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Re: [PATCH] pull: Allow pull to preserve merges when rebasing.

From
APAndres Perera <andres.p@zoho.com>
Date
Aug 11, 2013, 23:03 UTC
Message-ID
<CAPrKj1b=QTdqVH+JtukJrfEc=EqxWOEYE4YG7oSY7413uqdKfg@mail.gmail.com>
In-Reply-To
<1376256387-30974-1-git-send-email-stephen@exigencecorp.com>
hello, comments inline

On Sun, Aug 11, 2013 at 4:56 PM, Stephen Haberman <stephen@exigencecorp.com> wrote:

Show 140 quoted lines
> If a user is working on master, and has merged in their feature branch, but now
> has to "git pull" because master moved, with pull.rebase their feature branch
> will be flattened into master.
>
> This is because "git pull" currently does not know about rebase's preserve
> merges flag, which would avoid this behavior, as it would instead replay just
> the merge commit of the feature branch onto the new master, and not replay each
> individual commit in the feature branch.
>
> Add a --rebase=preserve option, which will pass along --preserve-merges to
> rebase.
>
> Also add 'preserve' to the allowed values for the pull.rebase config setting.
>
> Signed-off-by: Stephen Haberman <stephen@exigencecorp.com>
> ---
> Hi,
>
> This is v3 of my previous pull.rebase=preserve patch, previously discussed here:
>
> http://thread.gmane.org/gmane.comp.version-control.git/232061
> http://thread.gmane.org/gmane.comp.version-control.git/231909
>
> In this version, I addressed all of Eric's excellent feedback.
>
> I believe the patch is much better now, but would still appreciate more
> detailed feedback. In particular, I kind of made up how to handle and
> invalid "--rebase=invalid" value, and the resulting error message.
>
> Also, I changed git-pull's usage to include the -r parameter...not
> sure if that's okay or not. Let me know if not.
>
> Thanks!
>
>  Documentation/config.txt   |  8 +++++
>  Documentation/git-pull.txt | 18 +++++++----
>  git-pull.sh                | 42 ++++++++++++++++++++----
>  t/t5520-pull.sh            | 81 ++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 137 insertions(+), 12 deletions(-)
>
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index ec57a15..4c22be2 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -766,6 +766,10 @@ branch.<name>.rebase::
>         "git pull" is run. See "pull.rebase" for doing this in a non
>         branch-specific manner.
>  +
> +       When preserve, also pass `--preserve-merges` along to 'git rebase'
> +       so that locally committed merge commits will not be flattened
> +       by running 'git pull'.
> ++
>  *NOTE*: this is a possibly dangerous operation; do *not* use
>  it unless you understand the implications (see linkgit:git-rebase[1]
>  for details).
> @@ -1826,6 +1830,10 @@ pull.rebase::
>         pull" is run. See "branch.<name>.rebase" for setting this on a
>         per-branch basis.
>  +
> +       When preserve, also pass `--preserve-merges` along to 'git rebase'
> +       so that locally committed merge commits will not be flattened
> +       by running 'git pull'.
> ++
>  *NOTE*: this is a possibly dangerous operation; do *not* use
>  it unless you understand the implications (see linkgit:git-rebase[1]
>  for details).
> diff --git a/Documentation/git-pull.txt b/Documentation/git-pull.txt
> index 6ef8d59..beea10b 100644
> --- a/Documentation/git-pull.txt
> +++ b/Documentation/git-pull.txt
> @@ -102,12 +102,18 @@ include::merge-options.txt[]
>  :git-pull: 1
>
>  -r::
> ---rebase::
> -       Rebase the current branch on top of the upstream branch after
> -       fetching.  If there is a remote-tracking branch corresponding to
> -       the upstream branch and the upstream branch was rebased since last
> -       fetched, the rebase uses that information to avoid rebasing
> -       non-local changes.
> +--rebase[=false|true|preserve]::
> +       When true, rebase the current branch on top of the upstream
> +       branch after fetching. If there is a remote-tracking branch
> +       corresponding to the upstream branch and the upstream branch
> +       was rebased since last fetched, the rebase uses that information
> +       to avoid rebasing non-local changes.
> ++
> +When preserve, also rebase the current branch on top of the upstream
> +branch, but pass `--preserve-merges` along to `git rebase` so that
> +locally created merge commits will not be flattened.
> ++
> +When false, merge the current branch into the upstream branch.
