git.oblomov.eu Git - git/blob - builtin/checkout.c

   1 #define USE_THE_INDEX_COMPATIBILITY_MACROS
   2 #include "builtin.h"
   3 #include "advice.h"
   4 #include "blob.h"
   5 #include "branch.h"
   6 #include "cache-tree.h"
   7 #include "checkout.h"
   8 #include "commit.h"
   9 #include "config.h"
  10 #include "diff.h"
  11 #include "dir.h"
  12 #include "ll-merge.h"
  13 #include "lockfile.h"
  14 #include "merge-recursive.h"
  15 #include "object-store.h"
  16 #include "parse-options.h"
  17 #include "refs.h"
  18 #include "remote.h"
  19 #include "resolve-undo.h"
  20 #include "revision.h"
  21 #include "run-command.h"
  22 #include "submodule.h"
  23 #include "submodule-config.h"
  24 #include "tree.h"
  25 #include "tree-walk.h"
  26 #include "unpack-trees.h"
  27 #include "wt-status.h"
  28 #include "xdiff-interface.h"
  29
  30 static const char * const checkout_usage[] = {
  31         N_("git checkout [<options>] <branch>"),
  32         N_("git checkout [<options>] [<branch>] -- <file>..."),
  33         NULL,
  34 };
  35
  36 static const char * const switch_branch_usage[] = {
  37         N_("git switch [<options>] [<branch>]"),
  38         NULL,
  39 };
  40
  41 static const char * const restore_usage[] = {
  42         N_("git restore [<options>] [--source=<branch>] <file>..."),
  43         NULL,
  44 };
  45
  46 struct checkout_opts {
  47         int patch_mode;
  48         int quiet;
  49         int merge;
  50         int force;
  51         int force_detach;
  52         int implicit_detach;
  53         int writeout_stage;
  54         int overwrite_ignore;
  55         int ignore_skipworktree;
  56         int ignore_other_worktrees;
  57         int show_progress;
  58         int count_checkout_paths;
  59         int overlay_mode;
  60         int dwim_new_local_branch;
  61         int discard_changes;
  62         int accept_ref;
  63         int accept_pathspec;
  64         int switch_branch_doing_nothing_is_ok;
  65         int only_merge_on_switching_branches;
  66         int can_switch_when_in_progress;
  67         int orphan_from_empty_tree;
  68         int empty_pathspec_ok;
  69         int checkout_index;
  70         int checkout_worktree;
  71         const char *ignore_unmerged_opt;
  72         int ignore_unmerged;
  73         int pathspec_file_nul;
  74         const char *pathspec_from_file;
  75
  76         const char *new_branch;
  77         const char *new_branch_force;
  78         const char *new_orphan_branch;
  79         int new_branch_log;
  80         enum branch_track track;
  81         struct diff_options diff_options;
  82         char *conflict_style;
  83
  84         int branch_exists;
  85         const char *prefix;
  86         struct pathspec pathspec;
  87         const char *from_treeish;
  88         struct tree *source_tree;
  89 };
  90
  91 struct branch_info {
  92         const char *name; /* The short name used */
  93         const char *path; /* The full name of a real branch */
  94         struct commit *commit; /* The named commit */
  95         char *refname; /* The full name of the ref being checked out. */
  96         struct object_id oid; /* The object ID of the commit being checked out. */
  97         /*
  98          * if not null the branch is detached because it's already
  99          * checked out in this checkout
 100          */
 101         char *checkout;
 102 };
 103
 104 static int post_checkout_hook(struct commit *old_commit, struct commit *new_commit,
 105                               int changed)
 106 {
 107         return run_hook_le(NULL, "post-checkout",
 108                            oid_to_hex(old_commit ? &old_commit->object.oid : &null_oid),
 109                            oid_to_hex(new_commit ? &new_commit->object.oid : &null_oid),
 110                            changed ? "1" : "0", NULL);
 111         /* "new_commit" can be NULL when checking out from the index before
 112            a commit exists. */
 113
 114 }
 115
 116 static int update_some(const struct object_id *oid, struct strbuf *base,
 117                 const char *pathname, unsigned mode, int stage, void *context)
 118 {
 119         int len;
 120         struct cache_entry *ce;
 121         int pos;
 122
 123         if (S_ISDIR(mode))
 124                 return READ_TREE_RECURSIVE;
 125
 126         len = base->len + strlen(pathname);
 127         ce = make_empty_cache_entry(&the_index, len);
 128         oidcpy(&ce->oid, oid);
 129         memcpy(ce->name, base->buf, base->len);
 130         memcpy(ce->name + base->len, pathname, len - base->len);
 131         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
 132         ce->ce_namelen = len;
 133         ce->ce_mode = create_ce_mode(mode);
 134
 135         /*
 136          * If the entry is the same as the current index, we can leave the old
 137          * entry in place. Whether it is UPTODATE or not, checkout_entry will
 138          * do the right thing.
 139          */
 140         pos = cache_name_pos(ce->name, ce->ce_namelen);
 141         if (pos >= 0) {
 142                 struct cache_entry *old = active_cache[pos];
 143                 if (ce->ce_mode == old->ce_mode &&
 144                     !ce_intent_to_add(old) &&
 145                     oideq(&ce->oid, &old->oid)) {
 146                         old->ce_flags |= CE_UPDATE;
 147                         discard_cache_entry(ce);
 148                         return 0;
 149                 }
 150         }
 151
 152         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 153         return 0;
 154 }
 155
 156 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 157 {
 158         read_tree_recursive(the_repository, tree, "", 0, 0,
 159                             pathspec, update_some, NULL);
 160
 161         /* update the index with the given tree's info
 162          * for all args, expanding wildcards, and exit
 163          * with any non-zero return code.
