git.oblomov.eu Git - git/blob - builtin/checkout.c

   1 #include "builtin.h"
   2 #include "config.h"
   3 #include "lockfile.h"
   4 #include "parse-options.h"
   5 #include "refs.h"
   6 #include "commit.h"
   7 #include "tree.h"
   8 #include "tree-walk.h"
   9 #include "cache-tree.h"
  10 #include "unpack-trees.h"
  11 #include "dir.h"
  12 #include "run-command.h"
  13 #include "merge-recursive.h"
  14 #include "branch.h"
  15 #include "diff.h"
  16 #include "revision.h"
  17 #include "remote.h"
  18 #include "blob.h"
  19 #include "xdiff-interface.h"
  20 #include "ll-merge.h"
  21 #include "resolve-undo.h"
  22 #include "submodule-config.h"
  23 #include "submodule.h"
  24
  25 static const char * const checkout_usage[] = {
  26         N_("git checkout [<options>] <branch>"),
  27         N_("git checkout [<options>] [<branch>] -- <file>..."),
  28         NULL,
  29 };
  30
  31 struct checkout_opts {
  32         int patch_mode;
  33         int quiet;
  34         int merge;
  35         int force;
  36         int force_detach;
  37         int writeout_stage;
  38         int overwrite_ignore;
  39         int ignore_skipworktree;
  40         int ignore_other_worktrees;
  41         int show_progress;
  42
  43         const char *new_branch;
  44         const char *new_branch_force;
  45         const char *new_orphan_branch;
  46         int new_branch_log;
  47         enum branch_track track;
  48         struct diff_options diff_options;
  49
  50         int branch_exists;
  51         const char *prefix;
  52         struct pathspec pathspec;
  53         struct tree *source_tree;
  54 };
  55
  56 static int post_checkout_hook(struct commit *old, struct commit *new,
  57                               int changed)
  58 {
  59         return run_hook_le(NULL, "post-checkout",
  60                            oid_to_hex(old ? &old->object.oid : &null_oid),
  61                            oid_to_hex(new ? &new->object.oid : &null_oid),
  62                            changed ? "1" : "0", NULL);
  63         /* "new" can be NULL when checking out from the index before
  64            a commit exists. */
  65
  66 }
  67
  68 static int update_some(const unsigned char *sha1, struct strbuf *base,
  69                 const char *pathname, unsigned mode, int stage, void *context)
  70 {
  71         int len;
  72         struct cache_entry *ce;
  73         int pos;
  74
  75         if (S_ISDIR(mode))
  76                 return READ_TREE_RECURSIVE;
  77
  78         len = base->len + strlen(pathname);
  79         ce = xcalloc(1, cache_entry_size(len));
  80         hashcpy(ce->oid.hash, sha1);
  81         memcpy(ce->name, base->buf, base->len);
  82         memcpy(ce->name + base->len, pathname, len - base->len);
  83         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  84         ce->ce_namelen = len;
  85         ce->ce_mode = create_ce_mode(mode);
  86
  87         /*
  88          * If the entry is the same as the current index, we can leave the old
  89          * entry in place. Whether it is UPTODATE or not, checkout_entry will
  90          * do the right thing.
  91          */
  92         pos = cache_name_pos(ce->name, ce->ce_namelen);
  93         if (pos >= 0) {
  94                 struct cache_entry *old = active_cache[pos];
  95                 if (ce->ce_mode == old->ce_mode &&
  96                     !oidcmp(&ce->oid, &old->oid)) {
  97                         old->ce_flags |= CE_UPDATE;
  98                         free(ce);
  99                         return 0;
 100                 }
 101         }
 102
 103         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 104         return 0;
 105 }
 106
 107 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 108 {
 109         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 110
 111         /* update the index with the given tree's info
 112          * for all args, expanding wildcards, and exit
 113          * with any non-zero return code.
 114          */
 115         return 0;
 116 }
 117
 118 static int skip_same_name(const struct cache_entry *ce, int pos)
 119 {
 120         while (++pos < active_nr &&
 121                !strcmp(active_cache[pos]->name, ce->name))
 122                 ; /* skip */
 123         return pos;
 124 }
 125
 126 static int check_stage(int stage, const struct cache_entry *ce, int pos)
 127 {
 128         while (pos < active_nr &&
 129                !strcmp(active_cache[pos]->name, ce->name)) {
 130                 if (ce_stage(active_cache[pos]) == stage)
 131                         return 0;
 132                 pos++;
 133         }
 134         if (stage == 2)
 135                 return error(_("path '%s' does not have our version"), ce->name);
 136         else
 137                 return error(_("path '%s' does not have their version"), ce->name);
 138 }
 139
 140 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 141 {
 142         unsigned seen = 0;
 143         const char *name = ce->name;
 144
 145         while (pos < active_nr) {
 146                 ce = active_cache[pos];
 147                 if (strcmp(name, ce->name))
 148                         break;
 149                 seen |= (1 << ce_stage(ce));
 150                 pos++;
 151         }
 152         if ((stages & seen) != stages)
 153                 return error(_("path '%s' does not have all necessary versions"),
 154                              name);
 155         return 0;
 156 }
 157
 158 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 159                           const struct checkout *state)
 160 {
 161         while (pos < active_nr &&
 162                !strcmp(active_cache[pos]->name, ce->name)) {
 163                 if (ce_stage(active_cache[pos]) == stage)
 164                         return checkout_entry(active_cache[pos], state, NULL);
 165                 pos++;
 166         }
 167         if (stage == 2)
 168                 return error(_("path '%s' does not have our version"), ce->name);
 169         else
 170                 return error(_("path '%s' does not have their version"), ce->name);
 171 }
