RFR: 8271623: Omit enclosing instance fields from inner classes that don't use it

[Alex Buckley]

On 8/3/2021 12:56 PM, Rafael Winterhalter wrote:
> I do however think that you must retain the constructor to accept the 
> outer instance, no matter if it is stored in a field or not. Otherwise, 
> a public inner class might change its constructor and introduce a binary 
> incompatible change if a field access of the outer class is removed or 
> added and this class is recompiled independently. ...

The JLS mandates a constructor parameter for the outer instance -- 
https://docs.oracle.com/javase/specs/jls/se16/html/jls-8.html#jls-8.8.1-200 
-- and nothing in the patch appears to do away with that parameter. 
There's even a comment in Lower.java that "If the variable is never 
accessed, we skip creating an outer instance field and saving the 
constructor parameter to it." -- implying the parameter still exists.

It would be good for the CSR (JDK-8271717) to clarify that the 
T-accepting constructor in class T$I is still present after the change, 
and merely invokes a super constructor.

Alex