 164          */
 165         return 0;
 166 }
 167
 168 static int skip_same_name(const struct cache_entry *ce, int pos)
 169 {
 170         while (++pos < active_nr &&
 171                !strcmp(active_cache[pos]->name, ce->name))
 172                 ; /* skip */
 173         return pos;
 174 }
 175
 176 static int check_stage(int stage, const struct cache_entry *ce, int pos,
 177                        int overlay_mode)
 178 {
 179         while (pos < active_nr &&
 180                !strcmp(active_cache[pos]->name, ce->name)) {
 181                 if (ce_stage(active_cache[pos]) == stage)
 182                         return 0;
 183                 pos++;
 184         }
 185         if (!overlay_mode)
 186                 return 0;
 187         if (stage == 2)
 188                 return error(_("path '%s' does not have our version"), ce->name);
 189         else
 190                 return error(_("path '%s' does not have their version"), ce->name);
 191 }
 192
 193 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 194 {
 195         unsigned seen = 0;
 196         const char *name = ce->name;
 197
 198         while (pos < active_nr) {
 199                 ce = active_cache[pos];
 200                 if (strcmp(name, ce->name))
 201                         break;
 202                 seen |= (1 << ce_stage(ce));
 203                 pos++;
 204         }
 205         if ((stages & seen) != stages)
 206                 return error(_("path '%s' does not have all necessary versions"),
 207                              name);
 208         return 0;
 209 }
 210
 211 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 212                           const struct checkout *state, int *nr_checkouts,
 213                           int overlay_mode)
 214 {
 215         while (pos < active_nr &&
 216                !strcmp(active_cache[pos]->name, ce->name)) {
 217                 if (ce_stage(active_cache[pos]) == stage)
 218                         return checkout_entry(active_cache[pos], state,
 219                                               NULL, nr_checkouts);
 220                 pos++;
 221         }
 222         if (!overlay_mode) {
 223                 unlink_entry(ce);
 224                 return 0;
 225         }
 226         if (stage == 2)
 227                 return error(_("path '%s' does not have our version"), ce->name);
 228         else
 229                 return error(_("path '%s' does not have their version"), ce->name);
 230 }
 231
 232 static int checkout_merged(int pos, const struct checkout *state, int *nr_checkouts)
 233 {
 234         struct cache_entry *ce = active_cache[pos];
 235         const char *path = ce->name;
 236         mmfile_t ancestor, ours, theirs;
 237         int status;
 238         struct object_id oid;
 239         mmbuffer_t result_buf;
 240         struct object_id threeway[3];
 241         unsigned mode = 0;
 242         struct ll_merge_options ll_opts;
 243         int renormalize = 0;
 244
 245         memset(threeway, 0, sizeof(threeway));
 246         while (pos < active_nr) {
 247                 int stage;
 248                 stage = ce_stage(ce);
 249                 if (!stage || strcmp(path, ce->name))
 250                         break;
 251                 oidcpy(&threeway[stage - 1], &ce->oid);
 252                 if (stage == 2)
 253                         mode = create_ce_mode(ce->ce_mode);
 254                 pos++;
 255                 ce = active_cache[pos];
 256         }
 257         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 258                 return error(_("path '%s' does not have necessary versions"), path);
 259
 260         read_mmblob(&ancestor, &threeway[0]);
 261         read_mmblob(&ours, &threeway[1]);
 262         read_mmblob(&theirs, &threeway[2]);
 263
 264         memset(&ll_opts, 0, sizeof(ll_opts));
 265         git_config_get_bool("merge.renormalize", &renormalize);
 266         ll_opts.renormalize = renormalize;
 267         status = ll_merge(&result_buf, path, &ancestor, "base",
 268                           &ours, "ours", &theirs, "theirs",
 269                           state->istate, &ll_opts);
 270         free(ancestor.ptr);
 271         free(ours.ptr);
 272         free(theirs.ptr);
 273         if (status < 0 || !result_buf.ptr) {
 274                 free(result_buf.ptr);
 275                 return error(_("path '%s': cannot merge"), path);
 276         }
 277
 278         /*
 279          * NEEDSWORK:
 280          * There is absolutely no reason to write this as a blob object
 281          * and create a phony cache entry.  This hack is primarily to get
 282          * to the write_entry() machinery that massages the contents to
 283          * work-tree format and writes out which only allows it for a
 284          * cache entry.  The code in write_entry() needs to be refactored
 285          * to allow us to feed a <buffer, size, mode> instead of a cache
 286          * entry.  Such a refactoring would help merge_recursive as well
 287          * (it also writes the merge result to the object database even
 288          * when it may contain conflicts).
 289          */
 290         if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
 291                 die(_("Unable to add merge result for '%s'"), path);
 292         free(result_buf.ptr);
 293         ce = make_transient_cache_entry(mode, &oid, path, 2);
 294         if (!ce)
 295                 die(_("make_cache_entry failed for path '%s'"), path);
 296         status = checkout_entry(ce, state, NULL, nr_checkouts);
 297         discard_cache_entry(ce);
 298         return status;
 299 }
 300
 301 static void mark_ce_for_checkout_overlay(struct cache_entry *ce,
 302                                          char *ps_matched,
 303                                          const struct checkout_opts *opts)
 304 {
 305         ce->ce_flags &= ~CE_MATCHED;
 306         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 307                 return;
 308         if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 309                 /*
 310                  * "git checkout tree-ish -- path", but this entry
 311                  * is in the original index but is not in tree-ish
 312                  * or does not match the pathspec; it will not be
 313                  * checked out to the working tree.  We will not do
 314                  * anything to this entry at all.
 315                  */
 316                 return;
 317         /*
 318          * Either this entry came from the tree-ish we are
 319          * checking the paths out of, or we are checking out
 320          * of the index.
 321          *
 322          * If it comes from the tree-ish, we already know it
 323          * matches the pathspec and could just stamp
 324          * CE_MATCHED to it from update_some(). But we still
 325          * need ps_matched and read_tree_recursive (and
 326          * eventually tree_entry_interesting) cannot fill
 327          * ps_matched yet. Once it can, we can avoid calling
 328          * match_pathspec() for _all_ entries when
 329          * opts->source_tree != NULL.
 330          */
 331         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched))
 332                 ce->ce_flags |= CE_MATCHED;
 333 }
 334
 335 static void mark_ce_for_checkout_no_overlay(struct cache_entry *ce,
 336                                             char *ps_matched,
 337                                             const struct checkout_opts *opts)
 338 {
 339         ce->ce_flags &= ~CE_MATCHED;
 340         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 341                 return;
 342         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched)) {
 343                 ce->ce_flags |= CE_MATCHED;
 344                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 345                         /*
 346                          * In overlay mode, but the path is not in
 347                          * tree-ish, which means we should remove it
 348                          * from the index and the working tree.