 172
 173 static int checkout_merged(int pos, const struct checkout *state)
 174 {
 175         struct cache_entry *ce = active_cache[pos];
 176         const char *path = ce->name;
 177         mmfile_t ancestor, ours, theirs;
 178         int status;
 179         struct object_id oid;
 180         mmbuffer_t result_buf;
 181         struct object_id threeway[3];
 182         unsigned mode = 0;
 183
 184         memset(threeway, 0, sizeof(threeway));
 185         while (pos < active_nr) {
 186                 int stage;
 187                 stage = ce_stage(ce);
 188                 if (!stage || strcmp(path, ce->name))
 189                         break;
 190                 oidcpy(&threeway[stage - 1], &ce->oid);
 191                 if (stage == 2)
 192                         mode = create_ce_mode(ce->ce_mode);
 193                 pos++;
 194                 ce = active_cache[pos];
 195         }
 196         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 197                 return error(_("path '%s' does not have necessary versions"), path);
 198
 199         read_mmblob(&ancestor, &threeway[0]);
 200         read_mmblob(&ours, &threeway[1]);
 201         read_mmblob(&theirs, &threeway[2]);
 202
 203         /*
 204          * NEEDSWORK: re-create conflicts from merges with
 205          * merge.renormalize set, too
 206          */
 207         status = ll_merge(&result_buf, path, &ancestor, "base",
 208                           &ours, "ours", &theirs, "theirs", NULL);
 209         free(ancestor.ptr);
 210         free(ours.ptr);
 211         free(theirs.ptr);
 212         if (status < 0 || !result_buf.ptr) {
 213                 free(result_buf.ptr);
 214                 return error(_("path '%s': cannot merge"), path);
 215         }
 216
 217         /*
 218          * NEEDSWORK:
 219          * There is absolutely no reason to write this as a blob object
 220          * and create a phony cache entry.  This hack is primarily to get
 221          * to the write_entry() machinery that massages the contents to
 222          * work-tree format and writes out which only allows it for a
 223          * cache entry.  The code in write_entry() needs to be refactored
 224          * to allow us to feed a <buffer, size, mode> instead of a cache
 225          * entry.  Such a refactoring would help merge_recursive as well
 226          * (it also writes the merge result to the object database even
 227          * when it may contain conflicts).
 228          */
 229         if (write_sha1_file(result_buf.ptr, result_buf.size,
 230                             blob_type, oid.hash))
 231                 die(_("Unable to add merge result for '%s'"), path);
 232         free(result_buf.ptr);
 233         ce = make_cache_entry(mode, oid.hash, path, 2, 0);
 234         if (!ce)
 235                 die(_("make_cache_entry failed for path '%s'"), path);
 236         status = checkout_entry(ce, state, NULL);
 237         free(ce);
 238         return status;
 239 }
 240
 241 static int checkout_paths(const struct checkout_opts *opts,
 242                           const char *revision)
 243 {
 244         int pos;
 245         struct checkout state = CHECKOUT_INIT;
 246         static char *ps_matched;
 247         struct object_id rev;
 248         struct commit *head;
 249         int errs = 0;
 250         struct lock_file *lock_file;
 251
 252         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 253                 die(_("'%s' cannot be used with updating paths"), "--track");
 254
 255         if (opts->new_branch_log)
 256                 die(_("'%s' cannot be used with updating paths"), "-l");
 257
 258         if (opts->force && opts->patch_mode)
 259                 die(_("'%s' cannot be used with updating paths"), "-f");
 260
 261         if (opts->force_detach)
 262                 die(_("'%s' cannot be used with updating paths"), "--detach");
 263
 264         if (opts->merge && opts->patch_mode)
 265                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 266
 267         if (opts->force && opts->merge)
 268                 die(_("'%s' cannot be used with %s"), "-f", "-m");
 269
 270         if (opts->new_branch)
 271                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 272                     opts->new_branch);
 273
 274         if (opts->patch_mode)
 275                 return run_add_interactive(revision, "--patch=checkout",
 276                                            &opts->pathspec);
 277
 278         lock_file = xcalloc(1, sizeof(struct lock_file));
 279
 280         hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
 281         if (read_cache_preload(&opts->pathspec) < 0)
 282                 return error(_("index file corrupt"));
 283
 284         if (opts->source_tree)
 285                 read_tree_some(opts->source_tree, &opts->pathspec);
 286
 287         ps_matched = xcalloc(opts->pathspec.nr, 1);
 288
 289         /*
 290          * Make sure all pathspecs participated in locating the paths
 291          * to be checked out.
 292          */
 293         for (pos = 0; pos < active_nr; pos++) {
 294                 struct cache_entry *ce = active_cache[pos];
 295                 ce->ce_flags &= ~CE_MATCHED;
 296                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 297                         continue;
 298                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 299                         /*
 300                          * "git checkout tree-ish -- path", but this entry
 301                          * is in the original index; it will not be checked
 302                          * out to the working tree and it does not matter
 303                          * if pathspec matched this entry.  We will not do
 304                          * anything to this entry at all.
 305                          */
 306                         continue;
 307                 /*
 308                  * Either this entry came from the tree-ish we are
 309                  * checking the paths out of, or we are checking out
 310                  * of the index.
