builtin/checkout.c

   1 #include "builtin.h"
   2 #include "config.h"
   3 #include "checkout.h"
   4 #include "lockfile.h"
   5 #include "parse-options.h"
   6 #include "refs.h"
   7 #include "object-store.h"
   8 #include "commit.h"
   9 #include "tree.h"
  10 #include "tree-walk.h"
  11 #include "cache-tree.h"
  12 #include "unpack-trees.h"
  13 #include "dir.h"
  14 #include "run-command.h"
  15 #include "merge-recursive.h"
  16 #include "branch.h"
  17 #include "diff.h"
  18 #include "revision.h"
  19 #include "remote.h"
  20 #include "blob.h"
  21 #include "xdiff-interface.h"
  22 #include "ll-merge.h"
  23 #include "resolve-undo.h"
  24 #include "submodule-config.h"
  25 #include "submodule.h"
  26 #include "advice.h"
  27
  28 static int checkout_optimize_new_branch;
  29
  30 static const char * const checkout_usage[] = {
  31         N_("git checkout [<options>] <branch>"),
  32         N_("git checkout [<options>] [<branch>] -- <file>..."),
  33         NULL,
  34 };
  35
  36 struct checkout_opts {
  37         int patch_mode;
  38         int quiet;
  39         int merge;
  40         int force;
  41         int force_detach;
  42         int writeout_stage;
  43         int overwrite_ignore;
  44         int ignore_skipworktree;
  45         int ignore_other_worktrees;
  46         int show_progress;
  47         /*
  48          * If new checkout options are added, skip_merge_working_tree
  49          * should be updated accordingly.
  50          */
  51
  52         const char *new_branch;
  53         const char *new_branch_force;
  54         const char *new_orphan_branch;
  55         int new_branch_log;
  56         enum branch_track track;
  57         struct diff_options diff_options;
  58
  59         int branch_exists;
  60         const char *prefix;
  61         struct pathspec pathspec;
  62         struct tree *source_tree;
  63 };
  64
  65 static int post_checkout_hook(struct commit *old_commit, struct commit *new_commit,
  66                               int changed)
  67 {
  68         return run_hook_le(NULL, "post-checkout",
  69                            oid_to_hex(old_commit ? &old_commit->object.oid : &null_oid),
  70                            oid_to_hex(new_commit ? &new_commit->object.oid : &null_oid),
  71                            changed ? "1" : "0", NULL);
  72         /* "new_commit" can be NULL when checking out from the index before
  73            a commit exists. */
  74
  75 }
  76
  77 static int update_some(const struct object_id *oid, struct strbuf *base,
  78                 const char *pathname, unsigned mode, int stage, void *context)
  79 {
  80         int len;
  81         struct cache_entry *ce;
  82         int pos;
  83
  84         if (S_ISDIR(mode))
  85                 return READ_TREE_RECURSIVE;
  86
  87         len = base->len + strlen(pathname);
  88         ce = make_empty_cache_entry(&the_index, len);
  89         oidcpy(&ce->oid, oid);
  90         memcpy(ce->name, base->buf, base->len);
  91         memcpy(ce->name + base->len, pathname, len - base->len);
  92         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  93         ce->ce_namelen = len;
  94         ce->ce_mode = create_ce_mode(mode);
  95
  96         /*
  97          * If the entry is the same as the current index, we can leave the old
  98          * entry in place. Whether it is UPTODATE or not, checkout_entry will
  99          * do the right thing.
 100          */
 101         pos = cache_name_pos(ce->name, ce->ce_namelen);
 102         if (pos >= 0) {
 103                 struct cache_entry *old = active_cache[pos];
 104                 if (ce->ce_mode == old->ce_mode &&
 105                     oideq(&ce->oid, &old->oid)) {
 106                         old->ce_flags |= CE_UPDATE;
 107                         discard_cache_entry(ce);
 108                         return 0;
 109                 }
 110         }
 111
 112         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 113         return 0;
 114 }
 115
 116 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 117 {
 118         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 119
 120         /* update the index with the given tree's info
 121          * for all args, expanding wildcards, and exit
 122          * with any non-zero return code.
 123          */
 124         return 0;
 125 }
 126
 127 static int skip_same_name(const struct cache_entry *ce, int pos)
 128 {
 129         while (++pos < active_nr &&
 130                !strcmp(active_cache[pos]->name, ce->name))
 131                 ; /* skip */
 132         return pos;
 133 }
 134
 135 static int check_stage(int stage, const struct cache_entry *ce, int pos)
 136 {
 137         while (pos < active_nr &&
 138                !strcmp(active_cache[pos]->name, ce->name)) {
 139                 if (ce_stage(active_cache[pos]) == stage)
 140                         return 0;
 141                 pos++;
 142         }
 143         if (stage == 2)
 144                 return error(_("path '%s' does not have our version"), ce->name);
 145         else
 146                 return error(_("path '%s' does not have their version"), ce->name);
 147 }
 148
 149 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 150 {
 151         unsigned seen = 0;
 152         const char *name = ce->name;
 153
 154         while (pos < active_nr) {
 155                 ce = active_cache[pos];
 156                 if (strcmp(name, ce->name))
 157                         break;
 158                 seen |= (1 << ce_stage(ce));
 159                 pos++;
 160         }
 161         if ((stages & seen) != stages)
 162                 return error(_("path '%s' does not have all necessary versions"),
 163                              name);
 164         return 0;
 165 }
 166
 167 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 168                           const struct checkout *state)
 169 {
 170         while (pos < active_nr &&
 171                !strcmp(active_cache[pos]->name, ce->name)) {
 172                 if (ce_stage(active_cache[pos]) == stage)
 173                         return checkout_entry(active_cache[pos], state, NULL);
 174                 pos++;
 175         }
 176         if (stage == 2)
 177                 return error(_("path '%s' does not have our version"), ce->name);
 178         else
 179                 return error(_("path '%s' does not have their version"), ce->name);
 180 }
 181
 182 static int checkout_merged(int pos, const struct checkout *state)
 183 {
