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

[Augie Fackler]

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.

>
> 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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