 311                  *
 312                  * If it comes from the tree-ish, we already know it
 313                  * matches the pathspec and could just stamp
 314                  * CE_MATCHED to it from update_some(). But we still
 315                  * need ps_matched and read_tree_recursive (and
 316                  * eventually tree_entry_interesting) cannot fill
 317                  * ps_matched yet. Once it can, we can avoid calling
 318                  * match_pathspec() for _all_ entries when
 319                  * opts->source_tree != NULL.
 320                  */
 321                 if (ce_path_match(ce, &opts->pathspec, ps_matched))
 322                         ce->ce_flags |= CE_MATCHED;
 323         }
 324
 325         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 326                 free(ps_matched);
 327                 return 1;
 328         }
 329         free(ps_matched);
 330
 331         /* "checkout -m path" to recreate conflicted state */
 332         if (opts->merge)
 333                 unmerge_marked_index(&the_index);
 334
 335         /* Any unmerged paths? */
 336         for (pos = 0; pos < active_nr; pos++) {
 337                 const struct cache_entry *ce = active_cache[pos];
 338                 if (ce->ce_flags & CE_MATCHED) {
 339                         if (!ce_stage(ce))
 340                                 continue;
 341                         if (opts->force) {
 342                                 warning(_("path '%s' is unmerged"), ce->name);
 343                         } else if (opts->writeout_stage) {
 344                                 errs |= check_stage(opts->writeout_stage, ce, pos);
 345                         } else if (opts->merge) {
 346                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 347                         } else {
 348                                 errs = 1;
 349                                 error(_("path '%s' is unmerged"), ce->name);
 350                         }
 351                         pos = skip_same_name(ce, pos) - 1;
 352                 }
 353         }
 354         if (errs)
 355                 return 1;
 356
 357         /* Now we are committed to check them out */
 358         state.force = 1;
 359         state.refresh_cache = 1;
 360         state.istate = &the_index;
 361         for (pos = 0; pos < active_nr; pos++) {
 362                 struct cache_entry *ce = active_cache[pos];
 363                 if (ce->ce_flags & CE_MATCHED) {
 364                         if (!ce_stage(ce)) {
 365                                 errs |= checkout_entry(ce, &state, NULL);
 366                                 continue;
 367                         }
 368                         if (opts->writeout_stage)
 369                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 370                         else if (opts->merge)
 371                                 errs |= checkout_merged(pos, &state);
 372                         pos = skip_same_name(ce, pos) - 1;
 373                 }
 374         }
 375
 376         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 377                 die(_("unable to write new index file"));
 378
 379         read_ref_full("HEAD", 0, rev.hash, NULL);
 380         head = lookup_commit_reference_gently(&rev, 1);
 381
 382         errs |= post_checkout_hook(head, head, 0);
 383         return errs;
 384 }
 385
 386 static void show_local_changes(struct object *head,
 387                                const struct diff_options *opts)
 388 {
 389         struct rev_info rev;
 390         /* I think we want full paths, even if we're in a subdirectory. */
 391         init_revisions(&rev, NULL);
 392         rev.diffopt.flags = opts->flags;
 393         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 394         diff_setup_done(&rev.diffopt);
 395         add_pending_object(&rev, head, NULL);
 396         run_diff_index(&rev, 0);
 397 }
 398
 399 static void describe_detached_head(const char *msg, struct commit *commit)
 400 {
 401         struct strbuf sb = STRBUF_INIT;
 402         if (!parse_commit(commit))
 403                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 404         fprintf(stderr, "%s %s... %s\n", msg,
 405                 find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV), sb.buf);
 406         strbuf_release(&sb);
 407 }
 408
 409 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 410                       int worktree, int *writeout_error)
 411 {
 412         struct unpack_trees_options opts;
 413         struct tree_desc tree_desc;
 414
 415         memset(&opts, 0, sizeof(opts));
 416         opts.head_idx = -1;
 417         opts.update = worktree;
 418         opts.skip_unmerged = !worktree;
 419         opts.reset = 1;
 420         opts.merge = 1;
 421         opts.fn = oneway_merge;
 422         opts.verbose_update = o->show_progress;
 423         opts.src_index = &the_index;
 424         opts.dst_index = &the_index;
 425         parse_tree(tree);
 426         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 427         switch (unpack_trees(1, &tree_desc, &opts)) {
 428         case -2:
 429                 *writeout_error = 1;
 430                 /*
 431                  * We return 0 nevertheless, as the index is all right
 432                  * and more importantly we have made best efforts to
 433                  * update paths in the work tree, and we cannot revert
 434                  * them.
