Hello Simon, On 2014-03-24 at 09:37:32 +0100, Simon Peyton Jones wrote:
OK. Some questions.
· Where is a good place to get a conceptual understanding of submodules?
There were three links at the top of the Wiki page; I assume you want something better than that?
Concerning https://ghc.haskell.org/trac/ghc/wiki/WorkingConventions/Git/Submodules
· Under "Updating an existing source tree clone" you say we have to do "git submodule update --init". What happens if we forget? Couldn't sync-all do that? (Indeed it now emits a message to that effect
sync-all can do that of course; at this point, I'm just collecting all direct `git` commands one would have to enter if there wasn't a sync-all script -- once everything is in place, a new radically stripped down `sync-all` can be constructed for the common day-to-day invocations. The page also aims to make the underlying Git commands more transparent, with the hope that by explaining what happens under the hood, it may become less confusing when `sync-all` fails.
bash$ ./sync-all pull --rebase
Yes, sync-all does already call `git submodule update` in some occasions already, but its current implementation is far more confusing than it needs to be IMHO :-)
· Under “Overriding pushurl”, same question. Couldn’t that long “git submodule foreach” command be done by sync-all?
yes, it will (even though that specific invocation will be taken core by sync-all in the future, that snippet serves as an example for the versatile 'git submodule foreach' tool everyone working with submodules should at least know about -- it's not that far-fetched that one might want to do something non-standard sync-all doesn't handle)
· Under “Making changes”, this looks hard to me. Is “base” a submodule? Does that mean we have to remember to do some incantations before we modify base?
Actually, we're strongly considering to fold the non-upgradable GHC-specific packages tied to GHC, namely - base - ghc-prim - integer-{gmp,simple} - template-haskell into ghc.git (as was done with testsuite/) as those wouldn't benefit much from remaining an independent (submodule) repo anyway;
What if you forget and make the modifications first? Again, could some of this be automated, at least for the common workflow of pull/push?
for one, if you forget to associate a Git branch before committing on a detached-HEAD, you can simply 'git push origin HEAD:master' If you meant about forgetting to update ghc.git to point to the new commit, then that's actually a feature to avoid *having* to track each single push/commit to master of a submodule to ghc.git's master branch as well; For instance, utils/haddock 'master' is currently one rather unimportant commit[1] ahead of what 'ghc.git' references as its haddock.git commit right now. [1]: http://git.haskell.org/haddock.git/commitdiff/f3c7cd34d066cd40cb4983893165de...