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merge: handle --ff/--no-ff/--ff-only as a tri-state option
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These three options mean "favor fast-forwarding when possible,
without creating an unnecessary merge", "never fast-forward and
always create a merge commit even when the commit being merged is a
strict descendant", and "we do not want to create any merge commit;
update only when the merged commit is a strict descendant".

They are "pick one out of these three possibilities" options, and
correspond to "merge.ff" configuration that is tri-state (yes, no
and only).

However, the implementation did not follow the usual convention for
the command line options (later one wins, and command line overrides
what is in the configuration).

Fix this by consolidating two variables (fast_forward_only and
allow_fast_forward) used in the implementation into one enum that
can take one of the three possible values.

Signed-off-by: Miklos Vajna <vmiklos@suse.cz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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Miklos Vajna authored and Junio C Hamano committed Jul 2, 2013
1 parent 7a3187e commit a54841e
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Showing 2 changed files with 42 additions and 25 deletions.
55 changes: 33 additions & 22 deletions builtin/merge.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -47,8 +47,8 @@ static const char * const builtin_merge_usage[] = {
};

static int show_diffstat = 1, shortlog_len = -1, squash;
static int option_commit = 1, allow_fast_forward = 1;
static int fast_forward_only, option_edit = -1;
static int option_commit = 1;
static int option_edit = -1;
static int allow_trivial = 1, have_message, verify_signatures;
static int overwrite_ignore = 1;
static struct strbuf merge_msg = STRBUF_INIT;
Expand Down Expand Up @@ -76,6 +76,14 @@ static struct strategy all_strategy[] = {

static const char *pull_twohead, *pull_octopus;

enum ff_type {
FF_NO,
FF_ALLOW,
FF_ONLY
};

static enum ff_type fast_forward = FF_ALLOW;

static int option_parse_message(const struct option *opt,
const char *arg, int unset)
{
Expand Down Expand Up @@ -178,6 +186,13 @@ static int option_parse_n(const struct option *opt,
return 0;
}

static int option_parse_ff_only(const struct option *opt,
const char *arg, int unset)
{
fast_forward = FF_ONLY;
return 0;
}

static struct option builtin_merge_options[] = {
{ OPTION_CALLBACK, 'n', NULL, NULL, NULL,
N_("do not show a diffstat at the end of the merge"),
Expand All @@ -194,10 +209,10 @@ static struct option builtin_merge_options[] = {
N_("perform a commit if the merge succeeds (default)")),
OPT_BOOL('e', "edit", &option_edit,
N_("edit message before committing")),
OPT_BOOLEAN(0, "ff", &allow_fast_forward,
N_("allow fast-forward (default)")),
OPT_BOOLEAN(0, "ff-only", &fast_forward_only,
N_("abort if fast-forward is not possible")),
OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
{ OPTION_CALLBACK, 0, "ff-only", NULL, NULL,
N_("abort if fast-forward is not possible"),
PARSE_OPT_NOARG | PARSE_OPT_NONEG, option_parse_ff_only },
OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
OPT_BOOL(0, "verify-signatures", &verify_signatures,
N_("Verify that the named commit has a valid GPG signature")),
Expand Down Expand Up @@ -581,10 +596,9 @@ static int git_merge_config(const char *k, const char *v, void *cb)
else if (!strcmp(k, "merge.ff")) {
int boolval = git_config_maybe_bool(k, v);
if (0 <= boolval) {
allow_fast_forward = boolval;
fast_forward = boolval ? FF_ALLOW : FF_NO;
} else if (v && !strcmp(v, "only")) {
allow_fast_forward = 1;
fast_forward_only = 1;
fast_forward = FF_ONLY;
} /* do not barf on values from future versions of git */
return 0;
} else if (!strcmp(k, "merge.defaulttoupstream")) {
Expand Down Expand Up @@ -863,7 +877,7 @@ static int finish_automerge(struct commit *head,

