reflect: allocate hiter as part of MapIter

This reduces the number of allocations per
reflect map iteration from two to one.

For #46293

Change-Id: Ibcff5f42fc512e637b6e460bad4518e7ac83d4c3
Reviewed-on: https://go-review.googlesource.com/c/go/+/321889
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

1 files changed, 3 insertions, 4 deletions

diff --git a/src/reflect/all_test.go b/src/reflect/all_test.go
index 40ac6a95fa..6cb603cb16 100644
--- a/src/reflect/all_test.go
+++ b/src/reflect/all_test.go
@@ -370,10 +370,9 @@ func TestMapIterSet(t *testing.T) {
 			iter.SetValue(e)
 		}
 	}))
-	// Making a *MapIter and making an hiter both allocate.
-	// Those should be the only two allocations.
-	if got != 2 {
-		t.Errorf("wanted 2 allocs, got %d", got)
+	// Making a *MapIter allocates. This should be the only allocation.
+	if got != 1 {
+		t.Errorf("wanted 1 alloc, got %d", got)
 	}
 }