How to create patches for a merge?

When I use "git format-patch", it doesn't seem to include merges. How
can I perform a merge and then e-mail it to someone as a set of
patches?

For example, let's say that I merge two branches and perform another
commit on top of the merge:

git init

echo "initial file" > test.txt
git add test.txt
git commit -m "Commit A"

git checkout -b foo master
echo "foo" > test.txt
git commit -a -m "Commit B"

git checkout -b bar master
echo "bar" > test.txt
git commit -a -m "Commit C"

git merge foo
echo "foobar" > test.txt
git commit -a -m "Commit M"

echo "2nd line" >> test.txt
git commit -a -m "Commit D"

This creates the following tree:

    B
  /   \
A       M - D
  \   /
    C

Now I try to checkout the initial commit and replay the above changes:

git checkout -b replay master
git format-patch --stdout master..bar | git am -3

This produces a merge conflict. In this scenario, "git format-patch
master..bar" only produces 3 patches, omitting "Commit M". How do I
deal with this?

-Geoffrey Lee

On Thu, Feb 18, 2010 at 03:40:07AM -0800, Geoffrey Lee wrote:

When I use "git format-patch", it doesn't seem to include merges. How
can I perform a merge and then e-mail it to someone as a set of
patches?

Is it important that it be patches, or simply that it go over email? In
the latter case, you can use "git bundle" to create a set of commits,
including merges, and send them to the remote.

-Peff

On Thu, Feb 18, 2010 at 12:37 PM, Jeff King [off-list ref] wrote:

On Thu, Feb 18, 2010 at 03:40:07AM -0800, Geoffrey Lee wrote:

quoted

When I use "git format-patch", it doesn't seem to include merges. How
can I perform a merge and then e-mail it to someone as a set of
patches?

Is it important that it be patches, or simply that it go over email? In
the latter case, you can use "git bundle" to create a set of commits,
including merges, and send them to the remote.

I was not aware of "git bundle". That does exactly what I need. Thanks!

-Geoffrey Lee

On Fri, Feb 19, 2010 at 02:25:14AM -0800, Geoffrey Lee wrote:

On Thu, Feb 18, 2010 at 12:37 PM, Jeff King [off-list ref] wrote:

quoted

On Thu, Feb 18, 2010 at 03:40:07AM -0800, Geoffrey Lee wrote:

quoted

When I use "git format-patch", it doesn't seem to include merges. How
can I perform a merge and then e-mail it to someone as a set of
patches?

Is it important that it be patches, or simply that it go over email? In
the latter case, you can use "git bundle" to create a set of commits,
including merges, and send them to the remote.

I was not aware of "git bundle". That does exactly what I need. Thanks!

Below is git-send-bdl, a small wrapper I use for git bundle. It creates
bundles only for the commits which are not already known to the origin and
mails them to a configured address. It requires mutt for sending emails (the
-m option is just for show).  It should probably use sendmail. But maybe
this is still useful as a reference.

Have fun,
Clemens
---

#!/bin/bash

usage ()
{
	echo "`basename $0`: [-t <address>] [-m <mailer>] [-r <remote>] [<repo>...]" >&2
	exit 1
}

if ! test -x `which getopt`
then
	echo "fatal: getopt required but not found" >&2
	exit 2
fi

OPT=`getopt -o et:m:r: -- "$@"`
code=$?
if test $code -gt 0
then
	usage
	exit 1
fi
eval set -- "$OPT"

mailer=${GIT_SEND_BDL_MAILER:-mutt}
remote=origin
addr=
edit=
while test "$1" != "--"
do
	case "$1" in
		-r) remote="$2"; shift;;
		-m) mailer="$2"; shift;;
		-t) addr="$addr $2"; shift;;
		-e) edit=YesPlease;;
		-h) usage;;
		*) echo "unkown option: $1" >&2; exit 2;;
	esac
	shift
done
shift

if test -z $addr
then
	addr="$GIT_SEND_BDL_TO"
fi

if test $# -eq 0
then
	cdup=`git rev-parse --show-cdup 2>/dev/null`
	if test $? -gt 0
	then
		echo "fatal: no repositories specified and none found" >&2
		usage
	fi
	set -- "$PWD/${cdup}"
fi

if test -z "$addr"
then
	echo "fatal: no recipients specified" >&2
	usage
fi

if ! test -x `which $mailer`
then
	echo "fatal: mailer not found: $mailer" >&2
	usage
fi

bundle=()
while test $# -gt 0
do
	path=$1
	shift
	cd $path
	name=`basename "$PWD"`
	echo " * $name"
	target=/tmp/${name}.git
	if ! git remote | grep -q "^$remote\$"
	then
		echo error: unknown remote: $remote >&2
		continue
	fi
	refs="--branches"
	remote_refs=`git show-ref | cut -f2 -d' ' | \
			grep ^refs/remotes/$remote/`
	if test -n "$remote_refs"
	then
		refs="$refs --not $remote_refs"
	fi
	refs="$refs --tags"
	git bundle create $target $refs
	cd - >/dev/null
	bundle[${#bundle[@]}]=$target
done

attachments=
for i in ${bundle[@]}
do
	if test -f $i
	then
		attachments="$attachments $i"
	fi
done

exec 3</dev/null
if test -n "$edit"
then
	exec 3<&0
fi
$mailer -s 'git bundles' -a $attachments -- $addr <&3
ret=$?
exec 3<&-
if test $ret -gt 0
then
	echo "fatal: mailer exited with status $ret" >&2
	exit 1
fi

rm -f ${bundle[@]}