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