builtin/checkout.c

   1 #include "builtin.h"
   2 #include "config.h"
   3 #include "lockfile.h"
   4 #include "parse-options.h"
   5 #include "refs.h"
   6 #include "commit.h"
   7 #include "tree.h"
   8 #include "tree-walk.h"
   9 #include "cache-tree.h"
  10 #include "unpack-trees.h"
  11 #include "dir.h"
  12 #include "run-command.h"
  13 #include "merge-recursive.h"
  14 #include "branch.h"
  15 #include "diff.h"
  16 #include "revision.h"
  17 #include "remote.h"
  18 #include "blob.h"
  19 #include "xdiff-interface.h"
  20 #include "ll-merge.h"
  21 #include "resolve-undo.h"
  22 #include "submodule-config.h"
  23 #include "submodule.h"
  24
  25 static const char * const checkout_usage[] = {
  26         N_("git checkout [<options>] <branch>"),
  27         N_("git checkout [<options>] [<branch>] -- <file>..."),
  28         NULL,
  29 };
  30
  31 struct checkout_opts {
  32         int patch_mode;
  33         int quiet;
  34         int merge;
  35         int force;
  36         int force_detach;
  37         int writeout_stage;
  38         int overwrite_ignore;
  39         int ignore_skipworktree;
  40         int ignore_other_worktrees;
  41         int show_progress;
  42
  43         const char *new_branch;
  44         const char *new_branch_force;
  45         const char *new_orphan_branch;
  46         int new_branch_log;
  47         enum branch_track track;
  48         struct diff_options diff_options;
  49
  50         int branch_exists;
  51         const char *prefix;
  52         struct pathspec pathspec;
  53         struct tree *source_tree;
  54 };
  55
  56 static int post_checkout_hook(struct commit *old, struct commit *new,
  57                               int changed)
  58 {
  59         return run_hook_le(NULL, "post-checkout",
  60                            oid_to_hex(old ? &old->object.oid : &null_oid),
  61                            oid_to_hex(new ? &new->object.oid : &null_oid),
  62                            changed ? "1" : "0", NULL);
  63         /* "new" can be NULL when checking out from the index before
  64            a commit exists. */
  65
  66 }
  67
  68 static int update_some(const unsigned char *sha1, struct strbuf *base,
  69                 const char *pathname, unsigned mode, int stage, void *context)
  70 {
  71         int len;
  72         struct cache_entry *ce;
  73         int pos;
  74
  75         if (S_ISDIR(mode))
  76                 return READ_TREE_RECURSIVE;
  77
  78         len = base->len + strlen(pathname);
  79         ce = xcalloc(1, cache_entry_size(len));
  80         hashcpy(ce->oid.hash, sha1);
  81         memcpy(ce->name, base->buf, base->len);
  82         memcpy(ce->name + base->len, pathname, len - base->len);
  83         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  84         ce->ce_namelen = len;
  85         ce->ce_mode = create_ce_mode(mode);
  86
  87         /*
  88          * If the entry is the same as the current index, we can leave the old
  89          * entry in place. Whether it is UPTODATE or not, checkout_entry will
  90          * do the right thing.
  91          */
  92         pos = cache_name_pos(ce->name, ce->ce_namelen);
  93         if (pos >= 0) {
  94                 struct cache_entry *old = active_cache[pos];
  95                 if (ce->ce_mode == old->ce_mode &&
  96                     !oidcmp(&ce->oid, &old->oid)) {
  97                         old->ce_flags |= CE_UPDATE;
  98                         free(ce);
  99                         return 0;
 100                 }
 101         }
 102
 103         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 104         return 0;
 105 }
 106
 107 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 108 {
 109         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 110
 111         /* update the index with the given tree's info
 112          * for all args, expanding wildcards, and exit
 113          * with any non-zero return code.
 114          */
 115         return 0;
 116 }
 117
 118 static int skip_same_name(const struct cache_entry *ce, int pos)
 119 {
 120         while (++pos < active_nr &&
 121                !strcmp(active_cache[pos]->name, ce->name))
 122                 ; /* skip */
 123         return pos;
 124 }
 125
 126 static int check_stage(int stage, const struct cache_entry *ce, int pos)
 127 {
 128         while (pos < active_nr &&
 129                !strcmp(active_cache[pos]->name, ce->name)) {
 130                 if (ce_stage(active_cache[pos]) == stage)
 131                         return 0;
 132                 pos++;
 133         }
 134         if (stage == 2)
 135                 return error(_("path '%s' does not have our version"), ce->name);
 136         else
 137                 return error(_("path '%s' does not have their version"), ce->name);
 138 }
 139
 140 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 141 {
 142         unsigned seen = 0;
 143         const char *name = ce->name;
 144
 145         while (pos < active_nr) {
 146                 ce = active_cache[pos];
 147                 if (strcmp(name, ce->name))
 148                         break;
 149                 seen |= (1 << ce_stage(ce));
 150                 pos++;
 151         }
 152         if ((stages & seen) != stages)
 153                 return error(_("path '%s' does not have all necessary versions"),
 154                              name);
 155         return 0;
 156 }
 157
 158 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 159                           const struct checkout *state)
 160 {
 161         while (pos < active_nr &&
 162                !strcmp(active_cache[pos]->name, ce->name)) {
 163                 if (ce_stage(active_cache[pos]) == stage)
 164                         return checkout_entry(active_cache[pos], state, NULL);
 165                 pos++;
 166         }
 167         if (stage == 2)
 168                 return error(_("path '%s' does not have our version"), ce->name);
 169         else
 170                 return error(_("path '%s' does not have their version"), ce->name);
 171 }
 172
 173 static int checkout_merged(int pos, const struct checkout *state)
 174 {
 175         struct cache_entry *ce = active_cache[pos];
 176         const char *path = ce->name;
 177         mmfile_t ancestor, ours, theirs;
 178         int status;
 179         struct object_id oid;
