view tests/test-topic-stack-complex.t @ 3846:f9dad99a90d5

evolve: create a new commit instead of amending one of the divergents

This patch changes the behavior of evolve command while resolving
content-divergence to create a new commit instead of amending one of the
divergent ones.

In past, I have made this change, backed out this change and now today again I
am doing this change, so let's dive in some history.

Using cmdrewrite.amend() was never a good option as that requires hack to delete
the evolvestate and also gives us less control over things. We can't make the
commit on top of different parents as that of content-divergent ones. Due to all
these, I first made this change to create a new commit instead of amending one.

But, after few days, there was flakiness observed in the tests and turned out
that we need to do some dirstate dance as repo.dirstate.setparents() does not
always fix the dirstate. That flakiness was a blocker for progress at that time
and we decided to switch to amend back so that we can have things working with
some hacks and we can later fix the implementation part.

Now, yesterday while tackling resolving content-divergence of a stack which is
as follows:

C1 C2
 | |
B1 B2
 | |
A1 A2
 \/
base

where, A1-A2, B1-B2, C1-C2 are content-divergent with each other. Now we can
resolve A1-A2 very well because they have the same parent and let's say that
resolution leads to A3.
Now, we want to resolve B1-B2 and make the new resolution commit on top of A3 so
that we can end up something like:

C3
 |
B3
 |
A3
 |
base

however, amending one of the divergent changesets, it's not possible to create a
commit on a different parent like A3 here without some relocation. We should
prevent relocation as that may leads to some conflicts and should change the
parent before committing.

So, looking ahead, we can't move with using amend as still using that we will
need some relocation hacks making code ugly and prone to bad behaviors, bugs.
Let's change back to creating a new commit so that we can move forward in a good
way.

About repo.dirstate.setparents() not setting the dirstate, I have researched
yesterday night about how we can do that and found out that we can use
cmdrewrite._uncommitdirstate() here. Expect upcoming patches to improve the
documentation of that function.

There are lot of test changes because of change in hash but there is no behavior
change. The only behavior change is in test-evolve-abort-contentdiv.t which is
nice because creating a new commit helps us in stripping that while aborting.
We have a lot of testing of content-divergence and no behavior change gives
enough confidence for making this change.

I reviewed the patch carefully to make sure there is no behavior change and I
suggest reviewer to do the same.

Testing `hg stack` on complex cases when we have multiple successors because of
divergence, split etc.
  $ . "$TESTDIR/testlib/topic_setup.sh"

Setup

  $ cat << EOF >> $HGRCPATH
  > [experimental]
  > evolution = all
  > [ui]
  > interactive = True
  > [extensions]
  > show =
  > EOF
  $ echo "evolve=$(echo $(dirname $TESTDIR))/hgext3rd/evolve/" >> $HGRCPATH

  $ hg init test
  $ cd test
  $ echo foo > foo
  $ hg add foo
  $ hg ci -m "Added foo"
  $ hg phase -r . --public
  $ hg topic foo
  marked working directory as topic: foo
  $ echo a > a
  $ echo b > b
  $ hg ci -Aqm "Added a and b"
  $ echo c > c
  $ echo d > d
  $ hg ci -Aqm "Added c and d"
  $ echo e > e
  $ echo f > f
  $ hg ci -Aqm "Added e and f"
  $ hg show work
  @  f1d3 (foo) Added e and f
  o  8e82 (foo) Added c and d
  o  002b (foo) Added a and b
  o  f360 Added foo

Testing in case of split within the topic

  $ hg stack
  ### topic: foo
  ### target: default (branch)
  t3@ Added e and f (current)
  t2: Added c and d
  t1: Added a and b
  t0^ Added foo (base)
  $ hg prev
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  [2] Added c and d

  $ echo 0 > num
  $ cat > editor.sh << '__EOF__'
  > NUM=$(cat num)
  > NUM=`expr "$NUM" + 1`
  > echo "$NUM" > num
  > echo "split$NUM" > "$1"
  > __EOF__
  $ export HGEDITOR="\"sh\" \"editor.sh\""

  $ hg split << EOF
  > y
  > y
  > n
  > y
  > EOF
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  adding c
  adding d
  diff --git a/c b/c
  new file mode 100644
  examine changes to 'c'? [Ynesfdaq?] y
  
  @@ -0,0 +1,1 @@
  +c
  record change 1/2 to 'c'? [Ynesfdaq?] y
  
  diff --git a/d b/d
  new file mode 100644
  examine changes to 'd'? [Ynesfdaq?] n
  
  Done splitting? [yN] y
  1 new orphan changesets

  $ hg stack
  ### topic: foo
  ### target: default (branch)
  t4$ Added e and f (unstable)
  t3@ split2 (current)
  t2: split1
  t1: Added a and b
  t0^ Added foo (base)

  $ hg show work
  @  5cce (foo) split2
  o  f26c (foo) split1
  | *  f1d3 (foo) Added e and f
  | x  8e82 (foo) Added c and d
  |/
  o  002b (foo) Added a and b
  o  f360 Added foo

  $ hg prev
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  [4] split1
  $ echo foo > c
  $ hg diff
  diff -r f26c1b9addde c
  --- a/c	Thu Jan 01 00:00:00 1970 +0000
  +++ b/c	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +1,1 @@
  -c
  +foo

  $ hg amend
  1 new orphan changesets
  $ hg show work
  @  7d94 (foo) split1
  | *  5cce (foo) split2
  | x  f26c (foo) split1
  |/
  | *  f1d3 (foo) Added e and f
  | x  8e82 (foo) Added c and d
  |/
  o  002b (foo) Added a and b
  o  f360 Added foo

  $ hg stack
  ### topic: foo (2 heads)
  ### target: default (branch), 2 behind
  t4$ Added e and f (unstable)
  t3$ split2 (unstable)
  t2@ split1 (current)
  t1: Added a and b
  t0^ Added foo (base)