 184         struct cache_entry *ce = active_cache[pos];
 185         const char *path = ce->name;
 186         mmfile_t ancestor, ours, theirs;
 187         int status;
 188         struct object_id oid;
 189         mmbuffer_t result_buf;
 190         struct object_id threeway[3];
 191         unsigned mode = 0;
 192
 193         memset(threeway, 0, sizeof(threeway));
 194         while (pos < active_nr) {
 195                 int stage;
 196                 stage = ce_stage(ce);
 197                 if (!stage || strcmp(path, ce->name))
 198                         break;
 199                 oidcpy(&threeway[stage - 1], &ce->oid);
 200                 if (stage == 2)
 201                         mode = create_ce_mode(ce->ce_mode);
 202                 pos++;
 203                 ce = active_cache[pos];
 204         }
 205         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 206                 return error(_("path '%s' does not have necessary versions"), path);
 207
 208         read_mmblob(&ancestor, &threeway[0]);
 209         read_mmblob(&ours, &threeway[1]);
 210         read_mmblob(&theirs, &threeway[2]);
 211
 212         /*
 213          * NEEDSWORK: re-create conflicts from merges with
 214          * merge.renormalize set, too
 215          */
 216         status = ll_merge(&result_buf, path, &ancestor, "base",
 217                           &ours, "ours", &theirs, "theirs",
 218                           state->istate, NULL);
 219         free(ancestor.ptr);
 220         free(ours.ptr);
 221         free(theirs.ptr);
 222         if (status < 0 || !result_buf.ptr) {
 223                 free(result_buf.ptr);
 224                 return error(_("path '%s': cannot merge"), path);
 225         }
 226
 227         /*
 228          * NEEDSWORK:
 229          * There is absolutely no reason to write this as a blob object
 230          * and create a phony cache entry.  This hack is primarily to get
 231          * to the write_entry() machinery that massages the contents to
 232          * work-tree format and writes out which only allows it for a
 233          * cache entry.  The code in write_entry() needs to be refactored
 234          * to allow us to feed a <buffer, size, mode> instead of a cache
 235          * entry.  Such a refactoring would help merge_recursive as well
 236          * (it also writes the merge result to the object database even
 237          * when it may contain conflicts).
 238          */
 239         if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
 240                 die(_("Unable to add merge result for '%s'"), path);
 241         free(result_buf.ptr);
 242         ce = make_transient_cache_entry(mode, &oid, path, 2);
 243         if (!ce)
 244                 die(_("make_cache_entry failed for path '%s'"), path);
 245         status = checkout_entry(ce, state, NULL);
 246         discard_cache_entry(ce);
 247         return status;
 248 }
 249
 250 static int checkout_paths(const struct checkout_opts *opts,
 251                           const char *revision)
 252 {
 253         int pos;
 254         struct checkout state = CHECKOUT_INIT;
 255         static char *ps_matched;
 256         struct object_id rev;
 257         struct commit *head;
 258         int errs = 0;
 259         struct lock_file lock_file = LOCK_INIT;
 260
 261         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 262                 die(_("'%s' cannot be used with updating paths"), "--track");
 263
 264         if (opts->new_branch_log)
 265                 die(_("'%s' cannot be used with updating paths"), "-l");
 266
 267         if (opts->force && opts->patch_mode)
 268                 die(_("'%s' cannot be used with updating paths"), "-f");
 269
 270         if (opts->force_detach)
 271                 die(_("'%s' cannot be used with updating paths"), "--detach");
 272
 273         if (opts->merge && opts->patch_mode)
 274                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 275
 276         if (opts->force && opts->merge)
 277                 die(_("'%s' cannot be used with %s"), "-f", "-m");
 278
 279         if (opts->new_branch)
 280                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 281                     opts->new_branch);
 282
 283         if (opts->patch_mode)
 284                 return run_add_interactive(revision, "--patch=checkout",
 285                                            &opts->pathspec);
 286
 287         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 288         if (read_cache_preload(&opts->pathspec) < 0)
 289                 return error(_("index file corrupt"));
 290
 291         if (opts->source_tree)
 292                 read_tree_some(opts->source_tree, &opts->pathspec);
 293
 294         ps_matched = xcalloc(opts->pathspec.nr, 1);
 295
 296         /*
 297          * Make sure all pathspecs participated in locating the paths
 298          * to be checked out.
 299          */
 300         for (pos = 0; pos < active_nr; pos++) {
 301                 struct cache_entry *ce = active_cache[pos];
 302                 ce->ce_flags &= ~CE_MATCHED;
 303                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 304                         continue;
 305                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 306                         /*
 307                          * "git checkout tree-ish -- path", but this entry
 308                          * is in the original index; it will not be checked
 309                          * out to the working tree and it does not matter
 310                          * if pathspec matched this entry.  We will not do
 311                          * anything to this entry at all.
 312                          */
 313                         continue;
 314                 /*
 315                  * Either this entry came from the tree-ish we are
 316                  * checking the paths out of, or we are checking out
 317                  * of the index.
 318                  *
 319                  * If it comes from the tree-ish, we already know it
 320                  * matches the pathspec and could just stamp
 321                  * CE_MATCHED to it from update_some(). But we still
 322                  * need ps_matched and read_tree_recursive (and
 323                  * eventually tree_entry_interesting) cannot fill
 324                  * ps_matched yet. Once it can, we can avoid calling
 325                  * match_pathspec() for _all_ entries when
 326                  * opts->source_tree != NULL.