 180         mmbuffer_t result_buf;
 181         struct object_id threeway[3];
 182         unsigned mode = 0;
 183
 184         memset(threeway, 0, sizeof(threeway));
 185         while (pos < active_nr) {
 186                 int stage;
 187                 stage = ce_stage(ce);
 188                 if (!stage || strcmp(path, ce->name))
 189                         break;
 190                 oidcpy(&threeway[stage - 1], &ce->oid);
 191                 if (stage == 2)
 192                         mode = create_ce_mode(ce->ce_mode);
 193                 pos++;
 194                 ce = active_cache[pos];
 195         }
 196         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 197                 return error(_("path '%s' does not have necessary versions"), path);
 198
 199         read_mmblob(&ancestor, &threeway[0]);
 200         read_mmblob(&ours, &threeway[1]);
 201         read_mmblob(&theirs, &threeway[2]);
 202
 203         /*
 204          * NEEDSWORK: re-create conflicts from merges with
 205          * merge.renormalize set, too
 206          */
 207         status = ll_merge(&result_buf, path, &ancestor, "base",
 208                           &ours, "ours", &theirs, "theirs", NULL);
 209         free(ancestor.ptr);
 210         free(ours.ptr);
 211         free(theirs.ptr);
 212         if (status < 0 || !result_buf.ptr) {
 213                 free(result_buf.ptr);
 214                 return error(_("path '%s': cannot merge"), path);
 215         }
 216
 217         /*
 218          * NEEDSWORK:
 219          * There is absolutely no reason to write this as a blob object
 220          * and create a phony cache entry.  This hack is primarily to get
 221          * to the write_entry() machinery that massages the contents to
 222          * work-tree format and writes out which only allows it for a
 223          * cache entry.  The code in write_entry() needs to be refactored
 224          * to allow us to feed a <buffer, size, mode> instead of a cache
 225          * entry.  Such a refactoring would help merge_recursive as well
 226          * (it also writes the merge result to the object database even
 227          * when it may contain conflicts).
 228          */
 229         if (write_sha1_file(result_buf.ptr, result_buf.size,
 230                             blob_type, oid.hash))
 231                 die(_("Unable to add merge result for '%s'"), path);
 232         free(result_buf.ptr);
 233         ce = make_cache_entry(mode, oid.hash, path, 2, 0);
 234         if (!ce)
 235                 die(_("make_cache_entry failed for path '%s'"), path);
 236         status = checkout_entry(ce, state, NULL);
 237         free(ce);
 238         return status;
 239 }
 240
 241 static int checkout_paths(const struct checkout_opts *opts,
 242                           const char *revision)
 243 {
 244         int pos;
 245         struct checkout state = CHECKOUT_INIT;
 246         static char *ps_matched;
 247         struct object_id rev;
 248         struct commit *head;
 249         int errs = 0;
 250         struct lock_file *lock_file;
 251
 252         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 253                 die(_("'%s' cannot be used with updating paths"), "--track");
 254
 255         if (opts->new_branch_log)
 256                 die(_("'%s' cannot be used with updating paths"), "-l");
 257
 258         if (opts->force && opts->patch_mode)
 259                 die(_("'%s' cannot be used with updating paths"), "-f");
 260
 261         if (opts->force_detach)
 262                 die(_("'%s' cannot be used with updating paths"), "--detach");
 263
 264         if (opts->merge && opts->patch_mode)
 265                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 266
 267         if (opts->force && opts->merge)
 268                 die(_("'%s' cannot be used with %s"), "-f", "-m");
 269
 270         if (opts->new_branch)
 271                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 272                     opts->new_branch);
 273
 274         if (opts->patch_mode)
 275                 return run_add_interactive(revision, "--patch=checkout",
 276                                            &opts->pathspec);
 277
 278         lock_file = xcalloc(1, sizeof(struct lock_file));
 279
 280         hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
 281         if (read_cache_preload(&opts->pathspec) < 0)
 282                 return error(_("index file corrupt"));
 283
 284         if (opts->source_tree)
 285                 read_tree_some(opts->source_tree, &opts->pathspec);
 286
 287         ps_matched = xcalloc(opts->pathspec.nr, 1);
 288
 289         /*
 290          * Make sure all pathspecs participated in locating the paths
 291          * to be checked out.
 292          */
 293         for (pos = 0; pos < active_nr; pos++) {
 294                 struct cache_entry *ce = active_cache[pos];
 295                 ce->ce_flags &= ~CE_MATCHED;
 296                 if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 297                         continue;
 298                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 299                         /*
 300                          * "git checkout tree-ish -- path", but this entry
 301                          * is in the original index; it will not be checked
 302                          * out to the working tree and it does not matter
 303                          * if pathspec matched this entry.  We will not do
 304                          * anything to this entry at all.
 305                          */
 306                         continue;
 307                 /*
 308                  * Either this entry came from the tree-ish we are
 309                  * checking the paths out of, or we are checking out
 310                  * of the index.
 311                  *
 312                  * If it comes from the tree-ish, we already know it
 313                  * matches the pathspec and could just stamp
 314                  * CE_MATCHED to it from update_some(). But we still
 315                  * need ps_matched and read_tree_recursive (and
 316                  * eventually tree_entry_interesting) cannot fill
 317                  * ps_matched yet. Once it can, we can avoid calling
 318                  * match_pathspec() for _all_ entries when
 319                  * opts->source_tree != NULL.
