Merge commit 'v1.7.6' into jc/checkout-reflog-fix

* commit 'v1.7.6': (3211 commits)
  Git 1.7.6
  completion: replace core.abbrevguard to core.abbrev
  Git 1.7.6-rc3
  Documentation: git diff --check respects core.whitespace
  gitweb: 'pickaxe' and 'grep' features requires 'search' to be enabled
  t7810: avoid unportable use of "echo"
  plug a few coverity-spotted leaks
  builtin/gc.c: add missing newline in message
  tests: link shell libraries into valgrind directory
  t/Makefile: pass test opts to valgrind target properly
  sh-i18n--envsubst.c: do not #include getopt.h
  Fix typo: existant->existent
  Git 1.7.6-rc2
  gitweb: do not misparse nonnumeric content tag files that contain a digit
  Git 1.7.6-rc1
  fetch: do not leak a refspec
  t3703: skip more tests using colons in file names on Windows
  gitweb: Fix usability of $prevent_xss
  gitweb: Move "Requirements" up in gitweb/INSTALL
  gitweb: Describe CSSMIN and JSMIN in gitweb/INSTALL
  ...

diff --cc builtin/checkout.c
index 0000000000000000000000000000000000000000,28cdc51b85e7d433dca085c0080f964d19a391b4..48de146b734af3dfe0a77bb285bb19bd47061993
mode 000000,100644..100644
--- /dev/null
--- 2/builtin/checkout.c
+++ b/builtin/checkout.c
@@@ -1,0 -1,1090 +1,1093 @@@
 -      old.path = resolve_ref("HEAD", rev, 0, &flag);
+ #include "cache.h"
+ #include "builtin.h"
+ #include "parse-options.h"
+ #include "refs.h"
+ #include "commit.h"
+ #include "tree.h"
+ #include "tree-walk.h"
+ #include "cache-tree.h"
+ #include "unpack-trees.h"
+ #include "dir.h"
+ #include "run-command.h"
+ #include "merge-recursive.h"
+ #include "branch.h"
+ #include "diff.h"
+ #include "revision.h"
+ #include "remote.h"
+ #include "blob.h"
+ #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>",
+       "git checkout [options] [<branch>] -- <file>...",
+       NULL,
+ };
+ 
+ struct checkout_opts {
+       int quiet;
+       int merge;
+       int force;
+       int force_detach;
+       int writeout_stage;
+       int writeout_error;
+ 
+       /* not set by parse_options */
+       int branch_exists;
+ 
+       const char *new_branch;
+       const char *new_branch_force;
+       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,
+                             int changed)
+ {
+       return run_hook(NULL, "post-checkout",
+                       sha1_to_hex(old ? old->object.sha1 : null_sha1),
+                       sha1_to_hex(new ? new->object.sha1 : null_sha1),
+                       changed ? "1" : "0", NULL);
+       /* "new" can be NULL when checking out from the index before
+          a commit exists. */
+ 
+ }
+ 
+ static int update_some(const unsigned char *sha1, const char *base, int baselen,
+               const char *pathname, unsigned mode, int stage, void *context)
+ {
+       int len;
+       struct cache_entry *ce;
+ 
+       if (S_ISDIR(mode))
+               return READ_TREE_RECURSIVE;
+ 
+       len = baselen + strlen(pathname);
+       ce = xcalloc(1, cache_entry_size(len));
+       hashcpy(ce->sha1, sha1);
+       memcpy(ce->name, base, baselen);
+       memcpy(ce->name + baselen, pathname, len - baselen);
+       ce->ce_flags = create_ce_flags(len, 0);
+       ce->ce_mode = create_ce_mode(mode);
+       add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
+       return 0;
+ }
+ 
+ static int read_tree_some(struct tree *tree, const char **pathspec)
+ {
+       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
+        * with any non-zero return code.