 327                  */
 328                 if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched))
 329                         ce->ce_flags |= CE_MATCHED;
 330         }
 331
 332         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 333                 free(ps_matched);
 334                 return 1;
 335         }
 336         free(ps_matched);
 337
 338         /* "checkout -m path" to recreate conflicted state */
 339         if (opts->merge)
 340                 unmerge_marked_index(&the_index);
 341
 342         /* Any unmerged paths? */
 343         for (pos = 0; pos < active_nr; pos++) {
 344                 const struct cache_entry *ce = active_cache[pos];
 345                 if (ce->ce_flags & CE_MATCHED) {
 346                         if (!ce_stage(ce))
 347                                 continue;
 348                         if (opts->force) {
 349                                 warning(_("path '%s' is unmerged"), ce->name);
 350                         } else if (opts->writeout_stage) {
 351                                 errs |= check_stage(opts->writeout_stage, ce, pos);
 352                         } else if (opts->merge) {
 353                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 354                         } else {
 355                                 errs = 1;
 356                                 error(_("path '%s' is unmerged"), ce->name);
 357                         }
 358                         pos = skip_same_name(ce, pos) - 1;
 359                 }
 360         }
 361         if (errs)
 362                 return 1;
 363
 364         /* Now we are committed to check them out */
 365         state.force = 1;
 366         state.refresh_cache = 1;
 367         state.istate = &the_index;
 368
 369         enable_delayed_checkout(&state);
 370         for (pos = 0; pos < active_nr; pos++) {
 371                 struct cache_entry *ce = active_cache[pos];
 372                 if (ce->ce_flags & CE_MATCHED) {
 373                         if (!ce_stage(ce)) {
 374                                 errs |= checkout_entry(ce, &state, NULL);
 375                                 continue;
 376                         }
 377                         if (opts->writeout_stage)
 378                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 379                         else if (opts->merge)
 380                                 errs |= checkout_merged(pos, &state);
 381                         pos = skip_same_name(ce, pos) - 1;
 382                 }
 383         }
 384         errs |= finish_delayed_checkout(&state);
 385
 386         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 387                 die(_("unable to write new index file"));
 388
 389         read_ref_full("HEAD", 0, &rev, NULL);
 390         head = lookup_commit_reference_gently(the_repository, &rev, 1);
 391
 392         errs |= post_checkout_hook(head, head, 0);
 393         return errs;
 394 }
 395
 396 static void show_local_changes(struct object *head,
 397                                const struct diff_options *opts)
 398 {
 399         struct rev_info rev;
 400         /* I think we want full paths, even if we're in a subdirectory. */
 401         repo_init_revisions(the_repository, &rev, NULL);
 402         rev.diffopt.flags = opts->flags;
 403         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 404         diff_setup_done(&rev.diffopt);
 405         add_pending_object(&rev, head, NULL);
 406         run_diff_index(&rev, 0);
 407 }
 408
 409 static void describe_detached_head(const char *msg, struct commit *commit)
 410 {
 411         struct strbuf sb = STRBUF_INIT;
 412
 413         if (!parse_commit(commit))
 414                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 415         if (print_sha1_ellipsis()) {
 416                 fprintf(stderr, "%s %s... %s\n", msg,
 417                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 418         } else {
 419                 fprintf(stderr, "%s %s %s\n", msg,
 420                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 421         }
 422         strbuf_release(&sb);
 423 }
 424
 425 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 426                       int worktree, int *writeout_error)
 427 {
 428         struct unpack_trees_options opts;
 429         struct tree_desc tree_desc;
 430
 431         memset(&opts, 0, sizeof(opts));
 432         opts.head_idx = -1;
 433         opts.update = worktree;
 434         opts.skip_unmerged = !worktree;
 435         opts.reset = 1;
 436         opts.merge = 1;
 437         opts.fn = oneway_merge;
 438         opts.verbose_update = o->show_progress;
 439         opts.src_index = &the_index;
 440         opts.dst_index = &the_index;
 441         parse_tree(tree);
 442         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 443         switch (unpack_trees(1, &tree_desc, &opts)) {
 444         case -2:
 445                 *writeout_error = 1;
 446                 /*
 447                  * We return 0 nevertheless, as the index is all right
 448                  * and more importantly we have made best efforts to
 449                  * update paths in the work tree, and we cannot revert
 450                  * them.
 451                  */
 452                 /* fallthrough */
 453         case 0:
 454                 return 0;
 455         default:
 456                 return 128;
 457         }
 458 }
 459
 460 struct branch_info {
 461         const char *name; /* The short name used */
 462         const char *path; /* The full name of a real branch */
 463         struct commit *commit; /* The named commit */
 464         /*
 465          * if not null the branch is detached because it's already
 466          * checked out in this checkout
 467          */
 468         char *checkout;
 469 };
 470
 471 static void setup_branch_path(struct branch_info *branch)
 472 {
 473         struct strbuf buf = STRBUF_INIT;
 474
 475         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 476         if (strcmp(buf.buf, branch->name))
 477                 branch->name = xstrdup(buf.buf);
 478         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 479         branch->path = strbuf_detach(&buf, NULL);
 480 }
 481
 482 /*
 483  * Skip merging the trees, updating the index and working directory if and
 484  * only if we are creating a new branch via "git checkout -b <new_branch>."
 485  */
 486 static int skip_merge_working_tree(const struct checkout_opts *opts,
 487         const struct branch_info *old_branch_info,
 488         const struct branch_info *new_branch_info)
 489 {
 490         /*
 491          * Do the merge if sparse checkout is on and the user has not opted in
 492          * to the optimized behavior
 493          */
 494         if (core_apply_sparse_checkout && !checkout_optimize_new_branch)
 495                 return 0;
 496
 497         /*
 498          * We must do the merge if we are actually moving to a new commit.
 499          */
 500         if (!old_branch_info->commit || !new_branch_info->commit ||
 501                 !oideq(&old_branch_info->commit->object.oid,
 502                        &new_branch_info->commit->object.oid))
 503                 return 0;
 504
 505         /*
 506          * opts->patch_mode cannot be used with switching branches so is
 507          * not tested here
 508          */
 509
 510         /*
 511          * opts->quiet only impacts output so doesn't require a merge
 512          */
 513
 514         /*
 515          * Honor the explicit request for a three-way merge or to throw away
 516          * local changes
 517          */
 518         if (opts->merge || opts->force)
 519                 return 0;
 520
 521         /*
 522          * --detach is documented as "updating the index and the files in the
 523          * working tree" but this optimization skips those steps so fall through
 524          * to the regular code path.
