On 10 January 2011 11:19, Simon Marlow
Let us know what you think - would this make life harder or easier for you? Would it make you less likely or more likely to contribute?
Well, as a sometime-contributor I would certainly be happier hacking on GHC if it were git based. When working on a GHC branch, it is rather irritating to spend time work around the inevitable Darcs bugs rather than hacking on the code. However, I remember the last time this came up there were some issues that might make migration painful. From the top of my head: 1) Some people expressed concern that they would have to use two revision control systems to work on GHC, because not all GHC dependencies would be git-based. 2) There was also concern that Git isn't so great on Windows. I have heard that this is less of an issue now, but I never personally suffered from any problems, so can't be sure. (FWIW I used Git on Windows industrially ~1 year ago for 3 months and didn't have problems, though the people around me occasionally had issues with e.g. case insensitivity causing obscure error messages). 3) The git transition has the potential to make Ian's workflow (i.e. maintaining branches for old GHC releases) harder. AFAIK currently Ian just "darcs pulls" a particular patch from GHC HEAD into e.g. the GHC 7 branch. Darcs automatically works out which of the earlier patches are dependent on that patch and deals with pulling them in as well (if they are not already present). If GHC HQ transitioned to Git but committed all patches to master then Ian's job might be significantly harder because he would have to use "git cherry-pick" to pick out any bug fix patches that should be merged back to e.g. GHC 7. Unfortunately, Git does not provide any mechanism for automatically working out which earlier patches commits on the cherry-picked commit, so this will fail quite often. Ian will then have to manually identify the dependents. To make Ian's life easier GHC HQ could adopt a new workflow. For example, bug fixers could fix their bugs on *new* branches (one peg bug) which start from the last major GHC release (right now, GHC 7). After fixing the bug on that branch, they can then merge the branch into master. Now when Ian merges a bugfix to a GHC 7 patchlevel release he just needs to merge that bug fixing branch into the ongoing GHC 7 branch. Naturally other workflows are possible and I'm sure other list members will chime in with their own favourites :-) Has GHC HQ thought about these workflow issues? Are you happy with any changes that might be required to your workflows? Ultimately I'm quite concerned with keeping GHC HQ happy (as you guys do the lions share of the work!). I feel we should only make the switch if the most frequent committers (i.e. Simon, Simon and Ian) are *totally happy* with it and any associated workflow changes that may be required. Cheers, Max