Merge branch 'jc/maint-1.7.3-checkout-describe' into maint
authorJunio C Hamano <gitster@pobox.com>
Mon, 1 Aug 2011 21:43:18 +0000 (14:43 -0700)
committerJunio C Hamano <gitster@pobox.com>
Mon, 1 Aug 2011 21:43:18 +0000 (14:43 -0700)
* jc/maint-1.7.3-checkout-describe:
checkout -b <name>: correctly detect existing branch

1  2 
builtin/checkout.c
refs.c
refs.h
t/t2018-checkout-branch.sh
diff --combined builtin/checkout.c
index 28cdc51b85e7d433dca085c0080f964d19a391b4,88708d48bf5483a537839a2b1439af2880b1fd35..af1e7b579a83aef15e11c0c5dfa29447e485654c
@@@ -18,7 -18,6 +18,7 @@@
  #include "xdiff-interface.h"
  #include "ll-merge.h"
  #include "resolve-undo.h"
 +#include "submodule.h"
  
  static const char * const checkout_usage[] = {
        "git checkout [options] <branch>",
@@@ -30,7 -29,6 +30,7 @@@ struct checkout_opts 
        int quiet;
        int merge;
        int force;
 +      int force_detach;
        int writeout_stage;
        int writeout_error;
  
@@@ -42,7 -40,6 +42,7 @@@
        const char *new_orphan_branch;
        int new_branch_log;
        enum branch_track track;
 +      struct diff_options diff_options;
  };
  
  static int post_checkout_hook(struct commit *old, struct commit *new,
@@@ -79,10 -76,7 +79,10 @@@ static int update_some(const unsigned c
  
  static int read_tree_some(struct tree *tree, const char **pathspec)
  {
 -      read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 +      struct pathspec ps;
 +      init_pathspec(&ps, pathspec);
 +      read_tree_recursive(tree, "", 0, 0, &ps, update_some, NULL);
 +      free_pathspec(&ps);
  
        /* update the index with the given tree's info
         * for all args, expanding wildcards, and exit
@@@ -107,10 -101,9 +107,10 @@@ static int check_stage(int stage, struc
                        return 0;
                pos++;
        }
 -      return error("path '%s' does not have %s version",
 -                   ce->name,
 -                   (stage == 2) ? "our" : "their");
 +      if (stage == 2)
 +              return error(_("path '%s' does not have our version"), ce->name);
 +      else
 +              return error(_("path '%s' does not have their version"), ce->name);
  }
  
  static int check_all_stages(struct cache_entry *ce, int pos)
            ce_stage(active_cache[pos+1]) != 2 ||
            strcmp(active_cache[pos+2]->name, ce->name) ||
            ce_stage(active_cache[pos+2]) != 3)
 -              return error("path '%s' does not have all three versions",
 +              return error(_("path '%s' does not have all three versions"),
                             ce->name);
        return 0;
  }
@@@ -135,10 -128,9 +135,10 @@@ static int checkout_stage(int stage, st
                        return checkout_entry(active_cache[pos], state, NULL);
                pos++;
        }
 -      return error("path '%s' does not have %s version",
 -                   ce->name,
 -                   (stage == 2) ? "our" : "their");
 +      if (stage == 2)
 +              return error(_("path '%s' does not have our version"), ce->name);
 +      else
 +              return error(_("path '%s' does not have their version"), ce->name);
  }
  
  static int checkout_merged(int pos, struct checkout *state)
            ce_stage(active_cache[pos+1]) != 2 ||
            strcmp(active_cache[pos+2]->name, path) ||
            ce_stage(active_cache[pos+2]) != 3)
 -              return error("path '%s' does not have all 3 versions", path);
 +              return error(_("path '%s' does not have all 3 versions"), path);
  
        read_mmblob(&ancestor, active_cache[pos]->sha1);
        read_mmblob(&ours, active_cache[pos+1]->sha1);
        read_mmblob(&theirs, active_cache[pos+2]->sha1);
  
 +      /*
 +       * NEEDSWORK: re-create conflicts from merges with
 +       * merge.renormalize set, too
 +       */
        status = ll_merge(&result_buf, path, &ancestor, "base",
 -                        &ours, "ours", &theirs, "theirs", 0);
 +                        &ours, "ours", &theirs, "theirs", NULL);
        free(ancestor.ptr);
        free(ours.ptr);
        free(theirs.ptr);
        if (status < 0 || !result_buf.ptr) {
                free(result_buf.ptr);
 -              return error("path '%s': cannot merge", path);
 +              return error(_("path '%s': cannot merge"), path);
        }
  
        /*
         */
        if (write_sha1_file(result_buf.ptr, result_buf.size,
                            blob_type, sha1))
 -              die("Unable to add merge result for '%s'", path);
 +              die(_("Unable to add merge result for '%s'"), path);
        ce = make_cache_entry(create_ce_mode(active_cache[pos+1]->ce_mode),
                              sha1,
                              path, 2, 0);
        if (!ce)
 -              die("make_cache_entry failed for path '%s'", path);
 +              die(_("make_cache_entry failed for path '%s'"), path);
        status = checkout_entry(ce, state, NULL);
        return status;
  }
@@@ -217,7 -205,7 +217,7 @@@ static int checkout_paths(struct tree *
  
        newfd = hold_locked_index(lock_file, 1);
        if (read_cache_preload(pathspec) < 0)
 -              return error("corrupt index file");
 +              return error(_("corrupt index file"));
  
        if (source_tree)
                read_tree_some(source_tree, pathspec);
                        if (!ce_stage(ce))
                                continue;
                        if (opts->force) {
 -                              warning("path '%s' is unmerged", ce->name);
 +                              warning(_("path '%s' is unmerged"), ce->name);
                        } else if (stage) {
                                errs |= check_stage(stage, ce, pos);
                        } else if (opts->merge) {
                                errs |= check_all_stages(ce, pos);
                        } else {
                                errs = 1;
 -                              error("path '%s' is unmerged", ce->name);
 +                              error(_("path '%s' is unmerged"), ce->name);
                        }
                        pos = skip_same_name(ce, pos) - 1;
                }
  
        if (write_cache(newfd, active_cache, active_nr) ||
            commit_locked_index(lock_file))
 -              die("unable to write new index file");
 +              die(_("unable to write new index file"));
  
        resolve_ref("HEAD", rev, 0, &flag);
        head = lookup_commit_reference_gently(rev, 1);
        return errs;
  }
  