 349                          */
 350                         ce->ce_flags |= CE_REMOVE | CE_WT_REMOVE;
 351         }
 352 }
 353
 354 static int checkout_worktree(const struct checkout_opts *opts,
 355                              const struct branch_info *info)
 356 {
 357         struct checkout state = CHECKOUT_INIT;
 358         int nr_checkouts = 0, nr_unmerged = 0;
 359         int errs = 0;
 360         int pos;
 361
 362         state.force = 1;
 363         state.refresh_cache = 1;
 364         state.istate = &the_index;
 365
 366         init_checkout_metadata(&state.meta, info->refname,
 367                                info->commit ? &info->commit->object.oid : &info->oid,
 368                                NULL);
 369
 370         enable_delayed_checkout(&state);
 371         for (pos = 0; pos < active_nr; pos++) {
 372                 struct cache_entry *ce = active_cache[pos];
 373                 if (ce->ce_flags & CE_MATCHED) {
 374                         if (!ce_stage(ce)) {
 375                                 errs |= checkout_entry(ce, &state,
 376                                                        NULL, &nr_checkouts);
 377                                 continue;
 378                         }
 379                         if (opts->writeout_stage)
 380                                 errs |= checkout_stage(opts->writeout_stage,
 381                                                        ce, pos,
 382                                                        &state,
 383                                                        &nr_checkouts, opts->overlay_mode);
 384                         else if (opts->merge)
 385                                 errs |= checkout_merged(pos, &state,
 386                                                         &nr_unmerged);
 387                         pos = skip_same_name(ce, pos) - 1;
 388                 }
 389         }
 390         remove_marked_cache_entries(&the_index, 1);
 391         remove_scheduled_dirs();
 392         errs |= finish_delayed_checkout(&state, &nr_checkouts);
 393
 394         if (opts->count_checkout_paths) {
 395                 if (nr_unmerged)
 396                         fprintf_ln(stderr, Q_("Recreated %d merge conflict",
 397                                               "Recreated %d merge conflicts",
 398                                               nr_unmerged),
 399                                    nr_unmerged);
 400                 if (opts->source_tree)
 401                         fprintf_ln(stderr, Q_("Updated %d path from %s",
 402                                               "Updated %d paths from %s",
 403                                               nr_checkouts),
 404                                    nr_checkouts,
 405                                    find_unique_abbrev(&opts->source_tree->object.oid,
 406                                                       DEFAULT_ABBREV));
 407                 else if (!nr_unmerged || nr_checkouts)
 408                         fprintf_ln(stderr, Q_("Updated %d path from the index",
 409                                               "Updated %d paths from the index",
 410                                               nr_checkouts),
 411                                    nr_checkouts);
 412         }
 413
 414         return errs;
 415 }
 416
 417 static int checkout_paths(const struct checkout_opts *opts,
 418                           const struct branch_info *new_branch_info)
 419 {
 420         int pos;
 421         static char *ps_matched;
 422         struct object_id rev;
 423         struct commit *head;
 424         int errs = 0;
 425         struct lock_file lock_file = LOCK_INIT;
 426         int checkout_index;
 427
 428         trace2_cmd_mode(opts->patch_mode ? "patch" : "path");
 429
 430         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 431                 die(_("'%s' cannot be used with updating paths"), "--track");
 432
 433         if (opts->new_branch_log)
 434                 die(_("'%s' cannot be used with updating paths"), "-l");
 435
 436         if (opts->ignore_unmerged && opts->patch_mode)
 437                 die(_("'%s' cannot be used with updating paths"),
 438                     opts->ignore_unmerged_opt);
 439
 440         if (opts->force_detach)
 441                 die(_("'%s' cannot be used with updating paths"), "--detach");
 442
 443         if (opts->merge && opts->patch_mode)
 444                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 445
 446         if (opts->ignore_unmerged && opts->merge)
 447                 die(_("'%s' cannot be used with %s"),
 448                     opts->ignore_unmerged_opt, "-m");
 449
 450         if (opts->new_branch)
 451                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 452                     opts->new_branch);
 453
 454         if (!opts->checkout_worktree && !opts->checkout_index)
 455                 die(_("neither '%s' or '%s' is specified"),
 456                     "--staged", "--worktree");
 457
 458         if (!opts->checkout_worktree && !opts->from_treeish)
 459                 die(_("'%s' must be used when '%s' is not specified"),
 460                     "--worktree", "--source");
 461
 462         if (opts->checkout_index && !opts->checkout_worktree &&
 463             opts->writeout_stage)
 464                 die(_("'%s' or '%s' cannot be used with %s"),
 465                     "--ours", "--theirs", "--staged");
 466
 467         if (opts->checkout_index && !opts->checkout_worktree &&
 468             opts->merge)
 469                 die(_("'%s' or '%s' cannot be used with %s"),
 470                     "--merge", "--conflict", "--staged");
 471
 472         if (opts->patch_mode) {
 473                 const char *patch_mode;
 474                 const char *rev = new_branch_info->name;
 475                 char rev_oid[GIT_MAX_HEXSZ + 1];
 476
 477                 /*
 478                  * Since rev can be in the form of `<a>...<b>` (which is not
 479                  * recognized by diff-index), we will always replace the name
 480                  * with the hex of the commit (whether it's in `...` form or
 481                  * not) for the run_add_interactive() machinery to work
 482                  * properly. However, there is special logic for the HEAD case
 483                  * so we mustn't replace that.  Also, when we were given a
 484                  * tree-object, new_branch_info->commit would be NULL, but we
 485                  * do not have to do any replacement, either.
 486                  */
 487                 if (rev && new_branch_info->commit && strcmp(rev, "HEAD"))
 488                         rev = oid_to_hex_r(rev_oid, &new_branch_info->commit->object.oid);
 489
 490                 if (opts->checkout_index && opts->checkout_worktree)
 491                         patch_mode = "--patch=checkout";
 492                 else if (opts->checkout_index && !opts->checkout_worktree)
 493                         patch_mode = "--patch=reset";
 494                 else if (!opts->checkout_index && opts->checkout_worktree)
 495                         patch_mode = "--patch=worktree";
 496                 else
 497                         BUG("either flag must have been set, worktree=%d, index=%d",
 498                             opts->checkout_worktree, opts->checkout_index);
 499                 return run_add_interactive(rev, patch_mode, &opts->pathspec);
 500         }
 501
 502         repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 503         if (read_cache_preload(&opts->pathspec) < 0)
 504                 return error(_("index file corrupt"));
 505
 506         if (opts->source_tree)
 507                 read_tree_some(opts->source_tree, &opts->pathspec);
 508
 509         ps_matched = xcalloc(opts->pathspec.nr, 1);
 510
 511         /*
 512          * Make sure all pathspecs participated in locating the paths
 513          * to be checked out.
 514          */
 515         for (pos = 0; pos < active_nr; pos++)
 516                 if (opts->overlay_mode)
 517                         mark_ce_for_checkout_overlay(active_cache[pos],
 518                                                      ps_matched,
 519                                                      opts);
 520                 else
 521                         mark_ce_for_checkout_no_overlay(active_cache[pos],
 522                                                         ps_matched,
 523                                                         opts);
 524
 525         if (report_path_error(ps_matched, &opts->pathspec)) {
 526                 free(ps_matched);
 527                 return 1;
 528         }
 529         free(ps_matched);
 530
 531         /* "checkout -m path" to recreate conflicted state */
 532         if (opts->merge)
 533                 unmerge_marked_index(&the_index);
 534
 535         /* Any unmerged paths? */
 536         for (pos = 0; pos < active_nr; pos++) {
 537                 const struct cache_entry *ce = active_cache[pos];
 538                 if (ce->ce_flags & CE_MATCHED) {
 539                         if (!ce_stage(ce))
 540                                 continue;
 541                         if (opts->ignore_unmerged) {
 542                                 if (!opts->quiet)
 543                                         warning(_("path '%s' is unmerged"), ce->name);
 544                         } else if (opts->writeout_stage) {
 545                                 errs |= check_stage(opts->writeout_stage, ce, pos, opts->overlay_mode);
 546                         } else if (opts->merge) {
 547                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 548                         } else {
 549                                 errs = 1;
 550                                 error(_("path '%s' is unmerged"), ce->name);
 551                         }
 552                         pos = skip_same_name(ce, pos) - 1;
 553                 }
 554         }
 555         if (errs)
 556                 return 1;
 557
 558         /* Now we are committed to check them out */
 559         if (opts->checkout_worktree)
 560                 errs |= checkout_worktree(opts, new_branch_info);
 561         else
 562                 remove_marked_cache_entries(&the_index, 1);
 563
 564         /*
 565          * Allow updating the index when checking out from the index.
 566          * This is to save new stat info.
