This PR gets us to a point where I can file followups for less experienced contributors to help push it forward. There are many threads to pull!

I'm trying to see if I can pull some of the threads further, and I'm wondering if there's an easier way to discover and poke at autogenerated code.

In particular I'm wondering how to change this trait, used in domparser.rs:

59:impl DOMParserMethods for DOMParser {
60-    // https://w3c.github.io/DOM-Parsing/#the-domparser-interface
61-    fn ParseFromString(
62-        &self,
63-        s: DOMString,
64-        ty: DOMParserBinding::SupportedType,
65-        can_gc: CanGc,
66-    ) -> Fallible<DomRoot<Document>> {

to accept a fourth can_gc argument.

I've found the autogenerated code in out/Bindings/DOMParserBindings.rs:

276:pub trait DOMParserMethods {
277-    fn ParseFromString(&self, str: DOMString, type_: SupportedType) -> Fallible<DomRoot<Document>>;
278-}

And, through poking at CodegenRust.py:

6362- self.cgRoot = CGWrapper(CGIndenter(CGList(methods, "")),
6363:             pre=f"pub trait {descriptor.interface.identifier.name}Methods {{\n",
6364-             post="}")

and Configuration.py:

222-        else:
223:            self.returnType = "DomRoot<%s>" % typeName
224-            self.argumentType = "&%s" % typeName

made sure that this is the code responsible for the pub trait and DomRoot parts. But I can't seem to find what's responsible for the arguments (they seem to be queried from somewhere else and so are not particularly greppable, and are not specified in lists like in this PR) and if these can be modified without making all traits take can_gc

@last-genius Good question! A useful model for adding arguments to the generated methods is the InRealm arguments, which are manually annotated in Bindings.conf. there is code in CodegenRust.py that checks for these annotations and adds the argument if they're present.