Make slice iterator constructors unstably const

8 files changed, 185 insertions, 176 deletions

diff --git a/library/core/src/slice/iter.rs b/library/core/src/slice/iter.rs
index a687ed7129d..d48248749c2 100644
--- a/library/core/src/slice/iter.rs
+++ b/library/core/src/slice/iter.rs
@@ -93,9 +93,9 @@ unsafe impl<T: Sync> Send for Iter<'_, T> {}
 
 impl<'a, T> Iter<'a, T> {
     #[inline]
-    pub(super) fn new(slice: &'a [T]) -> Self {
+    pub(super) const fn new(slice: &'a [T]) -> Self {
         let len = slice.len();
-        let ptr: NonNull<T> = NonNull::from(slice).cast();
+        let ptr: NonNull<T> = NonNull::from_ref(slice).cast();
         // SAFETY: Similar to `IterMut::new`.
         unsafe {
             let end_or_len =
@@ -218,9 +218,9 @@ unsafe impl<T: Send> Send for IterMut<'_, T> {}
 
 impl<'a, T> IterMut<'a, T> {
     #[inline]
-    pub(super) fn new(slice: &'a mut [T]) -> Self {
+    pub(super) const fn new(slice: &'a mut [T]) -> Self {
         let len = slice.len();
-        let ptr: NonNull<T> = NonNull::from(slice).cast();
+        let ptr: NonNull<T> = NonNull::from_mut(slice).cast();
         // SAFETY: There are several things here:
         //
         // `ptr` has been obtained by `slice.as_ptr()` where `slice` is a valid
@@ -1335,7 +1335,7 @@ pub struct Windows<'a, T: 'a> {
 
 impl<'a, T: 'a> Windows<'a, T> {
     #[inline]
-    pub(super) fn new(slice: &'a [T], size: NonZero<usize>) -> Self {
+    pub(super) const fn new(slice: &'a [T], size: NonZero<usize>) -> Self {
         Self { v: slice, size }
     }
 }
@@ -1487,7 +1487,7 @@ pub struct Chunks<'a, T: 'a> {
 
 impl<'a, T: 'a> Chunks<'a, T> {
     #[inline]
-    pub(super) fn new(slice: &'a [T], size: usize) -> Self {
+    pub(super) const fn new(slice: &'a [T], size: usize) -> Self {
         Self { v: slice, chunk_size: size }
     }
 }
@@ -1677,7 +1677,7 @@ pub struct ChunksMut<'a, T: 'a> {
 
 impl<'a, T: 'a> ChunksMut<'a, T> {
     #[inline]
-    pub(super) fn new(slice: &'a mut [T], size: usize) -> Self {
+    pub(super) const fn new(slice: &'a mut [T], size: usize) -> Self {
         Self { v: slice, chunk_size: size, _marker: PhantomData }
     }
 }
@@ -1863,7 +1863,7 @@ pub struct ChunksExact<'a, T: 'a> {
 
 impl<'a, T> ChunksExact<'a, T> {
     #[inline]
-    pub(super) fn new(slice: &'a [T], chunk_size: usize) -> Self {
+    pub(super) const fn new(slice: &'a [T], chunk_size: usize) -> Self {
         let rem = slice.len() % chunk_size;
         let fst_len = slice.len() - rem;
         // SAFETY: 0 <= fst_len <= slice.len() by construction above
@@ -2043,7 +2043,7 @@ pub struct ChunksExactMut<'a, T: 'a> {
 
 impl<'a, T> ChunksExactMut<'a, T> {
     #[inline]
-    pub(super) fn new(slice: &'a mut [T], chunk_size: usize) -> Self {
+    pub(super) const fn new(slice: &'a mut [T], chunk_size: usize) -> Self {
         let rem = slice.len() % chunk_size;
         let fst_len = slice.len() - rem;
         // SAFETY: 0 <= fst_len <= slice.len() by construction above
@@ -2210,7 +2210,7 @@ pub struct ArrayWindows<'a, T: 'a, const N: usize> {
 
 impl<'a, T: 'a, const N: usize> ArrayWindows<'a, T, N> {
     #[inline]
-    pub(super) fn new(slice: &'a [T]) -> Self {
+    pub(super) const fn new(slice: &'a [T]) -> Self {
         let num_windows = slice.len().saturating_sub(N - 1);
         Self { slice_head: slice.as_ptr(), num: num_windows, marker: PhantomData }
     }
@@ -2334,8 +2334,10 @@ pub struct ArrayChunks<'a, T: 'a, const N: usize> {
 }
 
 impl<'a, T, const N: usize> ArrayChunks<'a, T, N> {
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
+    // #[rustc_const_unstable(feature = "slice_as_chunks", issue = "74985")]
     #[inline]
-    pub(super) fn new(slice: &'a [T]) -> Self {
+    pub(super) const fn new(slice: &'a [T]) -> Self {
         let (array_slice, rem) = slice.as_chunks();
         Self { iter: array_slice.iter(), rem }
     }
@@ -2460,8 +2462,9 @@ pub struct ArrayChunksMut<'a, T: 'a, const N: usize> {
 }
 
