5 files changed, 12 insertions, 10 deletions
diff --git a/library/alloc/src/alloc.rs b/library/alloc/src/alloc.rs
index 1663aa84921..0b142939755 100644
--- a/library/alloc/src/alloc.rs
+++ b/library/alloc/src/alloc.rs
@@ -3,7 +3,7 @@
 #![stable(feature = "alloc_module", since = "1.28.0")]
 
 #[cfg(not(test))]
-use core::intrinsics;
+use core::hint;
 
 #[cfg(not(test))]
 use core::ptr::{self, NonNull};
@@ -208,7 +208,7 @@ impl Global {
                 let new_size = new_layout.size();
 
                 // `realloc` probably checks for `new_size >= old_layout.size()` or something similar.
-                intrinsics::assume(new_size >= old_layout.size());
+                hint::assert_unchecked(new_size >= old_layout.size());
 
                 let raw_ptr = realloc(ptr.as_ptr(), old_layout, new_size);
                 let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?;
@@ -299,7 +299,7 @@ unsafe impl Allocator for Global {
             // SAFETY: `new_size` is non-zero. Other conditions must be upheld by the caller
             new_size if old_layout.align() == new_layout.align() => unsafe {
                 // `realloc` probably checks for `new_size <= old_layout.size()` or something similar.
-                intrinsics::assume(new_size <= old_layout.size());
+                hint::assert_unchecked(new_size <= old_layout.size());
 
                 let raw_ptr = realloc(ptr.as_ptr(), old_layout, new_size);
                 let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?;
diff --git a/library/alloc/src/lib.rs b/library/alloc/src/lib.rs
index 78629b39d34..02ecbe22b3e 100644
--- a/library/alloc/src/lib.rs
+++ b/library/alloc/src/lib.rs
@@ -129,6 +129,7 @@
 #![feature(fmt_internals)]
 #![feature(fn_traits)]
 #![feature(hasher_prefixfree_extras)]
+#![feature(hint_assert_unchecked)]
 #![feature(inline_const)]
 #![feature(inplace_iteration)]
 #![feature(iter_advance_by)]
diff --git a/library/alloc/src/raw_vec.rs b/library/alloc/src/raw_vec.rs
index 45e82240164..94e6924f41a 100644
--- a/library/alloc/src/raw_vec.rs
+++ b/library/alloc/src/raw_vec.rs
@@ -2,7 +2,7 @@
 
 use core::alloc::LayoutError;
 use core::cmp;
-use core::intrinsics;
+use core::hint;
 use core::mem::{self, ManuallyDrop, MaybeUninit, SizedTypeProperties};
 use core::ptr::{self, NonNull, Unique};
 use core::slice;
@@ -325,7 +325,7 @@ impl<T, A: Allocator> RawVec<T, A> {
         }
         unsafe {
             // Inform the optimizer that the reservation has succeeded or wasn't needed
-            core::intrinsics::assume(!self.needs_to_grow(len, additional));
+            hint::assert_unchecked(!self.needs_to_grow(len, additional));
         }
         Ok(())
     }
@@ -363,7 +363,7 @@ impl<T, A: Allocator> RawVec<T, A> {
         }
         unsafe {
             // Inform the optimizer that the reservation has succeeded or wasn't needed
-            core::intrinsics::assume(!self.needs_to_grow(len, additional));
+            hint::assert_unchecked(!self.needs_to_grow(len, additional));
         }
         Ok(())
     }
@@ -514,7 +514,7 @@ where
         debug_assert_eq!(old_layout.align(), new_layout.align());
         unsafe {
             // The allocator checks for alignment equality
-            intrinsics::assume(old_layout.align() == new_layout.align());
+            hint::assert_unchecked(old_layout.align() == new_layout.align());
             alloc.grow(ptr, old_layout, new_layout)
         }
     } else {
diff --git a/library/alloc/src/rc.rs b/library/alloc/src/rc.rs
index 263b1449de1..1eab681e956 100644
--- a/library/alloc/src/rc.rs
+++ b/library/alloc/src/rc.rs
@@ -252,6 +252,7 @@ use core::cell::Cell;
 use core::cmp::Ordering;
 use core::fmt;
 use core::hash::{Hash, Hasher};
+use core::hint;
 use core::intrinsics::abort;
 #[cfg(not(no_global_oom_handling))]
 use core::iter;
@@ -3268,7 +3269,7 @@ trait RcInnerPtr {
         // SAFETY: The reference count will never be zero when this is
         // called.
         unsafe {
-            core::intrinsics::assume(strong != 0);
+            hint::assert_unchecked(strong != 0);
         }
 
         let strong = strong.wrapping_add(1);
@@ -3301,7 +3302,7 @@ trait RcInnerPtr {
         // SAFETY: The reference count will never be zero when this is
         // called.
         unsafe {
-            core::intrinsics::assume(weak != 0);
+            hint::assert_unchecked(weak != 0);
         }
 
         let weak = weak.wrapping_add(1);
diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index 8aa0c6e7ed6..5504af28e88 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -1993,7 +1993,7 @@ impl<T, A: Allocator> Vec<T, A> {
         } else {
             unsafe {
                 self.len -= 1;
-                core::intrinsics::assume(self.len < self.capacity());
+                core::hint::assert_unchecked(self.len < self.capacity());
                 Some(ptr::read(self.as_ptr().add(self.len())))
             }
         }