# How to create patches for a merge? 5 messages from 2010-02-18 to 2010-02-20. Participants: Geoffrey Lee, Junio C Hamano, Jeff King, Clemens Buchacher. Thread: https://gitlist.dev/t/22709 ## Geoffrey Lee, 2010-02-18 11:40 Subject: How to create patches for a merge? Message-ID: <83d7aaa41002180340p2f9b7241h9c220b84ec5dd1d@mail.gmail.com> URL: https://gitlist.dev/e/83d7aaa41002180340p2f9b7241h9c220b84ec5dd1d%40mail.gmail.com ``` 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 ``` ## Junio C Hamano, 2010-02-18 18:10 Subject: Re: How to create patches for a merge? Message-ID: <7veikifm9m.fsf@alter.siamese.dyndns.org> URL: https://gitlist.dev/e/7veikifm9m.fsf%40alter.siamese.dyndns.org In-Reply-To: <83d7aaa41002180340p2f9b7241h9c220b84ec5dd1d@mail.gmail.com> ``` Geoffrey Lee writes: > 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? There is no provision for communicating how a conflict is resolved over patches. The answer to your "How do I deal with *this*" question would be "It is up to you.", if your "*this*" is "I want to communicate this as a patch". The steps to deal with "*this*" may go like this: - Think what shape of patch you want to see in order to convey what "Commit M" did to the recipient of your patch series. First, try to construct it, by hand if necessary, as a design of such a feature. - How would a recipient "apply" such a patch? As commonly used "patch" implementations, including "git apply", may not be able to read the above format, and they would certainly not create a merge commit, so you need to design the recieving side as well. - Then implement them ;-) The best I think of offhand to reproduce B---M---D / / A---C might go like this: (1) Emit diff between (A,B) as usual; (2) Emit diff between (A,C) as usual, but with additional information usually not found in regular patches to help recipient that this should be applied to the same commit as (1) is applied to; (3) Emit diff between (B,M) and (C,M), but make sure that they won't be seen as a patch to be applied by ordinary "patch" programs to avoid mistakes at the recipient side. Include some way to tell the recipient that these two "patches" need to be applied to the results of applying (1) and (2), and that the result needs to be recorded as a merge between them. (4) Emit D as usual; Then the recipient would start from something that resembles A (call it X) and do the following: (5) Apply (1); call that result B' B' / X (6) Apply (2), following that additional insn to apply the patch to the base of (5); call that result C' B' / X---C' (7) Apply (B,M) half of (3) to B' and call it M' B'..M' / X---C' (8) Apply (C,M) half of (3) to C' and call it M" B'--M' M" / . X------C' (9) If M' and M" do not match (which can happen when A and X are majorly different), merge them using X as their common ancestor, and resolve conflicts as necessary, and call the result M'". If M' and M" do match, be happy and call either of them M'". B'..M'..M'" B'..M'" / . or / . / M" X---C' / . X-------C' (10) Record M'" as children of B' and C'. B'--M'" / / X---C' (11) Apply (4); call that result D' B'--M'"-D' / / X---C' and you are done. ``` ## Jeff King, 2010-02-18 20:37 Subject: Re: How to create patches for a merge? Message-ID: <20100218203738.GB8110@coredump.intra.peff.net> URL: https://gitlist.dev/e/20100218203738.GB8110%40coredump.intra.peff.net In-Reply-To: <83d7aaa41002180340p2f9b7241h9c220b84ec5dd1d@mail.gmail.com> ``` 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 ``` ## Geoffrey Lee, 2010-02-19 10:25 Subject: Re: How to create patches for a merge? Message-ID: <83d7aaa41002190225o3255248re1581a86e1346f28@mail.gmail.com> URL: https://gitlist.dev/e/83d7aaa41002190225o3255248re1581a86e1346f28%40mail.gmail.com In-Reply-To: <20100218203738.GB8110@coredump.intra.peff.net> ``` On Thu, Feb 18, 2010 at 12:37 PM, Jeff King wrote: > 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. I was not aware of "git bundle". That does exactly what I need. Thanks! -Geoffrey Lee ``` ## Clemens Buchacher, 2010-02-20 17:39 Subject: Re: How to create patches for a merge? Message-ID: <20100220173910.GA4095@localhost> URL: https://gitlist.dev/e/20100220173910.GA4095%40localhost In-Reply-To: <83d7aaa41002190225o3255248re1581a86e1346f28@mail.gmail.com> ``` On Fri, Feb 19, 2010 at 02:25:14AM -0800, Geoffrey Lee wrote: > On Thu, Feb 18, 2010 at 12:37 PM, Jeff King wrote: > > 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. > > 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 $0`: [-t
] [-m ] [-r ] [...]" >&2 exit 1 } if ! test -x `which getopt` then echo "fatal: getopt required but not found" >&2 exit 2 fi OPT=`getopt -o et:m:r: -- "$@"` 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&2 exit 1 fi rm -f ${bundle[@]} ```