 impl<'a, T, const N: usize> ArrayChunksMut<'a, T, N> {
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
-    pub(super) fn new(slice: &'a mut [T]) -> Self {
+    pub(super) const fn new(slice: &'a mut [T]) -> Self {
         let (array_slice, rem) = slice.as_chunks_mut();
         Self { iter: array_slice.iter_mut(), rem }
     }
@@ -2579,7 +2582,7 @@ pub struct RChunks<'a, T: 'a> {
 
 impl<'a, T: 'a> RChunks<'a, T> {
     #[inline]
-    pub(super) fn new(slice: &'a [T], size: usize) -> Self {
+    pub(super) const fn new(slice: &'a [T], size: usize) -> Self {
         Self { v: slice, chunk_size: size }
     }
 }
@@ -2759,7 +2762,7 @@ pub struct RChunksMut<'a, T: 'a> {
 
 impl<'a, T: 'a> RChunksMut<'a, T> {
     #[inline]
-    pub(super) fn new(slice: &'a mut [T], size: usize) -> Self {
+    pub(super) const fn new(slice: &'a mut [T], size: usize) -> Self {
         Self { v: slice, chunk_size: size, _marker: PhantomData }
     }
 }
@@ -2950,7 +2953,7 @@ pub struct RChunksExact<'a, T: 'a> {
 
 impl<'a, T> RChunksExact<'a, T> {
     #[inline]
-    pub(super) fn new(slice: &'a [T], chunk_size: usize) -> Self {
+    pub(super) const fn new(slice: &'a [T], chunk_size: usize) -> Self {
         let rem = slice.len() % chunk_size;
         // SAFETY: 0 <= rem <= slice.len() by construction above
         let (fst, snd) = unsafe { slice.split_at_unchecked(rem) };
@@ -2976,7 +2979,8 @@ impl<'a, T> RChunksExact<'a, T> {
     /// ```
     #[must_use]
     #[stable(feature = "rchunks", since = "1.31.0")]
-    pub fn remainder(&self) -> &'a [T] {
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
+    pub const fn remainder(&self) -> &'a [T] {
         self.rem
     }
 }
@@ -3132,7 +3136,7 @@ pub struct RChunksExactMut<'a, T: 'a> {
 
 impl<'a, T> RChunksExactMut<'a, T> {
     #[inline]
-    pub(super) fn new(slice: &'a mut [T], chunk_size: usize) -> Self {
+    pub(super) const fn new(slice: &'a mut [T], chunk_size: usize) -> Self {
         let rem = slice.len() % chunk_size;
         // SAFETY: 0 <= rem <= slice.len() by construction above
         let (fst, snd) = unsafe { slice.split_at_mut_unchecked(rem) };
@@ -3144,7 +3148,8 @@ impl<'a, T> RChunksExactMut<'a, T> {
     /// elements.
     #[must_use = "`self` will be dropped if the result is not used"]
     #[stable(feature = "rchunks", since = "1.31.0")]
-    pub fn into_remainder(self) -> &'a mut [T] {
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
+    pub const fn into_remainder(self) -> &'a mut [T] {
         self.rem
     }
 }
@@ -3308,7 +3313,7 @@ pub struct ChunkBy<'a, T: 'a, P> {
 
 #[stable(feature = "slice_group_by", since = "1.77.0")]
 impl<'a, T: 'a, P> ChunkBy<'a, T, P> {
-    pub(super) fn new(slice: &'a [T], predicate: P) -> Self {
+    pub(super) const fn new(slice: &'a [T], predicate: P) -> Self {
         ChunkBy { slice, predicate }
     }
 }
@@ -3395,7 +3400,7 @@ pub struct ChunkByMut<'a, T: 'a, P> {
 
 #[stable(feature = "slice_group_by", since = "1.77.0")]
 impl<'a, T: 'a, P> ChunkByMut<'a, T, P> {
-    pub(super) fn new(slice: &'a mut [T], predicate: P) -> Self {
+    pub(super) const fn new(slice: &'a mut [T], predicate: P) -> Self {
         ChunkByMut { slice, predicate }
     }
 }
diff --git a/library/core/src/slice/mod.rs b/library/core/src/slice/mod.rs
index 5bb7243c449..ef8fb694a32 100644
--- a/library/core/src/slice/mod.rs
+++ b/library/core/src/slice/mod.rs
@@ -1043,9 +1043,10 @@ impl<T> [T] {
     /// assert_eq!(iterator.next(), None);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[rustc_diagnostic_item = "slice_iter"]
-    pub fn iter(&self) -> Iter<'_, T> {
+    pub const fn iter(&self) -> Iter<'_, T> {
         Iter::new(self)
     }
 
@@ -1062,9 +1063,10 @@ impl<T> [T] {
     /// }
     /// assert_eq!(x, &[3, 4, 6]);
     /// ```
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
-    pub fn iter_mut(&mut self) -> IterMut<'_, T> {
+    pub const fn iter_mut(&mut self) -> IterMut<'_, T> {
         IterMut::new(self)
     }
 
