From af1e3633f734930a50000cc424fbcdc6629885c3 Mon Sep 17 00:00:00 2001 From: Giacomo Stevanato Date: Wed, 26 Aug 2020 23:52:20 +0200 Subject: [PATCH] Set sift=true only when PeekMut yields a mutable reference --- library/alloc/src/collections/binary_heap.rs | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/library/alloc/src/collections/binary_heap.rs b/library/alloc/src/collections/binary_heap.rs index 477a598ff5b..e3b738a70c8 100644 --- a/library/alloc/src/collections/binary_heap.rs +++ b/library/alloc/src/collections/binary_heap.rs @@ -293,6 +293,7 @@ impl Deref for PeekMut<'_, T> { impl DerefMut for PeekMut<'_, T> { fn deref_mut(&mut self) -> &mut T { debug_assert!(!self.heap.is_empty()); + self.sift = true; // SAFE: PeekMut is only instantiated for non-empty heaps unsafe { self.heap.data.get_unchecked_mut(0) } } @@ -401,7 +402,7 @@ impl BinaryHeap { /// Cost is *O*(1) in the worst case. #[stable(feature = "binary_heap_peek_mut", since = "1.12.0")] pub fn peek_mut(&mut self) -> Option> { - if self.is_empty() { None } else { Some(PeekMut { heap: self, sift: true }) } + if self.is_empty() { None } else { Some(PeekMut { heap: self, sift: false }) } } /// Removes the greatest item from the binary heap and returns it, or `None` if it