 525          */
 526         if (opts->force_detach)
 527                 return 0;
 528
 529         /*
 530          * opts->writeout_stage cannot be used with switching branches so is
 531          * not tested here
 532          */
 533
 534         /*
 535          * Honor the explicit ignore requests
 536          */
 537         if (!opts->overwrite_ignore || opts->ignore_skipworktree ||
 538                 opts->ignore_other_worktrees)
 539                 return 0;
 540
 541         /*
 542          * opts->show_progress only impacts output so doesn't require a merge
 543          */
 544
 545         /*
 546          * If we aren't creating a new branch any changes or updates will
 547          * happen in the existing branch.  Since that could only be updating
 548          * the index and working directory, we don't want to skip those steps
 549          * or we've defeated any purpose in running the command.
 550          */
 551         if (!opts->new_branch)
 552                 return 0;
 553
 554         /*
 555          * new_branch_force is defined to "create/reset and checkout a branch"
 556          * so needs to go through the merge to do the reset
 557          */
 558         if (opts->new_branch_force)
 559                 return 0;
 560
 561         /*
 562          * A new orphaned branch requrires the index and the working tree to be
 563          * adjusted to <start_point>
 564          */
 565         if (opts->new_orphan_branch)
 566                 return 0;
 567
 568         /*
 569          * Remaining variables are not checkout options but used to track state
 570          */
 571
 572         return 1;
 573 }
 574
 575 static int merge_working_tree(const struct checkout_opts *opts,
 576                               struct branch_info *old_branch_info,
 577                               struct branch_info *new_branch_info,
 578                               int *writeout_error)
 579 {
 580         int ret;
 581         struct lock_file lock_file = LOCK_INIT;
 582
 583         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 584         if (read_cache_preload(NULL) < 0)
 585                 return error(_("index file corrupt"));
 586
 587         resolve_undo_clear();
 588         if (opts->force) {
 589                 ret = reset_tree(get_commit_tree(new_branch_info->commit),
 590                                  opts, 1, writeout_error);
 591                 if (ret)
 592                         return ret;
 593         } else {
 594                 struct tree_desc trees[2];
 595                 struct tree *tree;
 596                 struct unpack_trees_options topts;
 597
 598                 memset(&topts, 0, sizeof(topts));
 599                 topts.head_idx = -1;
 600                 topts.src_index = &the_index;
 601                 topts.dst_index = &the_index;
 602
 603                 setup_unpack_trees_porcelain(&topts, "checkout");
 604
 605                 refresh_cache(REFRESH_QUIET);
 606
 607                 if (unmerged_cache()) {
 608                         error(_("you need to resolve your current index first"));
 609                         return 1;
 610                 }
 611
 612                 /* 2-way merge to the new branch */
 613                 topts.initial_checkout = is_cache_unborn();
 614                 topts.update = 1;
 615                 topts.merge = 1;
 616                 topts.gently = opts->merge && old_branch_info->commit;
 617                 topts.verbose_update = opts->show_progress;
 618                 topts.fn = twoway_merge;
 619                 if (opts->overwrite_ignore) {
 620                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 621                         topts.dir->flags |= DIR_SHOW_IGNORED;
 622                         setup_standard_excludes(topts.dir);
 623                 }
 624                 tree = parse_tree_indirect(old_branch_info->commit ?
 625                                            &old_branch_info->commit->object.oid :
 626                                            the_hash_algo->empty_tree);
 627                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 628                 tree = parse_tree_indirect(&new_branch_info->commit->object.oid);
 629                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 630
 631                 ret = unpack_trees(2, trees, &topts);
 632                 clear_unpack_trees_porcelain(&topts);
 633                 if (ret == -1) {
 634                         /*
 635                          * Unpack couldn't do a trivial merge; either
 636                          * give up or do a real merge, depending on
 637                          * whether the merge flag was used.
 638                          */
 639                         struct tree *result;
 640                         struct tree *work;
 641                         struct merge_options o;
 642                         if (!opts->merge)
 643                                 return 1;
 644
 645                         /*
 646                          * Without old_branch_info->commit, the below is the same as
 647                          * the two-tree unpack we already tried and failed.
 648                          */
 649                         if (!old_branch_info->commit)
 650                                 return 1;
 651
 652                         /* Do more real merge */
 653
 654                         /*
 655                          * We update the index fully, then write the
 656                          * tree from the index, then merge the new
 657                          * branch with the current tree, with the old
 658                          * branch as the base. Then we reset the index
 659                          * (but not the working tree) to the new
 660                          * branch, leaving the working tree as the
 661                          * merged version, but skipping unmerged
 662                          * entries in the index.
 663                          */
 664
 665                         add_files_to_cache(NULL, NULL, 0);
 666                         /*
 667                          * NEEDSWORK: carrying over local changes
 668                          * when branches have different end-of-line
 669                          * normalization (or clean+smudge rules) is
 670                          * a pain; plumb in an option to set
 671                          * o.renormalize?
