verilator: Output generated headers

[hovind]

The generated headers are tracked through the CcInfo provider. This pull request adds the generated header files to the files field of the DefaultInfo provider.

In our case, we want to use the generated headers and verilated library outside of bazel. In other words, we want a the generated headers to be exposed as output files for a target.

I'm not sure if verilated.h and its dependencies should be packed in here as well, so I left it out for this PR.

Please don't hesitate to reach out!

[abrisco]

Why not use OutputGroupInfo? I would not expect the generated headers to be the thing I find in DefaultInfo.files They feel more like an implementation detail.

[hovind]

Why not use OutputGroupInfo? I would not expect the generated headers to be the thing I find in DefaultInfo.files They feel more like an implementation detail.

Using an OutputGroupInfo provider sounds much better, thanks!

Also thanks for taking a look, and for all the improvements to these rules.

[hovind]

Why not use OutputGroupInfo? I would not expect the generated headers to be the thing I find in DefaultInfo.files They feel more like an implementation detail.

I pushed a new proposal, all advice is much appreciated.