Selaed classes cant permit private classes

[Maurizio Cimadamore]

For "extends" at the class level, I think in reality you end up with 
cyclic inheritance, so there's not much to do.

For "extends" in a type-parameter, that's a valid question - althugh, if 
you think about it, having a class with a type-variable whose bound is a 
_private_ member of that class, seems not too useful (the only place 
where you can parameterize instances of that class correctly is that 
class itself).

Maurizio

On 26/08/2024 15:09, Olexandr Rotan wrote:
> So there is a special case for permits clause, but what about extends 
> clause? Should I also look into it, or, formally, this is a different 
> issue that requires (arguably) JLS change?
>
> On Mon, Aug 26, 2024 at 4:51 PM Maurizio Cimadamore 
> <maurizio.cimadamore at oracle.com> wrote:
>
>
>     On 26/08/2024 14:44, Maurizio Cimadamore wrote:
>>     That is, an “extends” or “permits” clause is not really
>>     type-checked as if inside the body of class C. This results in
>>     the accessibility problem you point out (which might or might not
>>     be a compiler glitch, I don’t think the JLS is crystal clear on
>>     how Tmp.A should be checked).
>
>     I stand corrected - see JLS 6.6:
>
>>     A member (class, interface, field, or method) of a class,
>>     interface, type parameter, or reference type, or a constructor of
>>     a class, is accessible only if (i) the class, interface, type
>>     parameter, or reference type is accessible, and (ii) the member
>>     or constructor is declared to permit access:
>>     [...]
>>
>>      *
>>
>>          Otherwise, the member or constructor is declared |private|.
>>         Access is permitted only when one of the following is true:
>>
>>          o
>>
>>             Access occurs from within the body of the top level class
>>             or interface that encloses the declaration of the member
>>             or constructor.
>>
>>           o Access occurs in the |permits| clause of the top level
>>             class or interface that encloses the declaration of the
>>             member.
>>          o
>>
>>             Access occurs in the record component list of the top
>>             level record class that encloses the declaration of the
>>             member.
>>
>     So, there's special accessibility pleads for "permits" clauses. So
>     yes, this is a javac bug.
>
>     I've added some comments to JDK-8338981.
>
>     Maurizio
>
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