Paul Burba wrote: > On Thu, Apr 19, 2012 at 12:57 PM, Julian Foad wrote: >> Branko Čibej wrote: >>> By the way, I'm all for removing support for merging into >>> mixed-revision >>> and/or switched-subtree working copies. There's too much room for >>> unexpected results in these cases. >> >> I don't necessarily disagree, but that sounds a bit unsubstantiated. >> Is there too much "room for unexpected results" because you don't have >> a mental model of what to expect? If I were to figure out and describe >> some sensible semantics and a use case, might you then change your mind? >> >> FWIW, I have an inkling of how a mixed-rev target WC should work: it's >> logically very similar to having different mergeinfo on different subtrees, >> except that the differences are on the target side of the merge rather than >> the source side of the merge. It requires some care to be sure that the >> parent-to-child inheritance of mergeinfo in the WC remains valid where base >> revision numbers differ. >> >> That said, I can't imagine any valid reason to need to support a >> mixed-rev target WC. >> >> I have thought very little about about how switched subtrees should >> work [and use cases]. >> >> Maybe Paul can help fill in some of the "how" and "why" gaps here? > > I believe I answered this question already, see: > http://svn.haxx.se/dev/archive-2012-03/0632.shtml If that doesn't > sufficiently answer your questions let me know.
Hi Paul. Yes, what you wrote there makes sense as to how we handle switched subtrees and "why" in a logical sense. I've just followed up with a reply to that email going into a bit more detail. I feel that with this level of functional spec, Switched Subtrees is something I can now add to the Symmetric Merge design proposal. I see there's already a brief statement about sparse WCs too: <http://svn.apache.org/repos/asf/subversion/trunk/notes/merge-tracking/func-spec.html#sparse-checkouts>. I'm not clear how the whole 'depth' thing works, though, if you add children to a directory that was initially sparse or exclude children from a directory that was initially depth non-empty. Do you have a pointer to some details about how a mixed-rev target WC is handled? I have now added a section "Mixed-Rev, Switched, or Sparse WC" to <http://wiki.apache.org/subversion/SymmetricMerge>. > As to removing support for merging into WCs with switched subtrees, > let's be clear that this *does* work today (if you think otherwise > please provide a use-case demonstrating what is broken). Now maybe we > want to restrict these types of merges to make further improvements > possible (e.g. Julian's symmetric merge work), that I won't argue > against, but I want to be clear that we are making the choice to > remove some existing functionality as a trade-off in implementing new > functionality, rather than fixing a broken feature. Totally clear, yes, if that's what we decide to do. - Julian
