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[PATCH v2] pull: require choice between rebase/merge on non-fast-forward pull

From
Junio C Hamano <gitster@pobox.com>
Date
Jul 18, 2013, 19:35 UTC
Message-ID
<7vvc471x1s.fsf_-_@alter.siamese.dyndns.org>
In-Reply-To
<7vmwpj3g0l.fsf@alter.siamese.dyndns.org>

Because it is so easy to let Git handle automatically a trivial merge with "git pull", a person who is new to Git may not realize that the project s/he is interacting with may prefer a "rebase" workflow.

Add a safety valve to fail "git pull" that does not explicitly specify what branch from which repository to integrate your history with, when it is neither a fast-forward or "already up-to-date", until/unless the user expressed her preference between the two ways of integration.

This can be an irritating backward incompatible change for old timers, but it can be a one time irritation by doing:

    git config --global pull.rebase false
once to say "I will always --merge", and they'd not even notice.
    http://thread.gmane.org/gmane.comp.version-control.git/225146/focus=225326
for a full discussion.
Helped-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 * This time with updates to the documentation and the test suite.
 Documentation/git-pull.txt |  9 ++++++++
 git-pull.sh                | 40 +++++++++++++++++++++++++++++++++++-
 t/t5520-pull.sh            | 51 ++++++++++++++++++++++++++++++++++++++++++++++
 t/t5524-pull-msg.sh        |  2 +-
 4 files changed, 100 insertions(+), 2 deletions(-)
diff --git a/Documentation/git-pull.txt b/Documentation/git-pull.txt
index 24ab07a..86f5170 100644
--- a/Documentation/git-pull.txt
+++ b/Documentation/git-pull.txt
@@ -97,6 +97,14 @@ must be given before the options meant for 'git fetch'.
 Options related to merging
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+When `git pull` that does not explicitly specify what branch from
+which repository is to be integrated with your history on the
+command line, recent Git will refuse to work until you specify how
+that integration should happen, either with a command line option
+(`--merge` or `--rebase`) or a configuration variable (`pull.rebase`
+or `branch.<name>.rebase`, which is the same as `--merge`
+(`--rebase`) when set to `false` (`true`) respectively.
+
 include::merge-options.txt[]
 
 :git-pull: 1
@@ -119,6 +127,7 @@ It rewrites history, which does not bode well when you
 published that history already.  Do *not* use this option
 unless you have read linkgit:git-rebase[1] carefully.
 
+--merge::
 --no-rebase::
 	Override earlier --rebase.
 
diff --git a/git-pull.sh b/git-pull.sh
index 638aabb..88c198f 100755
--- a/git-pull.sh
+++ b/git-pull.sh
@@ -41,13 +41,21 @@ test -f "$GIT_DIR/MERGE_HEAD" && die_merge
 strategy_args= diffstat= no_commit= squash= no_ff= ff_only=
 log_arg= verbosity= progress= recurse_submodules= verify_signatures=
 merge_args= edit=
+
 curr_branch=$(git symbolic-ref -q HEAD)
 curr_branch_short="${curr_branch#refs/heads/}"
+
+# See if we are configured to rebase by default.
+# The value $rebase is, throughout the main part of the code:
+#    (empty) - the user did not have any preference
+#    true    - the user told us to integrate by rebasing
+#    false   - the user told us to integrate by merging
 rebase=$(git config --bool branch.$curr_branch_short.rebase)
 if test -z "$rebase"
 then
 	rebase=$(git config --bool pull.rebase)
 fi
+
 dry_run=
 while :
 do
@@ -113,7 +121,8 @@ do
 	-r|--r|--re|--reb|--reba|--rebas|--rebase)
 		rebase=true
 		;;
-	--no-r|--no-re|--no-reb|--no-reba|--no-rebas|--no-rebase)
+	--no-r|--no-re|--no-reb|--no-reba|--no-rebas|--no-rebase|\
+	-m|--m|--me|--mer|--merg|--merge)
 		rebase=false
 		;;
 	--recurse-submodules)
@@ -219,6 +228,7 @@ test true = "$rebase" && {
 		fi
 	done
 }
+
 orig_head=$(git rev-parse -q --verify HEAD)
 git fetch $verbosity $progress $dry_run $recurse_submodules --update-head-ok "$@" || exit 1
 test -z "$dry_run" || exit 0
@@ -264,6 +274,34 @@ case "$merge_head" in
 		die "$(gettext "Cannot rebase onto multiple branches")"
 	fi
 	;;
+*)
+	# integrating with a single other history; be careful not to
+	# trigger this check when we will say "fast-forward" or "already
+	# up-to-date".
+	merge_head=${merge_head% }
+	if test -z "$rebase$no_ff$ff_only${squash#--no-squash}" &&
+		test -n "$orig_head" &&
+		test $# = 0 &&
+		! git merge-base --is-ancestor "$orig_head" "$merge_head" &&
+		! git merge-base --is-ancestor "$merge_head" "$orig_head"
+	then
+echo >&2 "orig-head was $orig_head"
+echo >&2 "merge-head is $merge_head"
+git show >&2 --oneline -s "$orig_head" "$merge_head"
+
+		die "The pull does not fast-forward; please specify
+if you want to merge or rebase.
+
+Use either
+
+    git pull --rebase
+    git pull --merge
+
+You can also use 'git config pull.rebase true' (if you want --rebase) or
+'git config pull.rebase false' (if you want --merge) to set this once for
+this project and forget about it."
+	fi
+	;;
 esac
 
 if test -z "$orig_head"
diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
index 6af6c63..1e91eca 100755
--- a/t/t5520-pull.sh
+++ b/t/t5520-pull.sh
@@ -255,4 +255,55 @@ test_expect_success 'git pull --rebase against local branch' '
 	test file = "$(cat file2)"
 '
 
