threads / discuss / 19435

git merge remote branch says "Merge commit ..."?

Subject: git merge remote branch says "Merge commit ..."?

## tl;dr

10 messages between May 21, 2009 and May 25, 2009.

replies: 9people: 5as markdown or json

skillzero@gmail.com· May 21, 2009, 19:50 UTC · lore

I noticed that if I do 'git merge origin/branch' that the log message says (using --log):

Merge commit 'origin/branch'
   * commit 'origin/branch':
     Fixed some bug.
If I do the same thing from a local tracking branch of origin/branch, it says:
Merge branch 'branch'
   * branch:
     Fixed some bug.

Is it expected that it say "commit" instead of "branch" when the branch is not a local tracking branch? I sometimes merge from remote branches when I don't need to do anything with that branch locally (e.g. I already did the work on another computer and I'm just merging the result into my test machine before I push to the shared server).

Jeff King· May 22, 2009, 07:49 UTC · re: skillzero@gmail.com · lore

Re: git merge remote branch says "Merge commit ..."?

On Thu, May 21, 2009 at 12:50:48PM -0700, skillzero@gmail.com wrote:
Show 20 quoted lines
> I noticed that if I do 'git merge origin/branch' that the log message
> says (using --log):
> 
> Merge commit 'origin/branch'
> 
>    * commit 'origin/branch':
>      Fixed some bug.
> 
> If I do the same thing from a local tracking branch of origin/branch, it says:
> 
> Merge branch 'branch'
> 
>    * branch:
>      Fixed some bug.
> 
> Is it expected that it say "commit" instead of "branch" when the
> branch is not a local tracking branch? I sometimes merge from remote
> branches when I don't need to do anything with that branch locally
> (e.g. I already did the work on another computer and I'm just merging
> the result into my test machine before I push to the shared server).

I think doing a "git merge origin/master" is perfectly normal for some workflows. For example:

  $ git fetch origin ;# grab it
  $ gitk origin/master...master ;# check if it is good to merge
  $ git merge origin/master ;# and merge it

The final step _could_ be a pull, but there is no point in repeating the fetch (which might be costly).

There is already code in fmt-merge-msg to handle remote branches; it looks like we just need to signal that code the same way "git fetch" would. Maybe something like the patch below (which is really just a cut-and-paste of the code directly above it to special-case real branches).

It gives a sensible "Merge" line but you end up with
  * remote branch 'origin/master':
    ...
instead of
  * origin/master:
    ...

So it probably requires some deeper digging into what git-fetch is doing, and to emulate that (I am pretty ignorant of this part of the code).

---
diff --git a/builtin-merge.c b/builtin-merge.c
index 0b58e5e..a74a4d0 100644
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@ -378,6 +378,17 @@ static void merge_name(const char *remote, struct strbuf *msg)
 		goto cleanup;
 	}
 
+	strbuf_setlen(&buf, 0);
+	strbuf_addstr(&buf, "refs/remotes/");
+	strbuf_addstr(&buf, remote);
+	resolve_ref(buf.buf, branch_head, 0, 0);
+
+	if (!hashcmp(remote_head->sha1, branch_head)) {
+		strbuf_addf(msg, "%s\t\tremote branch '%s'\n",
+				sha1_to_hex(branch_head), remote);
+		goto cleanup;
+	}
+
 	/* See if remote matches <name>^^^.. or <name>~<number> */
 	for (len = 0, ptr = remote + strlen(remote);
 	     remote < ptr && ptr[-1] == '^';
Eric Raible· May 22, 2009, 17:29 UTC · re: Jeff King · lore

Re: git merge remote branch says "Merge commit ..."?

Jeff King <peff <at> peff.net> writes:
Show 9 quoted lines
> I think doing a "git merge origin/master" is perfectly normal for some
> workflows. For example:
> 
>   $ git fetch origin ;# grab it
>   $ gitk origin/master...master ;# check if it is good to merge
>   $ git merge origin/master ;# and merge it
> 
> The final step _could_ be a pull, but there is no point in repeating the
> fetch (which might be costly).

My understanding is that if the objects already exist locally then this is not going to be costly at all. The negotiation of what is needed is cheap, isn't it?

