send-email: simplify Gmail example in the documentation

diff --git a/builtin/merge.c b/builtin/merge.c
index bf2f2614fbb5ba82df3dca5cad8f79dbe605feff..b555a1bf9cd46ea57bcbe1c8d8b7ac146fe9f81c 100644 (file)
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -64,6 +64,7 @@ static int option_renormalize;
 static int verbosity;
 static int allow_rerere_auto;
 static int abort_current_merge;
+static int allow_unrelated_histories;
 static int show_progress = -1;
 static int default_to_upstream = 1;
 static const char *sign_commit;
@@ -221,6 +222,8 @@ static struct option builtin_merge_options[] = {
        OPT__VERBOSITY(&verbosity),
        OPT_BOOL(0, "abort", &abort_current_merge,
                N_("abort the current in-progress merge")),
+       OPT_BOOL(0, "allow-unrelated-histories", &allow_unrelated_histories,
+                N_("allow merging unrelated histories")),
        OPT_SET_INT(0, "progress", &show_progress, N_("force progress reporting"), 1),
        { OPTION_STRING, 'S', "gpg-sign", &sign_commit, N_("key-id"),
          N_("GPG sign commit"), PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
@@ -819,6 +822,14 @@ static int merge_trivial(struct commit *head, struct commit_list *remoteheads)
 {
        unsigned char result_tree[20], result_commit[20];
        struct commit_list *parents, **pptr = &parents;
+       static struct lock_file lock;
+
+       hold_locked_index(&lock, 1);
+       refresh_cache(REFRESH_QUIET);
+       if (active_cache_changed &&
+           write_locked_index(&the_index, &lock, COMMIT_LOCK))
+               return error(_("Unable to write index."));
+       rollback_lock_file(&lock);
 
        write_tree_trivial(result_tree);
        printf(_("Wonderful.\n"));
@@ -1165,7 +1176,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
        struct commit *head_commit;
        struct strbuf buf = STRBUF_INIT;
        const char *head_arg;
-       int flag, i, ret = 0, head_subsumed;
+       int i, ret = 0, head_subsumed;
        int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
        struct commit_list *common = NULL;
        const char *best_strategy = NULL, *wt_strategy = NULL;
@@ -1179,7 +1190,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
         * Check if we are _not_ on a detached HEAD, i.e. if there is a
         * current branch.
         */
-       branch = branch_to_free = resolve_refdup("HEAD", 0, head_sha1, &flag);
+       branch = branch_to_free = resolve_refdup("HEAD", 0, head_sha1, NULL);
        if (branch && starts_with(branch, "refs/heads/"))
                branch += 11;
        if (!branch || is_null_sha1(head_sha1))
@@ -1187,6 +1198,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
        else
                head_commit = lookup_commit_or_die(head_sha1, "HEAD");
 
+       init_diff_ui_defaults();
        git_config(git_merge_config, NULL);
 
        if (branch_mergeoptions)
@@ -1397,9 +1409,12 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
        update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.oid.hash,
                   NULL, 0, UPDATE_REFS_DIE_ON_ERR);
 
-       if (remoteheads && !common)
-               ; /* No common ancestors found. We need a real merge. */
-       else if (!remoteheads ||
+       if (remoteheads && !common) {
+               /* No common ancestors found. */
+               if (!allow_unrelated_histories)
+                       die(_("refusing to merge unrelated histories"));
+               /* otherwise, we need a real merge. */
+       } else if (!remoteheads ||
                 (!remoteheads->next && !common->next &&
                  common->item == remoteheads->item)) {
                /*