Re: [RFD PATCH 00/32] subtree clone v2

[Nguyen Thai Ngoc Duy <pclouds@gmail.com>]

On Thu, Aug 26, 2010 at 12:50 PM, Elijah Newren <newren@gmail.com> wrote:
>> The second point (probably not needed if the above assumption is no
>> longer true, but I post anyway in case I forget it again). Without
>> whole trees, it's impossible to determine a trivial merge reliably. If
>> "you" adds a file and "upstream" adds another file, predecessor trees
>> will look different but merging them is trivial (at file level). If we
>> miss some trees that lead to those new files, the best thing we can do
>> is to claim it non-trivial.
>
> I'm not following this one.  Could you provide more detail?
>

Let's say in "ancestor" tree, we have

t1/f0
t2/t3/f0

In "you" tree, we have

t1/f0
t2/t3/f0
t2/t3/f1

In "upstream" tree, we have

t1/f0
t2/t3/f0
t2/t3/f2

The narrow tree is t1, so we the trees we have are toplevel tree and
t1. If we have all trees, that should be a trivial merge, which
results in f0, f1 and f2 inside t2/t3. But we don't have t2 and t3
trees in narrow repo. When we traverse toplevel tree of "ancestor",
"you" and "upstream", we can only see that t2 sha-1 is different. If
"t2" is a file, not a tree, then we can conclude non-trivial here. And
because we don't have t2, we can't descend to make better conclusion.
-- 
Duy