From f15858be5f09a9fdfbec9ccc68490e23e5db35ad Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Mon, 1 Nov 2021 20:26:07 -0600
Subject: [PATCH] [vector] Pre-allocate if iterator has random-access length

---
 src/hb-vector.hh | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/hb-vector.hh b/src/hb-vector.hh
index 92c74dc13..acd66a7fc 100644
--- a/src/hb-vector.hh
+++ b/src/hb-vector.hh
@@ -51,6 +51,8 @@ struct hb_vector_t
 	    hb_requires (hb_is_iterable (Iterable))>
   hb_vector_t (const Iterable &o) : hb_vector_t ()
   {
+    if (hb_iter (o).is_random_access_iterator)
+      alloc (hb_len (hb_iter (o)));
     hb_copy (o, *this);
   }
   hb_vector_t (const hb_vector_t &o) : hb_vector_t ()