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bjornggitster
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Teach 'git merge' and 'git pull' the option --ff-only
For convenience in scripts and aliases, add the option --ff-only to only allow fast-forwards (and up-to-date, despite the name). Disallow combining --ff-only and --no-ff, since they flatly contradict each other. Allow all other options to be combined with --ff-only (i.e. do not add any code to handle them specially), including the following options: * --strategy (one or more): As long as the chosen merge strategy results in up-to-date or fast-forward, the command will succeed. * --squash: I cannot imagine why anyone would want to squash commits only if fast-forward is possible, but I also see no reason why it should not be allowed. * --message: The message will always be ignored, but I see no need to explicitly disallow providing a redundant message. Acknowledgements: I did look at Yuval Kogman's earlier patch (107768 in gmane), mainly as shortcut to find my way in the code, but I did not copy anything directly. Signed-off-by: Björn Gustavsson <bgustavsson@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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‎Documentation/merge-options.txt‎

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -60,6 +60,11 @@
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a fast-forward, only update the branch pointer. This is
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the default behavior of git-merge.
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--ff-only::
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Refuse to merge and exit with a non-zero status unless the
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current `HEAD` is already up-to-date or the merge can be
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resolved as a fast-forward.
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-s <strategy>::
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--strategy=<strategy>::
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Use the given merge strategy; can be supplied more than

‎builtin-merge.c‎

Lines changed: 10 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -43,6 +43,7 @@ static const char * const builtin_merge_usage[] = {
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static int show_diffstat = 1, option_log, squash;
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static int option_commit = 1, allow_fast_forward = 1;
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static int fast_forward_only;
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static int allow_trivial = 1, have_message;
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static struct strbuf merge_msg;
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static struct commit_list *remoteheads;
@@ -167,6 +168,8 @@ static struct option builtin_merge_options[] = {
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"perform a commit if the merge succeeds (default)"),
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OPT_BOOLEAN(0, "ff", &allow_fast_forward,
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"allow fast forward (default)"),
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OPT_BOOLEAN(0, "ff-only", &fast_forward_only,
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"abort if fast forward is not possible"),
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OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
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"merge strategy to use", option_parse_strategy),
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OPT_CALLBACK('m', "message", &merge_msg, "message",
@@ -874,6 +877,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
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option_commit = 0;
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}
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if (!allow_fast_forward && fast_forward_only)
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die("You cannot combine --no-ff with --ff-only.");
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if (!argc)
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usage_with_options(builtin_merge_usage,
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builtin_merge_options);
@@ -1040,7 +1046,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
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* only one common.
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*/
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refresh_cache(REFRESH_QUIET);
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if (allow_trivial) {
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if (allow_trivial && !fast_forward_only) {
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/* See if it is really trivial. */
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git_committer_info(IDENT_ERROR_ON_NO_NAME);
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printf("Trying really trivial in-index merge...\n");
@@ -1079,6 +1085,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
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}
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}
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if (fast_forward_only)
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die("Not possible to fast forward, aborting.");
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/* We are going to make a new commit. */
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git_committer_info(IDENT_ERROR_ON_NO_NAME);
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‎git-pull.sh‎

Lines changed: 5 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -16,7 +16,8 @@ cd_to_toplevel
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test -z "$(git ls-files -u)" ||
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die "You are in the middle of a conflicted merge."
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strategy_args= diffstat= no_commit= squash= no_ff= log_arg= verbosity=
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strategy_args= diffstat= no_commit= squash= no_ff= ff_only=
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log_arg= verbosity=
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curr_branch=$(git symbolic-ref -q HEAD)
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curr_branch_short=$(echo "$curr_branch" | sed "s|refs/heads/||")
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rebase=$(git config --bool branch.$curr_branch_short.rebase)
@@ -45,6 +46,8 @@ do
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no_ff=--ff ;;
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--no-ff)
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no_ff=--no-ff ;;
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--ff-only)
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ff_only=--ff-only ;;
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-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
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--strateg=*|--strategy=*|\
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-s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
@@ -215,5 +218,5 @@ merge_name=$(git fmt-merge-msg $log_arg <"$GIT_DIR/FETCH_HEAD") || exit
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test true = "$rebase" &&
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exec git-rebase $diffstat $strategy_args --onto $merge_head \
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${oldremoteref:-$merge_head}
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exec git-merge $diffstat $no_commit $squash $no_ff $log_arg $strategy_args \
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exec git-merge $diffstat $no_commit $squash $no_ff $ff_only $log_arg $strategy_args \
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"$merge_name" HEAD $merge_head $verbosity

‎t/t7600-merge.sh‎

Lines changed: 41 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -243,6 +243,16 @@ test_expect_success 'merge c0 with c1' '
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test_debug 'gitk --all'
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test_expect_success 'merge c0 with c1 with --ff-only' '
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git reset --hard c0 &&
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git merge --ff-only c1 &&
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git merge --ff-only HEAD c0 c1 &&
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verify_merge file result.1 &&
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verify_head "$c1"
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'
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test_debug 'gitk --all'
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test_expect_success 'merge c1 with c2' '
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git reset --hard c1 &&
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test_tick &&
@@ -263,6 +273,14 @@ test_expect_success 'merge c1 with c2 and c3' '
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test_debug 'gitk --all'
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test_expect_success 'failing merges with --ff-only' '
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git reset --hard c1 &&
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test_tick &&
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test_must_fail git merge --ff-only c2 &&
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test_must_fail git merge --ff-only c3 &&
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test_must_fail git merge --ff-only c2 c3
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'
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test_expect_success 'merge c0 with c1 (no-commit)' '
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git reset --hard c0 &&
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git merge --no-commit c1 &&
@@ -303,6 +321,17 @@ test_expect_success 'merge c0 with c1 (squash)' '
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304322
test_debug 'gitk --all'
305323

324+
test_expect_success 'merge c0 with c1 (squash, ff-only)' '
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git reset --hard c0 &&
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git merge --squash --ff-only c1 &&
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verify_merge file result.1 &&
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verify_head $c0 &&
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verify_no_mergehead &&
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verify_diff squash.1 .git/SQUASH_MSG "[OOPS] bad squash message"
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'
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333+
test_debug 'gitk --all'
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test_expect_success 'merge c1 with c2 (squash)' '
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git reset --hard c1 &&
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git merge --squash c2 &&
@@ -314,6 +343,13 @@ test_expect_success 'merge c1 with c2 (squash)' '
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test_debug 'gitk --all'
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test_expect_success 'unsuccesful merge of c1 with c2 (squash, ff-only)' '
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git reset --hard c1 &&
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test_must_fail git merge --squash --ff-only c2
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'
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test_debug 'gitk --all'
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test_expect_success 'merge c1 with c2 and c3 (squash)' '
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git reset --hard c1 &&
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git merge --squash c2 c3 &&
@@ -432,6 +468,11 @@ test_expect_success 'combining --squash and --no-ff is refused' '
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test_must_fail git merge --no-ff --squash c1
433469
'
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471+
test_expect_success 'combining --ff-only and --no-ff is refused' '
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test_must_fail git merge --ff-only --no-ff c1 &&
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test_must_fail git merge --no-ff --ff-only c1
474+
'
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435476
test_expect_success 'merge c0 with c1 (ff overrides no-ff)' '
436477
git reset --hard c0 &&
437478
git config branch.master.mergeoptions "--no-ff" &&

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