 567          */
 568         if (opts->checkout_worktree && !opts->checkout_index && !opts->source_tree)
 569                 checkout_index = 1;
 570         else
 571                 checkout_index = opts->checkout_index;
 572
 573         if (checkout_index) {
 574                 if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 575                         die(_("unable to write new index file"));
 576         } else {
 577                 /*
 578                  * NEEDSWORK: if --worktree is not specified, we
 579                  * should save stat info of checked out files in the
 580                  * index to avoid the next (potentially costly)
 581                  * refresh. But it's a bit tricker to do...
 582                  */
 583                 rollback_lock_file(&lock_file);
 584         }
 585
 586         read_ref_full("HEAD", 0, &rev, NULL);
 587         head = lookup_commit_reference_gently(the_repository, &rev, 1);
 588
 589         errs |= post_checkout_hook(head, head, 0);
 590         return errs;
 591 }
 592
 593 static void show_local_changes(struct object *head,
 594                                const struct diff_options *opts)
 595 {
 596         struct rev_info rev;
 597         /* I think we want full paths, even if we're in a subdirectory. */
 598         repo_init_revisions(the_repository, &rev, NULL);
 599         rev.diffopt.flags = opts->flags;
 600         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 601         diff_setup_done(&rev.diffopt);
 602         add_pending_object(&rev, head, NULL);
 603         run_diff_index(&rev, 0);
 604 }
 605
 606 static void describe_detached_head(const char *msg, struct commit *commit)
 607 {
 608         struct strbuf sb = STRBUF_INIT;
 609
 610         if (!parse_commit(commit))
 611                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 612         if (print_sha1_ellipsis()) {
 613                 fprintf(stderr, "%s %s... %s\n", msg,
 614                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 615         } else {
 616                 fprintf(stderr, "%s %s %s\n", msg,
 617                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 618         }
 619         strbuf_release(&sb);
 620 }
 621
 622 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 623                       int worktree, int *writeout_error,
 624                       struct branch_info *info)
 625 {
 626         struct unpack_trees_options opts;
 627         struct tree_desc tree_desc;
 628
 629         memset(&opts, 0, sizeof(opts));
 630         opts.head_idx = -1;
 631         opts.update = worktree;
 632         opts.skip_unmerged = !worktree;
 633         opts.reset = 1;
 634         opts.merge = 1;
 635         opts.fn = oneway_merge;
 636         opts.verbose_update = o->show_progress;
 637         opts.src_index = &the_index;
 638         opts.dst_index = &the_index;
 639         init_checkout_metadata(&opts.meta, info->refname,
 640                                info->commit ? &info->commit->object.oid : &null_oid,
 641                                NULL);
 642         parse_tree(tree);
 643         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 644         switch (unpack_trees(1, &tree_desc, &opts)) {
 645         case -2:
 646                 *writeout_error = 1;
 647                 /*
 648                  * We return 0 nevertheless, as the index is all right
 649                  * and more importantly we have made best efforts to
 650                  * update paths in the work tree, and we cannot revert
 651                  * them.
 652                  */
 653                 /* fallthrough */
 654         case 0:
 655                 return 0;
 656         default:
 657                 return 128;
 658         }
 659 }
 660
 661 static void setup_branch_path(struct branch_info *branch)
 662 {
 663         struct strbuf buf = STRBUF_INIT;
 664
 665         /*
 666          * If this is a ref, resolve it; otherwise, look up the OID for our
 667          * expression.  Failure here is okay.
 668          */
 669         if (!dwim_ref(branch->name, strlen(branch->name), &branch->oid, &branch->refname, 0))
 670                 repo_get_oid_committish(the_repository, branch->name, &branch->oid);
 671
 672         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 673         if (strcmp(buf.buf, branch->name))
 674                 branch->name = xstrdup(buf.buf);
 675         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 676         branch->path = strbuf_detach(&buf, NULL);
 677 }
 678
 679 static int merge_working_tree(const struct checkout_opts *opts,
 680                               struct branch_info *old_branch_info,
 681                               struct branch_info *new_branch_info,
 682                               int *writeout_error)
 683 {
 684         int ret;
 685         struct lock_file lock_file = LOCK_INIT;
 686         struct tree *new_tree;
 687
 688         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 689         if (read_cache_preload(NULL) < 0)
 690                 return error(_("index file corrupt"));
 691
 692         resolve_undo_clear();
 693         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
 694                 if (new_branch_info->commit)
 695                         BUG("'switch --orphan' should never accept a commit as starting point");
 696                 new_tree = parse_tree_indirect(the_hash_algo->empty_tree);
 697         } else
 698                 new_tree = get_commit_tree(new_branch_info->commit);
 699         if (opts->discard_changes) {
 700                 ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
 701                 if (ret)
 702                         return ret;
 703         } else {
 704                 struct tree_desc trees[2];
 705                 struct tree *tree;
 706                 struct unpack_trees_options topts;
 707
 708                 memset(&topts, 0, sizeof(topts));
 709                 topts.head_idx = -1;
 710                 topts.src_index = &the_index;
 711                 topts.dst_index = &the_index;
 712
 713                 setup_unpack_trees_porcelain(&topts, "checkout");
 714
 715                 refresh_cache(REFRESH_QUIET);
 716
 717                 if (unmerged_cache()) {
 718                         error(_("you need to resolve your current index first"));
 719                         return 1;
 720                 }
 721
 722                 /* 2-way merge to the new branch */
 723                 topts.initial_checkout = is_cache_unborn();
 724                 topts.update = 1;
 725                 topts.merge = 1;
 726                 topts.quiet = opts->merge && old_branch_info->commit;
 727                 topts.verbose_update = opts->show_progress;
 728                 topts.fn = twoway_merge;
 729                 init_checkout_metadata(&topts.meta, new_branch_info->refname,
 730                                        new_branch_info->commit ?
 731                                        &new_branch_info->commit->object.oid :
 732                                        &new_branch_info->oid, NULL);
 733                 if (opts->overwrite_ignore) {
 734                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 735                         topts.dir->flags |= DIR_SHOW_IGNORED;
 736                         setup_standard_excludes(topts.dir);
 737                 }
 738                 tree = parse_tree_indirect(old_branch_info->commit ?
 739                                            &old_branch_info->commit->object.oid :
 740                                            the_hash_algo->empty_tree);
 741                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 742                 parse_tree(new_tree);
 743                 tree = new_tree;
 744                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 745
 746                 ret = unpack_trees(2, trees, &topts);
 747                 clear_unpack_trees_porcelain(&topts);
 748                 if (ret == -1) {
 749                         /*
 750                          * Unpack couldn't do a trivial merge; either
 751                          * give up or do a real merge, depending on
 752                          * whether the merge flag was used.
 753                          */
 754                         struct tree *work;
 755                         struct tree *old_tree;
 756                         struct merge_options o;
 757                         struct strbuf sb = STRBUF_INIT;
 758                         struct strbuf old_commit_shortname = STRBUF_INIT;
 759
 760                         if (!opts->merge)
 761                                 return 1;
 762
 763                         /*
 764                          * Without old_branch_info->commit, the below is the same as
 765                          * the two-tree unpack we already tried and failed.