@@ -1116,9 +1118,10 @@ impl<T> [T] {
     /// assert_eq!(array, ['s', 't', ' ', '2', '0', '1', '5', 'u', 'R']);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn windows(&self, size: usize) -> Windows<'_, T> {
+    pub const fn windows(&self, size: usize) -> Windows<'_, T> {
         let size = NonZero::new(size).expect("window size must be non-zero");
         Windows::new(self, size)
     }
@@ -1151,9 +1154,10 @@ impl<T> [T] {
     /// [`chunks_exact`]: slice::chunks_exact
     /// [`rchunks`]: slice::rchunks
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn chunks(&self, chunk_size: usize) -> Chunks<'_, T> {
+    pub const fn chunks(&self, chunk_size: usize) -> Chunks<'_, T> {
         assert!(chunk_size != 0, "chunk size must be non-zero");
         Chunks::new(self, chunk_size)
     }
@@ -1190,9 +1194,10 @@ impl<T> [T] {
     /// [`chunks_exact_mut`]: slice::chunks_exact_mut
     /// [`rchunks_mut`]: slice::rchunks_mut
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<'_, T> {
+    pub const fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<'_, T> {
         assert!(chunk_size != 0, "chunk size must be non-zero");
         ChunksMut::new(self, chunk_size)
     }
@@ -1228,9 +1233,10 @@ impl<T> [T] {
     /// [`chunks`]: slice::chunks
     /// [`rchunks_exact`]: slice::rchunks_exact
     #[stable(feature = "chunks_exact", since = "1.31.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T> {
+    pub const fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T> {
         assert!(chunk_size != 0, "chunk size must be non-zero");
         ChunksExact::new(self, chunk_size)
     }
@@ -1271,9 +1277,10 @@ impl<T> [T] {
     /// [`chunks_mut`]: slice::chunks_mut
     /// [`rchunks_exact_mut`]: slice::rchunks_exact_mut
     #[stable(feature = "chunks_exact", since = "1.31.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T> {
+    pub const fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T> {
         assert!(chunk_size != 0, "chunk size must be non-zero");
         ChunksExactMut::new(self, chunk_size)
     }
@@ -1429,9 +1436,10 @@ impl<T> [T] {
     ///
     /// [`chunks_exact`]: slice::chunks_exact
     #[unstable(feature = "array_chunks", issue = "74985")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N> {
+    pub const fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N> {
         assert!(N != 0, "chunk size must be non-zero");
         ArrayChunks::new(self)
     }
@@ -1592,9 +1600,10 @@ impl<T> [T] {
     ///
     /// [`chunks_exact_mut`]: slice::chunks_exact_mut
     #[unstable(feature = "array_chunks", issue = "74985")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N> {
+    pub const fn array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N> {
         assert!(N != 0, "chunk size must be non-zero");
         ArrayChunksMut::new(self)
     }
@@ -1625,9 +1634,10 @@ impl<T> [T] {
     ///
     /// [`windows`]: slice::windows
     #[unstable(feature = "array_windows", issue = "75027")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N> {
+    pub const fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N> {
         assert!(N != 0, "window size must be non-zero");
         ArrayWindows::new(self)
     }
@@ -1660,9 +1670,10 @@ impl<T> [T] {
     /// [`rchunks_exact`]: slice::rchunks_exact
     /// [`chunks`]: slice::chunks
     #[stable(feature = "rchunks", since = "1.31.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T> {
+    pub const fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T> {
         assert!(chunk_size != 0, "chunk size must be non-zero");
         RChunks::new(self, chunk_size)
     }
@@ -1699,9 +1710,10 @@ impl<T> [T] {
     /// [`rchunks_exact_mut`]: slice::rchunks_exact_mut
     /// [`chunks_mut`]: slice::chunks_mut
     #[stable(feature = "rchunks", since = "1.31.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<'_, T> {
+    pub const fn rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<'_, T> {
         assert!(chunk_size != 0, "chunk size must be non-zero");
         RChunksMut::new(self, chunk_size)
     }
@@ -1739,9 +1751,10 @@ impl<T> [T] {
     /// [`rchunks`]: slice::rchunks
     /// [`chunks_exact`]: slice::chunks_exact
     #[stable(feature = "rchunks", since = "1.31.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T> {
+    pub const fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T> {
         assert!(chunk_size != 0, "chunk size must be non-zero");
         RChunksExact::new(self, chunk_size)
     }
@@ -1783,9 +1796,10 @@ impl<T> [T] {
     /// [`rchunks_mut`]: slice::rchunks_mut
     /// [`chunks_exact_mut`]: slice::chunks_exact_mut
     #[stable(feature = "rchunks", since = "1.31.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
     #[track_caller]
-    pub fn rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<'_, T> {
+    pub const fn rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<'_, T> {
         assert!(chunk_size != 0, "chunk size must be non-zero");
         RChunksExactMut::new(self, chunk_size)
     }
@@ -1823,8 +1837,9 @@ impl<T> [T] {
     /// assert_eq!(iter.next(), None);
     /// ```
     #[stable(feature = "slice_group_by", since = "1.77.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
-    pub fn chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F>
+    pub const fn chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F>
     where
         F: FnMut(&T, &T) -> bool,
     {
@@ -1864,8 +1879,9 @@ impl<T> [T] {
     /// assert_eq!(iter.next(), None);
     /// ```
     #[stable(feature = "slice_group_by", since = "1.77.0")]
+    #[rustc_const_unstable(feature = "const_slice_make_iter", issue = "137737")]
     #[inline]
-    pub fn chunk_by_mut<F>(&mut self, pred: F) -> ChunkByMut<'_, T, F>
+    pub const fn chunk_by_mut<F>(&mut self, pred: F) -> ChunkByMut<'_, T, F>
     where
         F: FnMut(&T, &T) -> bool,
     {
diff --git a/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir
index 7ef532d222d..c75edde711e 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-abort.mir
@@ -22,74 +22,74 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
             debug i => _33;
             debug x => _34;
         }
-        scope 19 (inlined <Enumerate<std::slice::Iter<'_, T>> as Iterator>::next) {
+        scope 18 (inlined <Enumerate<std::slice::Iter<'_, T>> as Iterator>::next) {
             let mut _27: std::option::Option<&T>;
             let mut _30: (usize, bool);
             let mut _31: (usize, &T);
-            scope 20 {
+            scope 19 {
                 let _29: usize;
-                scope 25 {
+                scope 24 {
                 }
             }
-            scope 21 {
-                scope 22 {
-                    scope 28 (inlined <Option<(usize, &T)> as FromResidual<Option<Infallible>>>::from_residual) {
+            scope 20 {
+                scope 21 {
+                    scope 27 (inlined <Option<(usize, &T)> as FromResidual<Option<Infallible>>>::from_residual) {
                     }
                 }
             }
-            scope 23 {
-                scope 24 {
+            scope 22 {
+                scope 23 {
                 }
             }
-            scope 26 (inlined <Option<&T> as Try>::branch) {
+            scope 25 (inlined <Option<&T> as Try>::branch) {
                 let _28: &T;
-                scope 27 {
+                scope 26 {
                 }
             }
-            scope 29 (inlined <std::slice::Iter<'_, T> as Iterator>::next) {
+            scope 28 (inlined <std::slice::Iter<'_, T> as Iterator>::next) {
                 let _14: std::ptr::NonNull<T>;
                 let _16: std::ptr::NonNull<T>;
                 let mut _19: bool;
                 let mut _22: std::ptr::NonNull<T>;
                 let mut _24: usize;
                 let _26: &T;
-                scope 30 {
+                scope 29 {
                     let _15: *const T;
-                    scope 31 {
+                    scope 30 {
                         let _23: usize;
-                        scope 32 {
-                            scope 35 (inlined core::num::<impl usize>::unchecked_sub) {
-                                scope 36 (inlined core::ub_checks::check_language_ub) {
-                                    scope 37 (inlined core::ub_checks::check_language_ub::runtime) {
+                        scope 31 {
+                            scope 34 (inlined core::num::<impl usize>::unchecked_sub) {
+                                scope 35 (inlined core::ub_checks::check_language_ub) {
+                                    scope 36 (inlined core::ub_checks::check_language_ub::runtime) {
                                     }
                                 }
                             }
-                            scope 38 (inlined without_provenance_mut::<T>) {
+                            scope 37 (inlined without_provenance_mut::<T>) {
                             }
                         }
-                        scope 33 (inlined std::ptr::const_ptr::<impl *const T>::addr) {
-                            scope 34 (inlined std::ptr::const_ptr::<impl *const T>::cast::<()>) {
+                        scope 32 (inlined std::ptr::const_ptr::<impl *const T>::addr) {
+                            scope 33 (inlined std::ptr::const_ptr::<impl *const T>::cast::<()>) {
                             }
                         }
-                        scope 39 (inlined <NonNull<T> as PartialEq>::eq) {
+                        scope 38 (inlined <NonNull<T> as PartialEq>::eq) {
                             let mut _17: *mut T;
                             let mut _18: *mut T;
-                            scope 40 (inlined NonNull::<T>::as_ptr) {
+                            scope 39 (inlined NonNull::<T>::as_ptr) {
                             }
-                            scope 41 (inlined NonNull::<T>::as_ptr) {
+                            scope 40 (inlined NonNull::<T>::as_ptr) {
                             }
                         }
-                        scope 42 (inlined NonNull::<T>::add) {
+                        scope 41 (inlined NonNull::<T>::add) {
                             let mut _20: *const T;
                             let mut _21: *const T;
-                            scope 43 (inlined NonNull::<T>::as_ptr) {
+                            scope 42 (inlined NonNull::<T>::as_ptr) {
                             }
                         }
-                        scope 44 (inlined NonNull::<T>::as_ref::<'_>) {
+                        scope 43 (inlined NonNull::<T>::as_ref::<'_>) {
                             let _25: *const T;
-                            scope 45 (inlined NonNull::<T>::as_ptr) {
+                            scope 44 (inlined NonNull::<T>::as_ptr) {
                             }
-                            scope 46 (inlined std::ptr::mut_ptr::<impl *mut T>::cast_const) {
+                            scope 45 (inlined std::ptr::mut_ptr::<impl *mut T>::cast_const) {
                             }
                         }
                     }
@@ -109,33 +109,31 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
                     let _9: *const T;
                     scope 7 {
                     }
-                    scope 12 (inlined std::ptr::without_provenance::<T>) {
-                        scope 13 (inlined without_provenance_mut::<T>) {
+                    scope 11 (inlined std::ptr::without_provenance::<T>) {
+                        scope 12 (inlined without_provenance_mut::<T>) {
                         }
                     }
-                    scope 14 (inlined NonNull::<T>::as_ptr) {
+                    scope 13 (inlined NonNull::<T>::as_ptr) {
                     }
-                    scope 15 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
+                    scope 14 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
                     }
                 }
-                scope 8 (inlined <NonNull<[T]> as From<&[T]>>::from) {
-                    scope 9 (inlined NonNull::<[T]>::from_ref) {
-                        let mut _4: *const [T];
-                    }
+                scope 8 (inlined NonNull::<[T]>::from_ref) {
+                    let mut _4: *const [T];
                 }
-                scope 10 (inlined NonNull::<[T]>::cast::<T>) {
+                scope 9 (inlined NonNull::<[T]>::cast::<T>) {
                     let mut _5: *const T;
-                    scope 11 (inlined NonNull::<[T]>::as_ptr) {
+                    scope 10 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
             }
         }
     }
-    scope 16 (inlined <std::slice::Iter<'_, T> as Iterator>::enumerate) {
-        scope 17 (inlined Enumerate::<std::slice::Iter<'_, T>>::new) {
+    scope 15 (inlined <std::slice::Iter<'_, T> as Iterator>::enumerate) {
+        scope 16 (inlined Enumerate::<std::slice::Iter<'_, T>>::new) {
         }
     }
-    scope 18 (inlined <Enumerate<std::slice::Iter<'_, T>> as IntoIterator>::into_iter) {
+    scope 17 (inlined <Enumerate<std::slice::Iter<'_, T>> as IntoIterator>::into_iter) {
     }
 
