Rebase with obsoleted changesets in rebaseset

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This page collects situations and discussion about rebase where the rebaseset contains obsoleted changesets.

Contents

Situations

  Z E # E: unstable
  | |
 D' D # D: replaced by D'
  | |
  B C
  |/
  A

  E'
  |
  C'
  |
  Z 
  | 
  ~

This is probably the most interesting one.

      E  # E: unstable
      |
  Z D D' # D: replaced by D'
  | |/
  B C
  |/
  A

Option 1 (rebase markers): rebase -s C -d Z creates new markers, avoid potential merge conflicts (in case the user knows there will be a conflict and wants to edit D"' before rebase E'). Like Option 5, plus creating new markers. There is a couple of concerns:
- marker explosion (needs explain)
- user need to solve similar merge conflict for twice (D + D') (but same with common rebase behavior without obsmarkers)
- power user can always exclude troublemarkers using revset manually to get "Option 2" behavior.

      E'
      |
   D" D"' # D": replaced by D"'
    |/
    C'
   /
  Z
  |
  ~

Option 2 (skip troublemakers): rebase -s C -d Z (with some flag?) skips precursors(rebaseset):: in rebaseset. In the example case, E remains at the old position. The user need to run another rebase -s E -d D"' to move E. There is no D" like Option 1 so the user cannot create divergence easily and conflict of rebasing E can be handled later. The downside is not intuitive - users may expect C to be "extinct" (i.e. not shown up in hg sl) after rebase -s C -d ....
- may confuse the user a bit since the old revision is still hanging around
- power user cannot get "Option 1" behavior if they really want to

    D"'
    |
    C'E # E: unstable
   / /
  Z D D' # D: replaced by D'; D': replaced by D"'
  | |/
  B C # C: replaced by C'
  |/
  A

Option 3 (evolve): rebase -s C -d Z --evolve auto rebases E' to D"', does not create D", and does not create new markers. Like running "hg evolve" after Option 1. This is consistent with the --evolve flag below.

    E'
    |
    D"'
    |
    C'
   /
  Z
  |
  ~

Option 4 (current behavior, not ideal): rebase -s C -d Z aborts
Option 5 (current behavior with experimental.allowdivergence=1, not ideal): rebase -s C -d Z creates divergence

      E # E: unstable
      |
Z D'  D # D: replaced by D'
 \|  /
  B C
  |/
  A

Option 1: rebase -s C -d Z aborts (current default behavior)
Option 2: rebase -s C -d Z creates diverange (with experimental.allowdivergence=True)
Option 3: rebase -s C -d Z --evolve rebases roots to destination and evolves others

C'E'
| |
Z D'
 \|
  B
  |
  A

Mostly about how to deal with the "Successor is also in a rebase set" case.