InstantiateFunctionObject (etc) annotated with [UC] (user code)?

[bathos]

InstantiateFunctionObject is annotated with the [UC]/user code marker seemingly due to:

• InstantiateGeneratorFunctionObject and
• InstantiateAsyncGeneratorFunctionObject

Which in turn stem from DefinePropertyOrThrow(F, "prototype", ...) steps in both. As far as I can tell, these are mistaken annotations and these ops are guaranteed to succeed. The [UC]s “born” here propagate into a number of other places, too, like InitializeEnvironment which (definitionally?) could never run user code, right?

For InstantiateAsyncGeneratorFunctionObject, however, I notice the annotation only appears in the case that the declaration is a no-identifier default export production, not an ordinary declaration, which seemed kinda random until I noticed the ordinary declaration had an explicit ! while the default-export case didn’t. I think that’s probably the common theme (missing !s), though I’m not sure exactly how the [UC] annotations work yet and may be misunderstanding something.

I didn’t see any mention of these productions in #2548 and am unsure if they were already present when that was merged.

[bakkot]

This is a consequence of missing a ! in the Perform DefinePropertyOrThrow(...) steps within those algorithms (which I mentioned in #2548 (comment)), and will be fixed by #2547.

[bathos]

Ah, cool, I’ll close it given it’s covered elsewhere.