diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs
index dfb837d54f5..32470941755 100644
--- a/library/alloc/src/vec/mod.rs
+++ b/library/alloc/src/vec/mod.rs
@@ -59,9 +59,7 @@ use core::convert::TryFrom;
 use core::fmt;
 use core::hash::{Hash, Hasher};
 use core::intrinsics::{arith_offset, assume};
-use core::iter::{
-    FromIterator, TrustedLen,
-};
+use core::iter::{FromIterator};
 use core::marker::PhantomData;
 use core::mem::{self, ManuallyDrop, MaybeUninit};
 use core::ops::{self, Index, IndexMut, Range, RangeBounds};
@@ -125,6 +123,10 @@ use self::spec_from_iter::SpecFromIter;
 
 mod spec_from_iter;
 
+use self::spec_extend::SpecExtend;
+
+mod spec_extend;
+
 /// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'.
 ///
 /// # Examples
@@ -2160,82 +2162,6 @@ impl<T, A: Allocator> Extend<T> for Vec<T, A> {
     }
 }
 
-// Specialization trait used for Vec::extend
-trait SpecExtend<T, I> {
-    fn spec_extend(&mut self, iter: I);
-}
-
-impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
-where
-    I: Iterator<Item = T>,
-{
-    default fn spec_extend(&mut self, iter: I) {
-        self.extend_desugared(iter)
-    }
-}
-
-impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
-where
-    I: TrustedLen<Item = T>,
-{
-    default fn spec_extend(&mut self, iterator: I) {
-        // This is the case for a TrustedLen iterator.
-        let (low, high) = iterator.size_hint();
-        if let Some(high_value) = high {
-            debug_assert_eq!(
-                low,
-                high_value,
-                "TrustedLen iterator's size hint is not exact: {:?}",
-                (low, high)
-            );
-        }
-        if let Some(additional) = high {
-            self.reserve(additional);
-            unsafe {
-                let mut ptr = self.as_mut_ptr().add(self.len());
-                let mut local_len = SetLenOnDrop::new(&mut self.len);
-                iterator.for_each(move |element| {
-                    ptr::write(ptr, element);
-                    ptr = ptr.offset(1);
-                    // NB can't overflow since we would have had to alloc the address space
-                    local_len.increment_len(1);
-                });
-            }
-        } else {
-            self.extend_desugared(iterator)
-        }
-    }
-}
-
-impl<T, A: Allocator> SpecExtend<T, IntoIter<T>> for Vec<T, A> {
-    fn spec_extend(&mut self, mut iterator: IntoIter<T>) {
-        unsafe {
-            self.append_elements(iterator.as_slice() as _);
-        }
-        iterator.ptr = iterator.end;
-    }
-}
-
-impl<'a, T: 'a, I, A: Allocator + 'a> SpecExtend<&'a T, I> for Vec<T, A>
-where
-    I: Iterator<Item = &'a T>,
-    T: Clone,
-{
-    default fn spec_extend(&mut self, iterator: I) {
-        self.spec_extend(iterator.cloned())
-    }
-}
-
-impl<'a, T: 'a, A: Allocator + 'a> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A>
-where
-    T: Copy,
-{
-    fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) {
-        let slice = iterator.as_slice();
-        unsafe { self.append_elements(slice) };
-    }
-}
-
 impl<T, A: Allocator> Vec<T, A> {
     // leaf method to which various SpecFrom/SpecExtend implementations delegate when
     // they have no further optimizations to apply
diff --git a/library/alloc/src/vec/spec_extend.rs b/library/alloc/src/vec/spec_extend.rs
new file mode 100644
index 00000000000..6959733d074
--- /dev/null
+++ b/library/alloc/src/vec/spec_extend.rs
@@ -0,0 +1,82 @@
+use crate::alloc::{Allocator};
+use core::iter::{TrustedLen};
+use core::slice::{self};
+use core::ptr::{self};
+
+use super::{Vec, IntoIter, SetLenOnDrop};
+
+// Specialization trait used for Vec::extend
+pub(super) trait SpecExtend<T, I> {
+    fn spec_extend(&mut self, iter: I);
+}
+
+impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
+    where
+        I: Iterator<Item = T>,
+{
+    default fn spec_extend(&mut self, iter: I) {
+        self.extend_desugared(iter)
+    }
+}
+
+impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
+    where
+        I: TrustedLen<Item = T>,
+{
+    default fn spec_extend(&mut self, iterator: I) {
+        // This is the case for a TrustedLen iterator.
+        let (low, high) = iterator.size_hint();
+        if let Some(high_value) = high {
+            debug_assert_eq!(
+                low,
+                high_value,
+                "TrustedLen iterator's size hint is not exact: {:?}",
+                (low, high)
+            );
+        }
+        if let Some(additional) = high {
+            self.reserve(additional);
+            unsafe {
+                let mut ptr = self.as_mut_ptr().add(self.len());
+                let mut local_len = SetLenOnDrop::new(&mut self.len);
+                iterator.for_each(move |element| {
+                    ptr::write(ptr, element);
+                    ptr = ptr.offset(1);
+                    // NB can't overflow since we would have had to alloc the address space
+                    local_len.increment_len(1);
+                });
+            }
+        } else {
+            self.extend_desugared(iterator)
+        }
+    }
+}
+
+impl<T, A: Allocator> SpecExtend<T, IntoIter<T>> for Vec<T, A> {
+    fn spec_extend(&mut self, mut iterator: IntoIter<T>) {
+        unsafe {
+            self.append_elements(iterator.as_slice() as _);
+        }
+        iterator.ptr = iterator.end;
+    }
+}
+
+impl<'a, T: 'a, I, A: Allocator + 'a> SpecExtend<&'a T, I> for Vec<T, A>
+    where
+        I: Iterator<Item = &'a T>,
+        T: Clone,
+{
+    default fn spec_extend(&mut self, iterator: I) {
+        self.spec_extend(iterator.cloned())
+    }
+}
+
+impl<'a, T: 'a, A: Allocator + 'a> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A>
+    where
+        T: Copy,
+{
+    fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) {
+        let slice = iterator.as_slice();
+        unsafe { self.append_elements(slice) };
+    }
+}