From 41d5aa1b365516c5f1bad63bfa3bdd7ad0ba6842 Mon Sep 17 00:00:00 2001
From: dweiller <4678790+dweiller@users.noreply.github.com>
Date: Sat, 30 Dec 2023 18:17:26 +1100
Subject: [PATCH] prevent by-length slice compile error in static json parsing

---
 lib/std/json/static.zig | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/std/json/static.zig b/lib/std/json/static.zig
index ea0bb6c0f2..d4ae6053f4 100644
--- a/lib/std/json/static.zig
+++ b/lib/std/json/static.zig
@@ -402,21 +402,33 @@ pub fn innerParse(
                             },
                             .partial_string_escaped_1 => |arr| {
                                 if (i + arr.len > r.len) return error.LengthMismatch;
+                                // tell the compiler that the by-length slice below is valid;
+                                // this assert is required for the inequality to be comptime-known
+                                if (arr.len > r.len) unreachable;
                                 @memcpy(r[i..][0..arr.len], arr[0..]);
                                 i += arr.len;
                             },
                             .partial_string_escaped_2 => |arr| {
                                 if (i + arr.len > r.len) return error.LengthMismatch;
+                                // tell the compiler that the by-length slice below is valid;
+                                // this assert is required for the inequality to be comptime-known
+                                if (arr.len > r.len) unreachable;
                                 @memcpy(r[i..][0..arr.len], arr[0..]);
                                 i += arr.len;
                             },
                             .partial_string_escaped_3 => |arr| {
                                 if (i + arr.len > r.len) return error.LengthMismatch;
+                                // tell the compiler that the by-length slice below is valid;
+                                // this assert is required for the inequality to be comptime-known
+                                if (arr.len > r.len) unreachable;
                                 @memcpy(r[i..][0..arr.len], arr[0..]);
                                 i += arr.len;
                             },
                             .partial_string_escaped_4 => |arr| {
                                 if (i + arr.len > r.len) return error.LengthMismatch;
+                                // tell the compiler that the by-length slice below is valid;
+                                // this assert is required for the inequality to be comptime-known
+                                if (arr.len > r.len) unreachable;
                                 @memcpy(r[i..][0..arr.len], arr[0..]);
                                 i += arr.len;
                             },