     bb0: {
diff --git a/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-unwind.mir
index 33dbf04d028..bc72181b77c 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-unwind.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.enumerated_loop.PreCodegen.after.panic-unwind.mir
@@ -34,33 +34,31 @@ fn enumerated_loop(_1: &[T], _2: impl Fn(usize, &T)) -> () {
                     let _9: *const T;
                     scope 7 {
                     }
-                    scope 12 (inlined std::ptr::without_provenance::<T>) {
-                        scope 13 (inlined without_provenance_mut::<T>) {
+                    scope 11 (inlined std::ptr::without_provenance::<T>) {
+                        scope 12 (inlined without_provenance_mut::<T>) {
                         }
                     }
-                    scope 14 (inlined NonNull::<T>::as_ptr) {
+                    scope 13 (inlined NonNull::<T>::as_ptr) {
                     }
-                    scope 15 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
+                    scope 14 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
                     }
                 }
-                scope 8 (inlined <NonNull<[T]> as From<&[T]>>::from) {
-                    scope 9 (inlined NonNull::<[T]>::from_ref) {
-                        let mut _4: *const [T];
-                    }
+                scope 8 (inlined NonNull::<[T]>::from_ref) {
+                    let mut _4: *const [T];
                 }
-                scope 10 (inlined NonNull::<[T]>::cast::<T>) {
+                scope 9 (inlined NonNull::<[T]>::cast::<T>) {
                     let mut _5: *const T;
-                    scope 11 (inlined NonNull::<[T]>::as_ptr) {
+                    scope 10 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
             }
         }
     }
-    scope 16 (inlined <std::slice::Iter<'_, T> as Iterator>::enumerate) {
-        scope 17 (inlined Enumerate::<std::slice::Iter<'_, T>>::new) {
+    scope 15 (inlined <std::slice::Iter<'_, T> as Iterator>::enumerate) {
+        scope 16 (inlined Enumerate::<std::slice::Iter<'_, T>>::new) {
         }
     }
-    scope 18 (inlined <Enumerate<std::slice::Iter<'_, T>> as IntoIterator>::into_iter) {
+    scope 17 (inlined <Enumerate<std::slice::Iter<'_, T>> as IntoIterator>::into_iter) {
     }
 
