From f717f6b848fe77ee948424b82d4419dcc5666c52 Mon Sep 17 00:00:00 2001
From: Josh Matthews <josh@joshmatthews.net>
Date: Tue, 25 Mar 2025 10:08:45 -0400
Subject: [PATCH] script: Support converting JS values to Rc<Promise> with
 FromJSValConvertible. (#36097)

Signed-off-by: Josh Matthews <josh@joshmatthews.net>
---
 Cargo.lock                                    |  4 ++--
 components/script/dom/promise.rs              | 23 ++++++++++++++++++-
 components/script/dom/testbinding.rs          |  1 +
 .../script_bindings/codegen/Bindings.conf     |  2 +-
 .../webidls/TestBinding.webidl                |  1 +
 5 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index b153b07382a..8cc72e69b15 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4702,7 +4702,7 @@ dependencies = [
 [[package]]
 name = "mozjs"
 version = "0.14.1"
-source = "git+https://github.com/servo/mozjs#26c35182c1b2b7fb2fbfa93b82669533d92c3a60"
+source = "git+https://github.com/servo/mozjs#39db84352d79ffa3e4fe756c8034af9def788f22"
 dependencies = [
  "bindgen 0.71.1",
  "cc",
@@ -4714,7 +4714,7 @@ dependencies = [
 [[package]]
 name = "mozjs_sys"
 version = "0.128.9-0"
-source = "git+https://github.com/servo/mozjs#26c35182c1b2b7fb2fbfa93b82669533d92c3a60"
+source = "git+https://github.com/servo/mozjs#39db84352d79ffa3e4fe756c8034af9def788f22"
 dependencies = [
  "bindgen 0.71.1",
  "cc",
diff --git a/components/script/dom/promise.rs b/components/script/dom/promise.rs
index d7c309a7ded..dd09b1df3a1 100644
--- a/components/script/dom/promise.rs
+++ b/components/script/dom/promise.rs
@@ -15,7 +15,7 @@ use std::ptr;
 use std::rc::Rc;
 
 use dom_struct::dom_struct;
-use js::conversions::ToJSValConvertible;
+use js::conversions::{ConversionResult, FromJSValConvertibleRc, ToJSValConvertible};
 use js::jsapi::{
     AddRawValueRoot, CallArgs, GetFunctionNativeReserved, Heap, JS_ClearPendingException,
     JS_GetFunctionObject, JS_NewFunction, JSAutoRealm, JSContext, JSObject,
@@ -405,3 +405,24 @@ impl PromiseHelpers<crate::DomTypeHolder> for Promise {
         Promise::new_resolved(global, cx, value, CanGc::note())
     }
 }
+
+impl FromJSValConvertibleRc for Promise {
+    #[allow(unsafe_code)]
+    unsafe fn from_jsval(
+        cx: *mut JSContext,
+        value: HandleValue,
+    ) -> Result<ConversionResult<Rc<Promise>>, ()> {
+        if value.get().is_null() {
+            return Ok(ConversionResult::Failure("null not allowed".into()));
+        }
+        if !value.get().is_object() {
+            return Ok(ConversionResult::Failure("not an object".into()));
+        }
+        rooted!(in(cx) let obj = value.get().to_object());
+        if !IsPromiseObject(obj.handle()) {
+            return Ok(ConversionResult::Failure("not a promise".into()));
+        }
+        let promise = Promise::new_with_js_promise(obj.handle(), SafeJSContext::from_ptr(cx));
+        Ok(ConversionResult::Success(promise))
+    }
+}
diff --git a/components/script/dom/testbinding.rs b/components/script/dom/testbinding.rs
index d03196de940..4095ba1319a 100644
--- a/components/script/dom/testbinding.rs
+++ b/components/script/dom/testbinding.rs
@@ -910,6 +910,7 @@ impl TestBindingMethods<crate::DomTypeHolder> for TestBinding {
     fn FuncControlledMethodDisabled(&self) {}
     fn FuncControlledMethodEnabled(&self) {}
 
+    fn PassRecordPromise(&self, _: Record<DOMString, Rc<Promise>>) {}
     fn PassRecord(&self, _: Record<DOMString, i32>) {}
     fn PassRecordWithUSVStringKey(&self, _: Record<USVString, i32>) {}
     fn PassRecordWithByteStringKey(&self, _: Record<ByteString, i32>) {}
diff --git a/components/script_bindings/codegen/Bindings.conf b/components/script_bindings/codegen/Bindings.conf
index 4fa998a84c3..d5b1dc5c281 100644
--- a/components/script_bindings/codegen/Bindings.conf
+++ b/components/script_bindings/codegen/Bindings.conf
@@ -490,7 +490,7 @@ DOMInterfaces = {
 
 'Promise': {
     'spiderMonkeyInterface': True,
-    'additionalTraits': ["crate::dom::promise::PromiseHelpers<Self>"]
+    'additionalTraits': ["crate::dom::promise::PromiseHelpers<Self>", "js::conversions::FromJSValConvertibleRc"]
 },
 
 'Range': {
diff --git a/components/script_bindings/webidls/TestBinding.webidl b/components/script_bindings/webidls/TestBinding.webidl
index 88f1b4d51f7..92d95e4fe73 100644
--- a/components/script_bindings/webidls/TestBinding.webidl
+++ b/components/script_bindings/webidls/TestBinding.webidl
@@ -479,6 +479,7 @@ interface TestBinding {
   sequence<sequence<long>> returnSequenceSequence();
   undefined passUnionSequenceSequence((long or sequence<sequence<long>>) seq);
 
+  undefined passRecordPromise(record<DOMString, Promise<undefined>> arg);
   undefined passRecord(record<DOMString, long> arg);
   undefined passRecordWithUSVStringKey(record<USVString, long> arg);
   undefined passRecordWithByteStringKey(record<ByteString, long> arg);