Annotation Dependencies and Requires Static Transitive

[Anand Beh]

Thanks to you both for the advice.

Following on your suggestions, Caffeine changed to "requires static".
However, javac now produces a warning about the lack of transitivity:

warning: [exports] class Nullable in module
org.checkerframework.checker.qual is not indirectly exported using
requires transitive

Is this a bug in javac or is it anything we should be worried about?

Regards,
Anand

On 6/3/21, Alex Buckley <alex.buckley at oracle.com> wrote:
> Even without `transitive`, requiring modules with `static` means that
> anyone who habitually builds their entire stack from source will still
> need the errorprone and checker-qual modules at compile time.
>
> There are no "run-time only" dependencies in module declarations, unless
> services come into play, which is not realistic here. As Remi said,
> `requires static` is your best bet. Annotation types that are exported
> by a third party such as Google, in order for people to annotate their
> personal codebases, are not really an API that those personal codebases
> need to export -- any fourth party program that wishes to inspect the
> annotations in your codebase needs to arrange its own dependency on the
> annotation types from the third party.
>
> Alex
>
> On 6/3/2021 1:10 PM, Anand Beh wrote:
>> Hello,
>>
>> The cache library Caffeine recently added a full module descriptor. It
>> has no runtime dependencies, but it depends on metadata annotations
>> from checker-qual and errorprone, for example @NotNull and
>> @CanIgnoreReturnValue. The module looks like this:
>> module com.github.benmanes.caffeine {
>>    exports com.github.benmanes.caffeine.cache;
>>    exports com.github.benmanes.caffeine.cache.stats;
>>
>>    requires static transitive com.google.errorprone.annotations;
>>    requires static transitive org.checkerframework.checker.qual;
>> }
>>
>> The annotations are not required at runtime, hence static. They're
>> visibly placed on public methods and return types, so that API clients
>> can benefit from them for the purposes of annotation-based null
>> analysis, kotlin interop, etc. As the annotations are part of the API,
>> they're marked transitive.
>>
>> However, the "transitive" aspect imposes some requirements on users. I
>> am wondering if there is a more correct way to declare these
>> annotation dependencies than static transitive.
>>
>> One user would like to avoid the presence of these annotations at
>> compile-time. For reference, here's the relevant discussion:
>> https://github.com/ben-manes/caffeine/issues/535
>>
>> I'm not a maintainer of caffeine, though I was involved in its
>> modularization.
>>
>> Regards,
>> Anand
>>
>