+        */
+       return 0;
+ }
+ 
+ static int skip_same_name(struct cache_entry *ce, int pos)
+ {
+       while (++pos < active_nr &&
+              !strcmp(active_cache[pos]->name, ce->name))
+               ; /* skip */
+       return pos;
+ }
+ 
+ static int check_stage(int stage, struct cache_entry *ce, int pos)
+ {
+       while (pos < active_nr &&
+              !strcmp(active_cache[pos]->name, ce->name)) {
+               if (ce_stage(active_cache[pos]) == stage)
+                       return 0;
+               pos++;
+       }
+       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)
+ {
+       if (ce_stage(ce) != 1 ||
+           active_nr <= pos + 2 ||
+           strcmp(active_cache[pos+1]->name, ce->name) ||
+           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"),
+                            ce->name);
+       return 0;
+ }
+ 
+ static int checkout_stage(int stage, struct cache_entry *ce, int pos,
+                         struct checkout *state)
+ {
+       while (pos < active_nr &&
+              !strcmp(active_cache[pos]->name, ce->name)) {
+               if (ce_stage(active_cache[pos]) == stage)
+                       return checkout_entry(active_cache[pos], state, NULL);
+               pos++;
+       }
+       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)
+ {
+       struct cache_entry *ce = active_cache[pos];
+       const char *path = ce->name;
+       mmfile_t ancestor, ours, theirs;
+       int status;
+       unsigned char sha1[20];
+       mmbuffer_t result_buf;
+ 
+       if (ce_stage(ce) != 1 ||
+           active_nr <= pos + 2 ||
+           strcmp(active_cache[pos+1]->name, path) ||
+           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);
+ 
+       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", 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);
+       }
+ 
+       /*
+        * NEEDSWORK:
+        * There is absolutely no reason to write this as a blob object
+        * and create a phony cache entry just to leak.  This hack is
+        * primarily to get to the write_entry() machinery that massages
+        * the contents to work-tree format and writes out which only
+        * allows it for a cache entry.  The code in write_entry() needs
+        * to be refactored to allow us to feed a <buffer, size, mode>
+        * instead of a cache entry.  Such a refactoring would help
+        * merge_recursive as well (it also writes the merge result to the
+        * object database even when it may contain conflicts).
+        */
+       if (write_sha1_file(result_buf.ptr, result_buf.size,
+                           blob_type, sha1))
+               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);
+       status = checkout_entry(ce, state, NULL);
+       return status;
+ }
+ 
+ static int checkout_paths(struct tree *source_tree, const char **pathspec,
+                         struct checkout_opts *opts)
+ {
+       int pos;
+       struct checkout state;
+       static char *ps_matched;
+       unsigned char rev[20];
+       int flag;
+       struct commit *head;
+       int errs = 0;
+       int stage = opts->writeout_stage;
+       int merge = opts->merge;
+       int newfd;
+       struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+ 
+       newfd = hold_locked_index(lock_file, 1);
+       if (read_cache_preload(pathspec) < 0)
+               return error(_("corrupt index file"));
+ 
+       if (source_tree)
+               read_tree_some(source_tree, pathspec);
+ 
+       for (pos = 0; pathspec[pos]; pos++)
+               ;
+       ps_matched = xcalloc(1, pos);
+ 
+       for (pos = 0; pos < active_nr; pos++) {
+               struct cache_entry *ce = active_cache[pos];
+               match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, ps_matched);
+       }
+ 
+       if (report_path_error(ps_matched, pathspec, 0))
+               return 1;
+ 
+       /* "checkout -m path" to recreate conflicted state */
+       if (opts->merge)
+               unmerge_cache(pathspec);
+ 
+       /* Any unmerged paths? */
+       for (pos = 0; pos < active_nr; pos++) {
+               struct cache_entry *ce = active_cache[pos];
+               if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
+                       if (!ce_stage(ce))
+                               continue;
+                       if (opts->force) {
+                               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);
+                       }
+                       pos = skip_same_name(ce, pos) - 1;
+               }
+       }
+       if (errs)
+               return 1;
+ 
+       /* Now we are committed to check them out */
+       memset(&state, 0, sizeof(state));
+       state.force = 1;
+       state.refresh_cache = 1;
+       for (pos = 0; pos < active_nr; pos++) {
+               struct cache_entry *ce = active_cache[pos];
+               if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
+                       if (!ce_stage(ce)) {
+                               errs |= checkout_entry(ce, &state, NULL);
+                               continue;
+                       }
+                       if (stage)
+                               errs |= checkout_stage(stage, ce, pos, &state);