 320                  */
 321                 if (ce_path_match(ce, &opts->pathspec, ps_matched))
 322                         ce->ce_flags |= CE_MATCHED;
 323         }
 324
 325         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 326                 free(ps_matched);
 327                 return 1;
 328         }
 329         free(ps_matched);
 330
 331         /* "checkout -m path" to recreate conflicted state */
 332         if (opts->merge)
 333                 unmerge_marked_index(&the_index);
 334
 335         /* Any unmerged paths? */
 336         for (pos = 0; pos < active_nr; pos++) {
 337                 const struct cache_entry *ce = active_cache[pos];
 338                 if (ce->ce_flags & CE_MATCHED) {
 339                         if (!ce_stage(ce))
 340                                 continue;
 341                         if (opts->force) {
 342                                 warning(_("path '%s' is unmerged"), ce->name);
 343                         } else if (opts->writeout_stage) {
 344                                 errs |= check_stage(opts->writeout_stage, ce, pos);
 345                         } else if (opts->merge) {
 346                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 347                         } else {
 348                                 errs = 1;
 349                                 error(_("path '%s' is unmerged"), ce->name);
 350                         }
 351                         pos = skip_same_name(ce, pos) - 1;
 352                 }
 353         }
 354         if (errs)
 355                 return 1;
 356
 357         /* Now we are committed to check them out */
 358         state.force = 1;
 359         state.refresh_cache = 1;
 360         state.istate = &the_index;
 361
 362         enable_delayed_checkout(&state);
 363         for (pos = 0; pos < active_nr; pos++) {
 364                 struct cache_entry *ce = active_cache[pos];
 365                 if (ce->ce_flags & CE_MATCHED) {
 366                         if (!ce_stage(ce)) {
 367                                 errs |= checkout_entry(ce, &state, NULL);
 368                                 continue;
 369                         }
 370                         if (opts->writeout_stage)
 371                                 errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 372                         else if (opts->merge)
 373                                 errs |= checkout_merged(pos, &state);
 374                         pos = skip_same_name(ce, pos) - 1;
 375                 }
 376         }
 377         errs |= finish_delayed_checkout(&state);
 378
 379         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 380                 die(_("unable to write new index file"));
 381
 382         read_ref_full("HEAD", 0, rev.hash, NULL);
 383         head = lookup_commit_reference_gently(&rev, 1);
 384
 385         errs |= post_checkout_hook(head, head, 0);
 386         return errs;
 387 }
 388
 389 static void show_local_changes(struct object *head,
 390                                const struct diff_options *opts)
 391 {
 392         struct rev_info rev;
 393         /* I think we want full paths, even if we're in a subdirectory. */
 394         init_revisions(&rev, NULL);
 395         rev.diffopt.flags = opts->flags;
 396         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 397         diff_setup_done(&rev.diffopt);
 398         add_pending_object(&rev, head, NULL);
 399         run_diff_index(&rev, 0);
 400 }
 401
 402 static void describe_detached_head(const char *msg, struct commit *commit)
 403 {
 404         struct strbuf sb = STRBUF_INIT;
 405         if (!parse_commit(commit))
 406                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 407         fprintf(stderr, "%s %s... %s\n", msg,
 408                 find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV), sb.buf);
 409         strbuf_release(&sb);
 410 }
 411
 412 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 413                       int worktree, int *writeout_error)
 414 {
 415         struct unpack_trees_options opts;
 416         struct tree_desc tree_desc;
 417
 418         memset(&opts, 0, sizeof(opts));
 419         opts.head_idx = -1;
 420         opts.update = worktree;
 421         opts.skip_unmerged = !worktree;
 422         opts.reset = 1;
 423         opts.merge = 1;
 424         opts.fn = oneway_merge;
 425         opts.verbose_update = o->show_progress;
 426         opts.src_index = &the_index;
 427         opts.dst_index = &the_index;
 428         parse_tree(tree);
 429         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 430         switch (unpack_trees(1, &tree_desc, &opts)) {
 431         case -2:
 432                 *writeout_error = 1;
 433                 /*
 434                  * We return 0 nevertheless, as the index is all right
 435                  * and more importantly we have made best efforts to
 436                  * update paths in the work tree, and we cannot revert
 437                  * them.
