Merge branch 'mv/merge-ff-tristate'

The configuration variable "merge.ff" was cleary a tri-state to
choose one from "favor fast-forward when possible", "always create
a merge even when the history could fast-forward" and "do not
create any merge, only update when the history fast-forwards", but
the command line parser did not implement the usual convention of
"last one wins, and command line overrides the configuration"
correctly.

* mv/merge-ff-tristate:
merge: handle --ff/--no-ff/--ff-only as a tri-state option

diff --combined builtin/merge.c
index bad4536a8738237a87e51011f074814bd8b10ba3,149f32afb6eede8b65d1eed9f5def9237e0a908a..9505e7e426d302522f5e065d741fccd37290ea21
--- 1/builtin/merge.c
--- 2/builtin/merge.c
+++ b/builtin/merge.c
@@@ -47,8 -47,8 +47,8 @@@ static const char * const builtin_merge
  };
  
  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;
@@@ -76,6 -76,14 +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)
  {
@@@ -178,6 -186,13 +186,13 @@@ static int option_parse_n(const struct 
        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"),
@@@ -194,10 -209,10 +209,10 @@@
                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")),
@@@ -581,10 -596,9 +596,9 @@@ static int git_merge_config(const char 
        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")) {
@@@ -863,7 -877,7 +877,7 @@@ static int finish_automerge(struct comm
  
        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);
@@@ -948,7 -962,7 +962,7 @@@ static int evaluate_result(void
  }
  
  /*
 - * Pretend as if the user told us to merge with the tracking
 + * Pretend as if the user told us to merge with the remote-tracking
   * branch we have for the upstream of the current branch
   */
  static int setup_with_upstream(const char ***argv)
@@@ -967,7 -981,7 +981,7 @@@
        args = xcalloc(branch->merge_nr + 1, sizeof(char *));
        for (i = 0; i < branch->merge_nr; i++) {
                if (!branch->merge[i]->dst)
 -                      die(_("No remote tracking branch for %s from %s"),
 +                      die(_("No remote-tracking branch for %s from %s"),
                            branch->merge[i]->src, branch->remote_name);
                args[i] = branch->merge[i]->dst;
        }
@@@ -1008,7 -1022,7 +1022,7 @@@ static void write_merge_state(struct co
        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);
@@@ -1157,14 -1171,11 +1171,11 @@@ int cmd_merge(int argc, const char **ar
                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)
@@@ -1206,7 -1217,7 +1217,7 @@@
                                "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);
@@@ -1294,11 -1305,11 +1305,11 @@@
                            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)
@@@ -1315,7 -1326,7 +1326,7 @@@
  
        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;
        }
@@@ -1345,7 -1356,7 +1356,7 @@@
                 */
                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. */
@@@ -1392,7 -1403,7 +1403,7 @@@
                 * 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"));
@@@ -1433,7 -1444,7 +1444,7 @@@
                }
        }
  
-       if (fast_forward_only)
+       if (fast_forward == FF_ONLY)
                die(_("Not possible to fast-forward, aborting."));
  
        /* We are going to make a new commit. */