Bazel: building glog with custom version gflags

[levhuan]

It is my first time here, and I already read the contribution guideline. So I hope creating an issue is an appropriate step for this discussion.

I am working on a bazel workspace that needs to import and build both gflags and glog from source. I would like to build glog using the version of gflags in my workspace, instead of the one specified in glog WORKSPACE file. Hence, would the following change work and be accepted?

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "com_github_gflags_gflags",
    strip_prefix = "gflags-2.2.2",
    urls = [
        "https://mirror.bazel.build/github.com/gflags/gflags/archive/v2.2.2.tar.gz",
        "https://github.com/gflags/gflags/archive/v2.2.2.tar.gz",
    ],
)

to:

if "com_github_gflags_gflags" not in native.existing_rules():
    http_archive(
        name = "com_github_gflags_gflags",
        strip_prefix = "gflags-2.2.2",
        urls = [
            "https://mirror.bazel.build/github.com/gflags/gflags/archive/v2.2.2.tar.gz",
            "https://github.com/gflags/gflags/archive/v2.2.2.tar.gz",
        ],
    )

[drigz]

If I understand correctly, you shouldn't need to change glog to do what you want. Since Bazel ignores the WORKSPACE files of external repositories (see bazelbuild/bazel#1943), adding glog to your WORKSPACE will not add gflags: you'll have to add it yourself. You can add any version that you want, as long as it includes gflags/gflags@57ceb0e (2.2.2 is the first release with this commit).

Does that help?

PS: The if ... not in native.existing_rules(): pattern can't be used directly in the WORKSPACE file (if statements aren't allowed in BUILD or WORKSPACE files), but it is useful inside a dependencies macro that is intended to be called from the WORKSPACE to add a group of dependencies. glog doesn't provide a macro like that since it only has one (optional) dependency, so it's easier to let people add gflags to the top-level WORKSPACE themselves.

[levhuan]

Thanks for the response @drigz. Close the issue then.