 766                          */
 767                         if (!old_branch_info->commit)
 768                                 return 1;
 769                         old_tree = get_commit_tree(old_branch_info->commit);
 770
 771                         if (repo_index_has_changes(the_repository, old_tree, &sb))
 772                                 die(_("cannot continue with staged changes in "
 773                                       "the following files:\n%s"), sb.buf);
 774                         strbuf_release(&sb);
 775
 776                         /* Do more real merge */
 777
 778                         /*
 779                          * We update the index fully, then write the
 780                          * tree from the index, then merge the new
 781                          * branch with the current tree, with the old
 782                          * branch as the base. Then we reset the index
 783                          * (but not the working tree) to the new
 784                          * branch, leaving the working tree as the
 785                          * merged version, but skipping unmerged
 786                          * entries in the index.
 787                          */
 788
 789                         add_files_to_cache(NULL, NULL, 0);
 790                         init_merge_options(&o, the_repository);
 791                         o.verbosity = 0;
 792                         work = write_in_core_index_as_tree(the_repository);
 793
 794                         ret = reset_tree(new_tree,
 795                                          opts, 1,
 796                                          writeout_error, new_branch_info);
 797                         if (ret)
 798                                 return ret;
 799                         o.ancestor = old_branch_info->name;
 800                         if (old_branch_info->name == NULL) {
 801                                 strbuf_add_unique_abbrev(&old_commit_shortname,
 802                                                          &old_branch_info->commit->object.oid,
 803                                                          DEFAULT_ABBREV);
 804                                 o.ancestor = old_commit_shortname.buf;
 805                         }
 806                         o.branch1 = new_branch_info->name;
 807                         o.branch2 = "local";
 808                         ret = merge_trees(&o,
 809                                           new_tree,
 810                                           work,
 811                                           old_tree);
 812                         if (ret < 0)
 813                                 exit(128);
 814                         ret = reset_tree(new_tree,
 815                                          opts, 0,
 816                                          writeout_error, new_branch_info);
 817                         strbuf_release(&o.obuf);
 818                         strbuf_release(&old_commit_shortname);
 819                         if (ret)
 820                                 return ret;
 821                 }
 822         }
 823
 824         if (!cache_tree_fully_valid(active_cache_tree))
 825                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 826
 827         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 828                 die(_("unable to write new index file"));
 829
 830         if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
 831                 show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 832
 833         return 0;
 834 }
 835
 836 static void report_tracking(struct branch_info *new_branch_info)
 837 {
 838         struct strbuf sb = STRBUF_INIT;
 839         struct branch *branch = branch_get(new_branch_info->name);
 840
 841         if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 842                 return;
 843         fputs(sb.buf, stdout);
 844         strbuf_release(&sb);
 845 }
 846
 847 static void update_refs_for_switch(const struct checkout_opts *opts,
 848                                    struct branch_info *old_branch_info,
 849                                    struct branch_info *new_branch_info)
 850 {
 851         struct strbuf msg = STRBUF_INIT;
 852         const char *old_desc, *reflog_msg;
 853         if (opts->new_branch) {
 854                 if (opts->new_orphan_branch) {
 855                         char *refname;
 856
 857                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 858                         if (opts->new_branch_log &&
 859                             !should_autocreate_reflog(refname)) {
 860                                 int ret;
 861                                 struct strbuf err = STRBUF_INIT;
 862
 863                                 ret = safe_create_reflog(refname, 1, &err);
 864                                 if (ret) {
 865                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 866                                                 opts->new_orphan_branch, err.buf);
 867                                         strbuf_release(&err);
 868                                         free(refname);
 869                                         return;
 870                                 }
 871                                 strbuf_release(&err);
 872                         }
 873                         free(refname);
 874                 }
 875                 else
 876                         create_branch(the_repository,
 877                                       opts->new_branch, new_branch_info->name,
 878                                       opts->new_branch_force ? 1 : 0,
 879                                       opts->new_branch_force ? 1 : 0,
 880                                       opts->new_branch_log,
 881                                       opts->quiet,
 882                                       opts->track);
 883                 new_branch_info->name = opts->new_branch;
 884                 setup_branch_path(new_branch_info);
 885         }
 886
 887         old_desc = old_branch_info->name;
 888         if (!old_desc && old_branch_info->commit)
 889                 old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
 890
 891         reflog_msg = getenv("GIT_REFLOG_ACTION");
 892         if (!reflog_msg)
 893                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 894                         old_desc ? old_desc : "(invalid)", new_branch_info->name);
 895         else
 896                 strbuf_insertstr(&msg, 0, reflog_msg);
 897
 898         if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
 899                 /* Nothing to do. */
 900         } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
 901                 update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
 902                            REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 903                 if (!opts->quiet) {
 904                         if (old_branch_info->path &&
 905                             advice_detached_head && !opts->force_detach)
 906                                 detach_advice(new_branch_info->name);
 907                         describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 908                 }
 909         } else if (new_branch_info->path) {     /* Switch branches. */
 910                 if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
 911                         die(_("unable to update HEAD"));
 912                 if (!opts->quiet) {
 913                         if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
 914                                 if (opts->new_branch_force)
 915                                         fprintf(stderr, _("Reset branch '%s'\n"),
 916                                                 new_branch_info->name);
 917                                 else
 918                                         fprintf(stderr, _("Already on '%s'\n"),
 919                                                 new_branch_info->name);
 920                         } else if (opts->new_branch) {
 921                                 if (opts->branch_exists)
 922                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
 923                                 else
 924                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
 925                         } else {
 926                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 927                                         new_branch_info->name);
 928                         }
 929                 }
 930                 if (old_branch_info->path && old_branch_info->name) {
 931                         if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
 932                                 delete_reflog(old_branch_info->path);
 933                 }
 934         }
 935         remove_branch_state(the_repository, !opts->quiet);
 936         strbuf_release(&msg);
 937         if (!opts->quiet &&
 938             (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
 939                 report_tracking(new_branch_info);
 940 }
 941
 942 static int add_pending_uninteresting_ref(const char *refname,
 943                                          const struct object_id *oid,
 944                                          int flags, void *cb_data)
 945 {
 946         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 947         return 0;
 948 }
 949
 950 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 951 {
 952         strbuf_addstr(sb, "  ");
 953         strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 954         strbuf_addch(sb, ' ');
 955         if (!parse_commit(commit))
 956                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 957         strbuf_addch(sb, '\n');
 958 }
 959
 960 #define ORPHAN_CUTOFF 4
 961 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 962 {
 963         struct commit *c, *last = NULL;
 964         struct strbuf sb = STRBUF_INIT;
 965         int lost = 0;
 966         while ((c = get_revision(revs)) != NULL) {
 967                 if (lost < ORPHAN_CUTOFF)
 968                         describe_one_orphan(&sb, c);
 969                 last = c;
 970                 lost++;
 971         }
 972         if (ORPHAN_CUTOFF < lost) {
 973                 int more = lost - ORPHAN_CUTOFF;
 974                 if (more == 1)
 975                         describe_one_orphan(&sb, last);
 976                 else
 977                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 978         }
 979
 980         fprintf(stderr,
 981                 Q_(
 982                 /* The singular version */
 983                 "Warning: you are leaving %d commit behind, "
 984                 "not connected to\n"
 985                 "any of your branches:\n\n"
 986                 "%s\n",
 987                 /* The plural version */
 988                 "Warning: you are leaving %d commits behind, "
 989                 "not connected to\n"
 990                 "any of your branches:\n\n"
 991                 "%s\n",
 992                 /* Give ngettext() the count */
 993                 lost),
 994                 lost,
 995                 sb.buf);
 996         strbuf_release(&sb);
 997
 998         if (advice_detached_head)
 999                 fprintf(stderr,
1000                         Q_(
1001                         /* The singular version */
1002                         "If you want to keep it by creating a new branch, "
1003                         "this may be a good time\nto do so with:\n\n"
1004                         " git branch <new-branch-name> %s\n\n",
1005                         /* The plural version */
1006                         "If you want to keep them by creating a new branch, "
1007                         "this may be a good time\nto do so with:\n\n"
1008                         " git branch <new-branch-name> %s\n\n",
1009                         /* Give ngettext() the count */
1010                         lost),
1011                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
1012 }
1013
1014 /*
1015  * We are about to leave commit that was at the tip of a detached
1016  * HEAD.  If it is not reachable from any ref, this is the last chance
1017  * for the user to do so without resorting to reflog.