 435                  */
 436         case 0:
 437                 return 0;
 438         default:
 439                 return 128;
 440         }
 441 }
 442
 443 struct branch_info {
 444         const char *name; /* The short name used */
 445         const char *path; /* The full name of a real branch */
 446         struct commit *commit; /* The named commit */
 447         /*
 448          * if not null the branch is detached because it's already
 449          * checked out in this checkout
 450          */
 451         char *checkout;
 452 };
 453
 454 static void setup_branch_path(struct branch_info *branch)
 455 {
 456         struct strbuf buf = STRBUF_INIT;
 457
 458         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 459         if (strcmp(buf.buf, branch->name))
 460                 branch->name = xstrdup(buf.buf);
 461         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 462         branch->path = strbuf_detach(&buf, NULL);
 463 }
 464
 465 static int merge_working_tree(const struct checkout_opts *opts,
 466                               struct branch_info *old,
 467                               struct branch_info *new,
 468                               int *writeout_error)
 469 {
 470         int ret;
 471         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 472
 473         hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
 474         if (read_cache_preload(NULL) < 0)
 475                 return error(_("index file corrupt"));
 476
 477         resolve_undo_clear();
 478         if (opts->force) {
 479                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 480                 if (ret)
 481                         return ret;
 482         } else {
 483                 struct tree_desc trees[2];
 484                 struct tree *tree;
 485                 struct unpack_trees_options topts;
 486
 487                 memset(&topts, 0, sizeof(topts));
 488                 topts.head_idx = -1;
 489                 topts.src_index = &the_index;
 490                 topts.dst_index = &the_index;
 491
 492                 setup_unpack_trees_porcelain(&topts, "checkout");
 493
 494                 refresh_cache(REFRESH_QUIET);
 495
 496                 if (unmerged_cache()) {
 497                         error(_("you need to resolve your current index first"));
 498                         return 1;
 499                 }
 500
 501                 /* 2-way merge to the new branch */
 502                 topts.initial_checkout = is_cache_unborn();
 503                 topts.update = 1;
 504                 topts.merge = 1;
 505                 topts.gently = opts->merge && old->commit;
 506                 topts.verbose_update = opts->show_progress;
 507                 topts.fn = twoway_merge;
 508                 if (opts->overwrite_ignore) {
 509                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 510                         topts.dir->flags |= DIR_SHOW_IGNORED;
 511                         setup_standard_excludes(topts.dir);
 512                 }
 513                 tree = parse_tree_indirect(old->commit ?
 514                                            &old->commit->object.oid :
 515                                            &empty_tree_oid);
 516                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 517                 tree = parse_tree_indirect(&new->commit->object.oid);
 518                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 519
 520                 ret = unpack_trees(2, trees, &topts);
 521                 if (ret == -1) {
 522                         /*
 523                          * Unpack couldn't do a trivial merge; either
 524                          * give up or do a real merge, depending on
 525                          * whether the merge flag was used.
 526                          */
 527                         struct tree *result;
 528                         struct tree *work;
 529                         struct merge_options o;
 530                         if (!opts->merge)
 531                                 return 1;
 532
 533                         /*
 534                          * Without old->commit, the below is the same as
 535                          * the two-tree unpack we already tried and failed.
 536                          */
 537                         if (!old->commit)
 538                                 return 1;
 539
 540                         /* Do more real merge */
 541
 542                         /*
 543                          * We update the index fully, then write the
 544                          * tree from the index, then merge the new
 545                          * branch with the current tree, with the old
 546                          * branch as the base. Then we reset the index
 547                          * (but not the working tree) to the new
 548                          * branch, leaving the working tree as the
 549                          * merged version, but skipping unmerged
 550                          * entries in the index.
 551                          */
 552
 553                         add_files_to_cache(NULL, NULL, 0);
 554                         /*
 555                          * NEEDSWORK: carrying over local changes
 556                          * when branches have different end-of-line
 557                          * normalization (or clean+smudge rules) is
 558                          * a pain; plumb in an option to set
 559                          * o.renormalize?
 560                          */
 561                         init_merge_options(&o);
 562                         o.verbosity = 0;
 563                         work = write_tree_from_memory(&o);
 564
 565                         ret = reset_tree(new->commit->tree, opts, 1,
 566                                          writeout_error);
 567                         if (ret)
 568                                 return ret;
 569                         o.ancestor = old->name;
 570                         o.branch1 = new->name;
 571                         o.branch2 = "local";
 572                         ret = merge_trees(&o, new->commit->tree, work,
 573                                 old->commit->tree, &result);
 574                         if (ret < 0)
 575                                 exit(128);
 576                         ret = reset_tree(new->commit->tree, opts, 0,
 577                                          writeout_error);
 578                         strbuf_release(&o.obuf);
 579                         if (ret)
 580                                 return ret;
 581                 }
 582         }
 583
 584         if (!active_cache_tree)
 585                 active_cache_tree = cache_tree();
 586
 587         if (!cache_tree_fully_valid(active_cache_tree))
 588                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 589
 590         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 591                 die(_("unable to write new index file"));
 592
 593         if (!opts->force && !opts->quiet)
 594                 show_local_changes(&new->commit->object, &opts->diff_options);
 595
 596         return 0;
 597 }
 598
 599 static void report_tracking(struct branch_info *new)
 600 {
 601         struct strbuf sb = STRBUF_INIT;
 602         struct branch *branch = branch_get(new->name);
 603
 604         if (!format_tracking_info(branch, &sb))
 605                 return;
 606         fputs(sb.buf, stdout);
 607         strbuf_release(&sb);
 608 }
 609
 610 static void update_refs_for_switch(const struct checkout_opts *opts,
 611                                    struct branch_info *old,
 612                                    struct branch_info *new)
 613 {
 614         struct strbuf msg = STRBUF_INIT;
