SoV-3: constructor questions

[Dan Smith]

> On Jan 27, 2022, at 8:09 AM, Dan Heidinga <heidinga at redhat.com> wrote:
> 
>>> 2) What is the rationale behind the return type restrictions on <new> methods?
> ....
>> Treatment of <new> methods is still unresolved, so this (and the JEP) is just describing one possible approach. I tried to reach a conclusion on this a few months ago on this list, but we ended in an unresolved place. I'll try again...
>> 
>> Anyway, in this incarnation: the rule is that the return type must be a type that includes instances of the current class. So, in class Point, QPoint is okay, LObject is okay, but LString is not.
> 
> I don't understand the point of this restriction.  Since
> Ljava/lang/Object; is acceptable (and has to be), I can use a `<new>`
> method to return *any* class but the caller will need to downcast to
> use it.

I think the reason we might have some sort of restriction is if we intend for a language or reflection API to be able to rely on these methods having some consistent properties (imagine them being surfaced with java.lang.reflect.Constructor, for example). So think of the restriction as a placeholder ("we may have some sort of restriction on the return type, TBD"). We still need to do some work to figure out the precise requirements, if any.