+                       else if (merge)
+                               errs |= checkout_merged(pos, &state);
+                       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"));
+ 
+       resolve_ref("HEAD", rev, 0, &flag);
+       head = lookup_commit_reference_gently(rev, 1);
+ 
+       errs |= post_checkout_hook(head, head, 0);
+       return errs;
+ }
+ 
+ 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.diffopt.flags = opts->flags;
+       rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
+       if (diff_setup_done(&rev.diffopt) < 0)
+               die(_("diff_setup_done failed"));
+       add_pending_object(&rev, head, NULL);
+       run_diff_index(&rev, 0);
+ }
+ 
+ static void describe_detached_head(const char *msg, struct commit *commit)
+ {
+       struct strbuf sb = STRBUF_INIT;
+       parse_commit(commit);
+       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);
+ }
+ 
+ static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
+ {
+       struct unpack_trees_options opts;
+       struct tree_desc tree_desc;
+ 
+       memset(&opts, 0, sizeof(opts));
+       opts.head_idx = -1;
+       opts.update = worktree;
+       opts.skip_unmerged = !worktree;
+       opts.reset = 1;
+       opts.merge = 1;
+       opts.fn = oneway_merge;
+       opts.verbose_update = !o->quiet;
+       opts.src_index = &the_index;
+       opts.dst_index = &the_index;
+       parse_tree(tree);
+       init_tree_desc(&tree_desc, tree->buffer, tree->size);
+       switch (unpack_trees(1, &tree_desc, &opts)) {
+       case -2:
+               o->writeout_error = 1;
+               /*
+                * We return 0 nevertheless, as the index is all right
+                * and more importantly we have made best efforts to
+                * update paths in the work tree, and we cannot revert
+                * them.
+                */
+       case 0:
+               return 0;
+       default:
+               return 128;
+       }
+ }
+ 
+ struct branch_info {
+       const char *name; /* The short name used */
+       const char *path; /* The full name of a real branch */
+       struct commit *commit; /* The named commit */
+ };
+ 
+ static void setup_branch_path(struct branch_info *branch)
+ {
+       struct strbuf buf = STRBUF_INIT;
+ 
+       strbuf_branchname(&buf, branch->name);
+       if (strcmp(buf.buf, branch->name))
+               branch->name = xstrdup(buf.buf);
+       strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
+       branch->path = strbuf_detach(&buf, NULL);
+ }
+ 
+ static int merge_working_tree(struct checkout_opts *opts,
+                             struct branch_info *old, struct branch_info *new)
+ {
+       int ret;
+       struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
+       int newfd = hold_locked_index(lock_file, 1);
+ 
+       if (read_cache_preload(NULL) < 0)
+               return error(_("corrupt index file"));
+ 
+       resolve_undo_clear();
+       if (opts->force) {
+               ret = reset_tree(new->commit->tree, opts, 1);
+               if (ret)
+                       return ret;
+       } else {
+               struct tree_desc trees[2];
+               struct tree *tree;
+               struct unpack_trees_options topts;
+ 
+               memset(&topts, 0, sizeof(topts));
+               topts.head_idx = -1;
+               topts.src_index = &the_index;
+               topts.dst_index = &the_index;
+ 
+               setup_unpack_trees_porcelain(&topts, "checkout");
+ 
+               refresh_cache(REFRESH_QUIET);
+ 
+               if (unmerged_cache()) {
+                       error(_("you need to resolve your current index first"));
+                       return 1;
+               }
+ 
+               /* 2-way merge to the new branch */
+               topts.initial_checkout = is_cache_unborn();
+               topts.update = 1;
+               topts.merge = 1;
+               topts.gently = opts->merge && old->commit;
+               topts.verbose_update = !opts->quiet;
+               topts.fn = twoway_merge;
+               topts.dir = xcalloc(1, sizeof(*topts.dir));
+               topts.dir->flags |= DIR_SHOW_IGNORED;
+               topts.dir->exclude_per_dir = ".gitignore";
+               tree = parse_tree_indirect(old->commit ?
+                                          old->commit->object.sha1 :
+                                          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);
+ 
+               ret = unpack_trees(2, trees, &topts);
+               if (ret == -1) {
+                       /*
+                        * Unpack couldn't do a trivial merge; either
+                        * give up or do a real merge, depending on
+                        * whether the merge flag was used.
+                        */
+                       struct tree *result;
+                       struct tree *work;
+                       struct merge_options o;
+                       if (!opts->merge)
+                               return 1;
+ 
+                       /*
+                        * Without old->commit, the below is the same as
+                        * the two-tree unpack we already tried and failed.