1018  */
1019 static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
1020 {
1021         struct rev_info revs;
1022         struct object *object = &old_commit->object;
1023
1024         repo_init_revisions(the_repository, &revs, NULL);
1025         setup_revisions(0, NULL, &revs, NULL);
1026
1027         object->flags &= ~UNINTERESTING;
1028         add_pending_object(&revs, object, oid_to_hex(&object->oid));
1029
1030         for_each_ref(add_pending_uninteresting_ref, &revs);
1031         if (new_commit)
1032                 add_pending_oid(&revs, "HEAD",
1033                                 &new_commit->object.oid,
1034                                 UNINTERESTING);
1035
1036         if (prepare_revision_walk(&revs))
1037                 die(_("internal error in revision walk"));
1038         if (!(old_commit->object.flags & UNINTERESTING))
1039                 suggest_reattach(old_commit, &revs);
1040         else
1041                 describe_detached_head(_("Previous HEAD position was"), old_commit);
1042
1043         /* Clean up objects used, as they will be reused. */
1044         repo_clear_commit_marks(the_repository, ALL_REV_FLAGS);
1045 }
1046
1047 static int switch_branches(const struct checkout_opts *opts,
1048                            struct branch_info *new_branch_info)
1049 {
1050         int ret = 0;
1051         struct branch_info old_branch_info;
1052         void *path_to_free;
1053         struct object_id rev;
1054         int flag, writeout_error = 0;
1055         int do_merge = 1;
1056
1057         trace2_cmd_mode("branch");
1058
1059         memset(&old_branch_info, 0, sizeof(old_branch_info));
1060         old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
1061         if (old_branch_info.path)
1062                 old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
1063         if (!(flag & REF_ISSYMREF))
1064                 old_branch_info.path = NULL;
1065
1066         if (old_branch_info.path)
1067                 skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
1068
1069         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
1070                 if (new_branch_info->name)
1071                         BUG("'switch --orphan' should never accept a commit as starting point");
1072                 new_branch_info->commit = NULL;
1073                 new_branch_info->name = "(empty)";
1074                 do_merge = 1;
1075         }
1076
1077         if (!new_branch_info->name) {
1078                 new_branch_info->name = "HEAD";
1079                 new_branch_info->commit = old_branch_info.commit;
1080                 if (!new_branch_info->commit)
1081                         die(_("You are on a branch yet to be born"));
1082                 parse_commit_or_die(new_branch_info->commit);
1083
1084                 if (opts->only_merge_on_switching_branches)
1085                         do_merge = 0;
1086         }
1087
1088         if (do_merge) {
1089                 ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
1090                 if (ret) {
1091                         free(path_to_free);
1092                         return ret;
1093                 }
1094         }
1095
1096         if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
1097                 orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
1098
1099         update_refs_for_switch(opts, &old_branch_info, new_branch_info);
1100
1101         ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
1102         free(path_to_free);
1103         return ret || writeout_error;
1104 }
1105
1106 static int git_checkout_config(const char *var, const char *value, void *cb)
1107 {
1108         struct checkout_opts *opts = cb;
1109
1110         if (!strcmp(var, "diff.ignoresubmodules")) {
1111                 handle_ignore_submodules_arg(&opts->diff_options, value);
1112                 return 0;
1113         }
1114         if (!strcmp(var, "checkout.guess")) {
1115                 opts->dwim_new_local_branch = git_config_bool(var, value);
1116                 return 0;
1117         }
1118
1119         if (starts_with(var, "submodule."))
1120                 return git_default_submodule_config(var, value, NULL);
1121
1122         return git_xmerge_config(var, value, NULL);
1123 }
1124
1125 static void setup_new_branch_info_and_source_tree(
1126         struct branch_info *new_branch_info,
1127         struct checkout_opts *opts,
1128         struct object_id *rev,
1129         const char *arg)
1130 {
1131         struct tree **source_tree = &opts->source_tree;
1132         struct object_id branch_rev;
1133
1134         new_branch_info->name = arg;
1135         setup_branch_path(new_branch_info);
1136
1137         if (!check_refname_format(new_branch_info->path, 0) &&
1138             !read_ref(new_branch_info->path, &branch_rev))
1139                 oidcpy(rev, &branch_rev);
1140         else {
1141                 free((char *)new_branch_info->path);
1142                 new_branch_info->path = NULL; /* not an existing branch */
1143         }
1144
1145         new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
1146         if (!new_branch_info->commit) {
1147                 /* not a commit */
1148                 *source_tree = parse_tree_indirect(rev);
1149         } else {
1150                 parse_commit_or_die(new_branch_info->commit);
1151                 *source_tree = get_commit_tree(new_branch_info->commit);
1152         }
1153 }
1154
1155 static const char *parse_remote_branch(const char *arg,
1156                                        struct object_id *rev,
1157                                        int could_be_checkout_paths)
1158 {
1159         int num_matches = 0;
1160         const char *remote = unique_tracking_name(arg, rev, &num_matches);
1161
1162         if (remote && could_be_checkout_paths) {
1163                 die(_("'%s' could be both a local file and a tracking branch.\n"
1164                         "Please use -- (and optionally --no-guess) to disambiguate"),
1165                     arg);
1166         }
1167
1168         if (!remote && num_matches > 1) {
1169             if (advice_checkout_ambiguous_remote_branch_name) {
1170                     advise(_("If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
1171                              "you can do so by fully qualifying the name with the --track option:\n"
1172                              "\n"
1173                              "    git checkout --track origin/<name>\n"
1174                              "\n"
1175                              "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
1176                              "one remote, e.g. the 'origin' remote, consider setting\n"
1177                              "checkout.defaultRemote=origin in your config."));
1178             }
1179
1180             die(_("'%s' matched multiple (%d) remote tracking branches"),
1181                 arg, num_matches);
1182         }
1183
1184         return remote;
1185 }
1186
1187 static int parse_branchname_arg(int argc, const char **argv,
1188                                 int dwim_new_local_branch_ok,
1189                                 struct branch_info *new_branch_info,
1190                                 struct checkout_opts *opts,
1191                                 struct object_id *rev)
1192 {
1193         const char **new_branch = &opts->new_branch;
1194         int argcount = 0;
1195         const char *arg;
1196         int dash_dash_pos;
1197         int has_dash_dash = 0;
1198         int i;
1199
1200         /*
1201          * case 1: git checkout <ref> -- [<paths>]
1202          *
1203          *   <ref> must be a valid tree, everything after the '--' must be
1204          *   a path.