 438                  */
 439         case 0:
 440                 return 0;
 441         default:
 442                 return 128;
 443         }
 444 }
 445
 446 struct branch_info {
 447         const char *name; /* The short name used */
 448         const char *path; /* The full name of a real branch */
 449         struct commit *commit; /* The named commit */
 450         /*
 451          * if not null the branch is detached because it's already
 452          * checked out in this checkout
 453          */
 454         char *checkout;
 455 };
 456
 457 static void setup_branch_path(struct branch_info *branch)
 458 {
 459         struct strbuf buf = STRBUF_INIT;
 460
 461         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 462         if (strcmp(buf.buf, branch->name))
 463                 branch->name = xstrdup(buf.buf);
 464         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 465         branch->path = strbuf_detach(&buf, NULL);
 466 }
 467
 468 static int merge_working_tree(const struct checkout_opts *opts,
 469                               struct branch_info *old,
 470                               struct branch_info *new,
 471                               int *writeout_error)
 472 {
 473         int ret;
 474         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 475
 476         hold_locked_index(lock_file, LOCK_DIE_ON_ERROR);
 477         if (read_cache_preload(NULL) < 0)
 478                 return error(_("index file corrupt"));
 479
 480         resolve_undo_clear();
 481         if (opts->force) {
 482                 ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 483                 if (ret)
 484                         return ret;
 485         } else {
 486                 struct tree_desc trees[2];
 487                 struct tree *tree;
 488                 struct unpack_trees_options topts;
 489
 490                 memset(&topts, 0, sizeof(topts));
 491                 topts.head_idx = -1;
 492                 topts.src_index = &the_index;
 493                 topts.dst_index = &the_index;
 494
 495                 setup_unpack_trees_porcelain(&topts, "checkout");
 496
 497                 refresh_cache(REFRESH_QUIET);
 498
 499                 if (unmerged_cache()) {
 500                         error(_("you need to resolve your current index first"));
 501                         return 1;
 502                 }
 503
 504                 /* 2-way merge to the new branch */
 505                 topts.initial_checkout = is_cache_unborn();
 506                 topts.update = 1;
 507                 topts.merge = 1;
 508                 topts.gently = opts->merge && old->commit;
 509                 topts.verbose_update = opts->show_progress;
 510                 topts.fn = twoway_merge;
 511                 if (opts->overwrite_ignore) {
 512                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 513                         topts.dir->flags |= DIR_SHOW_IGNORED;
 514                         setup_standard_excludes(topts.dir);
 515                 }
 516                 tree = parse_tree_indirect(old->commit ?
 517                                            &old->commit->object.oid :
 518                                            &empty_tree_oid);
 519                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 520                 tree = parse_tree_indirect(&new->commit->object.oid);
 521                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 522
 523                 ret = unpack_trees(2, trees, &topts);
 524                 if (ret == -1) {
 525                         /*
 526                          * Unpack couldn't do a trivial merge; either
 527                          * give up or do a real merge, depending on
 528                          * whether the merge flag was used.
 529                          */
 530                         struct tree *result;
 531                         struct tree *work;
 532                         struct merge_options o;
 533                         if (!opts->merge)
 534                                 return 1;
 535
 536                         /*
 537                          * Without old->commit, the below is the same as
 538                          * the two-tree unpack we already tried and failed.
 539                          */
 540                         if (!old->commit)
 541                                 return 1;
 542
 543                         /* Do more real merge */
 544
 545                         /*
 546                          * We update the index fully, then write the
 547                          * tree from the index, then merge the new
 548                          * branch with the current tree, with the old
 549                          * branch as the base. Then we reset the index
 550                          * (but not the working tree) to the new
 551                          * branch, leaving the working tree as the
 552                          * merged version, but skipping unmerged
 553                          * entries in the index.
 554                          */
 555
 556                         add_files_to_cache(NULL, NULL, 0);
 557                         /*
 558                          * NEEDSWORK: carrying over local changes
 559                          * when branches have different end-of-line
 560                          * normalization (or clean+smudge rules) is
 561                          * a pain; plumb in an option to set
 562                          * o.renormalize?
 563                          */
 564                         init_merge_options(&o);
 565                         o.verbosity = 0;
 566                         work = write_tree_from_memory(&o);
 567
 568                         ret = reset_tree(new->commit->tree, opts, 1,
 569                                          writeout_error);
 570                         if (ret)
 571                                 return ret;
 572                         o.ancestor = old->name;
 573                         o.branch1 = new->name;
 574                         o.branch2 = "local";
 575                         ret = merge_trees(&o, new->commit->tree, work,
 576                                 old->commit->tree, &result);
 577                         if (ret < 0)
 578                                 exit(128);
 579                         ret = reset_tree(new->commit->tree, opts, 0,
 580                                          writeout_error);
 581                         strbuf_release(&o.obuf);
 582                         if (ret)
 583                                 return ret;
 584                 }
 585         }
 586
 587         if (!active_cache_tree)
 588                 active_cache_tree = cache_tree();
 589
 590         if (!cache_tree_fully_valid(active_cache_tree))
 591                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 592
 593         if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 594                 die(_("unable to write new index file"));
 595
 596         if (!opts->force && !opts->quiet)
 597                 show_local_changes(&new->commit->object, &opts->diff_options);
 598
 599         return 0;
 600 }
 601
 602 static void report_tracking(struct branch_info *new)
 603 {
 604         struct strbuf sb = STRBUF_INIT;
 605         struct branch *branch = branch_get(new->name);
 606
 607         if (!format_tracking_info(branch, &sb))
 608                 return;
 609         fputs(sb.buf, stdout);
 610         strbuf_release(&sb);
 611 }
 612
 613 static void update_refs_for_switch(const struct checkout_opts *opts,
 614                                    struct branch_info *old,
 615                                    struct branch_info *new)
 616 {
 617         struct strbuf msg = STRBUF_INIT;