 615         const char *old_desc, *reflog_msg;
 616         if (opts->new_branch) {
 617                 if (opts->new_orphan_branch) {
 618                         char *refname;
 619
 620                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 621                         if (opts->new_branch_log &&
 622                             !should_autocreate_reflog(refname)) {
 623                                 int ret;
 624                                 struct strbuf err = STRBUF_INIT;
 625
 626                                 ret = safe_create_reflog(refname, 1, &err);
 627                                 if (ret) {
 628                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 629                                                 opts->new_orphan_branch, err.buf);
 630                                         strbuf_release(&err);
 631                                         free(refname);
 632                                         return;
 633                                 }
 634                                 strbuf_release(&err);
 635                         }
 636                         free(refname);
 637                 }
 638                 else
 639                         create_branch(opts->new_branch, new->name,
 640                                       opts->new_branch_force ? 1 : 0,
 641                                       opts->new_branch_log,
 642                                       opts->new_branch_force ? 1 : 0,
 643                                       opts->quiet,
 644                                       opts->track);
 645                 new->name = opts->new_branch;
 646                 setup_branch_path(new);
 647         }
 648
 649         old_desc = old->name;
 650         if (!old_desc && old->commit)
 651                 old_desc = oid_to_hex(&old->commit->object.oid);
 652
 653         reflog_msg = getenv("GIT_REFLOG_ACTION");
 654         if (!reflog_msg)
 655                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 656                         old_desc ? old_desc : "(invalid)", new->name);
 657         else
 658                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 659
 660         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 661                 /* Nothing to do. */
 662         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 663                 update_ref(msg.buf, "HEAD", new->commit->object.oid.hash, NULL,
 664                            REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
 665                 if (!opts->quiet) {
 666                         if (old->path &&
 667                             advice_detached_head && !opts->force_detach)
 668                                 detach_advice(new->name);
 669                         describe_detached_head(_("HEAD is now at"), new->commit);
 670                 }
 671         } else if (new->path) { /* Switch branches. */
 672                 if (create_symref("HEAD", new->path, msg.buf) < 0)
 673                         die(_("unable to update HEAD"));
 674                 if (!opts->quiet) {
 675                         if (old->path && !strcmp(new->path, old->path)) {
 676                                 if (opts->new_branch_force)
 677                                         fprintf(stderr, _("Reset branch '%s'\n"),
 678                                                 new->name);
 679                                 else
 680                                         fprintf(stderr, _("Already on '%s'\n"),
 681                                                 new->name);
 682                         } else if (opts->new_branch) {
 683                                 if (opts->branch_exists)
 684                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 685                                 else
 686                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 687                         } else {
 688                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 689                                         new->name);
 690                         }
 691                 }
 692                 if (old->path && old->name) {
 693                         if (!ref_exists(old->path) && reflog_exists(old->path))
 694                                 delete_reflog(old->path);
 695                 }
 696         }
 697         remove_branch_state();
 698         strbuf_release(&msg);
 699         if (!opts->quiet &&
 700             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 701                 report_tracking(new);
 702 }
 703
 704 static int add_pending_uninteresting_ref(const char *refname,
 705                                          const struct object_id *oid,
 706                                          int flags, void *cb_data)
 707 {
 708         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 709         return 0;
 710 }
 711
 712 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 713 {
 714         strbuf_addstr(sb, "  ");
 715         strbuf_add_unique_abbrev(sb, commit->object.oid.hash, DEFAULT_ABBREV);
 716         strbuf_addch(sb, ' ');
 717         if (!parse_commit(commit))
 718                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 719         strbuf_addch(sb, '\n');
 720 }
 721
 722 #define ORPHAN_CUTOFF 4
 723 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 724 {
 725         struct commit *c, *last = NULL;
 726         struct strbuf sb = STRBUF_INIT;
 727         int lost = 0;
 728         while ((c = get_revision(revs)) != NULL) {
 729                 if (lost < ORPHAN_CUTOFF)
 730                         describe_one_orphan(&sb, c);
 731                 last = c;
 732                 lost++;
 733         }
 734         if (ORPHAN_CUTOFF < lost) {
 735                 int more = lost - ORPHAN_CUTOFF;
 736                 if (more == 1)
 737                         describe_one_orphan(&sb, last);
 738                 else
 739                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 740         }
 741
 742         fprintf(stderr,
 743                 Q_(
 744                 /* The singular version */
 745                 "Warning: you are leaving %d commit behind, "
 746                 "not connected to\n"
 747                 "any of your branches:\n\n"
 748                 "%s\n",
 749                 /* The plural version */
 750                 "Warning: you are leaving %d commits behind, "
 751                 "not connected to\n"
 752                 "any of your branches:\n\n"
 753                 "%s\n",
 754                 /* Give ngettext() the count */
 755                 lost),
 756                 lost,
 757                 sb.buf);
 758         strbuf_release(&sb);
 759
 760         if (advice_detached_head)
 761                 fprintf(stderr,
 762                         Q_(
 763                         /* The singular version */
 764                         "If you want to keep it by creating a new branch, "
 765                         "this may be a good time\nto do so with:\n\n"
 766                         " git branch <new-branch-name> %s\n\n",
 767                         /* The plural version */
 768                         "If you want to keep them by creating a new branch, "
 769                         "this may be a good time\nto do so with:\n\n"
 770                         " git branch <new-branch-name> %s\n\n",
 771                         /* Give ngettext() the count */
 772                         lost),
 773                         find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
 774 }
 775
 776 /*
 777  * We are about to leave commit that was at the tip of a detached
 778  * HEAD.  If it is not reachable from any ref, this is the last chance
 779  * for the user to do so without resorting to reflog.