+                        */
+                       if (!old->commit)
+                               return 1;
+ 
+                       /* Do more real merge */
+ 
+                       /*
+                        * We update the index fully, then write the
+                        * tree from the index, then merge the new
+                        * branch with the current tree, with the old
+                        * branch as the base. Then we reset the index
+                        * (but not the working tree) to the new
+                        * branch, leaving the working tree as the
+                        * merged version, but skipping unmerged
+                        * entries in the index.
+                        */
+ 
+                       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);
+ 
+                       ret = reset_tree(new->commit->tree, opts, 1);
+                       if (ret)
+                               return ret;
+                       o.ancestor = old->name;
+                       o.branch1 = new->name;
+                       o.branch2 = "local";
+                       merge_trees(&o, new->commit->tree, work,
+                               old->commit->tree, &result);
+                       ret = reset_tree(new->commit->tree, opts, 0);
+                       if (ret)
+                               return ret;
+               }
+       }
+ 
+       if (write_cache(newfd, active_cache, active_nr) ||
+           commit_locked_index(lock_file))
+               die(_("unable to write new index file"));
+ 
+       if (!opts->force && !opts->quiet)
+               show_local_changes(&new->commit->object, &opts->diff_options);
+ 
+       return 0;
+ }
+ 
+ static void report_tracking(struct branch_info *new)
+ {
+       struct strbuf sb = STRBUF_INIT;
+       struct branch *branch = branch_get(new->name);
+ 
+       if (!format_tracking_info(branch, &sb))
+               return;
+       fputs(sb.buf, stdout);
+       strbuf_release(&sb);
+ }
+ 
+ static void detach_advice(const char *old_path, const char *new_name)
+ {
+       const char fmt[] =
+       "Note: checking out '%s'.\n\n"
+       "You are in 'detached HEAD' state. You can look around, make experimental\n"
+       "changes and commit them, and you can discard any commits you make in this\n"
+       "state without impacting any branches by performing another checkout.\n\n"
+       "If you want to create a new branch to retain commits you create, you may\n"
+       "do so (now or later) by using -b with the checkout command again. Example:\n\n"
+       "  git checkout -b new_branch_name\n\n";
+ 
+       fprintf(stderr, fmt, new_name);
+ }
+ 
+ static void update_refs_for_switch(struct checkout_opts *opts,
+                                  struct branch_info *old,
+                                  struct branch_info *new)
+ {
+       struct strbuf msg = STRBUF_INIT;
+       const char *old_desc;
+       if (opts->new_branch) {
+               if (opts->new_orphan_branch) {
+                       if (opts->new_branch_log && !log_all_ref_updates) {
+                               int temp;
+                               char log_file[PATH_MAX];
+                               char *ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
+ 
+                               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"),
+                                           opts->new_orphan_branch);
+                                       log_all_ref_updates = temp;
+                                       return;
+                               }
+                               log_all_ref_updates = temp;
+                       }
+               }
+               else
+                       create_branch(old->name, opts->new_branch, new->name,
+                                     opts->new_branch_force ? 1 : 0,
+                                     opts->new_branch_log, opts->track);
+               new->name = opts->new_branch;
+               setup_branch_path(new);
+       }
+ 
+       old_desc = old->name;
+       if (!old_desc && old->commit)
+               old_desc = sha1_to_hex(old->commit->object.sha1);
+       strbuf_addf(&msg, "checkout: moving from %s to %s",
+                   old_desc ? old_desc : "(invalid)", new->name);
+ 
+       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"),
+                                       new->name);
+                       } 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];
+ 
+                       git_snpath(log_file, sizeof(log_file), "logs/%s", old->path);
+                       git_snpath(ref_file, sizeof(ref_file), "%s", old->path);
+                       if (!file_exists(ref_file) && file_exists(log_file))
+                               remove_path(log_file);
+               }
+       }
+       remove_branch_state();
+       strbuf_release(&msg);
+       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;
+       struct branch_info old;
+       unsigned char rev[20];
+       int flag;
+       memset(&old, 0, sizeof(old));
 -      if (!(flag & REF_ISSYMREF))
++      old.path = xstrdup(resolve_ref("HEAD", rev, 0, &flag));
+       old.commit = lookup_commit_reference_gently(rev, 1);
++      if (!(flag & REF_ISSYMREF)) {
++              free((char *)old.path);
+               old.path = NULL;
++      }
+ 
+       if (old.path && !prefixcmp(old.path, "refs/heads/"))
+               old.name = old.path + strlen("refs/heads/");
