[PATCH 2 of 2 V2] rebase: calculate ancestors for --base separately (issue5420)

[Pierre-Yves David]

On 11/19/2016 02:40 AM, Augie Fackler wrote:
> On Thu, Nov 17, 2016 at 11:49:58PM +0000, Jun Wu wrote:
>> # HG changeset patch
>> # User Jun Wu <quark at fb.com>
>> # Date 1479426495 0
>> #      Thu Nov 17 23:48:15 2016 +0000
>> # Node ID e5451a607d1ca53b2446ab049375e5dd5a055bb8
>> # Parent  87e0edc93d87b88e2925877469d8c142e01737fc
>> # Available At https://bitbucket.org/quark-zju/hg-draft
>> #              hg pull https://bitbucket.org/quark-zju/hg-draft -r e5451a607d1c
>> rebase: calculate ancestors for --base separately (issue5420)
>
> These are queued, thanks.

I'm a bit concerned about the lack of test covering situation with merge 
commit. There could be pathological case lurking there. I'll try to a 
have a deeper look at what this change imply is that case before giving 
it a second accept stamp.

>> Previously, the --base option only works with a single "branch" - if there
>> are multiple branching points, "rebase" will error out with:
>>
>>   abort: source is ancestor of destination
>>
>> This happens if the user has multiple draft branches with different
>> branching points, and uses "hg rebase -b 'draft()' -d master". The error
>> message looks cryptic to users who don't know the implementation detail.
>>
>> This patch changes the logic to calculate ancestors for each "base" branch
>> so it would work in the multiple branching points case.
>>
>> Note: if there are multiple bases where some of them are rebasable, while
>> some of them aren't because the branching point is the destination, the
>> current behavior is to abort with "nothing to rebase", which seems wrong.
>> However, that issue is not introduced by this patch - it exists for "-s" as
>> well. I have reported it as issue5422 and should be solved separately.
>>
>> diff --git a/hgext/rebase.py b/hgext/rebase.py
>> --- a/hgext/rebase.py
>> +++ b/hgext/rebase.py
>> @@ -722,10 +722,17 @@ def _definesets(ui, repo, destf=None, sr
>>              destf = str(dest)
>>
>> -        commonanc = repo.revs('ancestor(%ld, %d)', base, dest).first()
>> -        if commonanc is not None:
>> -            rebaseset = repo.revs('(%d::(%ld) - %d)::',
>> -                                  commonanc, base, commonanc)
>> -        else:
>> -            rebaseset = []
>> +        # calculate ancestors for individual bases
>> +        realbases = []
>> +        for b in repo.revs('roots(%ld)', base):
>> +            # branching point
>> +            bp = repo.revs('ancestor(%d, %d)', b, dest).first()
>> +            if bp is None:
>> +                continue
>> +            # move b to be the direct child of the branching point
>> +            b = repo.revs('%d::%d - %d', bp, b, bp).first()
>> +            if b is not None:
>> +                realbases.append(b)
>> +
>> +        rebaseset = repo.revs('%ld::', realbases)
>>
>>          if not rebaseset:
>> diff --git a/tests/test-rebase-base.t b/tests/test-rebase-base.t
>> new file mode 100644
>> --- /dev/null
>> +++ b/tests/test-rebase-base.t
>> @@ -0,0 +1,94 @@
>> +  $ cat >> $HGRCPATH <<EOF
>> +  > [extensions]
>> +  > rebase=
>> +  > drawdag=$TESTDIR/drawdag.py
>> +  >
>> +  > [phases]
>> +  > publish=False
>> +  >
>> +  > [alias]
>> +  > tglog = log -G --template "{rev}: {desc}"
>> +  > EOF
>> +
>> +  $ hg init a
>> +  $ cd a
>> +
>> +  $ hg debugdrawdag <<EOS
>> +  > g f
>> +  > |/
>> +  > e c d
>> +  > | |/
>> +  > | b
>> +  > |/
>> +  > a
>> +  > EOS
>> +
>> +  $ cd ..
>> +
>> +Pick a single base:
>> +
>> +  $ cp -a a a1 && cd a1
>> +  $ hg rebase -b c -d g -q
>> +  $ hg tglog
>> +  o  6: d
>> +  |
>> +  | o  5: c
>> +  |/
>> +  o  4: b
>> +  |
>> +  o  3: g
>> +  |
>> +  | o  2: f
>> +  |/
>> +  o  1: e
>> +  |
>> +  o  0: a
>> +
>> +  $ cd ..
>> +
>> +Pick a base that is already an descendant of dest:
>> +
>> +  $ cp -a a a2 && cd a2
>> +  $ hg rebase -b g -d e
>> +  nothing to rebase
>> +  [1]
>> +  $ hg rebase -b d -d a
>> +  nothing to rebase
>> +  [1]
>> +  $ hg rebase -b d+c+f+e -d a
>> +  nothing to rebase
>> +  [1]
>> +  $ cd ..
>> +
>> +Pick multiple bases (issue5420):
>> +
>> +  $ cp -a a a3 && cd a3
>> +  $ hg rebase -b d+f -d g -q
>> +  $ hg tglog
>> +  o  6: f
>> +  |
>> +  | o  5: d
>> +  | |
>> +  | | o  4: c
>> +  | |/
>> +  | o  3: b
>> +  |/
>> +  o  2: g
>> +  |
>> +  o  1: e
>> +  |
>> +  o  0: a
>> +
>> +  $ cd ..
>> +
>> +Mixed rebasable and non-rebasable bases (unresolved, issue5422):
>> +
>> +  $ cp -a a a4 && cd a4
>> +  $ hg debugdrawdag <<EOS
>> +  > h
>> +  > |
>> +  > g
>> +  > EOS
>> +  $ hg rebase -b d+f+h -d g
>> +  nothing to rebase
>> +  [1]
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-- 
Pierre-Yves David