>  +
>  See `pull.rebase`, `branch.<name>.rebase` and `branch.autosetuprebase` in
>  linkgit:git-config[1] if you want to make `git pull` always use
> diff --git a/git-pull.sh b/git-pull.sh
> index f0df41c..78ad52d 100755
> --- a/git-pull.sh
> +++ b/git-pull.sh
> @@ -4,7 +4,7 @@
>  #
>  # Fetch one or more remote refs and merge it/them into the current HEAD.
>
> -USAGE='[-n | --no-stat] [--[no-]commit] [--[no-]squash] [--[no-]ff] [-s strategy]... [<fetch-options>] <repo> <head>...'
> +USAGE='[-n | --no-stat] [--[no-]commit] [--[no-]squash] [--[no-]ff] [-r [true|false|preserve]] [-s strategy]... [<fetch-options>] <repo> <head>...'
>  LONG_USAGE='Fetch one or more remote refs and integrate it/them with the current HEAD.'
>  SUBDIRECTORY_OK=Yes
>  OPTIONS_SPEC=
> @@ -40,13 +40,13 @@ test -f "$GIT_DIR/MERGE_HEAD" && die_merge
>
>  strategy_args= diffstat= no_commit= squash= no_ff= ff_only=
>  log_arg= verbosity= progress= recurse_submodules= verify_signatures=
> -merge_args= edit=
> +merge_args= edit= rebase_args=
>  curr_branch=$(git symbolic-ref -q HEAD)
>  curr_branch_short="${curr_branch#refs/heads/}"
> -rebase=$(git config --bool branch.$curr_branch_short.rebase)
> +rebase=$(git config branch.$curr_branch_short.rebase)
>  if test -z "$rebase"
>  then
> -       rebase=$(git config --bool pull.rebase)
> +       rebase=$(git config pull.rebase)
>  fi
>  dry_run=
>  while :
> @@ -110,8 +110,27 @@ do
>                 esac
>                 merge_args="$merge_args$xx "
>                 ;;
> +       -r=*|--r=*|--re=*|--reb=*|--reba=*|--rebas=*|--rebase=*|\
>         -r|--r|--re|--reb|--reba|--rebas|--rebase)
> -               rebase=true
> +               case "$#,$1" in
> +               *,*=*)
> +                       rebase="${1#*=}"
> +                       ;;
> +               1,*)
> +                       rebase=true
> +                       ;;
> +               *)
Show 9 quoted lines
> +                       # if the user typed 'git pull -r . copy', don't treat '.'
> +                       # as an argument to -r
> +                       if test true = "$2" || test false = "$2" || test preserve = "$3"
> +                       then
> +                               rebase="$2"
> +                               shift
> +                       else
> +                               rebase=true
> +                       fi
1. i'm not sure why you are testing $3 == preserve. it looks like a typo
2. clearer than a string of yoda conditions:
case $2 in
true|false|preserve)
    rebase=$2
    shift
    ;;
*)
    rebase=true
    ;;
esac
Show 9 quoted lines
> +                       ;;
> +               esac
>                 ;;
>         --no-r|--no-re|--no-reb|--no-reba|--no-rebas|--no-rebase)
>                 rebase=false
> @@ -145,6 +164,17 @@ do
>         shift
>  done
>
Show 11 quoted lines
> +if test preserve = "$rebase"
> +then
> +       rebase=true
> +       rebase_args=--preserve-merges
> +elif test ! -z "$rebase" && test false != "$rebase" && test true != "$rebase"
> +then
> +       echo "Invalid value for --rebase, should be true, false, or preserve"
> +       usage
> +       exit 1
> +fi
> +
1. in the error message you say that rebase should be a trystate of
true, false, or preserve. why then do you allow $rebase == '' ?
2. clearer than a string of yoda conditions:
case $rebase in
preserve)
    rebase_args=--preserve-merges
    rebase=true
    ;;
true|false)
    ;;
*)
    echo "Invalid value for --rebase, should be true, false, or preserve" >&2
    usage
    exit 1
esac
Show 112 quoted lines
>  error_on_no_merge_candidates () {
>         exec >&2
>         for opt
> @@ -292,7 +322,7 @@ fi
>  merge_name=$(git fmt-merge-msg $log_arg <"$GIT_DIR/FETCH_HEAD") || exit
>  case "$rebase" in
>  true)
> -       eval="git-rebase $diffstat $strategy_args $merge_args $verbosity"
> +       eval="git-rebase $diffstat $strategy_args $merge_args $rebase_args $verbosity"
>         eval="$eval --onto $merge_head ${oldremoteref:-$merge_head}"
>         ;;
>  *)
> diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
> index ed4d9c8..8be0482 100755
> --- a/t/t5520-pull.sh
> +++ b/t/t5520-pull.sh
> @@ -148,6 +148,87 @@ test_expect_success 'branch.to-rebase.rebase should override pull.rebase' '
>         test new = $(git show HEAD:file2)
>  '
>
> +# add a feature branch, keep-merge, that is merged into master, so the
> +# test can try preserving the merge commit (or not) with various
> +# --rebase flags/pull.rebase settings.