     bb0: {
diff --git a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir
index 62787f3447c..38c509d0b53 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-abort.mir
@@ -18,50 +18,50 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
         scope 2 {
             debug x => _27;
         }
-        scope 17 (inlined <std::slice::Iter<'_, T> as Iterator>::next) {
+        scope 16 (inlined <std::slice::Iter<'_, T> as Iterator>::next) {
             let _13: std::ptr::NonNull<T>;
             let _15: std::ptr::NonNull<T>;
             let mut _18: bool;
             let mut _21: std::ptr::NonNull<T>;
             let mut _23: usize;
             let _25: &T;
-            scope 18 {
+            scope 17 {
                 let _14: *const T;
-                scope 19 {
+                scope 18 {
                     let _22: usize;
-                    scope 20 {
-                        scope 23 (inlined core::num::<impl usize>::unchecked_sub) {
-                            scope 24 (inlined core::ub_checks::check_language_ub) {
-                                scope 25 (inlined core::ub_checks::check_language_ub::runtime) {
+                    scope 19 {
+                        scope 22 (inlined core::num::<impl usize>::unchecked_sub) {
+                            scope 23 (inlined core::ub_checks::check_language_ub) {
+                                scope 24 (inlined core::ub_checks::check_language_ub::runtime) {
                                 }
                             }
                         }
-                        scope 26 (inlined without_provenance_mut::<T>) {
+                        scope 25 (inlined without_provenance_mut::<T>) {
                         }
                     }
-                    scope 21 (inlined std::ptr::const_ptr::<impl *const T>::addr) {
-                        scope 22 (inlined std::ptr::const_ptr::<impl *const T>::cast::<()>) {
+                    scope 20 (inlined std::ptr::const_ptr::<impl *const T>::addr) {
+                        scope 21 (inlined std::ptr::const_ptr::<impl *const T>::cast::<()>) {
                         }
                     }
-                    scope 27 (inlined <NonNull<T> as PartialEq>::eq) {
+                    scope 26 (inlined <NonNull<T> as PartialEq>::eq) {
                         let mut _16: *mut T;
                         let mut _17: *mut T;
-                        scope 28 (inlined NonNull::<T>::as_ptr) {
+                        scope 27 (inlined NonNull::<T>::as_ptr) {
                         }
-                        scope 29 (inlined NonNull::<T>::as_ptr) {
+                        scope 28 (inlined NonNull::<T>::as_ptr) {
                         }
                     }
-                    scope 30 (inlined NonNull::<T>::add) {
+                    scope 29 (inlined NonNull::<T>::add) {
                         let mut _19: *const T;
                         let mut _20: *const T;
-                        scope 31 (inlined NonNull::<T>::as_ptr) {
+                        scope 30 (inlined NonNull::<T>::as_ptr) {
                         }
                     }
-                    scope 32 (inlined NonNull::<T>::as_ref::<'_>) {
+                    scope 31 (inlined NonNull::<T>::as_ref::<'_>) {
                         let _24: *const T;
-                        scope 33 (inlined NonNull::<T>::as_ptr) {
+                        scope 32 (inlined NonNull::<T>::as_ptr) {
                         }
-                        scope 34 (inlined std::ptr::mut_ptr::<impl *mut T>::cast_const) {
+                        scope 33 (inlined std::ptr::mut_ptr::<impl *mut T>::cast_const) {
                         }
                     }
                 }
@@ -80,29 +80,27 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
                     let _9: *const T;
                     scope 7 {
                     }
-                    scope 12 (inlined std::ptr::without_provenance::<T>) {
-                        scope 13 (inlined without_provenance_mut::<T>) {
+                    scope 11 (inlined std::ptr::without_provenance::<T>) {
+                        scope 12 (inlined without_provenance_mut::<T>) {
                         }
                     }
-                    scope 14 (inlined NonNull::<T>::as_ptr) {
+                    scope 13 (inlined NonNull::<T>::as_ptr) {
                     }
-                    scope 15 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
+                    scope 14 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
                     }
                 }
-                scope 8 (inlined <NonNull<[T]> as From<&[T]>>::from) {
-                    scope 9 (inlined NonNull::<[T]>::from_ref) {
-                        let mut _4: *const [T];
-                    }
+                scope 8 (inlined NonNull::<[T]>::from_ref) {
+                    let mut _4: *const [T];
                 }
-                scope 10 (inlined NonNull::<[T]>::cast::<T>) {
+                scope 9 (inlined NonNull::<[T]>::cast::<T>) {
                     let mut _5: *const T;
-                    scope 11 (inlined NonNull::<[T]>::as_ptr) {
+                    scope 10 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
             }
         }
     }
-    scope 16 (inlined <std::slice::Iter<'_, T> as IntoIterator>::into_iter) {
+    scope 15 (inlined <std::slice::Iter<'_, T> as IntoIterator>::into_iter) {
     }
 
