[PATCH 2 of 4 V2] destutil: allow to specify an explicit source for the merge

[Pierre-Yves David]

On 02/14/2016 04:37 PM, Martin von Zweigbergk wrote:
>
>
> On Sun, Feb 14, 2016, 07:38 Pierre-Yves David
> <pierre-yves.david at ens-lyon.org <mailto:pierre-yves.david at ens-lyon.org>>
> wrote:
>
>     # HG changeset patch
>     # User Pierre-Yves David <pierre-yves.david at fb.com
>     <mailto:pierre-yves.david at fb.com>>
>     # Date 1454956349 -3600
>     #      Mon Feb 08 19:32:29 2016 +0100
>     # Node ID 6b38d0c01aeca0d3c2a2bbf3a0eadd04e37803e8
>     # Parent  0ffdd65816fcde6f970e60830fad8aa0bc67b970
>     # EXP-Topic destination
>     # Available At http://hg.netv6.net/marmoute-wip/mercurial/
>     #              hg pull http://hg.netv6.net/marmoute-wip/mercurial/
>     -r 6b38d0c01aec
>     destutil: allow to specify an explicit source for the merge
>
>     We can now specify from where the merge is performed. The
>     experimental revset
>     is updated to take revisions as argument, allowing to test the feature.
>
>     This will become very useful for pick the 'rebase' default
>     destination. For this
>     reason, we also exclude all descendants from the rebased set from
>     the candidate
>     destinations. This descendants exclusion was not necessary for merge
>     as default
>     destination would not be picked from anything else than a head.
>
>     I'm not super excited with the current error messages, but I would
>     prefer to
>     delay an overall messages rework once 'hg rebase' is done getting a
>     default
>     destination aligned with 'hg merge'.
>
>     diff --git a/mercurial/destutil.py b/mercurial/destutil.py
>     --- a/mercurial/destutil.py
>     +++ b/mercurial/destutil.py
>     @@ -183,13 +183,23 @@ msgdestmerge = {
>           'notatheads':
>               {'merge':
>                   (_('working directory not at a head revision'),
>                    _("use 'hg update' or merge with an explicit revision"))
>               },
>     +    'emptysourceset':
>     +        {'merge':
>     +            (_('source set is empty'),
>     +             None)
>     +        },
>     +    'multiplebranchessourceset':
>     +        {'merge':
>     +            (_('source set is rooted in multiple branches'),
>     +             None)
>     +        },
>           }
>
>     -def _destmergebook(repo, action='merge'):
>     +def _destmergebook(repo, action='merge', sourceset=None):
>           """find merge destination in the active bookmark case"""
>           node = None
>           bmheads = repo.bookmarkheads(repo._activebookmark)
>           curhead = repo[repo._activebookmark].node()
>           if len(bmheads) == 2:
>     @@ -204,30 +214,42 @@ def _destmergebook(repo, action='merge')
>               msg, hint = msgdestmerge['nootherbookmarks'][action]
>               raise error.Abort(msg, hint=hint)
>           assert node is not None
>           return node
>
>     -def _destmergebranch(repo, action='merge'):
>     +def _destmergebranch(repo, action='merge', sourceset=None):
>           """find merge destination based on branch heads"""
>           node = None
>     -    parent = repo.dirstate.p1()
>     -    branch = repo.dirstate.branch()
>     +
>     +    if sourceset is None:
>     +        sourceset = [repo[repo.dirstate.p1()].rev()]
>     +        branch = repo.dirstate.branch()
>     +    elif not sourceset:
>     +        msg, hint = msgdestmerge['emptysourceset'][action]
>     +        raise error.Abort(msg, hint=hint)
>     +    else:
>     +        branch = None
>     +        for ctx in repo.set('roots(%ld::%ld)', sourceset, sourceset):
>
>
> Can this ever be different from just
> repo.set('roots(%ld)', sourceset)? Typo? If it really is different,
> perhaps it deserves a comment about what it does?

If the sourceset is non-continuous (some hole in an ancestry line) roots 
would not return the roots of the planned rebase.

Mostly being safe as the function "contract" does not requires it.

-- 
Pierre-Yves David