Confusing error message for inner non-public service provider

[Vicente Romero]

Hi Alex,

Just to double check, the right javac behavior in this case should be to 
issue similar errors in both cases like:

some position here: error: ServiceImpl is not public in 
com.example.internal; cannot be accessed from outside package
some other position here: error: Outer.ServiceImpl is not public in 
com.example.internal; cannot be accessed from outside package

without mentioning in any case anything about visibility right?

Thanks,
Vicente


On 02/07/2017 02:21 PM, Alex Buckley wrote:
> On 2/7/2017 1:11 AM, Gunnar Morling wrote:
>>      ---
>>      package com.example;
>>      public interface SomeService {
>>          public void foo();
>>      }
>>      ---
>>      package com.example.internal;
>>      class Outer {
>>
>>          public static class ServiceImpl implements 
>> com.example.SomeService {
>>              public ServiceImpl() {}
>>              public void foo() {}
>>          }
>>      }
>>      ---
>>      package com.example.internal;
>>      class ServiceImpl implements com.example.SomeService {
>>          public ServiceImpl() {}
>>          public void foo() {}
>>      }
>>      ---
>>      module com.example {
>>          exports com.example;
>>          provides com.example.SomeService with 
>> com.example.internal.ServiceImpl;
>>          provides com.example.SomeService with
>> com.example.internal.Outer.ServiceImpl;
>>      }
>>      ---
>>
>> Essentially, I'm wondering:
>>
>> * Why Outer.ServiceImpl triggers the error about package visibility
>> while ServiceImpl doesn't (I had a look at the EDR JLS, but I couldn't
>> find an explanation for that, happy about any specific pointers).
>> * Why Outer.ServiceImpl triggers "does not have a default constructor"
>> (ServiceImpl does not). Maybe a hint would be nice that is caused by
>> Outer not having public access.
>
> Thanks for showing the code. Since everything in the same module, 
> package visibility is not relevant and javac shouldn't mention it.
>
> I suspect that javac is getting tripped up by the fact that 
> Outer.ServiceImpl is declared 'public' (as the JLS and ServiceLoader 
> both demand) but it isn't widely accessible, even within the 
> com.example module, due to Outer's default (package) access. I believe 
> the JLS and ServiceLoader rules are correct, so it's a javac bug.
>
> Alex