[llvm-dev] Clarification on expectations of buildbot email notifications (original) (raw)

via llvm-dev llvm-dev at lists.llvm.org
Wed Feb 20 07:39:30 PST 2019

Reid said:

I don't think whether a buildbot sends email should have anything to do with whether we revert to green or not. Very often, developers commit patches that cause regressions not caught by our buildbots. If the regression is severe enough, then I think community members have the right, and perhaps responsibility, to revert the change that caused it. Our team maintains bots that build chrome with trunk versions of clang, and we identify many regressions this way and end up doing many reverts as a result. I think it's important to continue this practice so that we don't let multiple regressions pile up.

My team also has internal bots and we see breakages way more often than we'd like. We are a bit reluctant to just go revert something, though, and typically try to engage the patch author first.

Engaging the author has a couple of up-sides: it respects the author's contribution and attention to the process; and once you've had to fix a particular problem yourself (rather than someone else cleaning up after your mess) you are less likely to repeat that mistake.

I think what's important, and what we should, after this discussion concludes, put in the developer policy, is that the person doing the revert has the responsibility to do their best to help the patch author reproduce the problem or at least understand the bug.

This can take many forms. They can link directly to an LLVM buildbot, which should be self-explanatory as far as reproduction goes. It can be an unreduced crash report. If they're nice, they can use CReduce to make it smaller. But, a reverter can't just say "Revert rNNN, breaks $RANDOMPROJECT on x8664-linux-gu". If they add, "reduction forthcoming" and they deliver on that promise, I think we should support that. In other words, the bar to revert should be low, so we can do it fast and save downstream consumers time and effort. If someone isn't making a good faith effort to follow up after a revert, then authors have a right to push back.

We have been on the wrong side of a revert where it was "this broke us" and then nothing. I was inclined to just re-apply the patch, but that's my "Mr Grumpy" avatar talking. How do we address failure to conform to the community norms?

I agree with Paul that we should remove the text about checking nightly builders. That suggestion seems a bit dated.

That was Tom Stellard, not me, but I agree with him. --paulr

More information about the llvm-dev mailing list