merge: introduce merge.ff configuration variable

This variable gives the default setting for --ff, --no-ff or --ff-only
options of "git merge" command.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/merge-config.txt b/Documentation/merge-config.txt
index 8920258baa515b048555be3448edea0403ce05be..861bd6f55352a12db6d1d680508e1d02a8e90d12 100644 (file)
--- a/Documentation/merge-config.txt
+++ b/Documentation/merge-config.txt
@@ -16,6 +16,16 @@ merge.defaultToUpstream::
        to their corresponding remote tracking branches, and the tips of
        these tracking branches are merged.
 
+merge.ff::
+       By default, git does not create an extra merge commit when merging
+       a commit that is a descendant of the current commit. Instead, the
+       tip of the current branch is fast-forwarded. When set to `false`,
+       this variable tells git to create an extra merge commit in such
+       a case (equivalent to giving the `--no-ff` option from the command
+       line). When set to `only`, only such fast-forward merges are
+       allowed (equivalent to giving the `--ff-only` option from the
+       command line).
+
 merge.log::
        In addition to branch names, populate the log message with at
        most the specified number of one-line descriptions from the

diff --git a/builtin/merge.c b/builtin/merge.c
index 0f03dff1160f68de6f406f038c1b5c2bbd6529c8..65c79630f0ee2a36d0caccb8e12f7f38993dfc79 100644 (file)
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -550,6 +550,15 @@ static int git_merge_config(const char *k, const char *v, void *cb)
                if (is_bool && shortlog_len)
                        shortlog_len = DEFAULT_MERGE_LOG_LEN;
                return 0;
+       } else if (!strcmp(k, "merge.ff")) {
+               int boolval = git_config_maybe_bool(k, v);
+               if (0 <= boolval) {
+                       allow_fast_forward = boolval;
+               } else if (v && !strcmp(v, "only")) {
+                       allow_fast_forward = 1;
+                       fast_forward_only = 1;
+               } /* do not barf on values from future versions of git */
+               return 0;
        } else if (!strcmp(k, "merge.defaulttoupstream")) {
                default_to_upstream = git_config_bool(k, v);
                return 0;

diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index 46b61ec3edbe68b350fa0a49b387269dc2c4c5d6..83a3a429964ef677665482a7bccbb3829d5562cf 100755 (executable)
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -225,12 +225,28 @@ test_expect_success 'merge c1 with c2 and c3' '
 
 test_debug 'git log --graph --decorate --oneline --all'
 
-test_expect_success 'failing merges with --ff-only' '
+test_expect_success 'merges with --ff-only' '
        git reset --hard c1 &&
        test_tick &&
        test_must_fail git merge --ff-only c2 &&
        test_must_fail git merge --ff-only c3 &&
-       test_must_fail git merge --ff-only c2 c3
+       test_must_fail git merge --ff-only c2 c3 &&
+       git reset --hard c0 &&
+       git merge c3 &&
+       verify_head $c3
+'
+
+test_expect_success 'merges with merge.ff=only' '
+       git reset --hard c1 &&
+       test_tick &&
+       test_when_finished "git config --unset merge.ff" &&
+       git config merge.ff only &&
+       test_must_fail git merge c2 &&
+       test_must_fail git merge c3 &&
+       test_must_fail git merge c2 c3 &&
+       git reset --hard c0 &&
+       git merge c3 &&
+       verify_head $c3
 '
 
 test_expect_success 'merge c0 with c1 (no-commit)' '
@@ -448,6 +464,29 @@ test_expect_success 'merge c0 with c1 (no-ff)' '
 
 test_debug 'git log --graph --decorate --oneline --all'
 
+test_expect_success 'merge c0 with c1 (merge.ff=false)' '
+       git reset --hard c0 &&
+       git config merge.ff false &&
+       test_tick &&
+       git merge c1 &&
+       git config --remove-section merge &&
+       verify_merge file result.1 &&
+       verify_parents $c0 $c1
+'
+test_debug 'git log --graph --decorate --oneline --all'
+
+test_expect_success 'combine branch.master.mergeoptions with merge.ff' '
+       git reset --hard c0 &&
+       git config branch.master.mergeoptions --ff
+       git config merge.ff false
+       test_tick &&
+       git merge c1 &&
+       git config --remove-section "branch.master" &&
+       git config --remove-section "merge" &&
+       verify_merge file result.1 &&
+       verify_parents "$c0"
+'
+
 test_expect_success 'combining --squash and --no-ff is refused' '
        test_must_fail git merge --squash --no-ff c1 &&
        test_must_fail git merge --no-ff --squash c1