1205          *
1206          * case 2: git checkout -- [<paths>]
1207          *
1208          *   everything after the '--' must be paths.
1209          *
1210          * case 3: git checkout <something> [--]
1211          *
1212          *   (a) If <something> is a commit, that is to
1213          *       switch to the branch or detach HEAD at it.  As a special case,
1214          *       if <something> is A...B (missing A or B means HEAD but you can
1215          *       omit at most one side), and if there is a unique merge base
1216          *       between A and B, A...B names that merge base.
1217          *
1218          *   (b) If <something> is _not_ a commit, either "--" is present
1219          *       or <something> is not a path, no -t or -b was given, and
1220          *       and there is a tracking branch whose name is <something>
1221          *       in one and only one remote (or if the branch exists on the
1222          *       remote named in checkout.defaultRemote), then this is a
1223          *       short-hand to fork local <something> from that
1224          *       remote-tracking branch.
1225          *
1226          *   (c) Otherwise, if "--" is present, treat it like case (1).
1227          *
1228          *   (d) Otherwise :
1229          *       - if it's a reference, treat it like case (1)
1230          *       - else if it's a path, treat it like case (2)
1231          *       - else: fail.
1232          *
1233          * case 4: git checkout <something> <paths>
1234          *
1235          *   The first argument must not be ambiguous.
1236          *   - If it's *only* a reference, treat it like case (1).
1237          *   - If it's only a path, treat it like case (2).
1238          *   - else: fail.
1239          *
1240          */
1241         if (!argc)
1242                 return 0;
1243
1244         if (!opts->accept_pathspec) {
1245                 if (argc > 1)
1246                         die(_("only one reference expected"));
1247                 has_dash_dash = 1; /* helps disambiguate */
1248         }
1249
1250         arg = argv[0];
1251         dash_dash_pos = -1;
1252         for (i = 0; i < argc; i++) {
1253                 if (opts->accept_pathspec && !strcmp(argv[i], "--")) {
1254                         dash_dash_pos = i;
1255                         break;
1256                 }
1257         }
1258         if (dash_dash_pos == 0)
1259                 return 1; /* case (2) */
1260         else if (dash_dash_pos == 1)
1261                 has_dash_dash = 1; /* case (3) or (1) */
1262         else if (dash_dash_pos >= 2)
1263                 die(_("only one reference expected, %d given."), dash_dash_pos);
1264         opts->count_checkout_paths = !opts->quiet && !has_dash_dash;
1265
1266         if (!strcmp(arg, "-"))
1267                 arg = "@{-1}";
1268
1269         if (get_oid_mb(arg, rev)) {
1270                 /*
1271                  * Either case (3) or (4), with <something> not being
1272                  * a commit, or an attempt to use case (1) with an
1273                  * invalid ref.
1274                  *
1275                  * It's likely an error, but we need to find out if
1276                  * we should auto-create the branch, case (3).(b).
1277                  */
1278                 int recover_with_dwim = dwim_new_local_branch_ok;
1279
1280                 int could_be_checkout_paths = !has_dash_dash &&
1281                         check_filename(opts->prefix, arg);
1282
1283                 if (!has_dash_dash && !no_wildcard(arg))
1284                         recover_with_dwim = 0;
1285
1286                 /*
1287                  * Accept "git checkout foo", "git checkout foo --"
1288                  * and "git switch foo" as candidates for dwim.
1289                  */
1290                 if (!(argc == 1 && !has_dash_dash) &&
1291                     !(argc == 2 && has_dash_dash) &&
1292                     opts->accept_pathspec)
1293                         recover_with_dwim = 0;
1294
1295                 if (recover_with_dwim) {
1296                         const char *remote = parse_remote_branch(arg, rev,
1297                                                                  could_be_checkout_paths);
1298                         if (remote) {
1299                                 *new_branch = arg;
1300                                 arg = remote;
1301                                 /* DWIMmed to create local branch, case (3).(b) */
1302                         } else {
1303                                 recover_with_dwim = 0;
1304                         }
1305                 }
1306
1307                 if (!recover_with_dwim) {
1308                         if (has_dash_dash)
1309                                 die(_("invalid reference: %s"), arg);
1310                         return argcount;
1311                 }
1312         }
1313
1314         /* we can't end up being in (2) anymore, eat the argument */
1315         argcount++;
1316         argv++;
1317         argc--;
1318
1319         setup_new_branch_info_and_source_tree(new_branch_info, opts, rev, arg);
1320
1321         if (!opts->source_tree)                   /* case (1): want a tree */
1322                 die(_("reference is not a tree: %s"), arg);
1323
1324         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1325                 /*
1326                  * Do not complain the most common case
1327                  *      git checkout branch
1328                  * even if there happen to be a file called 'branch';
1329                  * it would be extremely annoying.
1330                  */
1331                 if (argc)
1332                         verify_non_filename(opts->prefix, arg);
1333         } else if (opts->accept_pathspec) {
1334                 argcount++;
1335                 argv++;
1336                 argc--;
1337         }
1338
1339         return argcount;
1340 }
1341
1342 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1343 {
1344         int status;
1345         struct strbuf branch_ref = STRBUF_INIT;
1346
1347         trace2_cmd_mode("unborn");
1348
1349         if (!opts->new_branch)
1350                 die(_("You are on a branch yet to be born"));
1351         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1352         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1353         strbuf_release(&branch_ref);
1354         if (!opts->quiet)
1355                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1356                         opts->new_branch);
1357         return status;
1358 }
1359
1360 static void die_expecting_a_branch(const struct branch_info *branch_info)
1361 {
1362         struct object_id oid;
1363         char *to_free;
1364
1365         if (dwim_ref(branch_info->name, strlen(branch_info->name), &oid, &to_free, 0) == 1) {
1366                 const char *ref = to_free;
1367
1368                 if (skip_prefix(ref, "refs/tags/", &ref))
1369                         die(_("a branch is expected, got tag '%s'"), ref);
1370                 if (skip_prefix(ref, "refs/remotes/", &ref))
1371                         die(_("a branch is expected, got remote branch '%s'"), ref);
1372                 die(_("a branch is expected, got '%s'"), ref);
1373         }
1374         if (branch_info->commit)
1375                 die(_("a branch is expected, got commit '%s'"), branch_info->name);
1376         /*
1377          * This case should never happen because we already die() on
1378          * non-commit, but just in case.
