From a2d96f9040043f1ecfd6fb32c9b765912c012367 Mon Sep 17 00:00:00 2001
From: Jarred Sumner <709451+Jarred-Sumner@users.noreply.github.com>
Date: Sun, 11 Dec 2022 13:01:24 -0800
Subject: Fix checking the UTF-16 length twice

---
 src/string_immutable.zig | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

(limited to 'src/string_immutable.zig')

diff --git a/src/string_immutable.zig b/src/string_immutable.zig
index 646917840..76b8b7073 100644
--- a/src/string_immutable.zig
+++ b/src/string_immutable.zig
@@ -2419,18 +2419,33 @@ pub fn latin1ToCodepointBytesAssumeNotASCII16(char: u32) u16 {
 }
 
 pub fn copyUTF16IntoUTF8(buf: []u8, comptime Type: type, utf16: Type) EncodeIntoResult {
-    var remaining = buf;
-    var utf16_remaining = utf16;
-    var ended_on_non_ascii = false;
-
     if (comptime Type == []const u16) {
         if (bun.FeatureFlags.use_simdutf) {
-            const trimmed = bun.simdutf.trim.utf16(utf16_remaining);
+            if (utf16.len == 0)
+                return .{ .read = 0, .written = 0 };
+            const trimmed = bun.simdutf.trim.utf16(utf16);
+            if (trimmed.len == 0)
+                return .{ .read = 0, .written = 0 };
+
             const out_len = if (buf.len <= (trimmed.len * 3 + 2))
                 bun.simdutf.length.utf8.from.utf16.le(trimmed)
             else
                 buf.len;
 
+            return copyUTF16IntoUTF8WithBuffer(buf, Type, utf16, trimmed, out_len);
+        }
+    }
+
+    return copyUTF16IntoUTF8WithBuffer(buf, Type, utf16, utf16, utf16.len);
+}
+
+pub fn copyUTF16IntoUTF8WithBuffer(buf: []u8, comptime Type: type, utf16: Type, trimmed: Type, out_len: usize) EncodeIntoResult {
+    var remaining = buf;
+    var utf16_remaining = utf16;
+    var ended_on_non_ascii = false;
+
+    if (comptime Type == []const u16) {
+        if (bun.FeatureFlags.use_simdutf) {
             log("UTF16 {d} -> UTF8 {d}", .{ utf16.len, out_len });
 
             if (remaining.len >= out_len) {
-- 
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