 618         const char *old_desc, *reflog_msg;
 619         if (opts->new_branch) {
 620                 if (opts->new_orphan_branch) {
 621                         char *refname;
 622
 623                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 624                         if (opts->new_branch_log &&
 625                             !should_autocreate_reflog(refname)) {
 626                                 int ret;
 627                                 struct strbuf err = STRBUF_INIT;
 628
 629                                 ret = safe_create_reflog(refname, 1, &err);
 630                                 if (ret) {
 631                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 632                                                 opts->new_orphan_branch, err.buf);
 633                                         strbuf_release(&err);
 634                                         free(refname);
 635                                         return;
 636                                 }
 637                                 strbuf_release(&err);
 638                         }
 639                         free(refname);
 640                 }
 641                 else
 642                         create_branch(opts->new_branch, new->name,
 643                                       opts->new_branch_force ? 1 : 0,
 644                                       opts->new_branch_log,
 645                                       opts->new_branch_force ? 1 : 0,
 646                                       opts->quiet,
 647                                       opts->track);
 648                 new->name = opts->new_branch;
 649                 setup_branch_path(new);
 650         }
 651
 652         old_desc = old->name;
 653         if (!old_desc && old->commit)
 654                 old_desc = oid_to_hex(&old->commit->object.oid);
 655
 656         reflog_msg = getenv("GIT_REFLOG_ACTION");
 657         if (!reflog_msg)
 658                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 659                         old_desc ? old_desc : "(invalid)", new->name);
 660         else
 661                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 662
 663         if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 664                 /* Nothing to do. */
 665         } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 666                 update_ref(msg.buf, "HEAD", new->commit->object.oid.hash, NULL,
 667                            REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
 668                 if (!opts->quiet) {
 669                         if (old->path &&
 670                             advice_detached_head && !opts->force_detach)
 671                                 detach_advice(new->name);
 672                         describe_detached_head(_("HEAD is now at"), new->commit);
 673                 }
 674         } else if (new->path) { /* Switch branches. */
 675                 if (create_symref("HEAD", new->path, msg.buf) < 0)
 676                         die(_("unable to update HEAD"));
 677                 if (!opts->quiet) {
 678                         if (old->path && !strcmp(new->path, old->path)) {
 679                                 if (opts->new_branch_force)
 680                                         fprintf(stderr, _("Reset branch '%s'\n"),
 681                                                 new->name);
 682                                 else
 683                                         fprintf(stderr, _("Already on '%s'\n"),
 684                                                 new->name);
 685                         } else if (opts->new_branch) {
 686                                 if (opts->branch_exists)
 687                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 688                                 else
 689                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 690                         } else {
 691                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 692                                         new->name);
 693                         }
 694                 }
 695                 if (old->path && old->name) {
 696                         if (!ref_exists(old->path) && reflog_exists(old->path))
 697                                 delete_reflog(old->path);
 698                 }
 699         }
 700         remove_branch_state();
 701         strbuf_release(&msg);
 702         if (!opts->quiet &&
 703             (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 704                 report_tracking(new);
 705 }
 706
 707 static int add_pending_uninteresting_ref(const char *refname,
 708                                          const struct object_id *oid,
 709                                          int flags, void *cb_data)
 710 {
 711         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 712         return 0;
 713 }
 714
 715 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 716 {
 717         strbuf_addstr(sb, "  ");
 718         strbuf_add_unique_abbrev(sb, commit->object.oid.hash, DEFAULT_ABBREV);
 719         strbuf_addch(sb, ' ');
 720         if (!parse_commit(commit))
 721                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 722         strbuf_addch(sb, '\n');
 723 }
 724
 725 #define ORPHAN_CUTOFF 4
 726 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 727 {
 728         struct commit *c, *last = NULL;
 729         struct strbuf sb = STRBUF_INIT;
 730         int lost = 0;
 731         while ((c = get_revision(revs)) != NULL) {
 732                 if (lost < ORPHAN_CUTOFF)
 733                         describe_one_orphan(&sb, c);
 734                 last = c;
 735                 lost++;
 736         }
 737         if (ORPHAN_CUTOFF < lost) {
 738                 int more = lost - ORPHAN_CUTOFF;
 739                 if (more == 1)
 740                         describe_one_orphan(&sb, last);
 741                 else
 742                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 743         }
 744
 745         fprintf(stderr,
 746                 Q_(
 747                 /* The singular version */
 748                 "Warning: you are leaving %d commit behind, "
 749                 "not connected to\n"
 750                 "any of your branches:\n\n"
 751                 "%s\n",
 752                 /* The plural version */
 753                 "Warning: you are leaving %d commits behind, "
 754                 "not connected to\n"
 755                 "any of your branches:\n\n"
 756                 "%s\n",
 757                 /* Give ngettext() the count */
 758                 lost),
 759                 lost,
 760                 sb.buf);
 761         strbuf_release(&sb);
 762
 763         if (advice_detached_head)
 764                 fprintf(stderr,
 765                         Q_(
 766                         /* The singular version */
 767                         "If you want to keep it by creating a new branch, "
 768                         "this may be a good time\nto do so with:\n\n"
 769                         " git branch <new-branch-name> %s\n\n",
 770                         /* The plural version */
 771                         "If you want to keep them by creating a new branch, "
 772                         "this may be a good time\nto do so with:\n\n"
 773                         " git branch <new-branch-name> %s\n\n",
 774                         /* Give ngettext() the count */
 775                         lost),
 776                         find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
 777 }
 778
 779 /*
 780  * We are about to leave commit that was at the tip of a detached
 781  * HEAD.  If it is not reachable from any ref, this is the last chance
 782  * for the user to do so without resorting to reflog.
