When commit d1e894c6d7 (Document `rebase.forkpoint` in rebase man page,
2021-09-16) was submitted there was a discussion on if the forkpoint
behaviour of `git rebase' was sane. In my experience this wasn't sane.
Git rebase doesn't work if you don't have an upstream branch configured
(or something that says `merge = refs/heads/master' in the git config).
The behaviour of `git rebase' was that if you supply an upstream on the
command line that it behaves as if `--no-forkpoint' was supplied and if
you don't supply an upstream, it behaves as if `--forkpoint' was
supplied. This can result in a loss of commits if you don't know that
and if you don't know about `git reflog' or have other copies of your
changes. This can be seen with the following reproduction path:
mkdir reproduction
cd reproduction
git init .
echo "commit a" > file.txt
git add file.txt
git commit -m "First commit" file.txt
echo "commit b" >> file.txt
git commit -m "Second commit" file.txt
git switch -c foo
echo "commit c" >> file.txt"
git commit -m "Third commit" file.txt
git branch --set-upstream-to=master
git status
On branch foo
Your branch is ahead of 'master' by 1 commit.
git switch master
git merge foo
git reset --hard HEAD^
git switch foo
Switched to branch 'foo'
Your branch is ahead of 'master' by 1 commit.
git log --format='%C(yellow)%h%Creset %Cgreen%s%Creset'
5f427e3 Third commit
03ad791 Second commit
411e6d4 First commit
git rebase
git status
On branch foo
Your branch is up to date with 'master'.
git log --format='%C(yellow)%h%Creset %Cgreen%s%Creset'
03ad791 Second commit
411e6d4 First commit
This patch adds a warning where it will indicate that `rebase.forkpoint'
must be set in the git configuration and/or that you can supply a
`--forkpoint' or `--no-forkpoint' command line option to your `git
rebase' invocation.
Signed-off-by: Wesley Schwengle <wesleys@xxxxxxxxxxxxxxx>
---
builtin/rebase.c | 15 ++++++++++-
t/t3431-rebase-fork-point.sh | 50 ++++++++++++++++++++++++++++++++++++
2 files changed, 64 insertions(+), 1 deletion(-)
diff --git a/builtin/rebase.c b/builtin/rebase.c
index 50cb85751f..41dd9b6256 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -1604,8 +1604,21 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
NULL);
if (!options.upstream_name)
error_on_missing_default_upstream();
- if (options.fork_point < 0)
+ if (options.fork_point < 0) {
+ warning(_(
+ "Rebasing without specifying a forkpoint is discouraged. You can squelch\n"
+ "this message by running one of the following commands something before your\n"
+ "next rebase:\n"
+ "\n"
+ " git config rebase.forkpoint = false # This will become the new default\n"
+ " git config rebase.forkpoint = true # This is the old default\n"
+ "\n"
+ "You can replace \"git config\" with \"git config --global\" to set a default\n"
+ "preference for all repositories. You can also pass --no-fork-point, --fork-point\n"
+ "on the command line to override the configured default per invocation.\n"
+ ));
options.fork_point = 1;
+ }
} else {
options.upstream_name = argv[0];
argc--;
diff --git a/t/t3431-rebase-fork-point.sh b/t/t3431-rebase-fork-point.sh
index 4bfc779bb8..a583ca6228 100755
--- a/t/t3431-rebase-fork-point.sh
+++ b/t/t3431-rebase-fork-point.sh
@@ -113,4 +113,54 @@ test_expect_success 'rebase.forkPoint set to true and --root given' '
git rebase --root
'
+# The use of the diff -qw is because there is some kind of whitespace character
+# magic going on which probably has to do with the tabs. It only occurs when we
+# check STDERR
+test_expect_success 'rebase without forkpoint' '
+ git init rebase-forkpoint &&
+ cd rebase-forkpoint &&
+ git status >/tmp/foo &&
+ echo "commit a" > file.txt &&
+ git add file.txt &&
+ git commit -m "First commit" file.txt &&
+ echo "commit b" >> file.txt &&
+ git commit -m "Second commit" file.txt &&
+ git switch -c foo &&
+ echo "commit c" >> file.txt &&
+ git commit -m "Third commit" file.txt &&
+ git branch --set-upstream-to=main &&
+ git switch main &&
+ git merge foo &&
+ git reset --hard HEAD^ &&
+ git switch foo &&
+ commit=$(git log -n1 --format="%h") &&
+ git rebase >out 2>err &&
+ test_must_be_empty out &&
+ cat <<-\OEF > expect &&
+ warning: Rebasing without specifying a forkpoint is discouraged. You can squelch
+ this message by running one of the following commands something before your
+ next rebase:
+
+ git config rebase.forkpoint = false # This will become the new default
+ git config rebase.forkpoint = true # This is the old default
+
+ You can replace "git config" with "git config --global" to set a default
+ preference for all repositories. You can also pass --no-fork-point, --fork-point
+ on the command line to override the configured default per invocation.
+
+ Successfully rebased and updated refs/heads/foo.
+ OEF
+ diff -qw expect err &&
+ git reset --hard $commit &&
+ git rebase --fork-point >out 2>err &&
+ test_must_be_empty out &&
+ echo "Successfully rebased and updated refs/heads/foo." > expect &&
+ diff -qw expect err &&
+ git reset --hard $commit &&
+ git rebase --no-fork-point >out 2>err &&
+ test_must_be_empty err &&
+ echo "Current branch foo is up to date." > expect &&
+ test_cmp out expect
+'
+
test_done
--
2.42.0.rc2.7.gf9972720e9.dirty
