CONSTANT_Dynamic bootstrap signature restriction

[Dan Smith]

> On Mar 7, 2018, at 7:48 AM, Remi Forax <forax at univ-mlv.fr> wrote:
> 
>> This might not pan out, and if so we can drop the error check and return to where we were.
>> But it seems promising, and we don't want to get stuck in 11 making compatibility promises
>> about the interpretation of things like 'bootstrap(Object... args)'.
> 
> I think it's too late for that, once we had said that the bsm is called with methodhandle.invoke (or more recently invokeWithArguments), bootstrap(Object... args) is already a valid construct. 

The proposed rule detects a CONSTANT_Dynamic bootstrap of this form and rejects it, because the first parameter's type is not Lookup. This is an explicit check, not a side-effect of invokeWithArguments.

In a plausible future (one that we want to make space for), rather than reporting an error, CONSTANT_Dynamic resolution will notice the lack of Lookup as a first parameter, and so pass an argument array to invokeWithArguments that doesn't contain the Lookup, name, or type.

—Dan