Support for extracting/bundling headers in C/C++

[przydatek]

Description of the problem / feature request:

Getting C/C++ header files for a library built via Bazel.

Feature requests: what underlying problem are you trying to solve with this feature?

When building C/C++ library to be used in a project without Bazel one needs also a set of the header files with the API that the library offers. It would be nice if Bazel could add some support for creation of a bundle of the relevant headers, e.g. as a filegroup.

What operating system are you running Bazel on?

Linux

What's the output of bazel info release?

release 0.13.0

What's the output of git remote get-url origin ; git rev-parse master ; git rev-parse HEAD ?

https://github.com/google/tink
eb6673aff24a09947450d8922702f5f43fa9aaa2
eb6673aff24a09947450d8922702f5f43fa9aaa2

Have you found anything relevant by searching the web?

It seems the only way to do it now is "manually", see e.g. TensorFlow: https://github.com/tensorflow/tensorflow/blob/master/tensorflow/tools/lib_package/BUILD#L57
and tensorflow/tensorflow#3536

[hlopko]

This will be easily solved in Skylark when #4570 is implemented, I propose to wait until that happens.

[kingstarcraft]

If you build tensorflow with bazel on windows, you can try my tool to export the header. I have test my tool can work with tensorflow v1.12.0.

[oquenchil]

You can use the CcInfo provider for this:
https://docs.bazel.build/versions/master/skylark/lib/CcInfo.html

[gccunha1]

You can use the CcInfo provider for this: https://docs.bazel.build/versions/master/skylark/lib/CcInfo.html

Can someone provide a simple example on how to do this? I've been looking at the documentation and only found this example: https://github.com/bazelbuild/rules_cc/blob/main/examples/my_c_archive/my_c_archive.bzl

For me it's a bit hard to follow as I haven't really been using bazel at its full capacity