evolve: refactor content-divergence resolution logic
> What is the case we are looking at?
This is about refactoring the part of content-div resolution logic where it
decides which cset should be relocated and where.
> What is a "topologicial common ancestors" vs a "greatest common ancestors"?
`tca` is an ancestor which we can decide/find by looking at the at graph
visually for e.g
```
c3(*) c4(*)
| |
c2(x) c1(x)
c5 | /
\ | /
c0
```
(c5 is the successor of c2 and c1)
now here,
`tca` of c3 and c4 is: c0
`gca` of c3 and c4 is: c5
> What is the new top-level logic/behavior that makes it better?
The old code had some unnecessary edge cases just because we were using `gca`,
since it can point to a revision that is not a topological ancestor.
For e.g see b779b40f996e
Eventually, the code around this was getting messy unnecessarily. So I looked
into it and found a simple and more robust approach.
And in new code, it is simple and straightforward (and easy to understand),
where we handle the following 4 cases when solving content-div:
1) when both are on the same parent
=> (no need to do anything special, and simply proceed)
2) both are on the different parent but a) `tca` is the parent of one of them
or b) there is no non-obsolete revision between `tca` and one of the
divergent cset.
=> (relocate one to the other side and proceed)
3) both are on different parents and `tca` is not the parent of any of them and
there is at least one non-obsolete cset between tca and both the divergent
cset i.e (tca::div1) and (tca::div2) both the ranges have at least one non-obs
revision.
=> (this is the case which we don't handle yet, but the solution would be to
prompt the user to choose an evolve destination.)
4) both are in the parent-child relation
=> (both are merged and new cset will be based on the successor of `tca`)
Changes in test-evolve-issue5958.t demonstrate that new code also covered case4
because in a resolution of "two divergent csets with parent-child relation"
there should be one cset as a result and no orphan revs (as you can see there
was an orphan before this patch).
test of the fold command
------------------------
$ cat >> $HGRCPATH <<EOF
> [defaults]
> amend=-d "0 0"
> fold=-d "0 0"
> split=-d "0 0"
> amend=-d "0 0"
> [web]
> push_ssl = false
> allow_push = *
> [phases]
> publish = False
> [diff]
> git = 1
> unified = 0
> [ui]
> interactive = true
> [extensions]
> EOF
$ echo "topic=$(echo $(dirname $TESTDIR))/hgext3rd/topic/" >> $HGRCPATH
$ echo "evolve=$(echo $(dirname $TESTDIR))/hgext3rd/evolve/" >> $HGRCPATH
$ mkcommit() {
> echo "$1" > "$1"
> hg add "$1"
> hg ci -m "add $1" $2 $3
> }
$ logtopic() {
> hg log -G -T "{rev}:{node}\ntopics: {topics}"
> }
Check that fold keep the topic if all revisions have the topic
--------------------------------------------------------------
$ hg init testfold
$ cd testfold
$ mkcommit ROOT
$ hg topic myfeature
marked working directory as topic: myfeature
$ mkcommit feature1
active topic 'myfeature' grew its first changeset
(see 'hg help topics' for more information)
$ mkcommit feature2
$ logtopic
@ 2:d76a6166b18c835be9a487c5e21c7d260f0a1676
| topics: myfeature
o 1:39e7a938055e87615edf675c24a10997ff05bb06
| topics: myfeature
o 0:3e7df3b3b17c6deb4a1c70e790782fdf17af96a7
topics:
$ hg fold --exact -r "(tip~1)::" -m "folded"
2 changesets folded
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg stack
### topic: myfeature
### target: default (branch)
s1@ folded (current)
s0^ add ROOT (base)
$ logtopic
@ 3:4fd43e5bdc443dc8489edffac19bd8f93ccf1a5c
| topics: myfeature
o 0:3e7df3b3b17c6deb4a1c70e790782fdf17af96a7
topics:
$ hg summary
parent: 3:4fd43e5bdc44 tip
folded
branch: default
commit: (clean)
update: (current)
phases: 2 draft
topic: myfeature
Check that fold dismis the topic if not all revisions have the topic
--------------------------------------------------------------------
(I'm not sure this behavior make senses, but now it is tested)
$ hg topic --clear
$ mkcommit feature3
created new head
(consider using topic for lightweight branches. See 'hg help topic')
$ hg topic myotherfeature
marked working directory as topic: myotherfeature
$ mkcommit feature4
active topic 'myotherfeature' grew its first changeset
(see 'hg help topics' for more information)
$ logtopic
@ 5:5ded4d6d578c37f339b0716de2e46e12ece7cbde
| topics: myotherfeature
o 4:bdf6950b9b5b7c6b377c8132667c73ec86d5734f
| topics:
o 3:4fd43e5bdc443dc8489edffac19bd8f93ccf1a5c
| topics: myfeature
o 0:3e7df3b3b17c6deb4a1c70e790782fdf17af96a7
topics:
$ hg fold --exact -r "(tip~1)::" -m "folded 2"
active topic 'myotherfeature' is now empty
2 changesets folded
clearing empty topic "myotherfeature"
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ logtopic
@ 6:03da8f7238e9a4d708d6b8af402c91c68f271477
| topics:
o 3:4fd43e5bdc443dc8489edffac19bd8f93ccf1a5c
| topics: myfeature
o 0:3e7df3b3b17c6deb4a1c70e790782fdf17af96a7
topics:
$ hg summary
parent: 6:03da8f7238e9 tip
folded 2
branch: default
commit: (clean)
update: (current)
phases: 3 draft