+test_expect_success 'git pull that does not say how to integrate' '
+	git checkout -b other master^1 &&
+	>new &&
+	git add new &&
+	git commit -m "add new file" &&
+
+	git checkout -b test-to-integrate master &&
+
+	test_config branch.test-to-integrate.remote . &&
+	test_config branch.test-to-integrate.merge other &&
+
+	# need real integration
+	test_must_fail git pull &&
+	git reset --hard master &&
+
+
+	# configuration is explicit enough
+	for how in false true
+	do
+		test_config pull.rebase $how &&
+		git pull &&
+		git reset --hard master || break
+	done &&
+
+	# per branch configuration is explicit enough
+	test_unconfig pull.rebase &&
+	for how in false true
+	do
+		test_config branch.test-to-integrate.rebase $how &&
+		git pull &&
+		git reset --hard master || break
+	done &&
+
+	test_unconfig pull.rebase &&
+	test_unconfig branch.test-to-integrate &&
+
+	# already up to date
+	git reset --hard master &&
+	git branch -f other master^1
+	git pull &&
+
+	# fast forward
+	git reset --hard master &&
+	git checkout -B other master &&
+	>new &&
+	git add new &&
+	git commit -m "add new file" &&
+	git checkout -B test-to-integrate master &&
+	git pull
+'
+
 test_done
diff --git a/t/t5524-pull-msg.sh b/t/t5524-pull-msg.sh
index 8cccecc..660714b 100755
--- a/t/t5524-pull-msg.sh
+++ b/t/t5524-pull-msg.sh
@@ -25,7 +25,7 @@ test_expect_success setup '
 test_expect_success pull '
 (
 	cd cloned &&
-	git pull --log &&
+	git pull --log --merge &&
 	git log -2 &&
 	git cat-file commit HEAD >result &&
 	grep Dollar result

-- 
1.8.3.3-992-gf0e5e44
Previous: Junio C HamanoNext: Eric Sunshine
Message 53 of 69 in “first parent, commit graph layout, and pull merge direction”
  1. Andreas KreyMay 22, 2013
  2. Junio C HamanoMay 22, 2013
  3. Andreas KreyMay 23, 2013
  4. John SzakmeisterMay 23, 2013
  5. Jeremy RosenMay 23, 2013
  6. Andreas KreyMay 23, 2013
  7. John KeepingMay 23, 2013
  8. Junio C HamanoMay 23, 2013
  9. John KeepingMay 23, 2013
  10. Junio C HamanoMay 23, 2013
  11. John KeepingMay 23, 2013
  12. Felipe ContrerasMay 23, 2013
  13. Junio C HamanoMay 23, 2013
  14. Felipe ContrerasMay 23, 2013
  15. Junio C HamanoMay 23, 2013
  16. Felipe ContrerasMay 23, 2013
  17. Junio C HamanoMay 23, 2013
  18. Felipe ContrerasMay 23, 2013
  19. John KeepingMay 24, 2013
  20. John SzakmeisterMay 24, 2013
  21. Linus TorvaldsMay 24, 2013
  22. Junio C HamanoMay 24, 2013
  23. Linus TorvaldsMay 24, 2013
  24. Felipe ContrerasMay 24, 2013
  25. Felipe ContrerasMay 24, 2013
  26. Junio C HamanoMay 24, 2013
  27. Philip OakleyMay 24, 2013
  28. pull: require choice between rebase/merge on non-fast-forward pullJunio C Hamano, Jun 27, 2013
  29. W. Trevor KingJun 27, 2013
  30. Junio C HamanoJun 27, 2013
  31. W. Trevor KingJun 28, 2013
  32. Matthieu MoyJun 28, 2013
  33. W. Trevor KingJun 28, 2013
  34. Matthieu MoyJun 28, 2013
  35. W. Trevor KingJun 28, 2013
  36. Fredrik GustafssonJun 27, 2013
  37. Junio C HamanoJun 27, 2013
  38. W. Trevor KingJun 27, 2013
  39. Junio C HamanoJun 27, 2013
  40. Matthieu MoyJun 27, 2013
  41. W. Trevor KingJun 28, 2013
  42. John KeepingJun 28, 2013
  43. Junio C HamanoJun 28, 2013
  44. John KeepingJun 28, 2013
  45. Junio C HamanoJun 28, 2013
  46. John KeepingJul 2, 2013
  47. fixup! pull: require choice between rebase/merge on non-fast-forward pullJohn Keeping, Jul 14, 2013
  48. Junio C HamanoJul 15, 2013
  49. Felipe ContrerasAug 28, 2013
  50. John KeepingJul 18, 2013
  51. Andreas SchwabJul 18, 2013
  52. Junio C HamanoJul 18, 2013
  53. pull: require choice between rebase/merge on non-fast-forward pullJunio C Hamano, Jul 18, 2013
  54. Eric SunshineJul 19, 2013
  55. Junio C HamanoJul 19, 2013
  56. Eric SunshineJul 19, 2013
  57. Junio C HamanoJul 19, 2013
  58. Eric SunshineJul 19, 2013
  59. Junio C HamanoJul 19, 2013
  60. FlimmJan 22, 2014
  61. Andreas KreyMay 24, 2013
  62. Junio C HamanoMay 24, 2013
  63. Andreas KreyMay 23, 2013
  64. Holger Hellmuth (IKS)May 24, 2013
  65. Andreas KreyMay 24, 2013
  66. Holger Hellmuth (IKS)May 24, 2013
  67. Andreas KreyMay 24, 2013
  68. Felipe ContrerasMay 23, 2013
  69. Andreas KreyMay 23, 2013

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