Java compilation doesn't include cpu in output paths

[gregestren]

Tracking issue on Bazel Configurability Roadmap

Goal:

• Changing --cpu shouldn't re-compile Java compilations, which don't care about CPU.

This is a specialization of #6526. Currently deprioritized in favor of that issue, which technically solves this one.

I did some research a while back about what it would take to solve just this issue (can we do it faster than the general one?). The story is complicated. Can elaborate further on request.

[gregestren]

2018 EOY update:

This feature is on hold.

This is a specialization of #6526. Initial research suggests that a solution to this feature is complex enough that it's better to focus energies on the broader problem.

I've been prototyping an approach for #6526 that builds genrules and simple cc_* rules successfully in a way that would automatically solve this issue too. Next steps for that are to try building a java_binary, which will be especially interesting for this issue, and sharing more openly the design proposal and its consequences.

[gregestren]

This is a dupe of #8339, which is now the more relevant bug.