From b79defd7a90ef94ffa8840d45b38c87f64577b1c Mon Sep 17 00:00:00 2001
From: Nick Treleaven <n@trelsoft.com>
Date: Sun, 30 Jun 2019 12:24:04 +0100
Subject: [PATCH] Pre-allocate KMP prefix for string.index

---
 vlib/builtin/string.v | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/vlib/builtin/string.v b/vlib/builtin/string.v
index 1e8dfe1b0f..9c62625bf6 100644
--- a/vlib/builtin/string.v
+++ b/vlib/builtin/string.v
@@ -352,7 +352,7 @@ pub fn (s string) index(p string) int {
 	if p.len > s.len {
 		return -1
 	}
-	mut prefix := [0]
+	mut prefix := [0; p.len]
 	mut j := 0
 	for i := 1; i < p.len; i++ {
 		for p[j] != p[i] && j > 0 {
@@ -361,7 +361,7 @@ pub fn (s string) index(p string) int {
 		if p[j] == p[i] {
 			j++
 		}
-		prefix << j
+		prefix[i] = j
 	}
 	j = 0
 	for i := 0; i < s.len; i++ {