D1047: tweakdefaults: add restack command

[quark (Jun Wu)]

quark added a comment.


  In https://phab.mercurial-scm.org/D1047#17692, @durin42 wrote:
  
  > Counterproposal:
  >
  > `hg rebase --auto <REVSET>`
  >
  > or
  >
  > `hg rebase --auto -r <REVSET>`
  >
  > rather than introducing a new concept of a stack. I know Facebook has this concept internally, but for core hg we don't have the notion of a stack outside `mq` and `show`: the former is heavily deprecated, and the latter is experimental and still subject to change. Also, I feel like 'automatic rebase' is a pretty good description of what's actually happening to resolve the trivial orphans-only trouble cases. Thoughts?
  >
  > I'd be happy to spend a bit of time writing up a commit for rebase--auto if people want to play with it.
  
  
  I'm unconvinced that `--auto` should be bound to the concept of stabilization. I think it should be made more flexible. ex. some users may ask "why --auto does not rebase my commits to master"?
  
  Currently, rebase has a non-configurable `_destrebase` revset that is used when `-d` is not specified. It's basically useless. And we even have `commands.rebase.requiredest` to disable it.
  
  I think we can have proper ways to make it possible that the "default" behavior is useful and does the "--auto" thing, while still being flexible.
  
  What I'm thinking about is a config section like:
  
    [revsetalias:rebase.dest] # revsetalias that is only used in rebase destination scope
    auto = if(SRC is orphan and obsoleted,first(max((successors(max(roots(ALLSRC) & ::SRC)^)-obsolete())::)+max(::((roots(ALLSRC) & ::SRC)^)-obsolete()))))
    # missing bit: express "ifempty(x, trueset, falseset)" in revset language
  
  Benefit:
  
  1. Users can run `hg rebase -r 'draft()' -d auto`, which seems to be convenient enough.
  2. Sysadmins can override the config so it also works for rebasing to `master`. More flexible.
  
  In addition, we can have something like:
  
    [commands] # ignored by HGPLAIN
    rebase.defaultsrcdest = "not public()", auto # used when both src and dest are not provided
    rebase.defaultdest = auto # used when src is provided, but not dest
    rebase.defaultsrc = ("not public()" & ::.)+(.::)  # used when src is not provided, but dest is provided
  
  Then users can just run `hg rebase` without arguments.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D1047

To: quark, #hg-reviewers
Cc: durin42, martinvonz, lothiraldan, dlax, mercurial-devel