     bb0: {
diff --git a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir
index e5478e27918..158cc284b1a 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.forward_loop.PreCodegen.after.panic-unwind.mir
@@ -18,50 +18,50 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
         scope 2 {
             debug x => _27;
         }
-        scope 17 (inlined <std::slice::Iter<'_, T> as Iterator>::next) {
+        scope 16 (inlined <std::slice::Iter<'_, T> as Iterator>::next) {
             let _13: std::ptr::NonNull<T>;
             let _15: std::ptr::NonNull<T>;
             let mut _18: bool;
             let mut _21: std::ptr::NonNull<T>;
             let mut _23: usize;
             let _25: &T;
-            scope 18 {
+            scope 17 {
                 let _14: *const T;
-                scope 19 {
+                scope 18 {
                     let _22: usize;
-                    scope 20 {
-                        scope 23 (inlined core::num::<impl usize>::unchecked_sub) {
-                            scope 24 (inlined core::ub_checks::check_language_ub) {
-                                scope 25 (inlined core::ub_checks::check_language_ub::runtime) {
+                    scope 19 {
+                        scope 22 (inlined core::num::<impl usize>::unchecked_sub) {
+                            scope 23 (inlined core::ub_checks::check_language_ub) {
+                                scope 24 (inlined core::ub_checks::check_language_ub::runtime) {
                                 }
                             }
                         }
-                        scope 26 (inlined without_provenance_mut::<T>) {
+                        scope 25 (inlined without_provenance_mut::<T>) {
                         }
                     }
-                    scope 21 (inlined std::ptr::const_ptr::<impl *const T>::addr) {
-                        scope 22 (inlined std::ptr::const_ptr::<impl *const T>::cast::<()>) {
+                    scope 20 (inlined std::ptr::const_ptr::<impl *const T>::addr) {
+                        scope 21 (inlined std::ptr::const_ptr::<impl *const T>::cast::<()>) {
                         }
                     }
-                    scope 27 (inlined <NonNull<T> as PartialEq>::eq) {
+                    scope 26 (inlined <NonNull<T> as PartialEq>::eq) {
                         let mut _16: *mut T;
                         let mut _17: *mut T;
-                        scope 28 (inlined NonNull::<T>::as_ptr) {
+                        scope 27 (inlined NonNull::<T>::as_ptr) {
                         }
-                        scope 29 (inlined NonNull::<T>::as_ptr) {
+                        scope 28 (inlined NonNull::<T>::as_ptr) {
                         }
                     }
-                    scope 30 (inlined NonNull::<T>::add) {
+                    scope 29 (inlined NonNull::<T>::add) {
                         let mut _19: *const T;
                         let mut _20: *const T;
-                        scope 31 (inlined NonNull::<T>::as_ptr) {
+                        scope 30 (inlined NonNull::<T>::as_ptr) {
                         }
                     }
-                    scope 32 (inlined NonNull::<T>::as_ref::<'_>) {
+                    scope 31 (inlined NonNull::<T>::as_ref::<'_>) {
                         let _24: *const T;
-                        scope 33 (inlined NonNull::<T>::as_ptr) {
+                        scope 32 (inlined NonNull::<T>::as_ptr) {
                         }
-                        scope 34 (inlined std::ptr::mut_ptr::<impl *mut T>::cast_const) {
+                        scope 33 (inlined std::ptr::mut_ptr::<impl *mut T>::cast_const) {
                         }
                     }
                 }
@@ -80,29 +80,27 @@ fn forward_loop(_1: &[T], _2: impl Fn(&T)) -> () {
                     let _9: *const T;
                     scope 7 {
                     }
-                    scope 12 (inlined std::ptr::without_provenance::<T>) {
-                        scope 13 (inlined without_provenance_mut::<T>) {
+                    scope 11 (inlined std::ptr::without_provenance::<T>) {
+                        scope 12 (inlined without_provenance_mut::<T>) {
                         }
                     }
-                    scope 14 (inlined NonNull::<T>::as_ptr) {
+                    scope 13 (inlined NonNull::<T>::as_ptr) {
                     }
-                    scope 15 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
+                    scope 14 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
                     }
                 }
-                scope 8 (inlined <NonNull<[T]> as From<&[T]>>::from) {
-                    scope 9 (inlined NonNull::<[T]>::from_ref) {
-                        let mut _4: *const [T];
-                    }
+                scope 8 (inlined NonNull::<[T]>::from_ref) {
+                    let mut _4: *const [T];
                 }
-                scope 10 (inlined NonNull::<[T]>::cast::<T>) {
+                scope 9 (inlined NonNull::<[T]>::cast::<T>) {
                     let mut _5: *const T;
-                    scope 11 (inlined NonNull::<[T]>::as_ptr) {
+                    scope 10 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
             }
         }
     }
-    scope 16 (inlined <std::slice::Iter<'_, T> as IntoIterator>::into_iter) {
+    scope 15 (inlined <std::slice::Iter<'_, T> as IntoIterator>::into_iter) {
     }
 