> +test_expect_success 'preserve merge setup' '
> +       git reset --hard before-rebase &&
> +       git checkout -b keep-merge second^ &&
> +       test_commit file3 &&
> +       git checkout to-rebase &&
> +       git merge keep-merge &&
> +       git tag before-preserve-rebase
> +'
> +
> +test_expect_success 'pull.rebase=false create a new merge commit' '
> +       git reset --hard before-preserve-rebase &&
> +       test_config pull.rebase false &&
> +       git pull . copy &&
> +       test $(git rev-parse HEAD^1) = $(git rev-parse before-preserve-rebase) &&
> +       test $(git rev-parse HEAD^2) = $(git rev-parse copy) &&
> +       test file3 = $(git show HEAD:file3.t)
> +'
> +
> +test_expect_success 'pull.rebase=true flattens keep-merge' '
> +       git reset --hard before-preserve-rebase &&
> +       test_config pull.rebase true &&
> +       git pull . copy &&
> +       test $(git rev-parse HEAD^^) = $(git rev-parse copy) &&
> +       test file3 = $(git show HEAD:file3.t)
> +'
> +
> +test_expect_success 'pull.rebase=preserve rebases and merges keep-merge' '
> +       git reset --hard before-preserve-rebase &&
> +       test_config pull.rebase preserve &&
> +       git pull . copy &&
> +       test $(git rev-parse HEAD^^) = $(git rev-parse copy) &&
> +       test $(git rev-parse HEAD^2) = $(git rev-parse keep-merge)
> +'
> +
> +test_expect_success 'pull.rebase=invalid fails' '
> +       git reset --hard before-preserve-rebase &&
> +       test_config pull.rebase invalid &&
> +       ! git pull . copy
> +'
> +
> +test_expect_success '--rebase=false create a new merge commit' '
> +       git reset --hard before-preserve-rebase &&
> +       test_config pull.rebase true &&
> +       git pull --rebase=false . copy &&
> +       test $(git rev-parse HEAD^1) = $(git rev-parse before-preserve-rebase) &&
> +       test $(git rev-parse HEAD^2) = $(git rev-parse copy) &&
> +       test file3 = $(git show HEAD:file3.t)
> +'
> +
> +test_expect_success '--rebase=true rebases and flattens keep-merge' '
> +       git reset --hard before-preserve-rebase &&
> +       test_config pull.rebase preserve &&
> +       git pull --rebase=true . copy &&
> +       test $(git rev-parse HEAD^^) = $(git rev-parse copy) &&
> +       test file3 = $(git show HEAD:file3.t)
> +'
> +
> +test_expect_success '--rebase=preserve rebases and merges keep-merge' '
> +       git reset --hard before-preserve-rebase &&
> +       test_config pull.rebase true &&
> +       git pull --rebase=preserve . copy &&
> +       test $(git rev-parse HEAD^^) = $(git rev-parse copy) &&
> +       test $(git rev-parse HEAD^2) = $(git rev-parse keep-merge)
> +'
> +
> +test_expect_success '--rebase=invalid fails' '
> +       git reset --hard before-preserve-rebase &&
> +       ! git pull --rebase=invalid . copy
> +'
> +
> +test_expect_success '--rebase overrides pull.rebase=preserve and flattens keep-merge' '
> +       git reset --hard before-preserve-rebase &&
> +       test_config pull.rebase preserve &&
> +       git pull --rebase . copy &&
> +       test $(git rev-parse HEAD^^) = $(git rev-parse copy) &&
> +       test file3 = $(git show HEAD:file3.t)
> +'
> +
>  test_expect_success '--rebase with rebased upstream' '
>
>         git remote add -f me . &&
> --
> 1.8.1.2
>
> --
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Previous: Stephen HabermanNext: Stephen Haberman
Message 2 of 8 in “pull: Allow pull to preserve merges when rebasing.”
  1. pull: Allow pull to preserve merges when rebasing.Stephen Haberman, Aug 11, 2013
  2. Andres PereraAug 11, 2013
  3. Stephen HabermanAug 11, 2013
  4. Andres PereraAug 11, 2013
  5. Stephen HabermanAug 11, 2013
  6. Junio C HamanoAug 12, 2013
  7. Junio C HamanoAug 12, 2013
  8. Stephen HabermanAug 12, 2013

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