 780  */
 781 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 782 {
 783         struct rev_info revs;
 784         struct object *object = &old->object;
 785         struct object_array refs;
 786
 787         init_revisions(&revs, NULL);
 788         setup_revisions(0, NULL, &revs, NULL);
 789
 790         object->flags &= ~UNINTERESTING;
 791         add_pending_object(&revs, object, oid_to_hex(&object->oid));
 792
 793         for_each_ref(add_pending_uninteresting_ref, &revs);
 794         add_pending_oid(&revs, "HEAD", &new->object.oid, UNINTERESTING);
 795
 796         refs = revs.pending;
 797         revs.leak_pending = 1;
 798
 799         if (prepare_revision_walk(&revs))
 800                 die(_("internal error in revision walk"));
 801         if (!(old->object.flags & UNINTERESTING))
 802                 suggest_reattach(old, &revs);
 803         else
 804                 describe_detached_head(_("Previous HEAD position was"), old);
 805
 806         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 807         free(refs.objects);
 808 }
 809
 810 static int switch_branches(const struct checkout_opts *opts,
 811                            struct branch_info *new)
 812 {
 813         int ret = 0;
 814         struct branch_info old;
 815         void *path_to_free;
 816         struct object_id rev;
 817         int flag, writeout_error = 0;
 818         memset(&old, 0, sizeof(old));
 819         old.path = path_to_free = resolve_refdup("HEAD", 0, rev.hash, &flag);
 820         if (old.path)
 821                 old.commit = lookup_commit_reference_gently(&rev, 1);
 822         if (!(flag & REF_ISSYMREF))
 823                 old.path = NULL;
 824
 825         if (old.path)
 826                 skip_prefix(old.path, "refs/heads/", &old.name);
 827
 828         if (!new->name) {
 829                 new->name = "HEAD";
 830                 new->commit = old.commit;
 831                 if (!new->commit)
 832                         die(_("You are on a branch yet to be born"));
 833                 parse_commit_or_die(new->commit);
 834         }
 835
 836         ret = merge_working_tree(opts, &old, new, &writeout_error);
 837         if (ret) {
 838                 free(path_to_free);
 839                 return ret;
 840         }
 841
 842         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 843                 orphaned_commit_warning(old.commit, new->commit);
 844
 845         update_refs_for_switch(opts, &old, new);
 846
 847         ret = post_checkout_hook(old.commit, new->commit, 1);
 848         free(path_to_free);
 849         return ret || writeout_error;
 850 }
 851
 852 static int git_checkout_config(const char *var, const char *value, void *cb)
 853 {
 854         if (!strcmp(var, "diff.ignoresubmodules")) {
 855                 struct checkout_opts *opts = cb;
 856                 handle_ignore_submodules_arg(&opts->diff_options, value);
 857                 return 0;
 858         }
 859
 860         if (starts_with(var, "submodule."))
 861                 return submodule_config(var, value, NULL);
 862
 863         return git_xmerge_config(var, value, NULL);
 864 }
 865
 866 struct tracking_name_data {
 867         /* const */ char *src_ref;
 868         char *dst_ref;
 869         struct object_id *dst_oid;
 870         int unique;
 871 };
 872
 873 static int check_tracking_name(struct remote *remote, void *cb_data)
 874 {
 875         struct tracking_name_data *cb = cb_data;
 876         struct refspec query;
 877         memset(&query, 0, sizeof(struct refspec));
 878         query.src = cb->src_ref;
 879         if (remote_find_tracking(remote, &query) ||
 880             get_oid(query.dst, cb->dst_oid)) {
 881                 free(query.dst);
 882                 return 0;
 883         }
 884         if (cb->dst_ref) {
 885                 free(query.dst);
 886                 cb->unique = 0;
 887                 return 0;
 888         }
 889         cb->dst_ref = query.dst;
 890         return 0;
 891 }
 892
 893 static const char *unique_tracking_name(const char *name, struct object_id *oid)
 894 {
 895         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
 896         cb_data.src_ref = xstrfmt("refs/heads/%s", name);
 897         cb_data.dst_oid = oid;
 898         for_each_remote(check_tracking_name, &cb_data);
 899         free(cb_data.src_ref);
 900         if (cb_data.unique)
 901                 return cb_data.dst_ref;
 902         free(cb_data.dst_ref);
 903         return NULL;
 904 }
 905
 906 static int parse_branchname_arg(int argc, const char **argv,
 907                                 int dwim_new_local_branch_ok,
 908                                 struct branch_info *new,
 909                                 struct checkout_opts *opts,
 910                                 struct object_id *rev)
 911 {
 912         struct tree **source_tree = &opts->source_tree;
 913         const char **new_branch = &opts->new_branch;
 914         int argcount = 0;
 915         struct object_id branch_rev;
 916         const char *arg;
 917         int dash_dash_pos;
 918         int has_dash_dash = 0;
 919         int i;
 920
 921         /*
 922          * case 1: git checkout <ref> -- [<paths>]
 923          *
 924          *   <ref> must be a valid tree, everything after the '--' must be
 925          *   a path.
 926          *
 927          * case 2: git checkout -- [<paths>]
 928          *
 929          *   everything after the '--' must be paths.
 930          *
 931          * case 3: git checkout <something> [--]
 932          *
 933          *   (a) If <something> is a commit, that is to
 934          *       switch to the branch or detach HEAD at it.  As a special case,
 935          *       if <something> is A...B (missing A or B means HEAD but you can
 936          *       omit at most one side), and if there is a unique merge base
 937          *       between A and B, A...B names that merge base.
 938          *
 939          *   (b) If <something> is _not_ a commit, either "--" is present
 940          *       or <something> is not a path, no -t or -b was given, and
 941          *       and there is a tracking branch whose name is <something>
 942          *       in one and only one remote, then this is a short-hand to
 943          *       fork local <something> from that remote-tracking branch.
 944          *
 945          *   (c) Otherwise, if "--" is present, treat it like case (1).
 946          *
 947          *   (d) Otherwise :
 948          *       - if it's a reference, treat it like case (1)
 949          *       - else if it's a path, treat it like case (2)
 950          *       - else: fail.
 951          *
 952          * case 4: git checkout <something> <paths>
 953          *
 954          *   The first argument must not be ambiguous.
