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