 -static void show_local_changes(struct object *head)
 +static void show_local_changes(struct object *head, struct diff_options *opts)
  {
        struct rev_info rev;
        /* I think we want full paths, even if we're in a subdirectory. */
        init_revisions(&rev, NULL);
 -      rev.abbrev = 0;
 +      rev.diffopt.flags = opts->flags;
        rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
        if (diff_setup_done(&rev.diffopt) < 0)
 -              die("diff_setup_done failed");
 +              die(_("diff_setup_done failed"));
        add_pending_object(&rev, head, NULL);
        run_diff_index(&rev, 0);
  }
  
 -static void describe_detached_head(char *msg, struct commit *commit)
 +static void describe_detached_head(const char *msg, struct commit *commit)
  {
        struct strbuf sb = STRBUF_INIT;
 -      struct pretty_print_context ctx = {0};
        parse_commit(commit);
 -      pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, &ctx);
 +      pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
        fprintf(stderr, "%s %s... %s\n", msg,
                find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
        strbuf_release(&sb);
@@@ -371,7 -360,7 +371,7 @@@ static int merge_working_tree(struct ch
        int newfd = hold_locked_index(lock_file, 1);
  
        if (read_cache_preload(NULL) < 0)
 -              return error("corrupt index file");
 +              return error(_("corrupt index file"));
  
        resolve_undo_clear();
        if (opts->force) {
                topts.src_index = &the_index;
                topts.dst_index = &the_index;
  
 -              topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
 +              setup_unpack_trees_porcelain(&topts, "checkout");
  
                refresh_cache(REFRESH_QUIET);
  
                if (unmerged_cache()) {
 -                      error("you need to resolve your current index first");
 +                      error(_("you need to resolve your current index first"));
                        return 1;
                }
  
                topts.dir->exclude_per_dir = ".gitignore";
                tree = parse_tree_indirect(old->commit ?
                                           old->commit->object.sha1 :
 -                                         (unsigned char *)EMPTY_TREE_SHA1_BIN);
 +                                         EMPTY_TREE_SHA1_BIN);
                init_tree_desc(&trees[0], tree->buffer, tree->size);
                tree = parse_tree_indirect(new->commit->object.sha1);
                init_tree_desc(&trees[1], tree->buffer, tree->size);
                         */
  
                        add_files_to_cache(NULL, NULL, 0);
 +                      /*
 +                       * NEEDSWORK: carrying over local changes
 +                       * when branches have different end-of-line
 +                       * normalization (or clean+smudge rules) is
 +                       * a pain; plumb in an option to set
 +                       * o.renormalize?
 +                       */
                        init_merge_options(&o);
                        o.verbosity = 0;
                        work = write_tree_from_memory(&o);
  
        if (write_cache(newfd, active_cache, active_nr) ||
            commit_locked_index(lock_file))
 -              die("unable to write new index file");
 +              die(_("unable to write new index file"));
  
        if (!opts->force && !opts->quiet)
 -              show_local_changes(&new->commit->object);
 +              show_local_changes(&new->commit->object, &opts->diff_options);
  
        return 0;
  }
@@@ -524,7 -506,7 +524,7 @@@ static void update_refs_for_switch(stru
                                temp = log_all_ref_updates;
                                log_all_ref_updates = 1;
                                if (log_ref_setup(ref_name, log_file, sizeof(log_file))) {
 -                                      fprintf(stderr, "Can not do reflog for '%s'\n",
 +                                      fprintf(stderr, _("Can not do reflog for '%s'\n"),
                                            opts->new_orphan_branch);
                                        log_all_ref_updates = temp;
                                        return;
        strbuf_addf(&msg, "checkout: moving from %s to %s",
                    old_desc ? old_desc : "(invalid)", new->name);
  
 -      if (new->path) {
 +      if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 +              /* Nothing to do. */
 +      } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 +              update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 +                         REF_NODEREF, DIE_ON_ERR);
 +              if (!opts->quiet) {
 +                      if (old->path && advice_detached_head)
 +                              detach_advice(old->path, new->name);
 +                      describe_detached_head(_("HEAD is now at"), new->commit);
 +              }
 +      } else if (new->path) { /* Switch branches. */
                create_symref("HEAD", new->path, msg.buf);
                if (!opts->quiet) {
 -                      if (old->path && !strcmp(new->path, old->path))
 -                              fprintf(stderr, "Already on '%s'\n",
 +                      if (old->path && !strcmp(new->path, old->path)) {
 +                              fprintf(stderr, _("Already on '%s'\n"),
                                        new->name);
 -                      else
 -                              fprintf(stderr, "Switched to%s branch '%s'\n",
 -                                      opts->branch_exists ? " and reset" : " a new",
 +                      } else if (opts->new_branch) {
 +                              if (opts->branch_exists)
 +                                      fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 +                              else
 +                                      fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 +                      } else {
 +                              fprintf(stderr, _("Switched to branch '%s'\n"),
                                        new->name);
 +                      }
                }
                if (old->path && old->name) {
                        char log_file[PATH_MAX], ref_file[PATH_MAX];
                        if (!file_exists(ref_file) && file_exists(log_file))
                                remove_path(log_file);
                }
 -      } else if (strcmp(new->name, "HEAD")) {
 -              update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 -                         REF_NODEREF, DIE_ON_ERR);
 -              if (!opts->quiet) {
 -                      if (old->path && advice_detached_head)
 -                              detach_advice(old->path, new->name);
 -                      describe_detached_head("HEAD is now at", new->commit);
 -              }
        }
        remove_branch_state();
        strbuf_release(&msg);
 -      if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
 +      if (!opts->quiet &&
 +          (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
                report_tracking(new);
  }
  
