JDK 13 RFR of JDK-8146726 : Improve AbstractProcessor to issue warnings for repeated information

[Joseph D. Darcy]

Hi Stuart,

I think the current patch is a sufficient enough improvement to be 
pushed, reserving the ability for further improvements in the future :-)

Thanks,

-Joe

On 5/1/2019 2:01 PM, Stuart Marks wrote:
> Hi Joe,
>
> Thanks for the explanation of annotations and modules. I'll leave the 
> exact circumstances of issuing warnings up to you. Since it's just 
> about issuing warning messages, it's reasonable that it doesn't need 
> to be precise.
>
> My concern is that the deduplication+warning code is hard to 
> understand, and that someone in the future (maybe you!) will come 
> across it and have a difficult time figuring it out; they might also 
> worry about its precise behavior, not realizing that the warning 
> policy isn't be precise.
>
> It seems to me like the core of the algorithm can be implemented as 
> follows. Given a String[] array, the elements can be deduplicated into 
> a set this way:
>
>     List<String> dups = new ArrayList<>(Arrays.asList(array));
>     Set<String> result = new HashSet<>();
>     dups.removeIf(result::add);
>
> Now, 'result' contains the deduplicated items and 'dups' is a list 
> (which might itself contain duplicates!) of duplicated items. The 
> warning messages, if necessary, can then be generated from the 'dups' 
> list after the fact.
>
> I'm not entirely sure of the best way to handle module prefix removal. 
> If the index/substring logic were extracted into a message, the 
> initialization of 'dups' could be replaced with a short stream that 
> calls the module prefix removal function from map(). The exact 
> behavior of the for-loop as it stands, though, would be difficult to 
> implement this way. Then again, since the warning policy doesn't need 
> to be precise, maybe this is ok.
>
> I'll leave it up to you whether you want to continue reworking this code.
>
> s'marks
>