+ 
+       if (!new->name) {
+               new->name = "HEAD";
+               new->commit = old.commit;
+               if (!new->commit)
+                       die(_("You are on a branch yet to be born"));
+               parse_commit(new->commit);
+       }
+ 
+       ret = merge_working_tree(opts, &old, new);
+       if (ret)
+               return ret;
+ 
+       if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
+               orphaned_commit_warning(old.commit);
+ 
+       update_refs_for_switch(opts, &old, new);
+ 
+       ret = post_checkout_hook(old.commit, new->commit, 1);
++      free((char *)old.path);
+       return ret || opts->writeout_error;
+ }
+ 
+ static int git_checkout_config(const char *var, const char *value, void *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,
+                               struct checkout_opts *opts)
+ {
+       return run_add_interactive(revision, "--patch=checkout", pathspec);
+ }
+ 
+ struct tracking_name_data {
+       const char *name;
+       char *remote;
+       int unique;
+ };
+ 
+ static int check_tracking_name(const char *refname, const unsigned char *sha1,
+                              int flags, void *cb_data)
+ {
+       struct tracking_name_data *cb = cb_data;
+       const char *slash;
+ 
+       if (prefixcmp(refname, "refs/remotes/"))
+               return 0;
+       slash = strchr(refname + 13, '/');
+       if (!slash || strcmp(slash + 1, cb->name))
+               return 0;
+       if (cb->remote) {
+               cb->unique = 0;
+               return 0;
+       }
+       cb->remote = xstrdup(refname);
+       return 0;
+ }
+ 
+ static const char *unique_tracking_name(const char *name)
+ {
+       struct tracking_name_data cb_data = { NULL, NULL, 1 };
+       cb_data.name = name;
+       for_each_ref(check_tracking_name, &cb_data);
+       if (cb_data.unique)
+               return cb_data.remote;
+       free(cb_data.remote);
+       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];
+       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, "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, "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, "checkout our version for unmerged files",
+                           2),
+               OPT_SET_INT('3', "theirs", &opts.writeout_stage, "checkout their version for unmerged files",
+                           3),
+               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"),
+               { OPTION_BOOLEAN, 0, "guess", &dwim_new_local_branch, NULL,
+                 "second guess 'git checkout no-such-branch'",
+                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN },
+               OPT_END(),
+       };
+ 
+       memset(&opts, 0, sizeof(opts));
+       memset(&new, 0, sizeof(new));
+ 
+       gitmodules_config();
+       git_config(git_checkout_config, &opts);
+ 
+       opts.track = BRANCH_TRACK_UNSPECIFIED;
+ 
+       argc = parse_options(argc, argv, prefix, options, checkout_usage,
+                            PARSE_OPT_KEEP_DASHDASH);
+ 
+       /* 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"));
+ 
+       /* 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
+                          || 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"));
+               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"));
+               opts.new_branch = argv0 + 1;
+       }
+ 
+       if (opts.new_orphan_branch) {
+               if (opts.new_branch)
+                       die(_("--orphan and -b|-B are mutually exclusive"));
+               if (opts.track > 0)
+                       die(_("--orphan cannot be used with -t"));
+               opts.new_branch = opts.new_orphan_branch;
+       }
+ 
+       if (conflict_style) {
+               opts.merge = 1; /* implied */
+               git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
+       }
+ 
+       if (opts.force && opts.merge)
+               die(_("git checkout: -f and -m are incompatible"));
+ 
+       /*
+        * Extract branch name from command line arguments, so
+        * all that is left is pathspecs.
+        *
+        * Handle
+        *
+        *  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) {
+               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;
+       }
+ 
+       if (opts.track == BRANCH_TRACK_UNSPECIFIED)
+               opts.track = git_branch_track;
+ 
+       if (argc) {
+               const char **pathspec = get_pathspec(prefix, argv);
+ 
+               if (!pathspec)
+                       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]);
+                       } else {
+                               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."));
+ 
+               return checkout_paths(source_tree, pathspec, &opts);
+       }
+ 
+       if (patch_mode)
+               return interactive_checkout(new.name, NULL, &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."),
+                           opts.new_branch);
+               if (!get_sha1(buf.buf, rev)) {
+                       opts.branch_exists = 1;
+                       if (!opts.new_branch_force)
+                               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."));
+       }
+       if (opts.writeout_stage)
+               die(_("--ours/--theirs is incompatible with switching branches."));
+ 
+       return switch_branches(&opts, &new);
+ }