 +struct rev_list_args {
 +      int argc;
 +      int alloc;
 +      const char **argv;
 +};
 +
 +static void add_one_rev_list_arg(struct rev_list_args *args, const char *s)
 +{
 +      ALLOC_GROW(args->argv, args->argc + 1, args->alloc);
 +      args->argv[args->argc++] = s;
 +}
 +
 +static int add_one_ref_to_rev_list_arg(const char *refname,
 +                                     const unsigned char *sha1,
 +                                     int flags,
 +                                     void *cb_data)
 +{
 +      add_one_rev_list_arg(cb_data, refname);
 +      return 0;
 +}
 +
 +static int clear_commit_marks_from_one_ref(const char *refname,
 +                                    const unsigned char *sha1,
 +                                    int flags,
 +                                    void *cb_data)
 +{
 +      struct commit *commit = lookup_commit_reference_gently(sha1, 1);
 +      if (commit)
 +              clear_commit_marks(commit, -1);
 +      return 0;
 +}
 +
 +static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 +{
 +      parse_commit(commit);
 +      strbuf_addstr(sb, "  ");
 +      strbuf_addstr(sb,
 +              find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 +      strbuf_addch(sb, ' ');
 +      pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 +      strbuf_addch(sb, '\n');
 +}
 +
 +#define ORPHAN_CUTOFF 4
 +static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 +{
 +      struct commit *c, *last = NULL;
 +      struct strbuf sb = STRBUF_INIT;
 +      int lost = 0;
 +      while ((c = get_revision(revs)) != NULL) {
 +              if (lost < ORPHAN_CUTOFF)
 +                      describe_one_orphan(&sb, c);
 +              last = c;
 +              lost++;
 +      }
 +      if (ORPHAN_CUTOFF < lost) {
 +              int more = lost - ORPHAN_CUTOFF;
 +              if (more == 1)
 +                      describe_one_orphan(&sb, last);
 +              else
 +                      strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 +      }
 +
 +      fprintf(stderr,
 +              Q_(
 +              /* The singular version */
 +              "Warning: you are leaving %d commit behind, "
 +              "not connected to\n"
 +              "any of your branches:\n\n"
 +              "%s\n"
 +              "If you want to keep it by creating a new branch, "
 +              "this may be a good time\nto do so with:\n\n"
 +              " git branch new_branch_name %s\n\n",
 +              /* The plural version */
 +              "Warning: you are leaving %d commits behind, "
 +              "not connected to\n"
 +              "any of your branches:\n\n"
 +              "%s\n"
 +              "If you want to keep them by creating a new branch, "
 +              "this may be a good time\nto do so with:\n\n"
 +              " git branch new_branch_name %s\n\n",
 +              /* Give ngettext() the count */
 +              lost),
 +              lost,
 +              sb.buf,
 +              sha1_to_hex(commit->object.sha1));
 +      strbuf_release(&sb);
 +}
 +
 +/*
 + * We are about to leave commit that was at the tip of a detached
 + * HEAD.  If it is not reachable from any ref, this is the last chance
 + * for the user to do so without resorting to reflog.
 + */
 +static void orphaned_commit_warning(struct commit *commit)
 +{
 +      struct rev_list_args args = { 0, 0, NULL };
 +      struct rev_info revs;
 +
 +      add_one_rev_list_arg(&args, "(internal)");
 +      add_one_rev_list_arg(&args, sha1_to_hex(commit->object.sha1));
 +      add_one_rev_list_arg(&args, "--not");
 +      for_each_ref(add_one_ref_to_rev_list_arg, &args);
 +      add_one_rev_list_arg(&args, "--");
 +      add_one_rev_list_arg(&args, NULL);
 +
 +      init_revisions(&revs, NULL);
 +      if (setup_revisions(args.argc - 1, args.argv, &revs, NULL) != 1)
 +              die(_("internal error: only -- alone should have been left"));
 +      if (prepare_revision_walk(&revs))
 +              die(_("internal error in revision walk"));
 +      if (!(commit->object.flags & UNINTERESTING))
 +              suggest_reattach(commit, &revs);
 +      else
 +              describe_detached_head(_("Previous HEAD position was"), commit);
 +
 +      clear_commit_marks(commit, -1);
 +      for_each_ref(clear_commit_marks_from_one_ref, NULL);
 +}
 +
  static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
  {
        int ret = 0;
                new->name = "HEAD";
                new->commit = old.commit;
                if (!new->commit)
 -                      die("You are on a branch yet to be born");
 +                      die(_("You are on a branch yet to be born"));
                parse_commit(new->commit);
        }
  
        if (ret)
                return ret;
  
 -      /*
 -       * If we were on a detached HEAD, but have now moved to
 -       * a new commit, we want to mention the old commit once more
 -       * to remind the user that it might be lost.
 -       */
        if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 -              describe_detached_head("Previous HEAD position was", old.commit);
 +              orphaned_commit_warning(old.commit);
  
        update_refs_for_switch(opts, &old, new);
  
  
  static int git_checkout_config(const char *var, const char *value, void *cb)
  {
 -      return git_xmerge_config(var, value, cb);
 +      if (!strcmp(var, "diff.ignoresubmodules")) {
 +              struct checkout_opts *opts = cb;
 +              handle_ignore_submodules_arg(&opts->diff_options, value);
 +              return 0;
 +      }
 +
 +      if (!prefixcmp(var, "submodule."))
 +              return parse_submodule_config_option(var, value);
 +
 +      return git_xmerge_config(var, value, NULL);
  }
  
  static int interactive_checkout(const char *revision, const char **pathspec,
@@@ -800,145 -650,32 +800,145 @@@ static const char *unique_tracking_name
        return NULL;
  }
  