 672                          */
 673                         init_merge_options(&o);
 674                         o.verbosity = 0;
 675                         work = write_tree_from_memory(&o);
 676
 677                         ret = reset_tree(get_commit_tree(new_branch_info->commit),
 678                                          opts, 1,
 679                                          writeout_error);
 680                         if (ret)
 681                                 return ret;
 682                         o.ancestor = old_branch_info->name;
 683                         o.branch1 = new_branch_info->name;
 684                         o.branch2 = "local";
 685                         ret = merge_trees(&o,
 686                                           get_commit_tree(new_branch_info->commit),
 687                                           work,
 688                                           get_commit_tree(old_branch_info->commit),
 689                                           &result);
 690                         if (ret < 0)
 691                                 exit(128);
 692                         ret = reset_tree(get_commit_tree(new_branch_info->commit),
 693                                          opts, 0,
 694                                          writeout_error);
 695                         strbuf_release(&o.obuf);
 696                         if (ret)
 697                                 return ret;
 698                 }
 699         }
 700
 701         if (!active_cache_tree)
 702                 active_cache_tree = cache_tree();
 703
 704         if (!cache_tree_fully_valid(active_cache_tree))
 705                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 706
 707         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 708                 die(_("unable to write new index file"));
 709
 710         if (!opts->force && !opts->quiet)
 711                 show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 712
 713         return 0;
 714 }
 715
 716 static void report_tracking(struct branch_info *new_branch_info)
 717 {
 718         struct strbuf sb = STRBUF_INIT;
 719         struct branch *branch = branch_get(new_branch_info->name);
 720
 721         if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 722                 return;
 723         fputs(sb.buf, stdout);
 724         strbuf_release(&sb);
 725 }
 726
 727 static void update_refs_for_switch(const struct checkout_opts *opts,
 728                                    struct branch_info *old_branch_info,
 729                                    struct branch_info *new_branch_info)
 730 {
 731         struct strbuf msg = STRBUF_INIT;
 732         const char *old_desc, *reflog_msg;
 733         if (opts->new_branch) {
 734                 if (opts->new_orphan_branch) {
 735                         char *refname;
 736
 737                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 738                         if (opts->new_branch_log &&
 739                             !should_autocreate_reflog(refname)) {
 740                                 int ret;
 741                                 struct strbuf err = STRBUF_INIT;
 742
 743                                 ret = safe_create_reflog(refname, 1, &err);
 744                                 if (ret) {
 745                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 746                                                 opts->new_orphan_branch, err.buf);
 747                                         strbuf_release(&err);
 748                                         free(refname);
 749                                         return;
 750                                 }
 751                                 strbuf_release(&err);
 752                         }
 753                         free(refname);
 754                 }
 755                 else
 756                         create_branch(opts->new_branch, new_branch_info->name,
 757                                       opts->new_branch_force ? 1 : 0,
 758                                       opts->new_branch_force ? 1 : 0,
 759                                       opts->new_branch_log,
 760                                       opts->quiet,
 761                                       opts->track);
 762                 new_branch_info->name = opts->new_branch;
 763                 setup_branch_path(new_branch_info);
 764         }
 765
 766         old_desc = old_branch_info->name;
 767         if (!old_desc && old_branch_info->commit)
 768                 old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
 769
 770         reflog_msg = getenv("GIT_REFLOG_ACTION");
 771         if (!reflog_msg)
 772                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 773                         old_desc ? old_desc : "(invalid)", new_branch_info->name);
 774         else
 775                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 776
 777         if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
 778                 /* Nothing to do. */
 779         } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
 780                 update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
 781                            REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 782                 if (!opts->quiet) {
 783                         if (old_branch_info->path &&
 784                             advice_detached_head && !opts->force_detach)
 785                                 detach_advice(new_branch_info->name);
 786                         describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 787                 }
 788         } else if (new_branch_info->path) {     /* Switch branches. */
 789                 if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
 790                         die(_("unable to update HEAD"));
 791                 if (!opts->quiet) {
 792                         if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
 793                                 if (opts->new_branch_force)
 794                                         fprintf(stderr, _("Reset branch '%s'\n"),
 795                                                 new_branch_info->name);
 796                                 else
 797                                         fprintf(stderr, _("Already on '%s'\n"),
 798                                                 new_branch_info->name);
 799                         } else if (opts->new_branch) {
 800                                 if (opts->branch_exists)
 801                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
 802                                 else
 803                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
 804                         } else {
 805                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 806                                         new_branch_info->name);
 807                         }
 808                 }
 809                 if (old_branch_info->path && old_branch_info->name) {
 810                         if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
 811                                 delete_reflog(old_branch_info->path);
 812                 }
 813         }
 814         remove_branch_state();
 815         strbuf_release(&msg);
 816         if (!opts->quiet &&
 817             (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
 818                 report_tracking(new_branch_info);
 819 }
 820
 821 static int add_pending_uninteresting_ref(const char *refname,
 822                                          const struct object_id *oid,
 823                                          int flags, void *cb_data)
 824 {
 825         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 826         return 0;
 827 }
 828
 829 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 830 {
 831         strbuf_addstr(sb, "  ");
 832         strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 833         strbuf_addch(sb, ' ');
 834         if (!parse_commit(commit))
 835                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 836         strbuf_addch(sb, '\n');
 837 }
 838
 839 #define ORPHAN_CUTOFF 4
 840 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 841 {
 842         struct commit *c, *last = NULL;
 843         struct strbuf sb = STRBUF_INIT;
 844         int lost = 0;
 845         while ((c = get_revision(revs)) != NULL) {
 846                 if (lost < ORPHAN_CUTOFF)
 847                         describe_one_orphan(&sb, c);
 848                 last = c;
 849                 lost++;
 850         }
 851         if (ORPHAN_CUTOFF < lost) {
 852                 int more = lost - ORPHAN_CUTOFF;
 853                 if (more == 1)
 854                         describe_one_orphan(&sb, last);
 855                 else
 856                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 857         }
 858
 859         fprintf(stderr,
 860                 Q_(
 861                 /* The singular version */
 862                 "Warning: you are leaving %d commit behind, "
 863                 "not connected to\n"
 864                 "any of your branches:\n\n"
 865                 "%s\n",
 866                 /* The plural version */
 867                 "Warning: you are leaving %d commits behind, "
 868                 "not connected to\n"
 869                 "any of your branches:\n\n"
 870                 "%s\n",
 871                 /* Give ngettext() the count */
 872                 lost),
 873                 lost,
 874                 sb.buf);
 875         strbuf_release(&sb);
 876
 877         if (advice_detached_head)
 878                 fprintf(stderr,
 879                         Q_(
 880                         /* The singular version */
 881                         "If you want to keep it by creating a new branch, "
 882                         "this may be a good time\nto do so with:\n\n"
 883                         " git branch <new-branch-name> %s\n\n",
 884                         /* The plural version */
 885                         "If you want to keep them by creating a new branch, "
 886                         "this may be a good time\nto do so with:\n\n"
 887                         " git branch <new-branch-name> %s\n\n",
 888                         /* Give ngettext() the count */
 889                         lost),
 890                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 891 }
 892
 893 /*
 894  * We are about to leave commit that was at the tip of a detached
 895  * HEAD.  If it is not reachable from any ref, this is the last chance
 896  * for the user to do so without resorting to reflog.
