Generation of synthesized parameters

Peter Jensen peter.jensen at
Tue Jan 29 14:43:20 PST 2013

On 01/29/13 14:21, Joe Darcy wrote:
> On 1/29/2013 2:06 PM, Peter Jensen wrote:
>> On 01/29/13 12:14, Joe Darcy wrote:
>>> Hello,
>>> On 1/29/2013 11:40 AM, Eric McCorkle wrote:
>>>> In order to facilitate writing tests for the MethodParameters feature,
>>>> I'd like to get a complete list of all the cases when javac can 
>>>> generate
>>>> synthesized parameters.
>>>> Here is a list I've put together from email discussions and 
>>>> comments in JBS:
>>>> 1) outer "this" parameters
>>> Arguably, some outer this parameters would be *synthesized* with 
>>> others would be *synthetic*.
>>> Inner classes that are also member classes, (see diagram in "Nested, 
>>> Inner, Member, and Top-Level Classes," 
>>> are potentially callable from outside of the enclosing class and are 
>>> required to have an outer this parameter as the first parameter so 
>>> that code from different compilers can call each other.  The other 
>>> this parameter in this case is *synthesized* as it is mandated or 
>>> implied by the JLS.
>>> On the other hand, named inner classes defined inside a method or 
>>> constructor as well as anonymous classes only need to obey a 
>>> compiler-internal contract and any extra parameters in this case are 
>>> *synthetic*.  (Not all anonymous classes have an outer; an anonymous 
>>> class created inside a static initializer block does not.)
>>>> 2) extra values passed to constructor for enum values
>>> Such parameters are *synthetic*, they are a javac implementation 
>>> artifact not mandated or implied by the JLS.
>>>> 3) hidden values passed to constructors of inner classes for final
>>>> variables
>>> You'll can check the JLS regarding whether these are synthesized or 
>>> synthetic, but I would assume they are synthetic.
>>>> 4) JLS mandated public no-arg constructors added by the compiler to
>>>> classes with no declared constructor: synthesized
>>> This is not a parameter, but another language structure.
>>> HTH,
>>> -Joe
>>>> 5) The two parameters pre-ended to enum constructors by javac
>>>> Does this capture everything, or does it miss something?
>>>> Ideally, I would like to put together a complete list of all cases 
>>>> that
>>>> should generate synthesized parameters.  (If one already exists, then
>>>> that's great).
>>>> Thanks,
>>>> Eric
>> Argument pf synthetic enum valueOf() method. Synthetic or synthesized ?
> The valueOf method itself is *synthesized* as the JLS mandates is 
> creation, but I do not think the individual parameters of the method 
> should be marked as such.
It's currently marked marked neither synthetic nor synthesized. So, it 
should get ACC_SYNTHESIZED in the future. Same for values().
The single parameter is recorded with the name 'name', and no flags.

> -Joe

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