 +static int parse_branchname_arg(int argc, const char **argv,
 +                              int dwim_new_local_branch_ok,
 +                              struct branch_info *new,
 +                              struct tree **source_tree,
 +                              unsigned char rev[20],
 +                              const char **new_branch)
 +{
 +      int argcount = 0;
 +      unsigned char branch_rev[20];
 +      const char *arg;
 +      int has_dash_dash;
 +
 +      /*
 +       * case 1: git checkout <ref> -- [<paths>]
 +       *
 +       *   <ref> must be a valid tree, everything after the '--' must be
 +       *   a path.
 +       *
 +       * case 2: git checkout -- [<paths>]
 +       *
 +       *   everything after the '--' must be paths.
 +       *
 +       * case 3: git checkout <something> [<paths>]
 +       *
 +       *   With no paths, if <something> is a commit, that is to
 +       *   switch to the branch or detach HEAD at it.  As a special case,
 +       *   if <something> is A...B (missing A or B means HEAD but you can
 +       *   omit at most one side), and if there is a unique merge base
 +       *   between A and B, A...B names that merge base.
 +       *
 +       *   With no paths, if <something> is _not_ a commit, no -t nor -b
 +       *   was given, and there is a tracking branch whose name is
 +       *   <something> in one and only one remote, then this is a short-hand
 +       *   to fork local <something> from that remote-tracking branch.
 +       *
 +       *   Otherwise <something> shall not be ambiguous.
 +       *   - If it's *only* a reference, treat it like case (1).
 +       *   - If it's only a path, treat it like case (2).
 +       *   - else: fail.
 +       *
 +       */
 +      if (!argc)
 +              return 0;
 +
 +      if (!strcmp(argv[0], "--"))     /* case (2) */
 +              return 1;
 +
 +      arg = argv[0];
 +      has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
 +
 +      if (!strcmp(arg, "-"))
 +              arg = "@{-1}";
 +
 +      if (get_sha1_mb(arg, rev)) {
 +              if (has_dash_dash)          /* case (1) */
 +                      die(_("invalid reference: %s"), arg);
 +              if (dwim_new_local_branch_ok &&
 +                  !check_filename(NULL, arg) &&
 +                  argc == 1) {
 +                      const char *remote = unique_tracking_name(arg);
 +                      if (!remote || get_sha1(remote, rev))
 +                              return argcount;
 +                      *new_branch = arg;
 +                      arg = remote;
 +                      /* DWIMmed to create local branch */
 +              } else {
 +                      return argcount;
 +              }
 +      }
 +
 +      /* we can't end up being in (2) anymore, eat the argument */
 +      argcount++;
 +      argv++;
 +      argc--;
 +
 +      new->name = arg;
 +      setup_branch_path(new);
 +
 +      if (check_ref_format(new->path) == CHECK_REF_FORMAT_OK &&
 +          resolve_ref(new->path, branch_rev, 1, NULL))
 +              hashcpy(rev, branch_rev);
 +      else
 +              new->path = NULL; /* not an existing branch */
 +
 +      new->commit = lookup_commit_reference_gently(rev, 1);
 +      if (!new->commit) {
 +              /* not a commit */
 +              *source_tree = parse_tree_indirect(rev);
 +      } else {
 +              parse_commit(new->commit);
 +              *source_tree = new->commit->tree;
 +      }
 +
 +      if (!*source_tree)                   /* case (1): want a tree */
 +              die(_("reference is not a tree: %s"), arg);
 +      if (!has_dash_dash) {/* case (3 -> 1) */
 +              /*
 +               * Do not complain the most common case
 +               *      git checkout branch
 +               * even if there happen to be a file called 'branch';
 +               * it would be extremely annoying.
 +               */
 +              if (argc)
 +                      verify_non_filename(NULL, arg);
 +      } else {
 +              argcount++;
 +              argv++;
 +              argc--;
 +      }
 +
 +      return argcount;
 +}
 +
  int cmd_checkout(int argc, const char **argv, const char *prefix)
  {
        struct checkout_opts opts;
        unsigned char rev[20];
 -      const char *arg;
        struct branch_info new;
        struct tree *source_tree = NULL;
        char *conflict_style = NULL;
        int patch_mode = 0;
        int dwim_new_local_branch = 1;
        struct option options[] = {
 -              OPT__QUIET(&opts.quiet),
 +              OPT__QUIET(&opts.quiet, "suppress progress reporting"),
                OPT_STRING('b', NULL, &opts.new_branch, "branch",
                           "create and checkout a new branch"),
                OPT_STRING('B', NULL, &opts.new_branch_force, "branch",
                           "create/reset and checkout a branch"),
 -              OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
 -              OPT_SET_INT('t', "track",  &opts.track, "track",
 +              OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "create reflog for new branch"),
 +              OPT_BOOLEAN(0, "detach", &opts.force_detach, "detach the HEAD at named commit"),
 +              OPT_SET_INT('t', "track",  &opts.track, "set upstream info for new branch",
                        BRANCH_TRACK_EXPLICIT),
                OPT_STRING(0, "orphan", &opts.new_orphan_branch, "new branch", "new unparented branch"),
 -              OPT_SET_INT('2', "ours", &opts.writeout_stage, "stage",
 +              OPT_SET_INT('2', "ours", &opts.writeout_stage, "checkout our version for unmerged files",
                            2),
 -              OPT_SET_INT('3', "theirs", &opts.writeout_stage, "stage",
 +              OPT_SET_INT('3', "theirs", &opts.writeout_stage, "checkout their version for unmerged files",
                            3),
 -              OPT_BOOLEAN('f', "force", &opts.force, "force"),
 -              OPT_BOOLEAN('m', "merge", &opts.merge, "merge"),
 +              OPT__FORCE(&opts.force, "force checkout (throw away local modifications)"),
 +              OPT_BOOLEAN('m', "merge", &opts.merge, "perform a 3-way merge with the new branch"),
                OPT_STRING(0, "conflict", &conflict_style, "style",
                           "conflict style (merge or diff3)"),
                OPT_BOOLEAN('p', "patch", &patch_mode, "select hunks interactively"),
                  PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
                OPT_END(),
        };
 -      int has_dash_dash;
  
        memset(&opts, 0, sizeof(opts));
        memset(&new, 0, sizeof(new));
  