 955          *   - If it's *only* a reference, treat it like case (1).
 956          *   - If it's only a path, treat it like case (2).
 957          *   - else: fail.
 958          *
 959          */
 960         if (!argc)
 961                 return 0;
 962
 963         arg = argv[0];
 964         dash_dash_pos = -1;
 965         for (i = 0; i < argc; i++) {
 966                 if (!strcmp(argv[i], "--")) {
 967                         dash_dash_pos = i;
 968                         break;
 969                 }
 970         }
 971         if (dash_dash_pos == 0)
 972                 return 1; /* case (2) */
 973         else if (dash_dash_pos == 1)
 974                 has_dash_dash = 1; /* case (3) or (1) */
 975         else if (dash_dash_pos >= 2)
 976                 die(_("only one reference expected, %d given."), dash_dash_pos);
 977
 978         if (!strcmp(arg, "-"))
 979                 arg = "@{-1}";
 980
 981         if (get_oid_mb(arg, rev)) {
 982                 /*
 983                  * Either case (3) or (4), with <something> not being
 984                  * a commit, or an attempt to use case (1) with an
 985                  * invalid ref.
 986                  *
 987                  * It's likely an error, but we need to find out if
 988                  * we should auto-create the branch, case (3).(b).
 989                  */
 990                 int recover_with_dwim = dwim_new_local_branch_ok;
 991
 992                 if (!has_dash_dash &&
 993                     (check_filename(opts->prefix, arg) || !no_wildcard(arg)))
 994                         recover_with_dwim = 0;
 995                 /*
 996                  * Accept "git checkout foo" and "git checkout foo --"
 997                  * as candidates for dwim.
 998                  */
 999                 if (!(argc == 1 && !has_dash_dash) &&
1000                     !(argc == 2 && has_dash_dash))
1001                         recover_with_dwim = 0;
1002
1003                 if (recover_with_dwim) {
1004                         const char *remote = unique_tracking_name(arg, rev);
1005                         if (remote) {
1006                                 *new_branch = arg;
1007                                 arg = remote;
1008                                 /* DWIMmed to create local branch, case (3).(b) */
1009                         } else {
1010                                 recover_with_dwim = 0;
1011                         }
1012                 }
1013
1014                 if (!recover_with_dwim) {
1015                         if (has_dash_dash)
1016                                 die(_("invalid reference: %s"), arg);
1017                         return argcount;
1018                 }
1019         }
1020
1021         /* we can't end up being in (2) anymore, eat the argument */
1022         argcount++;
1023         argv++;
1024         argc--;
1025
1026         new->name = arg;
1027         setup_branch_path(new);
1028
1029         if (!check_refname_format(new->path, 0) &&
1030             !read_ref(new->path, branch_rev.hash))
1031                 oidcpy(rev, &branch_rev);
1032         else
1033                 new->path = NULL; /* not an existing branch */
1034
1035         new->commit = lookup_commit_reference_gently(rev, 1);
1036         if (!new->commit) {
1037                 /* not a commit */
1038                 *source_tree = parse_tree_indirect(rev);
1039         } else {
1040                 parse_commit_or_die(new->commit);
1041                 *source_tree = new->commit->tree;
1042         }
1043
1044         if (!*source_tree)                   /* case (1): want a tree */
1045                 die(_("reference is not a tree: %s"), arg);
1046         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1047                 /*
1048                  * Do not complain the most common case
1049                  *      git checkout branch
1050                  * even if there happen to be a file called 'branch';
1051                  * it would be extremely annoying.
1052                  */
1053                 if (argc)
1054                         verify_non_filename(opts->prefix, arg);
1055         } else {
1056                 argcount++;
1057                 argv++;
1058                 argc--;
1059         }
1060
1061         return argcount;
1062 }
1063
1064 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1065 {
1066         int status;
1067         struct strbuf branch_ref = STRBUF_INIT;
1068
1069         if (!opts->new_branch)
1070                 die(_("You are on a branch yet to be born"));
1071         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1072         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1073         strbuf_release(&branch_ref);
1074         if (!opts->quiet)
1075                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1076                         opts->new_branch);
1077         return status;
1078 }
1079
1080 static int checkout_branch(struct checkout_opts *opts,
1081                            struct branch_info *new)
1082 {
1083         if (opts->pathspec.nr)
1084                 die(_("paths cannot be used with switching branches"));
1085
1086         if (opts->patch_mode)
1087                 die(_("'%s' cannot be used with switching branches"),
1088                     "--patch");
1089
1090         if (opts->writeout_stage)
1091                 die(_("'%s' cannot be used with switching branches"),
1092                     "--ours/--theirs");
1093
1094         if (opts->force && opts->merge)
1095                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1096
1097         if (opts->force_detach && opts->new_branch)
1098                 die(_("'%s' cannot be used with '%s'"),
1099                     "--detach", "-b/-B/--orphan");
1100
1101         if (opts->new_orphan_branch) {
1102                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1103                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1104         } else if (opts->force_detach) {
1105                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1106                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1107         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1108                 opts->track = git_branch_track;
1109
1110         if (new->name && !new->commit)
1111                 die(_("Cannot switch branch to a non-commit '%s'"),
1112                     new->name);
1113
1114         if (new->path && !opts->force_detach && !opts->new_branch &&
1115             !opts->ignore_other_worktrees) {
1116                 struct object_id oid;
1117                 int flag;
1118                 char *head_ref = resolve_refdup("HEAD", 0, oid.hash, &flag);
1119                 if (head_ref &&
1120                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)))
1121                         die_if_checked_out(new->path, 1);
1122                 free(head_ref);
1123         }
1124
1125         if (!new->commit && opts->new_branch) {
1126                 struct object_id rev;
1127                 int flag;
1128
1129                 if (!read_ref_full("HEAD", 0, rev.hash, &flag) &&
1130                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1131                         return switch_unborn_to_new_branch(opts);
1132         }
1133         return switch_branches(opts, new);
1134 }
1135
1136 int cmd_checkout(int argc, const char **argv, const char *prefix)