     bb0: {
diff --git a/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-abort.mir b/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-abort.mir
index 4b7ab4516d2..00366762108 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-abort.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-abort.mir
@@ -18,7 +18,7 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
         scope 2 {
             debug x => _17;
         }
-        scope 19 (inlined <Rev<std::slice::Iter<'_, T>> as Iterator>::next) {
+        scope 18 (inlined <Rev<std::slice::Iter<'_, T>> as Iterator>::next) {
             let mut _14: &mut std::slice::Iter<'_, T>;
         }
     }
@@ -34,33 +34,31 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
                     let _9: *const T;
                     scope 7 {
                     }
-                    scope 12 (inlined std::ptr::without_provenance::<T>) {
-                        scope 13 (inlined without_provenance_mut::<T>) {
+                    scope 11 (inlined std::ptr::without_provenance::<T>) {
+                        scope 12 (inlined without_provenance_mut::<T>) {
                         }
                     }
-                    scope 14 (inlined NonNull::<T>::as_ptr) {
+                    scope 13 (inlined NonNull::<T>::as_ptr) {
                     }
-                    scope 15 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
+                    scope 14 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
                     }
                 }
-                scope 8 (inlined <NonNull<[T]> as From<&[T]>>::from) {
-                    scope 9 (inlined NonNull::<[T]>::from_ref) {
-                        let mut _4: *const [T];
-                    }
+                scope 8 (inlined NonNull::<[T]>::from_ref) {
+                    let mut _4: *const [T];
                 }
-                scope 10 (inlined NonNull::<[T]>::cast::<T>) {
+                scope 9 (inlined NonNull::<[T]>::cast::<T>) {
                     let mut _5: *const T;
-                    scope 11 (inlined NonNull::<[T]>::as_ptr) {
+                    scope 10 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
             }
         }
     }
-    scope 16 (inlined <std::slice::Iter<'_, T> as Iterator>::rev) {
-        scope 17 (inlined Rev::<std::slice::Iter<'_, T>>::new) {
+    scope 15 (inlined <std::slice::Iter<'_, T> as Iterator>::rev) {
+        scope 16 (inlined Rev::<std::slice::Iter<'_, T>>::new) {
         }
     }
-    scope 18 (inlined <Rev<std::slice::Iter<'_, T>> as IntoIterator>::into_iter) {
+    scope 17 (inlined <Rev<std::slice::Iter<'_, T>> as IntoIterator>::into_iter) {
     }
 
