Review request: update javac to properly output mandated parameters in MethodParameters attributes

[Maurizio Cimadamore]

On 13/02/13 16:06, Eric McCorkle wrote:
> For the purposes of this patch, can we go ahead and push it as is, so as
> to make M7, and possibly submit a one-liner at a later date if we decide
> to make private constructor's outer this mandated?
Sure

Maurizio
>
> On 02/13/13 05:28, Maurizio Cimadamore wrote:
>> I agree with John - also, to my knowledge, all compilers out there treat
>> private class/non-private class in the same way - i.e. by adding an
>> extra constructor parameter for accepting the enclosing instance.
>>
>> Maurizio
>>
>> On 13/02/13 06:22, John Rose wrote:
>>> On Feb 12, 2013, at 5:50 PM, Alex Buckley <alex.buckley at oracle.com
>>> <mailto:alex.buckley at oracle.com>> wrote:
>>>
>>>> Per the new discussion in JLS 8.8.9 which appears in 8misc.pdf, it is
>>>> possible for a _non-private_ inner member class to be instantiated by
>>>> code in a totally different compilation unit, _compiled by a
>>>> different compiler than compiled the inner member class_.
>>> Since even private member classes have mandated names, it is possible
>>> to use reflection (with access control overrides as needed) to attempt
>>> to instantiate even private member classes.  This suggests to me that
>>> 'private' might not be enough isolation to allow complete freedom
>>> to the compiler.
>>>
>>> On the other hand, non-member classes (anonymous and locals) do not
>>> have mandated bytecode names (there is always a $[0-9]+ component in
>>> the name), so it is reasonable to say none of the constructors and/or
>>> arguments need to have any mandated structure.
>>>
>>> I realize that the JLS is one step away from reflective APIs, but
>>> there is a logical connection here, since the Core Reflection API
>>> claims to be able to (a) replicate legal member accesses, and (b)
>>> override access protection modifiers ('private' etc.).
>>>
>>>> Hence the mandated parameter which allows all compilers to reify the
>>>> immediately enclosing instance. But a _private_ inner member class
>>>> can only be instantiated within the same compilation unit, so it's
>>>> the compiler's choice how to reify the immediately enclosing instance
>>>> in that case, and I believe javac has always used ACC_SYNTHETIC for
>>>> that class's default ctor.
>>> It's always used ACC_SYNTHETIC but that doesn't mean that ACC_MANDATED
>>> would be better for some bits of the puzzle.
>>>
>>> — John
>>>
>>> P.S. Do we still mandate names of certain inner class fields, such as
>>> 'this$NNN'?  The original motivation for this was to allow debuggers a
>>> somewhat easier time presenting compiler-generated data structures.
>>>
>>> It's a stretch, but it might be reasonable to require that the names
>>> of the constructor parameters match the names of the concrete private
>>> class fields they initialize.