Re: [PATCH] rebase --preserve-merges keeps empty merge commits

Matthieu Moy [off-list ref] writes:

Phil Hord [off-list ref] writes:

quoted

Subject: [PATCH] rebase --preserve-merges keeps empty merge commits

I would rephrase it as

  rebase --preserve-merges: keep empty merge commits

we usually give orders in commit messages, not state facts (it's not
clear from the existing subject line whether keeping merge commit is the
new behavior or a bug that the commit tries to fix).

Thanks for giving a concise rationale on our use of imperative mood.

Phil, I think you meant to and forgot to sign-off; here is what I'll
queue.

Thanks.

-- >8 --
From: Phil Hord <redacted>
Date: Sat, 12 Jan 2013 15:46:01 -0500
Subject: [PATCH] rebase --preserve-merges: keep all merge commits including empty ones

Since 90e1818f9a  (git-rebase: add keep_empty flag, 2012-04-20)
'git rebase --preserve-merges' fails to preserve empty merge commits
unless --keep-empty is also specified.  Merge commits should be
preserved in order to preserve the structure of the rebased graph,
even if the merge commit does not introduce changes to the parent.

Teach rebase not to drop merge commits only because they are empty.

A special case which is not handled by this change is for a merge commit
whose parents are now the same commit because all the previous different
parents have been dropped as a result of this rebase or some previous
operation.

Signed-off-by: Phil Hord <redacted>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Junio C Hamano <redacted>
---
 git-rebase--interactive.sh | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 0c19b7c..2fed92f 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh

@@ -175,6 +175,11 @@ is_empty_commit() {
 	test "$tree" = "$ptree"
 }
 
+is_merge_commit()
+{
+	git rev-parse --verify --quiet "$1"^2 >/dev/null 2>&1
+}
+
 # Run command with GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL, and
 # GIT_AUTHOR_DATE exported from the current environment.
 do_with_author () {

@@ -796,7 +801,7 @@ git rev-list $merges_option --pretty=oneline --abbrev-commit \
 while read -r shortsha1 rest
 do
 
-	if test -z "$keep_empty" && is_empty_commit $shortsha1
+	if test -z "$keep_empty" && is_empty_commit $shortsha1 && ! is_merge_commit $shortsha1
 	then
 		comment_out="# "
 	else

-- 
1.8.1.1.338.g126d652