- Eric
Jeff King· May 22, 2009, 17:54 UTC · re: Eric Raible · lore

Re: git merge remote branch says "Merge commit ..."?

On Fri, May 22, 2009 at 05:29:41PM +0000, Eric Raible wrote:
Show 15 quoted lines
> Jeff King <peff <at> peff.net> writes:
> 
> > I think doing a "git merge origin/master" is perfectly normal for some
> > workflows. For example:
> > 
> >   $ git fetch origin ;# grab it
> >   $ gitk origin/master...master ;# check if it is good to merge
> >   $ git merge origin/master ;# and merge it
> > 
> > The final step _could_ be a pull, but there is no point in repeating the
> > fetch (which might be costly).
> 
> My understanding is that if the objects already exist
> locally then this is not going to be costly at all.
> The negotiation of what is needed is cheap, isn't it?

No, it is not terribly expensive. But you do have to talk to the server, which may mean making an ssh connection, or the server may be overloaded and slow. So it can take a few seconds instead of a few microseconds.

There is actually another reason not to pull, though: you just inspected what is in origin/master, so that is what you are expecting to merge. If there is new stuff on the remote, you probably don't want to merge it without similarly inspecting it.

-Peff
Eric Raible· May 22, 2009, 18:08 UTC · re: Jeff King · lore

Re: git merge remote branch says

Jeff King <peff <at> peff.net> writes:
Show 28 quoted lines
> On Fri, May 22, 2009 at 05:29:41PM +0000, Eric Raible wrote:
> 
> > Jeff King <peff <at> peff.net> writes:
> > 
> > > I think doing a "git merge origin/master" is perfectly normal for some
> > > workflows. For example:
> > > 
> > >   $ git fetch origin ;# grab it
> > >   $ gitk origin/master...master ;# check if it is good to merge
> > >   $ git merge origin/master ;# and merge it
> > > 
> > > The final step _could_ be a pull, but there is no point in repeating the
> > > fetch (which might be costly).
> > 
> > My understanding is that if the objects already exist
> > locally then this is not going to be costly at all.
> > The negotiation of what is needed is cheap, isn't it?
> 
> No, it is not terribly expensive. But you do have to talk to the server,
> which may mean making an ssh connection, or the server may be overloaded
> and slow. So it can take a few seconds instead of a few microseconds.
> 
> There is actually another reason not to pull, though: you just inspected
> what is in origin/master, so that is what you are expecting to merge.
> If there is new stuff on the remote, you probably don't want to merge it
> without similarly inspecting it.
> 
> -Peff

I wasn't trying to argue that a pull would be a good idea, but more that it's not that expensive because of the content-addressable nature of git's object store.

And saying that is "might be costly" could be misleading to people who haven't groked how a commit is a commit is a commit.

- Eric
Jeff King· May 22, 2009, 18:10 UTC · re: Eric Raible · lore

Re: git merge remote branch says

On Fri, May 22, 2009 at 06:08:41PM +0000, Eric Raible wrote:
Show 6 quoted lines
> I wasn't trying to argue that a pull would be a good idea, but more
> that it's not that expensive because of the content-addressable
> nature of git's object store.
> 
> And saying that is "might be costly" could be misleading to people
> who haven't groked how a commit is a commit is a commit.

OK, then I agree with you. My "costly" was just "I don't want to touch the network if I don't have to".

-Peff
Johannes Sixt· May 22, 2009, 18:30 UTC · re: Jeff King · lore

Re: git merge remote branch says "Merge commit ..."?

On Freitag, 22. Mai 2009, Jeff King wrote:
> No, it is not terribly expensive. But you do have to talk to the server,
> which may mean making an ssh connection, or the server may be overloaded
> and slow. So it can take a few seconds instead of a few microseconds.

It's certainly doable without a remote connection with some digging in the configuration.

Git-gui has some magic to find out the remote when you request to merge a remote tracking branch. That is, even though you clickety-click through to do the equivalent of 'git merge origin/master', it comes up with a merge message that is the same as if you had said 'git pull origin master' on the command line. It doesn't need a connection to do that.

