absorb: preserve changesets which were already empty
Most commands in Mercurial (commit, rebase, absorb itself) don’t create empty
changesets or drop them if they become empty. If there’s a changeset that’s
empty, it must be a deliberate choice of the user. At least it shouldn’t be
absorb’s responsibility to prune them. The fact that changesets that became
empty during absorb are pruned, is unaffected by this.
This case was found while writing patches which make it possible to configure
absorb and rebase to not drop empty changesets. Even without having such config
set, I think it’s valuable to preserve changesets which were already empty.
--- a/hgext/absorb.py Mon Jun 01 11:07:33 2020 +0200
+++ b/hgext/absorb.py Mon Jun 01 20:57:14 2020 +0200
@@ -782,7 +782,9 @@
# nothing changed, nothing commited
nextp1 = ctx
continue
- if self._willbecomenoop(memworkingcopy, ctx, nextp1):
+ if ctx.files() and self._willbecomenoop(
+ memworkingcopy, ctx, nextp1
+ ):
# changeset is no longer necessary
self.replacemap[ctx.node()] = None
msg = _(b'became empty and was dropped')
--- a/tests/test-absorb.t Mon Jun 01 11:07:33 2020 +0200
+++ b/tests/test-absorb.t Mon Jun 01 20:57:14 2020 +0200
@@ -587,3 +587,21 @@
b | 0
2 files changed, 1 insertions(+), 0 deletions(-)
+
+ $ cd ..
+ $ hg init repo8
+ $ cd repo8
+ $ echo a1 > a
+ $ hg commit -m a -A a
+ $ hg commit -m empty --config ui.allowemptycommit=True
+ $ echo a2 > a
+ $ hg absorb --apply-changes --verbose | grep became
+ 0:ecf99a8d6699: 1 file(s) changed, became 2:7e3ccf8e2fa5
+ 1:97f72456ae0d: 1 file(s) changed, became 3:2df488325d6f
+ $ hg log -T '{rev} {desc}\n' -G --stat
+ @ 3 empty
+ |
+ o 2 a
+ a | 1 +
+ 1 files changed, 1 insertions(+), 0 deletions(-)
+