fix memory leak when vec::IntoIter panics during drop

src/liballoc/vec.rs

@@ -2626,13 +2626,21 @@ impl<T: Clone> Clone for IntoIter<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 unsafe impl<#[may_dangle] T> Drop for IntoIter<T> {
  fn drop(&mut self) {
+ struct DropGuard<'a, T>(&'a mut IntoIter<T>);
+
+ impl<T> Drop for DropGuard<'_, T> {
+ fn drop(&mut self) {
+ // RawVec handles deallocation
+ let _ = unsafe { RawVec::from_raw_parts(self.0.buf.as_ptr(), self.0.cap) };
+ }
+ }
+
+ let guard = DropGuard(self);
  // destroy the remaining elements
  unsafe {
- ptr::drop_in_place(self.as_mut_slice());
+ ptr::drop_in_place(guard.0.as_mut_slice());
  }
-
- // RawVec handles deallocation
- let _ = unsafe { RawVec::from_raw_parts(self.buf.as_ptr(), self.cap) };
+ // now `guard` will be dropped and do the rest
  }
 }