 783  */
 784 static void orphaned_commit_warning(struct commit *old, struct commit *new)
 785 {
 786         struct rev_info revs;
 787         struct object *object = &old->object;
 788         struct object_array refs;
 789
 790         init_revisions(&revs, NULL);
 791         setup_revisions(0, NULL, &revs, NULL);
 792
 793         object->flags &= ~UNINTERESTING;
 794         add_pending_object(&revs, object, oid_to_hex(&object->oid));
 795
 796         for_each_ref(add_pending_uninteresting_ref, &revs);
 797         add_pending_oid(&revs, "HEAD", &new->object.oid, UNINTERESTING);
 798
 799         refs = revs.pending;
 800         revs.leak_pending = 1;
 801
 802         if (prepare_revision_walk(&revs))
 803                 die(_("internal error in revision walk"));
 804         if (!(old->object.flags & UNINTERESTING))
 805                 suggest_reattach(old, &revs);
 806         else
 807                 describe_detached_head(_("Previous HEAD position was"), old);
 808
 809         clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 810         free(refs.objects);
 811 }
 812
 813 static int switch_branches(const struct checkout_opts *opts,
 814                            struct branch_info *new)
 815 {
 816         int ret = 0;
 817         struct branch_info old;
 818         void *path_to_free;
 819         struct object_id rev;
 820         int flag, writeout_error = 0;
 821         memset(&old, 0, sizeof(old));
 822         old.path = path_to_free = resolve_refdup("HEAD", 0, rev.hash, &flag);
 823         if (old.path)
 824                 old.commit = lookup_commit_reference_gently(&rev, 1);
 825         if (!(flag & REF_ISSYMREF))
 826                 old.path = NULL;
 827
 828         if (old.path)
 829                 skip_prefix(old.path, "refs/heads/", &old.name);
 830
 831         if (!new->name) {
 832                 new->name = "HEAD";
 833                 new->commit = old.commit;
 834                 if (!new->commit)
 835                         die(_("You are on a branch yet to be born"));
 836                 parse_commit_or_die(new->commit);
 837         }
 838
 839         ret = merge_working_tree(opts, &old, new, &writeout_error);
 840         if (ret) {
 841                 free(path_to_free);
 842                 return ret;
 843         }
 844
 845         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
 846                 orphaned_commit_warning(old.commit, new->commit);
 847
 848         update_refs_for_switch(opts, &old, new);
 849
 850         ret = post_checkout_hook(old.commit, new->commit, 1);
 851         free(path_to_free);
 852         return ret || writeout_error;
 853 }
 854
 855 static int git_checkout_config(const char *var, const char *value, void *cb)
 856 {
 857         if (!strcmp(var, "diff.ignoresubmodules")) {
 858                 struct checkout_opts *opts = cb;
 859                 handle_ignore_submodules_arg(&opts->diff_options, value);
 860                 return 0;
 861         }
 862
 863         if (starts_with(var, "submodule."))
 864                 return submodule_config(var, value, NULL);
 865
 866         return git_xmerge_config(var, value, NULL);
 867 }
 868
 869 struct tracking_name_data {
 870         /* const */ char *src_ref;
 871         char *dst_ref;
 872         struct object_id *dst_oid;
 873         int unique;
 874 };
 875
 876 static int check_tracking_name(struct remote *remote, void *cb_data)
 877 {
 878         struct tracking_name_data *cb = cb_data;
 879         struct refspec query;
 880         memset(&query, 0, sizeof(struct refspec));
 881         query.src = cb->src_ref;
 882         if (remote_find_tracking(remote, &query) ||
 883             get_oid(query.dst, cb->dst_oid)) {
 884                 free(query.dst);
 885                 return 0;
 886         }
 887         if (cb->dst_ref) {
 888                 free(query.dst);
 889                 cb->unique = 0;
 890                 return 0;
 891         }
 892         cb->dst_ref = query.dst;
 893         return 0;
 894 }
 895
 896 static const char *unique_tracking_name(const char *name, struct object_id *oid)
 897 {
 898         struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
 899         cb_data.src_ref = xstrfmt("refs/heads/%s", name);
 900         cb_data.dst_oid = oid;
 901         for_each_remote(check_tracking_name, &cb_data);
 902         free(cb_data.src_ref);
 903         if (cb_data.unique)
 904                 return cb_data.dst_ref;
 905         free(cb_data.dst_ref);
 906         return NULL;
 907 }
 908
 909 static int parse_branchname_arg(int argc, const char **argv,
 910                                 int dwim_new_local_branch_ok,
 911                                 struct branch_info *new,
 912                                 struct checkout_opts *opts,
 913                                 struct object_id *rev)
 914 {
 915         struct tree **source_tree = &opts->source_tree;
 916         const char **new_branch = &opts->new_branch;
 917         int argcount = 0;
 918         struct object_id branch_rev;
 919         const char *arg;
 920         int dash_dash_pos;
 921         int has_dash_dash = 0;
 922         int i;
 923
 924         /*
 925          * case 1: git checkout <ref> -- [<paths>]
 926          *
 927          *   <ref> must be a valid tree, everything after the '--' must be
 928          *   a path.
 929          *
 930          * case 2: git checkout -- [<paths>]
 931          *
 932          *   everything after the '--' must be paths.
 933          *
 934          * case 3: git checkout <something> [--]
 935          *
 936          *   (a) If <something> is a commit, that is to
 937          *       switch to the branch or detach HEAD at it.  As a special case,
 938          *       if <something> is A...B (missing A or B means HEAD but you can
 939          *       omit at most one side), and if there is a unique merge base
 940          *       between A and B, A...B names that merge base.
 941          *
 942          *   (b) If <something> is _not_ a commit, either "--" is present
 943          *       or <something> is not a path, no -t or -b was given, and
 944          *       and there is a tracking branch whose name is <something>
 945          *       in one and only one remote, then this is a short-hand to
 946          *       fork local <something> from that remote-tracking branch.
 947          *
 948          *   (c) Otherwise, if "--" is present, treat it like case (1).
 949          *
 950          *   (d) Otherwise :
 951          *       - if it's a reference, treat it like case (1)
 952          *       - else if it's a path, treat it like case (2)
 953          *       - else: fail.