 897  */
 898 static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
 899 {
 900         struct rev_info revs;
 901         struct object *object = &old_commit->object;
 902
 903         repo_init_revisions(the_repository, &revs, NULL);
 904         setup_revisions(0, NULL, &revs, NULL);
 905
 906         object->flags &= ~UNINTERESTING;
 907         add_pending_object(&revs, object, oid_to_hex(&object->oid));
 908
 909         for_each_ref(add_pending_uninteresting_ref, &revs);
 910         add_pending_oid(&revs, "HEAD", &new_commit->object.oid, UNINTERESTING);
 911
 912         if (prepare_revision_walk(&revs))
 913                 die(_("internal error in revision walk"));
 914         if (!(old_commit->object.flags & UNINTERESTING))
 915                 suggest_reattach(old_commit, &revs);
 916         else
 917                 describe_detached_head(_("Previous HEAD position was"), old_commit);
 918
 919         /* Clean up objects used, as they will be reused. */
 920         clear_commit_marks_all(ALL_REV_FLAGS);
 921 }
 922
 923 static int switch_branches(const struct checkout_opts *opts,
 924                            struct branch_info *new_branch_info)
 925 {
 926         int ret = 0;
 927         struct branch_info old_branch_info;
 928         void *path_to_free;
 929         struct object_id rev;
 930         int flag, writeout_error = 0;
 931         memset(&old_branch_info, 0, sizeof(old_branch_info));
 932         old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
 933         if (old_branch_info.path)
 934                 old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
 935         if (!(flag & REF_ISSYMREF))
 936                 old_branch_info.path = NULL;
 937
 938         if (old_branch_info.path)
 939                 skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
 940
 941         if (!new_branch_info->name) {
 942                 new_branch_info->name = "HEAD";
 943                 new_branch_info->commit = old_branch_info.commit;
 944                 if (!new_branch_info->commit)
 945                         die(_("You are on a branch yet to be born"));
 946                 parse_commit_or_die(new_branch_info->commit);
 947         }
 948
 949         /* optimize the "checkout -b <new_branch> path */
 950         if (skip_merge_working_tree(opts, &old_branch_info, new_branch_info)) {
 951                 if (!checkout_optimize_new_branch && !opts->quiet) {
 952                         if (read_cache_preload(NULL) < 0)
 953                                 return error(_("index file corrupt"));
 954                         show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 955                 }
 956         } else {
 957                 ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
 958                 if (ret) {
 959                         free(path_to_free);
 960                         return ret;
 961                 }
 962         }
 963
 964         if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
 965                 orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
 966
 967         update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 968
 969         ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 970         free(path_to_free);
 971         return ret || writeout_error;
 972 }
 973
 974 static int git_checkout_config(const char *var, const char *value, void *cb)
 975 {
 976         if (!strcmp(var, "checkout.optimizenewbranch")) {
 977                 checkout_optimize_new_branch = git_config_bool(var, value);
 978                 return 0;
 979         }
 980
 981         if (!strcmp(var, "diff.ignoresubmodules")) {
 982                 struct checkout_opts *opts = cb;
 983                 handle_ignore_submodules_arg(&opts->diff_options, value);
 984                 return 0;
 985         }
 986
 987         if (starts_with(var, "submodule."))
 988                 return git_default_submodule_config(var, value, NULL);
 989
 990         return git_xmerge_config(var, value, NULL);
 991 }
 992
 993 static int parse_branchname_arg(int argc, const char **argv,
 994                                 int dwim_new_local_branch_ok,
 995                                 struct branch_info *new_branch_info,
 996                                 struct checkout_opts *opts,
 997                                 struct object_id *rev,
 998                                 int *dwim_remotes_matched)
 999 {
1000         struct tree **source_tree = &opts->source_tree;
1001         const char **new_branch = &opts->new_branch;
1002         int argcount = 0;
1003         struct object_id branch_rev;
1004         const char *arg;
1005         int dash_dash_pos;
1006         int has_dash_dash = 0;
1007         int i;
1008
1009         /*
1010          * case 1: git checkout <ref> -- [<paths>]
1011          *
1012          *   <ref> must be a valid tree, everything after the '--' must be
1013          *   a path.
1014          *
1015          * case 2: git checkout -- [<paths>]
1016          *
1017          *   everything after the '--' must be paths.
1018          *
1019          * case 3: git checkout <something> [--]
1020          *
1021          *   (a) If <something> is a commit, that is to
1022          *       switch to the branch or detach HEAD at it.  As a special case,
1023          *       if <something> is A...B (missing A or B means HEAD but you can
1024          *       omit at most one side), and if there is a unique merge base
1025          *       between A and B, A...B names that merge base.
1026          *
1027          *   (b) If <something> is _not_ a commit, either "--" is present
1028          *       or <something> is not a path, no -t or -b was given, and
1029          *       and there is a tracking branch whose name is <something>
1030          *       in one and only one remote (or if the branch exists on the
1031          *       remote named in checkout.defaultRemote), then this is a
1032          *       short-hand to fork local <something> from that
1033          *       remote-tracking branch.
1034          *
1035          *   (c) Otherwise, if "--" is present, treat it like case (1).
1036          *
1037          *   (d) Otherwise :
1038          *       - if it's a reference, treat it like case (1)
1039          *       - else if it's a path, treat it like case (2)
1040          *       - else: fail.
1041          *
1042          * case 4: git checkout <something> <paths>
1043          *
1044          *   The first argument must not be ambiguous.
1045          *   - If it's *only* a reference, treat it like case (1).
1046          *   - If it's only a path, treat it like case (2).
1047          *   - else: fail.
