From 9eb0399a9d506f5f421180fa00ee3eec61a3a41e Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <nnethercote@mozilla.com>
Date: Wed, 20 May 2020 09:47:21 +1000
Subject: [PATCH] Adjust the zero check in `RawVec::grow`.

This was supposed to land as part of #72227. (I wish `git push` would
abort when you have uncommited changes.)
---
 src/liballoc/raw_vec.rs | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/liballoc/raw_vec.rs b/src/liballoc/raw_vec.rs
index f348b5b69780b..2bd4733db420b 100644
--- a/src/liballoc/raw_vec.rs
+++ b/src/liballoc/raw_vec.rs
@@ -401,16 +401,15 @@ impl<T, A: AllocRef> RawVec<T, A> {
         needed_extra_capacity: usize,
         placement: ReallocPlacement,
     ) -> Result<(), TryReserveError> {
+        // This is ensured by the calling contexts.
+        debug_assert!(needed_extra_capacity > 0);
+
         if mem::size_of::<T>() == 0 {
             // Since we return a capacity of `usize::MAX` when `elem_size` is
             // 0, getting to here necessarily means the `RawVec` is overfull.
             return Err(CapacityOverflow);
         }
 
-        if needed_extra_capacity == 0 {
-            return Ok(());
-        }
-
         // Nothing we can really do about these checks, sadly.
         let required_cap =
             used_capacity.checked_add(needed_extra_capacity).ok_or(CapacityOverflow)?;