 954          *
 955          * case 4: git checkout <something> <paths>
 956          *
 957          *   The first argument must not be ambiguous.
 958          *   - If it's *only* a reference, treat it like case (1).
 959          *   - If it's only a path, treat it like case (2).
 960          *   - else: fail.
 961          *
 962          */
 963         if (!argc)
 964                 return 0;
 965
 966         arg = argv[0];
 967         dash_dash_pos = -1;
 968         for (i = 0; i < argc; i++) {
 969                 if (!strcmp(argv[i], "--")) {
 970                         dash_dash_pos = i;
 971                         break;
 972                 }
 973         }
 974         if (dash_dash_pos == 0)
 975                 return 1; /* case (2) */
 976         else if (dash_dash_pos == 1)
 977                 has_dash_dash = 1; /* case (3) or (1) */
 978         else if (dash_dash_pos >= 2)
 979                 die(_("only one reference expected, %d given."), dash_dash_pos);
 980
 981         if (!strcmp(arg, "-"))
 982                 arg = "@{-1}";
 983
 984         if (get_oid_mb(arg, rev)) {
 985                 /*
 986                  * Either case (3) or (4), with <something> not being
 987                  * a commit, or an attempt to use case (1) with an
 988                  * invalid ref.
 989                  *
 990                  * It's likely an error, but we need to find out if
 991                  * we should auto-create the branch, case (3).(b).
 992                  */
 993                 int recover_with_dwim = dwim_new_local_branch_ok;
 994
 995                 if (!has_dash_dash &&
 996                     (check_filename(opts->prefix, arg) || !no_wildcard(arg)))
 997                         recover_with_dwim = 0;
 998                 /*
 999                  * Accept "git checkout foo" and "git checkout foo --"
1000                  * as candidates for dwim.
1001                  */
1002                 if (!(argc == 1 && !has_dash_dash) &&
1003                     !(argc == 2 && has_dash_dash))
1004                         recover_with_dwim = 0;
1005
1006                 if (recover_with_dwim) {
1007                         const char *remote = unique_tracking_name(arg, rev);
1008                         if (remote) {
1009                                 *new_branch = arg;
1010                                 arg = remote;
1011                                 /* DWIMmed to create local branch, case (3).(b) */
1012                         } else {
1013                                 recover_with_dwim = 0;
1014                         }
1015                 }
1016
1017                 if (!recover_with_dwim) {
1018                         if (has_dash_dash)
1019                                 die(_("invalid reference: %s"), arg);
1020                         return argcount;
1021                 }
1022         }
1023
1024         /* we can't end up being in (2) anymore, eat the argument */
1025         argcount++;
1026         argv++;
1027         argc--;
1028
1029         new->name = arg;
1030         setup_branch_path(new);
1031
1032         if (!check_refname_format(new->path, 0) &&
1033             !read_ref(new->path, branch_rev.hash))
1034                 oidcpy(rev, &branch_rev);
1035         else
1036                 new->path = NULL; /* not an existing branch */
1037
1038         new->commit = lookup_commit_reference_gently(rev, 1);
1039         if (!new->commit) {
1040                 /* not a commit */
1041                 *source_tree = parse_tree_indirect(rev);
1042         } else {
1043                 parse_commit_or_die(new->commit);
1044                 *source_tree = new->commit->tree;
1045         }
1046
1047         if (!*source_tree)                   /* case (1): want a tree */
1048                 die(_("reference is not a tree: %s"), arg);
1049         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1050                 /*
1051                  * Do not complain the most common case
1052                  *      git checkout branch
1053                  * even if there happen to be a file called 'branch';
1054                  * it would be extremely annoying.
1055                  */
1056                 if (argc)
1057                         verify_non_filename(opts->prefix, arg);
1058         } else {
1059                 argcount++;
1060                 argv++;
1061                 argc--;
1062         }
1063
1064         return argcount;
1065 }
1066
1067 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1068 {
1069         int status;
1070         struct strbuf branch_ref = STRBUF_INIT;
1071
1072         if (!opts->new_branch)
1073                 die(_("You are on a branch yet to be born"));
1074         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1075         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1076         strbuf_release(&branch_ref);
1077         if (!opts->quiet)
1078                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1079                         opts->new_branch);
1080         return status;
1081 }
1082
1083 static int checkout_branch(struct checkout_opts *opts,
1084                            struct branch_info *new)
1085 {
1086         if (opts->pathspec.nr)
1087                 die(_("paths cannot be used with switching branches"));
1088
1089         if (opts->patch_mode)
1090                 die(_("'%s' cannot be used with switching branches"),
1091                     "--patch");
1092
1093         if (opts->writeout_stage)
1094                 die(_("'%s' cannot be used with switching branches"),
1095                     "--ours/--theirs");
1096
1097         if (opts->force && opts->merge)
1098                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1099
1100         if (opts->force_detach && opts->new_branch)
1101                 die(_("'%s' cannot be used with '%s'"),
1102                     "--detach", "-b/-B/--orphan");
1103
1104         if (opts->new_orphan_branch) {
1105                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1106                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1107         } else if (opts->force_detach) {
1108                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1109                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1110         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1111                 opts->track = git_branch_track;
1112
1113         if (new->name && !new->commit)
1114                 die(_("Cannot switch branch to a non-commit '%s'"),
1115                     new->name);
1116
1117         if (new->path && !opts->force_detach && !opts->new_branch &&
1118             !opts->ignore_other_worktrees) {
1119                 struct object_id oid;
1120                 int flag;
1121                 char *head_ref = resolve_refdup("HEAD", 0, oid.hash, &flag);
1122                 if (head_ref &&
1123                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)))
1124                         die_if_checked_out(new->path, 1);
1125                 free(head_ref);
1126         }
1127
1128         if (!new->commit && opts->new_branch) {
1129                 struct object_id rev;
1130                 int flag;
1131
1132                 if (!read_ref_full("HEAD", 0, rev.hash, &flag) &&
1133                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1134                         return switch_unborn_to_new_branch(opts);
1135         }
1136         return switch_branches(opts, new);
