diff --git a/compiler/rustc_arena/src/lib.rs b/compiler/rustc_arena/src/lib.rs
index 524baf5b07fec..6217bf46a942d 100644
--- a/compiler/rustc_arena/src/lib.rs
+++ b/compiler/rustc_arena/src/lib.rs
@@ -510,19 +510,6 @@ impl DroplessArena {
         }
     }
 
-    /// Used by `Lift` to check whether this slice is allocated
-    /// in this arena.
-    #[inline]
-    pub fn contains_slice<T>(&self, slice: &[T]) -> bool {
-        for chunk in self.chunks.borrow_mut().iter_mut() {
-            let ptr = slice.as_ptr().cast::<u8>().cast_mut();
-            if chunk.start() <= ptr && chunk.end() >= ptr {
-                return true;
-            }
-        }
-        false
-    }
-
     /// Allocates a string slice that is copied into the `DroplessArena`, returning a
     /// reference to it. Will panic if passed an empty string.
     ///