Repoint --coverage_report_generator default to CoverageOutputGenerator

[ghost]

From #6450 (comment):

The default value of the --coverage_report_generator flag is broken and we
didn't get to fixing it. It should be an easy change though, PRs are always
welcome. :)

This change does that, but using
@bazel_tools//tools/test/CoverageOutputGenerator/java/com/google/devtools/coverageoutputgenerator:Main.
(CoverageOutputGenerator supersedes LcovMerger per #7412.)

Resolves #6450.

[ulfjack]

Hi Ryan, thanks for the patch. I have been looking at issues around coverage for the last few days, and I think we might want to move in the opposite direction. I have a change to redirect everything to @remote_coverage_tools//:lcov_merger and @remote_coverage_tools//:coverage_report_generator. That'll make it easier for users to replace these tools, e.g., by setting --override_repository to provide a different @remote_coverage_tools repository.

My change is here:
https://bazel-review.googlesource.com/c/bazel/+/123156

Unfortunately, there's still a problem which I haven't had the time to debug yet. WDYT?

[ghost]

Thanks for taking a look.

My change is here:
https://bazel-review.googlesource.com/c/bazel/+/123156

Unfortunately, there's still a problem which I haven't had the time to debug yet. WDYT?

As an outsider, I'm not in a good position to weigh in on the @remote_coverage_tools topic. After reading #4685, it seems like the right thing to do, and so I can close this PR.

[ghost]

I had a peek at the Gerrit link, and while it indicated a merge conflict I was able to cleanly apply to master @ b494074.

[ulfjack]

Yeah, we configured Gerrit to always prevent merges. Did you try the patch? Does it work?

[ghost]

Yeah, we configured Gerrit to always prevent merges. Did you try the patch? Does it work?

Ah, gotcha. As far as #6450 is concerned, yes, the patch works. (I can use --combined_output=lcov w/o specifying any add'l flags, and IntelliJ's coverage UI works w/ a vanilla .bazelrc.)