Bug report: "git-merge --ff" should fail if branches have diverged

Bug report: "git-merge --ff" should fail if branches have diverged

[Sean Gies]

Git developers, I have a small bug report:

When I specify the "--ff" option to git-merge, I expect it to perform a fast-forward merge or none at all. If the branches have diverged and a fast-forward cannot be done, I expect the command to fail. With git 1.7.6, if "git-merge -ff" cannot fast-forward, it falls back to creating the merge commit I did not want.

Thank you,
-Sean

Re: Bug report: "git-merge --ff" should fail if branches have diverged

[Junio C Hamano]

Sean Gies <Sean.Gies@imgtec.com> writes:

> When I specify the "--ff" option to git-merge, I expect it to perform a
> fast-forward merge or none at all.

That expectation needs to be adjusted with s/--ff/--ff-only/, I think.

The "--no-ff" option says "Never do fast-forward and always create extra
commit even when the side branch is a descendant", and the "--ff" option
is a way to countermand it, i.e. "It is ok to fast-forward this merge".

And there is another one "I do not want anything bug fast forward", and
that is spelled --ff-only.

[PATCH] Documentation/merge-options.txt: group "ff" related options together

[Junio C Hamano]

The --ff-only option was not described next to --ff and --no-ff options in
"git merge" documentation, even though these three are logically together,
describing one option that takes one of three values.

Also the description for '--ff' and '--no-ff' discussed what '--ff' means,
and mentioned '--no-ff' as if it were a side-note to '--ff'.

Make them into three top-level entries and list them together. This way,
it would be more clear that the user can choose one from these three.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

 * Perhaps a patch like this would be an improvement to make it easier to
   find the options.

 Documentation/merge-options.txt |   22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/Documentation/merge-options.txt b/Documentation/merge-options.txt
index f2f1d0f..0bcbe0a 100644
--- a/Documentation/merge-options.txt
+++ b/Documentation/merge-options.txt
@@ -24,13 +24,18 @@ updated behaviour, the environment variable `GIT_MERGE_AUTOEDIT` can be
 set to `no` at the beginning of them.
 
 --ff::
+	When the merge resolves as a fast-forward, only update the branch
+	pointer, without creating a merge commit.  This is the default
+	behavior.
+
 --no-ff::
-	Do not generate a merge commit if the merge resolved as
-	a fast-forward, only update the branch pointer. This is
-	the default behavior of git-merge.
-+
-With --no-ff Generate a merge commit even if the merge
-resolved as a fast-forward.
+	Create a merge commit even when the merge resolves as a
+	fast-forward.
+
+--ff-only::
+	Refuse to merge and exit with a non-zero status unless the
+	current `HEAD` is already up-to-date or the merge can be
+	resolved as a fast-forward.
 
 --log[=<n>]::
 --no-log::
@@ -65,11 +70,6 @@ merge.
 With --no-squash perform the merge and commit the result. This
 option can be used to override --squash.
 
---ff-only::
-	Refuse to merge and exit with a non-zero status unless the
-	current `HEAD` is already up-to-date or the merge can be
-	resolved as a fast-forward.
-
 -s <strategy>::
 --strategy=<strategy>::
 	Use the given merge strategy; can be supplied more than