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
`--fork-point' or `--no-fork-point' command line option to your `git
rebase' invocation.
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).
You would than need to use `git rebase <upstream>' to rebase. If you
configure an upstream it would seem logical to be able to run `git
rebase' without arguments. However doing so would trigger a different
kind of behavior. `git rebase <upstream>' behaves as if
`--no-fork-point' was supplied and without it behaves as if
`--fork-point' was supplied. This behavior can result in a loss of
commits and can surprise users. The following reproduction path exposes
this behavior:
git init reproduction
cd reproduction
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 --oneline
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 --oneline
03ad791 Second commit
411e6d4 First commit
Signed-off-by: Wesley Schwengle <wesleys@xxxxxxxxxxxxxxx>
---
builtin/rebase.c | 16 +++++++++-
t/t3431-rebase-fork-point.sh | 62 ++++++++++++++++++++++++++++++++++++
2 files changed, 77 insertions(+), 1 deletion(-)
diff --git a/builtin/rebase.c b/builtin/rebase.c
index 2108001600..ee7db9ba0c 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -1608,8 +1608,22 @@ 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(_(
+ "When \"git rebase\" is run without specifying <upstream> on the\n"
+ "command line, the current default is to use the fork-point\n"
+ "heuristics. This is expected to change in a future version\n"
+ "of Git, and you will have to explicitly give \"--fork-point\" from\n"
+ "the command line if you keep using the fork-point mode. You can\n"
+ "run \"git config rebase.forkpoint false\" to adopt the new default\n"
+ "in advance and that will also squelch the message.\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..908867ae0f 100755
--- a/t/t3431-rebase-fork-point.sh
+++ b/t/t3431-rebase-fork-point.sh
@@ -113,4 +113,66 @@ 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 rebase.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: When "git rebase" is run without specifying <upstream> on the
+ command line, the current default is to use the fork-point
+ heuristics. This is expected to change in a future version
+ of Git, and you will have to explicitly give "--fork-point" from
+ the command line if you keep using the fork-point mode. You can
+ run "git config rebase.forkpoint false" to adopt the new default
+ in advance and that will also squelch the message.
+
+ 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 &&
+ git config --add rebase.forkpoint true &&
+ git rebase >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 config --replace-all rebase.forkpoint false &&
+ git rebase >out 2>err &&
+ test_must_be_empty err &&
+ echo "Current branch foo is up to date." > expect &&
+ test_cmp out expect
+'
+
test_done
--
2.42.0.103.g5622fd1409.dirty
