gain access to up-to-date kcov

[rpoyner-tri]

Is your feature request related to a problem? Please describe.
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Problems we cope with, owing to have a perpetually out-of-date kcov:

• kcov fails ("status: 0x85") reproducibly on some binaries (tracker for kcov bug 339) #17978 and all its works
• kcov#368 workaround scars

Development features we could offer, if we had a current kcov:

• code coverage in Reviewable (see patch by Nate Gallaher: SimonKagstrom/kcov@afbd484)

Why we currently can't get up-to-date kcov:

• debian maintenance is dead.
• ubuntu maintenance is dead.
• reviving/doing either is likely significant effort.
• license is hostile: GPL-v2

Describe the solution you'd like
A clear and concise description of what you want to happen.

• Somehow (modulo effort and license gymnastics), gain access to updated kcov.
• Remove above-described scars from drake source code.
• Eventually (separate issue), integrate Reviewable coverage viewing.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Private hosted debian package that we maintain 💀
Assume maintenance in debian/ubuntu 💀
Limp along with death by 1k cuts 🤮

Additional context
Add any other context or screenshots about the feature request here.

[EricCousineau-TRI]

Assigning to Betsy per component: continuous integration. \cc @jwnimmer-tri as owner of component: build system

[jwnimmer-tri]

Thanks for the ping. I'll re-triage to Rico for now. I don't think this will fit into our Kitware board in the next few months.

[jwnimmer-tri]

Since kcov builds already use bespoke flags (i.e., not sharing a build cache with regular builds), it might be worth trying out bazel's built-in code coverage reporting (lcov?) again now.

[rpoyner-tri]

From f2f with @jwnimmer-tri today:

• a way forward with kcov might be to offer a docker-based hermetic build script for a a deb of kcov; and have Drake retrieve the built deb from S3. This is similar to some other existing dependency in use by Drake.
• sub-problem: does writing a build script for a package propagate viral licensing? If so, the script might have to live in its own repo.
• alternative: evaluate the built-in bazel support for coverage; it was thought to be not-ready years ago, but maybe times have changed.

[jwnimmer-tri]

This is similar to some other existing dependency in use by Drake.

Here:
https://github.com/RobotLocomotion/drake/blob/master/setup/ubuntu/source_distribution/install_bazelisk.sh