Hi all, Sadly `master` has been broken for much of the day. The causal-chain is roughly the following: 1. Last week a haddock merge-request was prematurely merged by a haddock developer, despite not being compilable, to the `ghc-head` branch. 2. marge-bot failed during a merge on Sunday 3. On Monday I finished merging the half-merged batch manually, not aware of the inconsistent submodule state. However, while doing so some unintended changes crept in, relying on an unmerged haddock commit. 4. in an attempt to fix the inconsistent submodule state another developer merged the unmerged commit 5. I notice the unintentional commits on `master` and start to back them out 6. I note that even after backing out the unintentional commits the tree *still* doesn't build due to haddock 7. I perform a fair amount of head-scratching trying to figure out what is going on; eventually I find the non-building commit. 8. I eventually sort out what needs to be backed-out and in what order I take a few lessons from this: * manual merges, no matter how "straightforward", are always a vector for mistakes. I should have triple-checked my work before pushing manually pushing the half-merged branch. * haddock submodule changes going in prematurely come with a very high cost, especially if they don't build. It turns out I had run into the non-compilable haddock commit a few times last week but had chalked it up to in-flight changes. On the whole, I am really starting to wonder whether we can't improve our model for dealing with haddock; it is currently quite easy for haddock and GHC to enter an inconsistent state. Moreover, the fact that `haddock`'s `ghc-head` branch runs ahead of `master` means that we won't realize the problem until it's too late. One small improvement would be to move Haddock to GitLab. This would at least ensure that there is a clear connection between haddock MRs and their corresponding GHC changes. I have suggested this to Alex. Beyond this, it would be great if someone could step up to finish the hi-haddock change [1]. I suspect this refactoring has the potential to greatly improve this situation: the interface file AST tends to be more stable that the Core AST and has significantly less surface area. After this is in place Haddock could then use either its own AST or a frozen HsSyn AST from GHC (faciliated by TTG) internally, greatly reducing the coupling between Haddock and GHC. Any takers? Cheers, - Ben