1048          *
1049          */
1050         if (!argc)
1051                 return 0;
1052
1053         arg = argv[0];
1054         dash_dash_pos = -1;
1055         for (i = 0; i < argc; i++) {
1056                 if (!strcmp(argv[i], "--")) {
1057                         dash_dash_pos = i;
1058                         break;
1059                 }
1060         }
1061         if (dash_dash_pos == 0)
1062                 return 1; /* case (2) */
1063         else if (dash_dash_pos == 1)
1064                 has_dash_dash = 1; /* case (3) or (1) */
1065         else if (dash_dash_pos >= 2)
1066                 die(_("only one reference expected, %d given."), dash_dash_pos);
1067
1068         if (!strcmp(arg, "-"))
1069                 arg = "@{-1}";
1070
1071         if (get_oid_mb(arg, rev)) {
1072                 /*
1073                  * Either case (3) or (4), with <something> not being
1074                  * a commit, or an attempt to use case (1) with an
1075                  * invalid ref.
1076                  *
1077                  * It's likely an error, but we need to find out if
1078                  * we should auto-create the branch, case (3).(b).
1079                  */
1080                 int recover_with_dwim = dwim_new_local_branch_ok;
1081
1082                 if (!has_dash_dash &&
1083                     (check_filename(opts->prefix, arg) || !no_wildcard(arg)))
1084                         recover_with_dwim = 0;
1085                 /*
1086                  * Accept "git checkout foo" and "git checkout foo --"
1087                  * as candidates for dwim.
1088                  */
1089                 if (!(argc == 1 && !has_dash_dash) &&
1090                     !(argc == 2 && has_dash_dash))
1091                         recover_with_dwim = 0;
1092
1093                 if (recover_with_dwim) {
1094                         const char *remote = unique_tracking_name(arg, rev,
1095                                                                   dwim_remotes_matched);
1096                         if (remote) {
1097                                 *new_branch = arg;
1098                                 arg = remote;
1099                                 /* DWIMmed to create local branch, case (3).(b) */
1100                         } else {
1101                                 recover_with_dwim = 0;
1102                         }
1103                 }
1104
1105                 if (!recover_with_dwim) {
1106                         if (has_dash_dash)
1107                                 die(_("invalid reference: %s"), arg);
1108                         return argcount;
1109                 }
1110         }
1111
1112         /* we can't end up being in (2) anymore, eat the argument */
1113         argcount++;
1114         argv++;
1115         argc--;
1116
1117         new_branch_info->name = arg;
1118         setup_branch_path(new_branch_info);
1119
1120         if (!check_refname_format(new_branch_info->path, 0) &&
1121             !read_ref(new_branch_info->path, &branch_rev))
1122                 oidcpy(rev, &branch_rev);
1123         else
1124                 new_branch_info->path = NULL; /* not an existing branch */
1125
1126         new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
1127         if (!new_branch_info->commit) {
1128                 /* not a commit */
1129                 *source_tree = parse_tree_indirect(rev);
1130         } else {
1131                 parse_commit_or_die(new_branch_info->commit);
1132                 *source_tree = get_commit_tree(new_branch_info->commit);
1133         }
1134
1135         if (!*source_tree)                   /* case (1): want a tree */
1136                 die(_("reference is not a tree: %s"), arg);
1137         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1138                 /*
1139                  * Do not complain the most common case
1140                  *      git checkout branch
1141                  * even if there happen to be a file called 'branch';
1142                  * it would be extremely annoying.
1143                  */
1144                 if (argc)
1145                         verify_non_filename(opts->prefix, arg);
1146         } else {
1147                 argcount++;
1148                 argv++;
1149                 argc--;
1150         }
1151
1152         return argcount;
1153 }
1154
1155 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1156 {
1157         int status;
1158         struct strbuf branch_ref = STRBUF_INIT;
1159
1160         if (!opts->new_branch)
1161                 die(_("You are on a branch yet to be born"));
1162         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1163         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1164         strbuf_release(&branch_ref);
1165         if (!opts->quiet)
1166                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1167                         opts->new_branch);
1168         return status;
1169 }
1170
1171 static int checkout_branch(struct checkout_opts *opts,
1172                            struct branch_info *new_branch_info)
1173 {
1174         if (opts->pathspec.nr)
1175                 die(_("paths cannot be used with switching branches"));
1176
1177         if (opts->patch_mode)
1178                 die(_("'%s' cannot be used with switching branches"),
1179                     "--patch");
1180
1181         if (opts->writeout_stage)
1182                 die(_("'%s' cannot be used with switching branches"),
1183                     "--ours/--theirs");
1184
1185         if (opts->force && opts->merge)
1186                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1187
1188         if (opts->force_detach && opts->new_branch)
1189                 die(_("'%s' cannot be used with '%s'"),
1190                     "--detach", "-b/-B/--orphan");
1191
1192         if (opts->new_orphan_branch) {
1193                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1194                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1195         } else if (opts->force_detach) {
1196                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1197                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1198         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1199                 opts->track = git_branch_track;
1200
1201         if (new_branch_info->name && !new_branch_info->commit)
1202                 die(_("Cannot switch branch to a non-commit '%s'"),
1203                     new_branch_info->name);
1204
1205         if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1206             !opts->ignore_other_worktrees) {
1207                 int flag;
1208                 char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1209                 if (head_ref &&
1210                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1211                         die_if_checked_out(new_branch_info->path, 1);
1212                 free(head_ref);
1213         }
1214
1215         if (!new_branch_info->commit && opts->new_branch) {
1216                 struct object_id rev;
1217                 int flag;
1218
1219                 if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1220                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1221                         return switch_unborn_to_new_branch(opts);
1222         }
1223         return switch_branches(opts, new_branch_info);
1224 }
1225
1226 int cmd_checkout(int argc, const char **argv, const char *prefix)
1227 {
1228         struct checkout_opts opts;
1229         struct branch_info new_branch_info;
1230         char *conflict_style = NULL;
1231         int dwim_new_local_branch = 1;
1232         int dwim_remotes_matched = 0;
1233         struct option options[] = {
1234                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1235                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1236                            N_("create and checkout a new branch")),
1237                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1238                            N_("create/reset and checkout a branch")),
1239                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1240                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1241                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1242                         BRANCH_TRACK_EXPLICIT),
