't any way to
     // prevent std from accidentally introducing a panic to these functions. Another is from
     // user code from `main` or, more nefariously, as described in e.g. issue #86030.