1137 }
1138
1139 int cmd_checkout(int argc, const char **argv, const char *prefix)
1140 {
1141         struct checkout_opts opts;
1142         struct branch_info new;
1143         char *conflict_style = NULL;
1144         int dwim_new_local_branch = 1;
1145         struct option options[] = {
1146                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1147                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1148                            N_("create and checkout a new branch")),
1149                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1150                            N_("create/reset and checkout a branch")),
1151                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1152                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1153                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1154                         BRANCH_TRACK_EXPLICIT),
1155                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1156                 OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1157                             2),
1158                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1159                             3),
1160                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1161                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1162                 OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1163                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1164                            N_("conflict style (merge or diff3)")),
1165                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1166                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1167                          N_("do not limit pathspecs to sparse entries only")),
1168                 OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1169                                 N_("second guess 'git checkout <no-such-branch>'")),
1170                 OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1171                          N_("do not check if another worktree is holding the given ref")),
1172                 { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1173                             "checkout", "control recursive updating of submodules",
1174                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1175                 OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1176                 OPT_END(),
1177         };
1178
1179         memset(&opts, 0, sizeof(opts));
1180         memset(&new, 0, sizeof(new));
1181         opts.overwrite_ignore = 1;
1182         opts.prefix = prefix;
1183         opts.show_progress = -1;
1184
1185         gitmodules_config();
1186         git_config(git_checkout_config, &opts);
1187
1188         opts.track = BRANCH_TRACK_UNSPECIFIED;
1189
1190         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1191                              PARSE_OPT_KEEP_DASHDASH);
1192
1193         if (opts.show_progress < 0) {
1194                 if (opts.quiet)
1195                         opts.show_progress = 0;
1196                 else
1197                         opts.show_progress = isatty(2);
1198         }
1199
1200         if (conflict_style) {
1201                 opts.merge = 1; /* implied */
1202                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1203         }
1204
1205         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1206                 die(_("-b, -B and --orphan are mutually exclusive"));
1207
1208         /*
1209          * From here on, new_branch will contain the branch to be checked out,
1210          * and new_branch_force and new_orphan_branch will tell us which one of
1211          * -b/-B/--orphan is being used.
1212          */
1213         if (opts.new_branch_force)
1214                 opts.new_branch = opts.new_branch_force;
1215
1216         if (opts.new_orphan_branch)
1217                 opts.new_branch = opts.new_orphan_branch;
1218
1219         /* --track without -b/-B/--orphan should DWIM */
1220         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1221                 const char *argv0 = argv[0];
1222                 if (!argc || !strcmp(argv0, "--"))
1223                         die (_("--track needs a branch name"));
1224                 skip_prefix(argv0, "refs/", &argv0);
1225                 skip_prefix(argv0, "remotes/", &argv0);
1226                 argv0 = strchr(argv0, '/');
1227                 if (!argv0 || !argv0[1])
1228                         die (_("Missing branch name; try -b"));
1229                 opts.new_branch = argv0 + 1;
1230         }
1231
1232         /*
1233          * Extract branch name from command line arguments, so
1234          * all that is left is pathspecs.
1235          *
1236          * Handle
1237          *
1238          *  1) git checkout <tree> -- [<paths>]
1239          *  2) git checkout -- [<paths>]
1240          *  3) git checkout <something> [<paths>]
1241          *
1242          * including "last branch" syntax and DWIM-ery for names of
1243          * remote branches, erroring out for invalid or ambiguous cases.
1244          */
1245         if (argc) {
1246                 struct object_id rev;
1247                 int dwim_ok =
1248                         !opts.patch_mode &&
1249                         dwim_new_local_branch &&
1250                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1251                         !opts.new_branch;
1252                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1253                                              &new, &opts, &rev);
1254                 argv += n;
1255                 argc -= n;
1256         }
1257
1258         if (argc) {
1259                 parse_pathspec(&opts.pathspec, 0,
1260                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1261                                prefix, argv);
1262
1263                 if (!opts.pathspec.nr)
1264                         die(_("invalid path specification"));
1265
1266                 /*
1267                  * Try to give more helpful suggestion.
1268                  * new_branch && argc > 1 will be caught later.
1269                  */
1270                 if (opts.new_branch && argc == 1)
1271                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1272                                 argv[0], opts.new_branch);
1273
1274                 if (opts.force_detach)
1275                         die(_("git checkout: --detach does not take a path argument '%s'"),
1276                             argv[0]);
1277
1278                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1279                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1280                               "checking out of the index."));
1281         }
1282
1283         if (opts.new_branch) {
1284                 struct strbuf buf = STRBUF_INIT;
1285
1286                 opts.branch_exists =
1287                         validate_new_branchname(opts.new_branch, &buf,
1288                                                 !!opts.new_branch_force,
1289                                                 !!opts.new_branch_force);
1290
1291                 strbuf_release(&buf);
1292         }
1293
1294         if (opts.patch_mode || opts.pathspec.nr)
1295                 return checkout_paths(&opts, new.name);
1296         else
1297                 return checkout_branch(&opts, &new);
1298 }