[libcxx-commits] [PATCH] D68480: Implementation of C++20's P1135R6 for libcxx

Mon Feb 24 12:57:33 PST 2020

davide added a comment.

In D68480#1889935 <https://reviews.llvm.org/D68480#1889935>, @ldionne wrote:

> In D68480#1889799 <https://reviews.llvm.org/D68480#1889799>, @davide wrote:
>
> > This is the second time something like this happened. When you make such large scale changes -- make sure to run the lldb testsuite, or be ready to revert. We already had this discussion in the past, but clearly it didn't prevent the problem from happening again.
>
>
> Last time's discussion didn't get anywhere, as running the LLDB test suite on each commit we make to libc++ isn't a viable option.
>
> Libc++'s test matrix is insanely large, and actually we can't even see all of it cause some uses are behind closed doors. Whenever we make a non-trivial change (and BTW this is a purely additive change), it breaks someone somewhere. And you can rest assured that we do run a lot of testing locally to make sure we don't break people before committing, but it can't catch everything. That's just the way it is, and we try to fix it as quickly as possible -- I've spent all day so far trying to fix the consequences of applying this patch. This is not a lack of diligence, it's just that the nature of libc++ makes it difficult to test comprehensively.
>
> I don't know what this commit broke in LLDB, if anything, but instead it's more useful to comment here with a link to the failure so we can help fix it. Being combative is no help, as we're all in the same boat.

I would like to reiterate that the policy in LLVM is that commit that break projects can be reverted willy-nilly.
I would also like to stress that my use cases are not behind closed doors -- LLDB is part of the LLVM umbrella.
I thought we reached an agreement last time, but looks like there was a miscommunication or misunderstanding on your side, so let me reiterate that you have two options:

1. Run the lldb testsuite for changes that impact layout of structures -- or in any case you consider non-trivial, or if you don't think you can do this, at least ping somebody from lldb to take a look at the changes before they're committed. This of course requires some judgement on your side. When in doubt ask, as sending an e-mail is cheap.
2. You commit without pre-commit checking lldb because you consider the additive cost of running `ninja check-lldb` is prohibitive. This is your choice, but don't be surprised if people will revert your commit if it breaks things.

Hopefully this clarifies my position.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D68480/new/

https://reviews.llvm.org/D68480