This change creates packages under src/google/protobuf/{io,stubs,testing} and moves build definitions there. Future changes will handle .../util and .../compiler, and finally src/google/protobuf.
These are all "toolchain-y" things, like copts, link_opts, and config_settings. These are very different from what is in //toolchain, though, so I chose the somewhat common name build_defs for the package. For now, I am only using this package for purely internal things. (Most public "defs"-type things should come from rules_proto/rules_cc, anyhow.)
This adds logic to generate files with lists of files in cmake and automake syntax. This will allow Bazel to serve as the single Source of Truth for library sources, with cmake and automake using Bazel-derived definitions.
The definition files are not yet generated or checked in, but that will be a fairly straightforward set of follow-up changes.
This avoids conflicting names in a couple of cases.
1. Within google, we want to sync files but not name them BUILD (since the structure doesn't match).
2. On case-insensitive filesystems, `build` may be used for a build directory. Naming `BUILD.bazel` avoids potentioal conflicts.
This change adds `rules_pkg`-based targets that will produce source distribution archives, similar to `make dist`.
These rules produce nearly the same outputs as `make dist`. However, there are some differences and caveats:
1. The outputs do not contain vendored googletest sources.
2. You have to run `autogen.sh` before `blaze build pkg:all`. This produces several autotools-related files directly into the source tree.
3. The output .zip files do not have a directory prefix like `protobuf-3.20.1-rc-1` (this will be addressed after [Substitute package variables in `pkg_zip#package_dir`. bazelbuild/rules_pkg#577](https://github.com/bazelbuild/rules_pkg/pull/577); the tar files do have this prefix, though.)
4. One file is missing from the archives, which is produced during the `make` build: benchmarks/gogo/cpp_no_group/cpp_benchmark.cc
5. In several places, I have explicitly excluded some files that are not in the autotools distribution outputs. I think most of those files should probably be included, but for now, I'm aiming for parity with `make dist`. These are marked with comments, so it should be easy to clean them up later.
This change moves the `pkg_*` rules into the `//pkg` package, which cleans up the root package.
It also adds an experimental `cc_dist_library` rule, which is similar to Bazel's `cc_import` rule. The goal of `cc_dist_library` is to produce output libraries from several targets. For example, splitting `//:protobuf` into multiple targets means that `bazel-bin/libprotobuf.a` won't contain all of the objects. The `cc_dist_library` creates a single library from several different `cc_library` targets. This may be useful for future packaging targets.
David L. Jones
Deanna Garcia
Adam Cozzette
Joshua Haberman