tree a31ca72702b1c2166dd43084991d0c22ba6f0c54
parent 765751395cf12e5842145d56ec339a1a07a1ea53
author David Benjamin <davidben@google.com> 1710892574 +1000
committer Boringssl LUCI CQ <boringssl-scoped@luci-project-accounts.iam.gserviceaccount.com> 1714169988 +0000

Add a standalone Bazel build

Now that we can generate build files, we can actually maintain a Bazel
build in HEAD, without synthesizing a separate "-with-bazel" branch.
(Though we'll still need both for a transition, and until all the other
build modes have migrated.) Note this has a slightly different directory
structure than the old -with-bazel branch. But the targets are the same
and #include <openssl/whatever.h> still works, so hopefully it's
compatible.

For now, I'm only setting this up with the new bzlmod scheme. Also since
pulling in googletest is much less tedious with bzlmod, I've wired up
tests and everything.

https://bazel.build/external/overview#bzlmod

To build, run commands like:

   bazelisk build ...
   bazelisk test ...
   bazelisk run :bssl

The thinking is we can also go add this to CI and whatnot.

This is also intended to replace the boringssl module in the
bazel-central-registry which someone else set up already. To ease the
transition, I've seeded the compatibility_level value with theirs. (I
think we want to never bump it. Although we don't do SemVer, I think
bzlmod's MVS version selection scheme is generally reasonable. Bumping
it just introduces hiccups into the update process where projects need
to coordinate updates, and we do not want that.)

I wasn't clear on what to put in the version field in the tree, so I
just went with 0.0.0-dev so we don't have to change it, but it's still
vaguely analogous to the versions already in there.

As part of this, I've added support for Bazel's runfiles mechanism in
crypto/test/test_data.cc. This is completely undocumented and I had to
figure out how it works by guessing, but I believe this is the
officially supported way to make cc_test(data = ...) work? The official
documentation says to use devtools_build::GetDataDependencyFilepath, but
that API does not exist in the first place. I've also made it build with
C++17 for now, so we can build libpki, but C++14 consumers should still
be able to use this module, just not build libpki.

To that end, one difference between this and the old module is that we
no longer specify the C++ version in the build. From what I can tell,
Bazel does *not* want libraries to set the C/C++ version and prefers it
only come from the root. Unfortunately, they provide zero tools to
effectively manage this. I've followed this pattern for C++ versions, as
we can assume that Bazel projects are very aware of their C++ version,
but I've explicitly ignored it for the C version. Projects tend not to
change ABIs by C version, so it should be fine to set it internally.

For context when reviewing, the unreadable MODULE.bazel.lock is
automatically generated. I think the idea is that subsequent diffs will
be more readable??

Bug: 542
Change-Id: I88f68b2602a75f58cc6d18832a956f01dc054f58
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/67301
Auto-Submit: David Benjamin <davidben@google.com>
Commit-Queue: Bob Beck <bbe@google.com>
Reviewed-by: Bob Beck <bbe@google.com>