 -      git_config(git_checkout_config, NULL);
 +      gitmodules_config();
 +      git_config(git_checkout_config, &opts);
  
        opts.track = BRANCH_TRACK_UNSPECIFIED;
  
  
        /* we can assume from now on new_branch = !new_branch_force */
        if (opts.new_branch && opts.new_branch_force)
 -              die("-B cannot be used with -b");
 +              die(_("-B cannot be used with -b"));
  
        /* copy -B over to -b, so that we can just check the latter */
        if (opts.new_branch_force)
                opts.new_branch = opts.new_branch_force;
  
        if (patch_mode && (opts.track > 0 || opts.new_branch
 -                         || opts.new_branch_log || opts.merge || opts.force))
 -              die ("--patch is incompatible with all other options");
 +                         || opts.new_branch_log || opts.merge || opts.force
 +                         || opts.force_detach))
 +              die (_("--patch is incompatible with all other options"));
 +
 +      if (opts.force_detach && (opts.new_branch || opts.new_orphan_branch))
 +              die(_("--detach cannot be used with -b/-B/--orphan"));
 +      if (opts.force_detach && 0 < opts.track)
 +              die(_("--detach cannot be used with -t"));
  
        /* --track without -b should DWIM */
        if (0 < opts.track && !opts.new_branch) {
                const char *argv0 = argv[0];
                if (!argc || !strcmp(argv0, "--"))
 -                      die ("--track needs a branch name");
 +                      die (_("--track needs a branch name"));
                if (!prefixcmp(argv0, "refs/"))
                        argv0 += 5;
                if (!prefixcmp(argv0, "remotes/"))
                        argv0 += 8;
                argv0 = strchr(argv0, '/');
                if (!argv0 || !argv0[1])
 -                      die ("Missing branch name; try -b");
 +                      die (_("Missing branch name; try -b"));
                opts.new_branch = argv0 + 1;
        }
  
        if (opts.new_orphan_branch) {
                if (opts.new_branch)
 -                      die("--orphan and -b|-B are mutually exclusive");
 +                      die(_("--orphan and -b|-B are mutually exclusive"));
                if (opts.track > 0)
 -                      die("--orphan cannot be used with -t");
 +                      die(_("--orphan cannot be used with -t"));
                opts.new_branch = opts.new_orphan_branch;
        }
  
        }
  
        if (opts.force && opts.merge)
 -              die("git checkout: -f and -m are incompatible");
 +              die(_("git checkout: -f and -m are incompatible"));
  
        /*
 -       * case 1: git checkout <ref> -- [<paths>]
 -       *
 -       *   <ref> must be a valid tree, everything after the '--' must be
 -       *   a path.
 -       *
 -       * case 2: git checkout -- [<paths>]
 +       * Extract branch name from command line arguments, so
 +       * all that is left is pathspecs.
         *
 -       *   everything after the '--' must be paths.
 +       * Handle
         *
 -       * case 3: git checkout <something> [<paths>]
 -       *
 -       *   With no paths, if <something> is a commit, that is to
 -       *   switch to the branch or detach HEAD at it.  As a special case,
 -       *   if <something> is A...B (missing A or B means HEAD but you can
 -       *   omit at most one side), and if there is a unique merge base
 -       *   between A and B, A...B names that merge base.
 -       *
 -       *   With no paths, if <something> is _not_ a commit, no -t nor -b
 -       *   was given, and there is a tracking branch whose name is
 -       *   <something> in one and only one remote, then this is a short-hand
 -       *   to fork local <something> from that remote tracking branch.
 -       *
 -       *   Otherwise <something> shall not be ambiguous.
 -       *   - If it's *only* a reference, treat it like case (1).
 -       *   - If it's only a path, treat it like case (2).
 -       *   - else: fail.
 +       *  1) git checkout <tree> -- [<paths>]
 +       *  2) git checkout -- [<paths>]
 +       *  3) git checkout <something> [<paths>]
         *
 +       * including "last branch" syntax and DWIM-ery for names of
 +       * remote branches, erroring out for invalid or ambiguous cases.
         */
        if (argc) {
 -              if (!strcmp(argv[0], "--")) {       /* case (2) */
 -                      argv++;
 -                      argc--;
 -                      goto no_reference;
 -              }
 -
 -              arg = argv[0];
 -              has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
 -
 -              if (!strcmp(arg, "-"))
 -                      arg = "@{-1}";
 -
 -              if (get_sha1_mb(arg, rev)) {
 -                      if (has_dash_dash)          /* case (1) */
 -                              die("invalid reference: %s", arg);
 -                      if (!patch_mode &&
 -                          dwim_new_local_branch &&
 -                          opts.track == BRANCH_TRACK_UNSPECIFIED &&
 -                          !opts.new_branch &&
 -                          !check_filename(NULL, arg) &&
 -                          argc == 1) {
 -                              const char *remote = unique_tracking_name(arg);
 -                              if (!remote || get_sha1(remote, rev))
 -                                      goto no_reference;
 -                              opts.new_branch = arg;
 -                              arg = remote;
 -                              /* DWIMmed to create local branch */
 -                      }
 -                      else
 -                              goto no_reference;
 -              }
 -
 -              /* we can't end up being in (2) anymore, eat the argument */
 -              argv++;
 -              argc--;
 -
 -              new.name = arg;
 -              if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
 -                      setup_branch_path(&new);
 -
 -                      if ((check_ref_format(new.path) == CHECK_REF_FORMAT_OK) &&
 -                          resolve_ref(new.path, rev, 1, NULL))
 -                              ;
 -                      else
 -                              new.path = NULL;
 -                      parse_commit(new.commit);
 -                      source_tree = new.commit->tree;
 -              } else
 -                      source_tree = parse_tree_indirect(rev);
 -
 -              if (!source_tree)                   /* case (1): want a tree */
 -                      die("reference is not a tree: %s", arg);
 -              if (!has_dash_dash) {/* case (3 -> 1) */
 -                      /*
 -                       * Do not complain the most common case
 -                       *      git checkout branch
 -                       * even if there happen to be a file called 'branch';
 -                       * it would be extremely annoying.
 -                       */
 -                      if (argc)
 -                              verify_non_filename(NULL, arg);
 -              }
 -              else {
 -                      argv++;
 -                      argc--;
 -              }
 +              int dwim_ok =
 +                      !patch_mode &&
 +                      dwim_new_local_branch &&
 +                      opts.track == BRANCH_TRACK_UNSPECIFIED &&
 +                      !opts.new_branch;
 +              int n = parse_branchname_arg(argc, argv, dwim_ok,
 +                              &new, &source_tree, rev, &opts.new_branch);
 +              argv += n;
 +              argc -= n;
        }
  
