[MERGE] Merge now warns when it encounters a criss-cross

[John Arbash Meinel]

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Aaron Bentley wrote:
> Michael Hudson wrote:
>> Martin Pool wrote:
> 
>>> Maybe we can come up with a better message though:
>>>
>>> +                warning('Warning: criss-cross merge encountered.')
>>>
>>> So ok, the user now feels warned.  What are they to do?  If you could
>>> tell them what they should do, or what the consequences are, or how to
>>> avoid it, that would be better.
> 
> Well, I'm sort-of caught.  Normally in criss-cross merging situations, I
> recommend using merge --weave.  But with packs, this is not really a
> realistic option.
> 
> I'm gonna see if I can implement per-file merge bases as a behavior that
> happens when a criss-cross is encountered.  That would reduce the
> consequences of criss-cross merge.

Would it be reasonable to do this even in the absence of criss-cross? I realize
it is much more needed there, but I'm wondering if we couldn't get slightly
fewer conflicts if we did it all the time. (I suppose if there isn't a criss
cross, we would expect the per-file graph to be uninteresting?)

> 
> I think, in theory, I can implement a cheaper version of annotate merge
> (because the type of annotation it needs is very restricted), but I
> don't think I can do it on this deadline.
> 
>> You could link to http://revctrl.org/CrissCrossMerge, though that
>> might be a bit hard core :-) Perhaps writing a friendlier page on the
>> Bazaar wiki and linking to that would be sane, though.
> 
> 
> So it seems like documentation is The Right Thing.  Should I say
> "Warning: criss-cross merge encountered.  See
> http://doc.bazaar-vcs.org/latest/en/user-guide/criss_cross.html" ?
> 
> Should I refer to local docs? "Warning: criss-cross merge encountered.
> See "Criss-cross merging" in the User Guide"?
> 
> Aaron

Well, you can have it as a help topic. And then they can do:

bzr help criss-cross-merge

Which makes it very easy to link from the error message.

John
=:->
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