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