 -no_reference:
 -
        if (opts.track == BRANCH_TRACK_UNSPECIFIED)
                opts.track = git_branch_track;
  
                const char **pathspec = get_pathspec(prefix, argv);
  
                if (!pathspec)
 -                      die("invalid path specification");
 +                      die(_("invalid path specification"));
  
                if (patch_mode)
                        return interactive_checkout(new.name, pathspec, &opts);
                /* Checkout paths */
                if (opts.new_branch) {
                        if (argc == 1) {
 -                              die("git checkout: updating paths is incompatible with switching branches.\nDid you intend to checkout '%s' which can not be resolved as commit?", argv[0]);
 +                              die(_("git checkout: updating paths is incompatible with switching branches.\nDid you intend to checkout '%s' which can not be resolved as commit?"), argv[0]);
                        } else {
 -                              die("git checkout: updating paths is incompatible with switching branches.");
 +                              die(_("git checkout: updating paths is incompatible with switching branches."));
                        }
                }
  
 +              if (opts.force_detach)
 +                      die(_("git checkout: --detach does not take a path argument"));
 +
                if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
 -                      die("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index.");
 +                      die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index."));
  
                return checkout_paths(source_tree, pathspec, &opts);
        }
        if (opts.new_branch) {
                struct strbuf buf = STRBUF_INIT;
                if (strbuf_check_branch_ref(&buf, opts.new_branch))
 -                      die("git checkout: we do not like '%s' as a branch name.",
 +                      die(_("git checkout: we do not like '%s' as a branch name."),
                            opts.new_branch);
-               if (!get_sha1(buf.buf, rev)) {
+               if (ref_exists(buf.buf)) {
                        opts.branch_exists = 1;
                        if (!opts.new_branch_force)
 -                              die("git checkout: branch %s already exists",
 +                              die(_("git checkout: branch %s already exists"),
                                    opts.new_branch);
                }
                strbuf_release(&buf);
        }
  
        if (new.name && !new.commit) {
 -              die("Cannot switch branch to a non-commit.");
 +              die(_("Cannot switch branch to a non-commit."));
        }
        if (opts.writeout_stage)
 -              die("--ours/--theirs is incompatible with switching branches.");
 +              die(_("--ours/--theirs is incompatible with switching branches."));
  
        return switch_branches(&opts, &new);
  }
diff --combined refs.c
index b10419a69815ef1c005915f3606c992659e60c77,92cd0d14c32de85b35fff22cab3dd82e4bd2b757..3a8789d3857d17a3a0a94ba2750e9f22857b8667
--- 1/refs.c
--- 2/refs.c
+++ b/refs.c
@@@ -157,7 -157,7 +157,7 @@@ static struct cached_refs 
        char did_packed;
        struct ref_list *loose;
        struct ref_list *packed;
 -} cached_refs;
 +} cached_refs, submodule_refs;
  static struct ref_list *current_ref;
  
  static struct ref_list *extra_refs;
@@@ -229,45 -229,23 +229,45 @@@ void clear_extra_refs(void
        extra_refs = NULL;
  }
  
 -static struct ref_list *get_packed_refs(void)
 +static struct ref_list *get_packed_refs(const char *submodule)
  {
 -      if (!cached_refs.did_packed) {
 -              FILE *f = fopen(git_path("packed-refs"), "r");
 -              cached_refs.packed = NULL;
 +      const char *packed_refs_file;
 +      struct cached_refs *refs;
 +
 +      if (submodule) {
 +              packed_refs_file = git_path_submodule(submodule, "packed-refs");
 +              refs = &submodule_refs;
 +              free_ref_list(refs->packed);
 +      } else {
 +              packed_refs_file = git_path("packed-refs");
 +              refs = &cached_refs;
 +      }
 +
 +      if (!refs->did_packed || submodule) {
 +              FILE *f = fopen(packed_refs_file, "r");
 +              refs->packed = NULL;
                if (f) {
 -                      read_packed_refs(f, &cached_refs);
 +                      read_packed_refs(f, refs);
                        fclose(f);
                }
 -              cached_refs.did_packed = 1;
 +              refs->did_packed = 1;
        }
 -      return cached_refs.packed;
 +      return refs->packed;
  }
  
 -static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 +static struct ref_list *get_ref_dir(const char *submodule, const char *base,
 +                                  struct ref_list *list)
  {
 -      DIR *dir = opendir(git_path("%s", base));
 +      DIR *dir;
 +      const char *path;
 +
 +      if (submodule)
 +              path = git_path_submodule(submodule, "%s", base);
 +      else
 +              path = git_path("%s", base);
 +
 +
 +      dir = opendir(path);
  
        if (dir) {
                struct dirent *de;
                        struct stat st;
                        int flag;
                        int namelen;
 +                      const char *refdir;
  