1137 {
1138         struct checkout_opts opts;
1139         struct branch_info new;
1140         char *conflict_style = NULL;
1141         int dwim_new_local_branch = 1;
1142         struct option options[] = {
1143                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1144                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1145                            N_("create and checkout a new branch")),
1146                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1147                            N_("create/reset and checkout a branch")),
1148                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1149                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1150                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1151                         BRANCH_TRACK_EXPLICIT),
1152                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1153                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1154                             2),
1155                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1156                             3),
1157                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1158                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1159                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1160                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1161                            N_("conflict style (merge or diff3)")),
1162                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1163                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1164                          N_("do not limit pathspecs to sparse entries only")),
1165                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1166                                 N_("second guess 'git checkout <no-such-branch>'")),
1167                 OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1168                          N_("do not check if another worktree is holding the given ref")),
1169                 { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1170                             "checkout", "control recursive updating of submodules",
1171                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1172                 OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1173                 OPT_END(),
1174         };
1175
1176         memset(&opts, 0, sizeof(opts));
1177         memset(&new, 0, sizeof(new));
1178         opts.overwrite_ignore = 1;
1179         opts.prefix = prefix;
1180         opts.show_progress = -1;
1181
1182         gitmodules_config();
1183         git_config(git_checkout_config, &opts);
1184
1185         opts.track = BRANCH_TRACK_UNSPECIFIED;
1186
1187         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1188                              PARSE_OPT_KEEP_DASHDASH);
1189
1190         if (opts.show_progress < 0) {
1191                 if (opts.quiet)
1192                         opts.show_progress = 0;
1193                 else
1194                         opts.show_progress = isatty(2);
1195         }
1196
1197         if (conflict_style) {
1198                 opts.merge = 1; /* implied */
1199                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1200         }
1201
1202         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1203                 die(_("-b, -B and --orphan are mutually exclusive"));
1204
1205         /*
1206          * From here on, new_branch will contain the branch to be checked out,
1207          * and new_branch_force and new_orphan_branch will tell us which one of
1208          * -b/-B/--orphan is being used.
1209          */
1210         if (opts.new_branch_force)
1211                 opts.new_branch = opts.new_branch_force;
1212
1213         if (opts.new_orphan_branch)
1214                 opts.new_branch = opts.new_orphan_branch;
1215
1216         /* --track without -b/-B/--orphan should DWIM */
1217         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1218                 const char *argv0 = argv[0];
1219                 if (!argc || !strcmp(argv0, "--"))
1220                         die (_("--track needs a branch name"));
1221                 skip_prefix(argv0, "refs/", &argv0);
1222                 skip_prefix(argv0, "remotes/", &argv0);
1223                 argv0 = strchr(argv0, '/');
1224                 if (!argv0 || !argv0[1])
1225                         die (_("Missing branch name; try -b"));
1226                 opts.new_branch = argv0 + 1;
1227         }
1228
1229         /*
1230          * Extract branch name from command line arguments, so
1231          * all that is left is pathspecs.
1232          *
1233          * Handle
1234          *
1235          *  1) git checkout <tree> -- [<paths>]
1236          *  2) git checkout -- [<paths>]
1237          *  3) git checkout <something> [<paths>]
1238          *
1239          * including "last branch" syntax and DWIM-ery for names of
1240          * remote branches, erroring out for invalid or ambiguous cases.
1241          */
1242         if (argc) {
1243                 struct object_id rev;
1244                 int dwim_ok =
1245                         !opts.patch_mode &&
1246                         dwim_new_local_branch &&
1247                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1248                         !opts.new_branch;
1249                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1250                                              &new, &opts, &rev);
1251                 argv += n;
1252                 argc -= n;
1253         }
1254
1255         if (argc) {
1256                 parse_pathspec(&opts.pathspec, 0,
1257                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1258                                prefix, argv);
1259
1260                 if (!opts.pathspec.nr)
1261                         die(_("invalid path specification"));
1262
1263                 /*
1264                  * Try to give more helpful suggestion.
1265                  * new_branch && argc > 1 will be caught later.
1266                  */
1267                 if (opts.new_branch && argc == 1)
1268                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1269                                 argv[0], opts.new_branch);
1270
1271                 if (opts.force_detach)
1272                         die(_("git checkout: --detach does not take a path argument '%s'"),
1273                             argv[0]);
1274
1275                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1276                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1277                               "checking out of the index."));
1278         }
1279
1280         if (opts.new_branch) {
1281                 struct strbuf buf = STRBUF_INIT;
1282
1283                 opts.branch_exists =
1284                         validate_new_branchname(opts.new_branch, &buf,
1285                                                 !!opts.new_branch_force,
1286                                                 !!opts.new_branch_force);
1287
1288                 strbuf_release(&buf);
1289         }
1290
1291         if (opts.patch_mode || opts.pathspec.nr)
1292                 return checkout_paths(&opts, new.name);
1293         else
1294                 return checkout_branch(&opts, &new);
1295 }