1243                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1244                 OPT_SET_INT_F('2', "ours", &opts.writeout_stage,
1245                               N_("checkout our version for unmerged files"),
1246                               2, PARSE_OPT_NONEG),
1247                 OPT_SET_INT_F('3', "theirs", &opts.writeout_stage,
1248                               N_("checkout their version for unmerged files"),
1249                               3, PARSE_OPT_NONEG),
1250                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)"),
1251                            PARSE_OPT_NOCOMPLETE),
1252                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1253                 OPT_BOOL_F(0, "overwrite-ignore", &opts.overwrite_ignore,
1254                            N_("update ignored files (default)"),
1255                            PARSE_OPT_NOCOMPLETE),
1256                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1257                            N_("conflict style (merge or diff3)")),
1258                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1259                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1260                          N_("do not limit pathspecs to sparse entries only")),
1261                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1262                                 N_("second guess 'git checkout <no-such-branch>'")),
1263                 OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1264                          N_("do not check if another worktree is holding the given ref")),
1265                 { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1266                             "checkout", "control recursive updating of submodules",
1267                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1268                 OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1269                 OPT_END(),
1270         };
1271
1272         memset(&opts, 0, sizeof(opts));
1273         memset(&new_branch_info, 0, sizeof(new_branch_info));
1274         opts.overwrite_ignore = 1;
1275         opts.prefix = prefix;
1276         opts.show_progress = -1;
1277
1278         git_config(git_checkout_config, &opts);
1279
1280         opts.track = BRANCH_TRACK_UNSPECIFIED;
1281
1282         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1283                              PARSE_OPT_KEEP_DASHDASH);
1284
1285         if (opts.show_progress < 0) {
1286                 if (opts.quiet)
1287                         opts.show_progress = 0;
1288                 else
1289                         opts.show_progress = isatty(2);
1290         }
1291
1292         if (conflict_style) {
1293                 opts.merge = 1; /* implied */
1294                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1295         }
1296
1297         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1298                 die(_("-b, -B and --orphan are mutually exclusive"));
1299
1300         /*
1301          * From here on, new_branch will contain the branch to be checked out,
1302          * and new_branch_force and new_orphan_branch will tell us which one of
1303          * -b/-B/--orphan is being used.
1304          */
1305         if (opts.new_branch_force)
1306                 opts.new_branch = opts.new_branch_force;
1307
1308         if (opts.new_orphan_branch)
1309                 opts.new_branch = opts.new_orphan_branch;
1310
1311         /* --track without -b/-B/--orphan should DWIM */
1312         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1313                 const char *argv0 = argv[0];
1314                 if (!argc || !strcmp(argv0, "--"))
1315                         die(_("--track needs a branch name"));
1316                 skip_prefix(argv0, "refs/", &argv0);
1317                 skip_prefix(argv0, "remotes/", &argv0);
1318                 argv0 = strchr(argv0, '/');
1319                 if (!argv0 || !argv0[1])
1320                         die(_("missing branch name; try -b"));
1321                 opts.new_branch = argv0 + 1;
1322         }
1323
1324         /*
1325          * Extract branch name from command line arguments, so
1326          * all that is left is pathspecs.
1327          *
1328          * Handle
1329          *
1330          *  1) git checkout <tree> -- [<paths>]
1331          *  2) git checkout -- [<paths>]
1332          *  3) git checkout <something> [<paths>]
1333          *
1334          * including "last branch" syntax and DWIM-ery for names of
1335          * remote branches, erroring out for invalid or ambiguous cases.
1336          */
1337         if (argc) {
1338                 struct object_id rev;
1339                 int dwim_ok =
1340                         !opts.patch_mode &&
1341                         dwim_new_local_branch &&
1342                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1343                         !opts.new_branch;
1344                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1345                                              &new_branch_info, &opts, &rev,
1346                                              &dwim_remotes_matched);
1347                 argv += n;
1348                 argc -= n;
1349         }
1350
1351         if (argc) {
1352                 parse_pathspec(&opts.pathspec, 0,
1353                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1354                                prefix, argv);
1355
1356                 if (!opts.pathspec.nr)
1357                         die(_("invalid path specification"));
1358
1359                 /*
1360                  * Try to give more helpful suggestion.
1361                  * new_branch && argc > 1 will be caught later.
1362                  */
1363                 if (opts.new_branch && argc == 1)
1364                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1365                                 argv[0], opts.new_branch);
1366
1367                 if (opts.force_detach)
1368                         die(_("git checkout: --detach does not take a path argument '%s'"),
1369                             argv[0]);
1370
1371                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1372                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1373                               "checking out of the index."));
1374         }
1375
1376         if (opts.new_branch) {
1377                 struct strbuf buf = STRBUF_INIT;
1378
1379                 if (opts.new_branch_force)
1380                         opts.branch_exists = validate_branchname(opts.new_branch, &buf);
1381                 else
1382                         opts.branch_exists =
1383                                 validate_new_branchname(opts.new_branch, &buf, 0);
1384                 strbuf_release(&buf);
1385         }
1386
1387         UNLEAK(opts);
1388         if (opts.patch_mode || opts.pathspec.nr) {
1389                 int ret = checkout_paths(&opts, new_branch_info.name);
1390                 if (ret && dwim_remotes_matched > 1 &&
1391                     advice_checkout_ambiguous_remote_branch_name)
1392                         advise(_("'%s' matched more than one remote tracking branch.\n"
1393                                  "We found %d remotes with a reference that matched. So we fell back\n"
1394                                  "on trying to resolve the argument as a path, but failed there too!\n"
1395                                  "\n"
1396                                  "If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
1397                                  "you can do so by fully qualifying the name with the --track option:\n"
1398                                  "\n"
1399                                  "    git checkout --track origin/<name>\n"
1400                                  "\n"
1401                                  "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
1402                                  "one remote, e.g. the 'origin' remote, consider setting\n"
1403                                  "checkout.defaultRemote=origin in your config."),
1404                                argv[0],
1405                                dwim_remotes_matched);
1406                 return ret;
1407         } else {
1408                 return checkout_branch(&opts, &new_branch_info);
1409         }
1410 }