                        if (de->d_name[0] == '.')
                                continue;
                        if (has_extension(de->d_name, ".lock"))
                                continue;
                        memcpy(ref + baselen, de->d_name, namelen+1);
 -                      if (stat(git_path("%s", ref), &st) < 0)
 +                      refdir = submodule
 +                              ? git_path_submodule(submodule, "%s", ref)
 +                              : git_path("%s", ref);
 +                      if (stat(refdir, &st) < 0)
                                continue;
                        if (S_ISDIR(st.st_mode)) {
 -                              list = get_ref_dir(ref, list);
 +                              list = get_ref_dir(submodule, ref, list);
                                continue;
                        }
 -                      if (!resolve_ref(ref, sha1, 1, &flag)) {
 +                      if (submodule) {
                                hashclr(sha1);
 -                              flag |= REF_BROKEN;
 -                      }
 +                              flag = 0;
 +                              if (resolve_gitlink_ref(submodule, ref, sha1) < 0) {
 +                                      hashclr(sha1);
 +                                      flag |= REF_BROKEN;
 +                              }
 +                      } else
 +                              if (!resolve_ref(ref, sha1, 1, &flag)) {
 +                                      hashclr(sha1);
 +                                      flag |= REF_BROKEN;
 +                              }
                        list = add_ref(ref, sha1, flag, list, NULL);
                }
                free(ref);
@@@ -356,16 -322,10 +356,16 @@@ void warn_dangling_symref(FILE *fp, con
        for_each_rawref(warn_if_dangling_symref, &data);
  }
  
 -static struct ref_list *get_loose_refs(void)
 +static struct ref_list *get_loose_refs(const char *submodule)
  {
 +      if (submodule) {
 +              free_ref_list(submodule_refs.loose);
 +              submodule_refs.loose = get_ref_dir(submodule, "refs", NULL);
 +              return submodule_refs.loose;
 +      }
 +
        if (!cached_refs.did_loose) {
 -              cached_refs.loose = get_ref_dir("refs", NULL);
 +              cached_refs.loose = get_ref_dir(NULL, "refs", NULL);
                cached_refs.did_loose = 1;
        }
        return cached_refs.loose;
@@@ -499,7 -459,7 +499,7 @@@ const char *resolve_ref(const char *ref
                git_snpath(path, sizeof(path), "%s", ref);
                /* Special case: non-existing file. */
                if (lstat(path, &st) < 0) {
 -                      struct ref_list *list = get_packed_refs();
 +                      struct ref_list *list = get_packed_refs(NULL);
                        while (list) {
                                if (!strcmp(ref, list->name)) {
                                        hashcpy(sha1, list->sha1);
@@@ -628,7 -588,7 +628,7 @@@ int peel_ref(const char *ref, unsigned 
                return -1;
  
        if ((flag & REF_ISPACKED)) {
 -              struct ref_list *list = get_packed_refs();
 +              struct ref_list *list = get_packed_refs(NULL);
  
                while (list) {
                        if (!strcmp(list->name, ref)) {
@@@ -655,12 -615,12 +655,12 @@@ fallback
        return -1;
  }
  
 -static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 -                         int flags, void *cb_data)
 +static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
 +                         int trim, int flags, void *cb_data)
  {
        int retval = 0;
 -      struct ref_list *packed = get_packed_refs();
 -      struct ref_list *loose = get_loose_refs();
 +      struct ref_list *packed = get_packed_refs(submodule);
 +      struct ref_list *loose = get_loose_refs(submodule);
  
        struct ref_list *extra;
  
@@@ -697,54 -657,24 +697,54 @@@ end_each
        return retval;
  }
  
 -int head_ref(each_ref_fn fn, void *cb_data)
 +
 +static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
  {
        unsigned char sha1[20];
        int flag;
  
 +      if (submodule) {
 +              if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
 +                      return fn("HEAD", sha1, 0, cb_data);
 +
 +              return 0;
 +      }
 +
        if (resolve_ref("HEAD", sha1, 1, &flag))
                return fn("HEAD", sha1, flag, cb_data);
 +
        return 0;
  }
  
 +int head_ref(each_ref_fn fn, void *cb_data)
 +{
 +      return do_head_ref(NULL, fn, cb_data);
 +}
 +
 +int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 +{
 +      return do_head_ref(submodule, fn, cb_data);
 +}
 +
  int for_each_ref(each_ref_fn fn, void *cb_data)
  {
 -      return do_for_each_ref("refs/", fn, 0, 0, cb_data);
 +      return do_for_each_ref(NULL, "refs/", fn, 0, 0, cb_data);
 +}
 +
 +int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 +{
 +      return do_for_each_ref(submodule, "refs/", fn, 0, 0, cb_data);
  }
  
  int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
  {
 -      return do_for_each_ref(prefix, fn, strlen(prefix), 0, cb_data);
 +      return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
 +}
 +
 +int for_each_ref_in_submodule(const char *submodule, const char *prefix,
 +              each_ref_fn fn, void *cb_data)
 +{
 +      return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
  }
  
  int for_each_tag_ref(each_ref_fn fn, void *cb_data)
        return for_each_ref_in("refs/tags/", fn, cb_data);
  }
  
 +int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 +{
 +      return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 +}
 +
  int for_each_branch_ref(each_ref_fn fn, void *cb_data)
  {
        return for_each_ref_in("refs/heads/", fn, cb_data);
  }
  
 +int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 +{
 +      return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 +}
 +
  int for_each_remote_ref(each_ref_fn fn, void *cb_data)
  {
        return for_each_ref_in("refs/remotes/", fn, cb_data);
  }
  
 +int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 +{
 +      return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 +}
 +
  int for_each_replace_ref(each_ref_fn fn, void *cb_data)
  {
 -      return do_for_each_ref("refs/replace/", fn, 13, 0, cb_data);
 +      return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
  }
  
  int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
@@@ -819,7 -734,7 +819,7 @@@ int for_each_glob_ref(each_ref_fn fn, c
  
  int for_each_rawref(each_ref_fn fn, void *cb_data)
  {
 -      return do_for_each_ref("refs/", fn, 0,
 +      return do_for_each_ref(NULL, "refs/", fn, 0,
                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
  }
  
