Duplicates in transferList for structured cloning

[Ms2ger]

10:44:20 <Ms2ger> annevk, if you pass the same object twice in transferList when structured cloning, where does the spec handle that?
10:47:09 <annevk> Ms2ger: good question, maybe the throwing early on https://html.spec.whatwg.org/multipage/structured-data.html#structuredserializewithtransfer needs to be moved down
10:47:17 <annevk> early on in*
10:48:28 <annevk> Ms2ger: would need to create a test where StructuredSerializeInternal throws something other than a DataCloneError to see if they actually happen later
10:56:22 <annevk> Ms2ger: curiously Safari does not throw on buffer = new ArrayBuffer(10);postMessage(null, "*", [buffer, buffer]);
11:07:09 <annevk> Ms2ger: are you going to file issues here?
11:07:22 <Ms2ger> Yeah, in a minute
11:09:15 <annevk> I can never remember how to write a getter in an object literal
11:10:48 <annevk> So buffer = new MessageChannel().port1;postMessage({ get data() { throw 'hi'; } }, "*", [buffer, buffer]); suggests duplicates are caught earlier on though
11:11:35 <annevk> So basically before we set memory[transferable] we should have "If memory[transferable] exists, throw a ..."
11:18:28 <annevk> At least it's an easy fix...