"split" using the evolog?

[BatmanAoD]

Is there a way to "split" a commit using the evolog?

I.e., given a change foo at commit f2 but previously f1, is there an easy way to restore f1, then recreate f2 as a new commit on top of that?

(One way to accomplish this is jj duplicate f1, jj new <the new commit>, jj restore --from f2, but I'm wondering if there's an easier way.)

[ilyagr]

No. I was thinking of implementing something like this in #4097 . I think it might be nicer as some version of jj duplicate, as discussed in #4097 (comment).

For the evolog part of it, there is a discussion in #4129

[tim-janik]

Is there a way to "split" a commit using the evolog?

I.e., given a change foo at commit f2 but previously f1, is there an easy way to restore f1, then recreate f2 as a new commit on top of that?

(One way to accomplish this is jj duplicate f1, jj new <the new commit>, jj restore --from f2, but I'm wondering if there's an easier way.)

jj-fzf can restore a "missing" commit from successive snapshots in the op log (Ctrl+O).
It does that by creating an empty new commit before @, and then restoring into it while keeping the descendants (Alt+W).

The same could be done from the evolog, just manually pick out the old commit, here 3ed8:

⮞ jj evolog -p -r @
@  srtvvyqx [email protected] 2024-12-06 04:04:42 c5fb70b4
│  (no description set)
│  diff --git a/data b/data
│  index 8e1e71d5ce..257cc5642c 100644
│  --- a/data
│  +++ b/data
│  @@ -1,1 +1,1 @@
│  -f1
│  +foo
○  srtvvyqx hidden [email protected] 2024-12-06 04:04:42 3ed80c55
│  (no description set)
│  diff --git a/data b/data
│  new file mode 100644
│  index 0000000000..8e1e71d5ce
│  --- /dev/null
│  +++ b/data
│  @@ -1,0 +1,1 @@
│  +f1
○  srtvvyqx hidden [email protected] 2024-12-06 04:04:24 29219075
   (empty) (no description set)
⮞ jj new --no-edit --before srtvvyqx
Created new commit qmyzmvlr 5edb9771 (empty) (no description set)
Rebased 1 descendant commits
Working copy now at: srtvvyqx 2896819f (no description set)
Parent commit      : qmyzmvlr 5edb9771 (empty) (no description set)
⮞ jj restore -f 3ed80c55 -t @- --restore-descendants
Created qmyzmvlr aad51e49 (no description set)
Rebased 1 descendant commits (while preserving their content)
Working copy now at: srtvvyqx 59615359 (no description set)
Parent commit      : qmyzmvlr aad51e49 (no description set)
⮞ jj log -p -n2
@  srtvvyqx [email protected] 2024-12-06 04:05:48 59615359
│  (no description set)
│  diff --git a/data b/data
│  index 8e1e71d5ce..257cc5642c 100644
│  --- a/data
│  +++ b/data
│  @@ -1,1 +1,1 @@
│  -f1
│  +foo
○  qmyzmvlr [email protected] 2024-12-06 04:05:48 git_head() aad51e49
│  (no description set)
│  diff --git a/data b/data
│  new file mode 100644
│  index 0000000000..8e1e71d5ce
│  --- /dev/null
│  +++ b/data
│  @@ -1,0 +1,1 @@
│  +f1