-- Hannes
Jeff King· May 23, 2009, 09:17 UTC · re: Johannes Sixt · lore

Re: git merge remote branch says "Merge commit ..."?

On Fri, May 22, 2009 at 08:30:34PM +0200, Johannes Sixt wrote:
Show 7 quoted lines
> On Freitag, 22. Mai 2009, Jeff King wrote:
> > No, it is not terribly expensive. But you do have to talk to the server,
> > which may mean making an ssh connection, or the server may be overloaded
> > and slow. So it can take a few seconds instead of a few microseconds.
> 
> It's certainly doable without a remote connection with some digging in the 
> configuration.
Er, I think we have gotten a bit off track.

Yes, it's clearly possible to pretend you fetched but not actually do so when doing "git merge origin/master" (and the patch I posted does something close, but doesn't fill in the actual remote name; you just get "remote branch origin/master").

All the other part of this thread was just me claiming that:
  git fetch origin
  git log origin...
  git merge origin

Is a totally valid workflow, and that the answer should not be "those people should just run pull".

Show 5 quoted lines
> Git-gui has some magic to find out the remote when you request to merge a 
> remote tracking branch. That is, even though you clickety-click through to do 
> the equivalent of 'git merge origin/master', it comes up with a merge message 
> that is the same as if you had said 'git pull origin master' on the command 
> line. It doesn't need a connection to do that.

Right. We could probably use similar logic in "git merge". I'm not sure if it is worth the trouble to end up with "Merge branch 'master' of origin" instead of "Merge remote branch 'origin/master'".

-Peff
Junio C Hamano· May 23, 2009, 09:26 UTC · re: Jeff King · lore

Re: git merge remote branch says "Merge commit ..."?

Jeff King <peff@peff.net> writes:
> Right. We could probably use similar logic in "git merge". I'm not sure
> if it is worth the trouble to end up with "Merge branch 'master' of
> origin" instead of "Merge remote branch 'origin/master'".
I do not think it is worth doing that to lose information, either.
Jeff King· May 25, 2009, 09:44 UTC · re: Junio C Hamano · lore

Re: git merge remote branch says "Merge commit ..."?

On Sat, May 23, 2009 at 02:26:58AM -0700, Junio C Hamano wrote:
Show 5 quoted lines
> > Right. We could probably use similar logic in "git merge". I'm not sure
> > if it is worth the trouble to end up with "Merge branch 'master' of
> > origin" instead of "Merge remote branch 'origin/master'".
> 
> I do not think it is worth doing that to lose information, either.
So would you be in favor of this patch?
-- >8 --
Subject: [PATCH] merge: indicate remote tracking branches in merge message

Previously when merging directly from a local tracking branch like:

  git merge origin/master
The merge message said:
   Merge commit 'origin/master'
     * commit 'origin/master':
       ...
Instead, let's be more explicit about what we are merging:
   Merge remote branch 'origin/master'
     * origin/master:
       ...

We accomplish this by recognizing remote tracking branches in git-merge when we build the simulated FETCH_HEAD output that we feed to fmt-merge-msg.

Signed-off-by: Jeff King <peff@peff.net>
---
This is not quite identical to the one I posted before; it adds the
magic "of ." at the end of the line, which matches how regular
non-remote branches are handled.
 builtin-merge.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/builtin-merge.c b/builtin-merge.c
index 0b58e5e..b6f60e9 100644
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@ -378,6 +378,17 @@ static void merge_name(const char *remote, struct strbuf *msg)
 		goto cleanup;
 	}
 
+	strbuf_setlen(&buf, 0);
+	strbuf_addstr(&buf, "refs/remotes/");
+	strbuf_addstr(&buf, remote);
+	resolve_ref(buf.buf, branch_head, 0, 0);
+
+	if (!hashcmp(remote_head->sha1, branch_head)) {
+		strbuf_addf(msg, "%s\t\tremote branch '%s' of .\n",
+				sha1_to_hex(branch_head), remote);
+		goto cleanup;
+	}
+
 	/* See if remote matches <name>^^^.. or <name>~<number> */
 	for (len = 0, ptr = remote + strlen(remote);
 	     remote < ptr && ptr[-1] == '^';

-- 
1.6.3.1.250.g01b8b.dirty

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