@@@ -1043,7 -958,7 +1043,7 @@@ static struct ref_lock *lock_ref_sha1_b
         * name is a proper prefix of our refname.
         */
        if (missing &&
 -           !is_refname_available(ref, NULL, get_packed_refs(), 0)) {
 +           !is_refname_available(ref, NULL, get_packed_refs(NULL), 0)) {
                last_errno = ENOTDIR;
                goto error_return;
        }
@@@ -1106,7 -1021,7 +1106,7 @@@ static int repack_without_ref(const cha
        int fd;
        int found = 0;
  
 -      packed_ref_list = get_packed_refs();
 +      packed_ref_list = get_packed_refs(NULL);
        for (list = packed_ref_list; list; list = list->next) {
                if (!strcmp(refname, list->name)) {
                        found = 1;
@@@ -1175,15 -1090,6 +1175,15 @@@ int delete_ref(const char *refname, con
        return ret;
  }
  
 +/*
 + * People using contrib's git-new-workdir have .git/logs/refs ->
 + * /some/other/path/.git/logs/refs, and that may live on another device.
 + *
 + * IOW, to avoid cross device rename errors, the temporary renamed log must
 + * live into logs/refs.
 + */
 +#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
 +
  int rename_ref(const char *oldref, const char *newref, const char *logmsg)
  {
        static const char renamed_ref[] = "RENAMED-REF";
        if (!symref)
                return error("refname %s not found", oldref);
  
 -      if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
 +      if (!is_refname_available(newref, oldref, get_packed_refs(NULL), 0))
                return 1;
  
 -      if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
 +      if (!is_refname_available(newref, oldref, get_loose_refs(NULL), 0))
                return 1;
  
        lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
        if (write_ref_sha1(lock, orig_sha1, logmsg))
                return error("unable to save current sha1 in %s", renamed_ref);
  
 -      if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
 -              return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
 +      if (log && rename(git_path("logs/%s", oldref), git_path(TMP_RENAMED_LOG)))
 +              return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
                        oldref, strerror(errno));
  
        if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
        }
  
   retry:
 -      if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
 +      if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newref))) {
                if (errno==EISDIR || errno==ENOTDIR) {
                        /*
                         * rename(a, b) when b is an existing
                        }
                        goto retry;
                } else {
 -                      error("unable to move logfile tmp-renamed-log to logs/%s: %s",
 +                      error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
                                newref, strerror(errno));
                        goto rollback;
                }
                error("unable to restore logfile %s from %s: %s",
                        oldref, newref, strerror(errno));
        if (!logmoved && log &&
 -          rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
 -              error("unable to restore logfile %s from tmp-renamed-log: %s",
 +          rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldref)))
 +              error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
                        oldref, strerror(errno));
  
        return 1;
@@@ -1451,7 -1357,7 +1451,7 @@@ int write_ref_sha1(struct ref_lock *loc
        }
        o = parse_object(sha1);
        if (!o) {
 -              error("Trying to write ref %s with nonexistant object %s",
 +              error("Trying to write ref %s with nonexistent object %s",
                        lock->ref_name, sha1_to_hex(sha1));
                unlock_ref(lock);
                return -1;
@@@ -1826,6 -1732,12 +1826,12 @@@ int update_ref(const char *action, cons
        return 0;
  }
  
+ int ref_exists(char *refname)
+ {
+       unsigned char sha1[20];
+       return !!resolve_ref(refname, sha1, 1, NULL);
+ }
  struct ref *find_ref_by_name(const struct ref *list, const char *name)
  {
        for ( ; list; list = list->next)
diff --combined refs.h
index 5e7a9a59f5f6b687d15eb37a11696433bdc8f15c,070a7d9caa53f94cbbad984c3d8ae2c3fbfe7b87..5de06e57e7a9644a7dd51832552e9d1afa53c8cd
--- 1/refs.h
--- 2/refs.h
+++ b/refs.h
@@@ -28,14 -28,6 +28,14 @@@ extern int for_each_replace_ref(each_re
  extern int for_each_glob_ref(each_ref_fn, const char *pattern, void *);
  extern int for_each_glob_ref_in(each_ref_fn, const char *pattern, const char* prefix, void *);
  
 +extern int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data);
 +extern int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data);
 +extern int for_each_ref_in_submodule(const char *submodule, const char *prefix,
 +              each_ref_fn fn, void *cb_data);
 +extern int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data);
 +extern int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data);
 +extern int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data);
 +
  static inline const char *has_glob_specials(const char *pattern)
  {
        return strpbrk(pattern, "?*[");
@@@ -54,6 -46,7 +54,7 @@@ extern void warn_dangling_symref(FILE *
   */
  extern void add_extra_ref(const char *refname, const unsigned char *sha1, int flags);
  extern void clear_extra_refs(void);
+ extern int ref_exists(char *);
  
  extern int peel_ref(const char *, unsigned char *);
  
index fa69016381b0196c49472af51e36948ec7c5a2a9,741d84257b5704b059074d5376cd10f3d358daba..a42e03967b1df3001df24089f2c50008c092ac51
@@@ -124,12 -124,6 +124,12 @@@ test_expect_success 'checkout -B to an 
        do_checkout branch2 "" -B
  '
  
 +test_expect_success 'checkout -B to an existing branch from detached HEAD resets branch to HEAD' '
 +      git checkout $(git rev-parse --verify HEAD) &&
 +
 +      do_checkout branch2 "" -B
 +'
 +
  test_expect_success 'checkout -B to an existing branch with an explicit ref resets branch to that ref' '
        git checkout branch1 &&
  
@@@ -169,4 -163,15 +169,15 @@@ test_expect_success 'checkout -f -B to 
        test_must_fail test_dirty_mergeable
  '
  
+ test_expect_success 'checkout -b <describe>' '
+       git tag -f -m "First commit" initial initial &&
+       git checkout -f change1 &&
+       name=$(git describe) &&
+       git checkout -b $name &&
+       git diff --exit-code change1 &&
+       echo "refs/heads/$name" >expect &&
+       git symbolic-ref HEAD >actual &&
+       test_cmp expect actual
+ '
  test_done