From 5615ba762d2e1b620275e064acd678d1eddbad35 Mon Sep 17 00:00:00 2001
From: Karl Seguin <k@openmymind.io>
Date: Thu, 7 May 2026 10:11:56 +0800
Subject: [PATCH] Give setters an arity of 1

Static functions don't take a 'self' so their arity isn't + 1.

Fixes a handful of IDL test cases.
---
 src/browser/js/Snapshot.zig | 1 +
 src/browser/js/bridge.zig   | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/browser/js/Snapshot.zig b/src/browser/js/Snapshot.zig
index 93bf9f6b..92ef4d68 100644
--- a/src/browser/js/Snapshot.zig
+++ b/src/browser/js/Snapshot.zig
@@ -633,6 +633,7 @@ fn attachClass(comptime JsApi: type, isolate: *v8.Isolate, template: *const v8.F
                     const cb = v8.v8__FunctionTemplate__New__Config(isolate, &.{
                         .callback = setter,
                         .signature = getter_signature,
+                        .length = 1,
                     }).?;
                     const setter_name_str = "set " ++ name;
                     const setter_name_v8 = v8.v8__String__NewFromUtf8(isolate, setter_name_str.ptr, v8.kNormal, @intCast(setter_name_str.len));
diff --git a/src/browser/js/bridge.zig b/src/browser/js/bridge.zig
index 6ffe578a..366f83af 100644
--- a/src/browser/js/bridge.zig
+++ b/src/browser/js/bridge.zig
@@ -153,7 +153,9 @@ pub const Function = struct {
             .cache = opts.cache,
             .static = opts.static,
             .wpt_only = opts.wpt_only,
-            .arity = getArity(@TypeOf(func), 1),
+            // Non-static methods receive `self` as their first param; static
+            // methods don't, so don't skip the first param for them.
+            .arity = getArity(@TypeOf(func), if (opts.static) 0 else 1),
             .func = if (opts.noop) noopFunction else struct {
                 fn wrap(handle: ?*const v8.FunctionCallbackInfo) callconv(.c) void {
                     Caller.Function.call(T, handle.?, func, opts);