From 3cb00c5bcd3dec191bea0cbab9fcac77c0e3a910 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <andrew@ziglang.org>
Date: Wed, 18 Dec 2024 18:24:55 -0800
Subject: [PATCH] std.ArrayHashMap: allow passing empty values array

in which case the values array is set to undefined
---
 lib/std/array_hash_map.zig | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/std/array_hash_map.zig b/lib/std/array_hash_map.zig
index 4e18aecf9d..22c736d0a5 100644
--- a/lib/std/array_hash_map.zig
+++ b/lib/std/array_hash_map.zig
@@ -641,10 +641,13 @@ pub fn ArrayHashMapUnmanaged(
             return self;
         }
 
+        /// An empty `value_list` may be passed, in which case the values array becomes `undefined`.
         pub fn reinit(self: *Self, gpa: Allocator, key_list: []const K, value_list: []const V) Oom!void {
             try self.entries.resize(gpa, key_list.len);
             @memcpy(self.keys(), key_list);
-            if (@sizeOf(V) != 0) {
+            if (value_list.len == 0) {
+                @memset(self.values(), undefined);
+            } else {
                 assert(key_list.len == value_list.len);
                 @memcpy(self.values(), value_list);
             }