free_commit_list(common);
parents = remoteheads;
if (!head_subsumed || !allow_fast_forward)
if (!head_subsumed || fast_forward == FF_NO)
commit_list_insert(head, &parents);
strbuf_addch(&merge_msg, '\n');
prepare_to_commit(remoteheads);
Expand Down Expand Up @@ -1008,7 +1022,7 @@ static void write_merge_state(struct commit_list *remoteheads)
if (fd < 0)
die_errno(_("Could not open '%s' for writing"), filename);
strbuf_reset(&buf);
if (!allow_fast_forward)
if (fast_forward == FF_NO)
strbuf_addf(&buf, "no-ff");
if (write_in_full(fd, buf.buf, buf.len) != buf.len)
die_errno(_("Could not write to '%s'"), filename);
Expand Down Expand Up @@ -1157,14 +1171,11 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
show_diffstat = 0;

if (squash) {
if (!allow_fast_forward)
if (fast_forward == FF_NO)
die(_("You cannot combine --squash with --no-ff."));
option_commit = 0;
}

if (!allow_fast_forward && fast_forward_only)
die(_("You cannot combine --no-ff with --ff-only."));

if (!abort_current_merge) {
if (!argc) {
if (default_to_upstream)
Expand Down Expand Up @@ -1206,7 +1217,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
"empty head"));
if (squash)
die(_("Squash commit into empty head not supported yet"));
if (!allow_fast_forward)
if (fast_forward == FF_NO)
die(_("Non-fast-forward commit does not make sense into "
"an empty head"));
remoteheads = collect_parents(head_commit, &head_subsumed, argc, argv);
Expand Down Expand Up @@ -1294,11 +1305,11 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
sha1_to_hex(commit->object.sha1));
setenv(buf.buf, merge_remote_util(commit)->name, 1);
strbuf_reset(&buf);
if (!fast_forward_only &&
if (fast_forward != FF_ONLY &&
merge_remote_util(commit) &&
merge_remote_util(commit)->obj &&
merge_remote_util(commit)->obj->type == OBJ_TAG)
allow_fast_forward = 0;
fast_forward = FF_NO;
}

if (option_edit < 0)
Expand All @@ -1315,7 +1326,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)

for (i = 0; i < use_strategies_nr; i++) {
if (use_strategies[i]->attr & NO_FAST_FORWARD)
allow_fast_forward = 0;
fast_forward = FF_NO;
if (use_strategies[i]->attr & NO_TRIVIAL)
allow_trivial = 0;
}
Expand Down Expand Up @@ -1345,7 +1356,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
*/
finish_up_to_date("Already up-to-date.");
goto done;
} else if (allow_fast_forward && !remoteheads->next &&
} else if (fast_forward != FF_NO && !remoteheads->next &&
!common->next &&
!hashcmp(common->item->object.sha1, head_commit->object.sha1)) {
/* Again the most common case of merging one remote. */
Expand Down Expand Up @@ -1392,7 +1403,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
* only one common.
*/
refresh_cache(REFRESH_QUIET);
if (allow_trivial && !fast_forward_only) {
if (allow_trivial && fast_forward != FF_ONLY) {
/* See if it is really trivial. */
git_committer_info(IDENT_STRICT);
printf(_("Trying really trivial in-index merge...\n"));
Expand Down Expand Up @@ -1433,7 +1444,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
}
}

if (fast_forward_only)
if (fast_forward == FF_ONLY)
die(_("Not possible to fast-forward, aborting."));

/* We are going to make a new commit. */
Expand Down
12 changes: 9 additions & 3 deletions t/t7600-merge.sh
View file
Original file line number Diff line number Diff line change
Expand Up @@ -497,9 +497,15 @@ test_expect_success 'combining --squash and --no-ff is refused' '
test_must_fail git merge --no-ff --squash c1
'

test_expect_success 'combining --ff-only and --no-ff is refused' '
test_must_fail git merge --ff-only --no-ff c1 &&
test_must_fail git merge --no-ff --ff-only c1
test_expect_success 'option --ff-only overwrites --no-ff' '
git merge --no-ff --ff-only c1 &&
test_must_fail git merge --no-ff --ff-only c2
'

test_expect_success 'option --ff-only overwrites merge.ff=only config' '
git reset --hard c0 &&
test_config merge.ff only &&
git merge --no-ff c1
'

test_expect_success 'merge c0 with c1 (ff overrides no-ff)' '
Expand Down

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