     bb0: {
diff --git a/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-unwind.mir b/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-unwind.mir
index b2c15247cd7..e1d710fb689 100644
--- a/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-unwind.mir
+++ b/tests/mir-opt/pre-codegen/slice_iter.reverse_loop.PreCodegen.after.panic-unwind.mir
@@ -18,7 +18,7 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
         scope 2 {
             debug x => _17;
         }
-        scope 19 (inlined <Rev<std::slice::Iter<'_, T>> as Iterator>::next) {
+        scope 18 (inlined <Rev<std::slice::Iter<'_, T>> as Iterator>::next) {
             let mut _14: &mut std::slice::Iter<'_, T>;
         }
     }
@@ -34,33 +34,31 @@ fn reverse_loop(_1: &[T], _2: impl Fn(&T)) -> () {
                     let _9: *const T;
                     scope 7 {
                     }
-                    scope 12 (inlined std::ptr::without_provenance::<T>) {
-                        scope 13 (inlined without_provenance_mut::<T>) {
+                    scope 11 (inlined std::ptr::without_provenance::<T>) {
+                        scope 12 (inlined without_provenance_mut::<T>) {
                         }
                     }
-                    scope 14 (inlined NonNull::<T>::as_ptr) {
+                    scope 13 (inlined NonNull::<T>::as_ptr) {
                     }
-                    scope 15 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
+                    scope 14 (inlined std::ptr::mut_ptr::<impl *mut T>::add) {
                     }
                 }
-                scope 8 (inlined <NonNull<[T]> as From<&[T]>>::from) {
-                    scope 9 (inlined NonNull::<[T]>::from_ref) {
-                        let mut _4: *const [T];
-                    }
+                scope 8 (inlined NonNull::<[T]>::from_ref) {
+                    let mut _4: *const [T];
                 }
-                scope 10 (inlined NonNull::<[T]>::cast::<T>) {
+                scope 9 (inlined NonNull::<[T]>::cast::<T>) {
                     let mut _5: *const T;
-                    scope 11 (inlined NonNull::<[T]>::as_ptr) {
+                    scope 10 (inlined NonNull::<[T]>::as_ptr) {
                     }
                 }
             }
         }
     }
-    scope 16 (inlined <std::slice::Iter<'_, T> as Iterator>::rev) {
-        scope 17 (inlined Rev::<std::slice::Iter<'_, T>>::new) {
+    scope 15 (inlined <std::slice::Iter<'_, T> as Iterator>::rev) {
+        scope 16 (inlined Rev::<std::slice::Iter<'_, T>>::new) {
         }
     }
-    scope 18 (inlined <Rev<std::slice::Iter<'_, T>> as IntoIterator>::into_iter) {
+    scope 17 (inlined <Rev<std::slice::Iter<'_, T>> as IntoIterator>::into_iter) {
     }
 
     bb0: {