1379          */
1380         die(_("a branch is expected, got '%s'"), branch_info->name);
1381 }
1382
1383 static void die_if_some_operation_in_progress(void)
1384 {
1385         struct wt_status_state state;
1386
1387         memset(&state, 0, sizeof(state));
1388         wt_status_get_state(the_repository, &state, 0);
1389
1390         if (state.merge_in_progress)
1391                 die(_("cannot switch branch while merging\n"
1392                       "Consider \"git merge --quit\" "
1393                       "or \"git worktree add\"."));
1394         if (state.am_in_progress)
1395                 die(_("cannot switch branch in the middle of an am session\n"
1396                       "Consider \"git am --quit\" "
1397                       "or \"git worktree add\"."));
1398         if (state.rebase_interactive_in_progress || state.rebase_in_progress)
1399                 die(_("cannot switch branch while rebasing\n"
1400                       "Consider \"git rebase --quit\" "
1401                       "or \"git worktree add\"."));
1402         if (state.cherry_pick_in_progress)
1403                 die(_("cannot switch branch while cherry-picking\n"
1404                       "Consider \"git cherry-pick --quit\" "
1405                       "or \"git worktree add\"."));
1406         if (state.revert_in_progress)
1407                 die(_("cannot switch branch while reverting\n"
1408                       "Consider \"git revert --quit\" "
1409                       "or \"git worktree add\"."));
1410         if (state.bisect_in_progress)
1411                 warning(_("you are switching branch while bisecting"));
1412 }
1413
1414 static int checkout_branch(struct checkout_opts *opts,
1415                            struct branch_info *new_branch_info)
1416 {
1417         if (opts->pathspec.nr)
1418                 die(_("paths cannot be used with switching branches"));
1419
1420         if (opts->patch_mode)
1421                 die(_("'%s' cannot be used with switching branches"),
1422                     "--patch");
1423
1424         if (opts->overlay_mode != -1)
1425                 die(_("'%s' cannot be used with switching branches"),
1426                     "--[no]-overlay");
1427
1428         if (opts->writeout_stage)
1429                 die(_("'%s' cannot be used with switching branches"),
1430                     "--ours/--theirs");
1431
1432         if (opts->force && opts->merge)
1433                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1434
1435         if (opts->discard_changes && opts->merge)
1436                 die(_("'%s' cannot be used with '%s'"), "--discard-changes", "--merge");
1437
1438         if (opts->force_detach && opts->new_branch)
1439                 die(_("'%s' cannot be used with '%s'"),
1440                     "--detach", "-b/-B/--orphan");
1441
1442         if (opts->new_orphan_branch) {
1443                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1444                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1445                 if (opts->orphan_from_empty_tree && new_branch_info->name)
1446                         die(_("'%s' cannot take <start-point>"), "--orphan");
1447         } else if (opts->force_detach) {
1448                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1449                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1450         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1451                 opts->track = git_branch_track;
1452
1453         if (new_branch_info->name && !new_branch_info->commit)
1454                 die(_("Cannot switch branch to a non-commit '%s'"),
1455                     new_branch_info->name);
1456
1457         if (!opts->switch_branch_doing_nothing_is_ok &&
1458             !new_branch_info->name &&
1459             !opts->new_branch &&
1460             !opts->force_detach)
1461                 die(_("missing branch or commit argument"));
1462
1463         if (!opts->implicit_detach &&
1464             !opts->force_detach &&
1465             !opts->new_branch &&
1466             !opts->new_branch_force &&
1467             new_branch_info->name &&
1468             !new_branch_info->path)
1469                 die_expecting_a_branch(new_branch_info);
1470
1471         if (!opts->can_switch_when_in_progress)
1472                 die_if_some_operation_in_progress();
1473
1474         if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1475             !opts->ignore_other_worktrees) {
1476                 int flag;
1477                 char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1478                 if (head_ref &&
1479                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1480                         die_if_checked_out(new_branch_info->path, 1);
1481                 free(head_ref);
1482         }
1483
1484         if (!new_branch_info->commit && opts->new_branch) {
1485                 struct object_id rev;
1486                 int flag;
1487
1488                 if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1489                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1490                         return switch_unborn_to_new_branch(opts);
1491         }
1492         return switch_branches(opts, new_branch_info);
1493 }
1494
1495 static struct option *add_common_options(struct checkout_opts *opts,
1496                                          struct option *prevopts)
1497 {
1498         struct option options[] = {
1499                 OPT__QUIET(&opts->quiet, N_("suppress progress reporting")),
1500                 OPT_CALLBACK_F(0, "recurse-submodules", NULL,
1501                             "checkout", "control recursive updating of submodules",
1502                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater),
1503                 OPT_BOOL(0, "progress", &opts->show_progress, N_("force progress reporting")),
1504                 OPT_BOOL('m', "merge", &opts->merge, N_("perform a 3-way merge with the new branch")),
1505                 OPT_STRING(0, "conflict", &opts->conflict_style, N_("style"),
1506                            N_("conflict style (merge or diff3)")),
1507                 OPT_END()
1508         };
1509         struct option *newopts = parse_options_concat(prevopts, options);
1510         free(prevopts);
1511         return newopts;
1512 }
1513
1514 static struct option *add_common_switch_branch_options(
1515         struct checkout_opts *opts, struct option *prevopts)
1516 {
1517         struct option options[] = {
1518                 OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
1519                 OPT_SET_INT('t', "track",  &opts->track, N_("set upstream info for new branch"),
1520                         BRANCH_TRACK_EXPLICIT),
1521                 OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
1522                            PARSE_OPT_NOCOMPLETE),
1523                 OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1524                 OPT_BOOL_F(0, "overwrite-ignore", &opts->overwrite_ignore,
1525                            N_("update ignored files (default)"),
1526                            PARSE_OPT_NOCOMPLETE),
1527                 OPT_BOOL(0, "ignore-other-worktrees", &opts->ignore_other_worktrees,
1528                          N_("do not check if another worktree is holding the given ref")),
1529                 OPT_END()
1530         };
1531         struct option *newopts = parse_options_concat(prevopts, options);
1532         free(prevopts);
1533         return newopts;
1534 }
1535
1536 static struct option *add_checkout_path_options(struct checkout_opts *opts,
1537                                                 struct option *prevopts)
1538 {
1539         struct option options[] = {
1540                 OPT_SET_INT_F('2', "ours", &opts->writeout_stage,
1541                               N_("checkout our version for unmerged files"),
1542                               2, PARSE_OPT_NONEG),
1543                 OPT_SET_INT_F('3', "theirs", &opts->writeout_stage,
1544                               N_("checkout their version for unmerged files"),
1545                               3, PARSE_OPT_NONEG),
1546                 OPT_BOOL('p', "patch", &opts->patch_mode, N_("select hunks interactively")),
1547                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts->ignore_skipworktree,
1548                          N_("do not limit pathspecs to sparse entries only")),
1549                 OPT_PATHSPEC_FROM_FILE(&opts->pathspec_from_file),
1550                 OPT_PATHSPEC_FILE_NUL(&opts->pathspec_file_nul),
1551                 OPT_END()
1552         };
1553         struct option *newopts = parse_options_concat(prevopts, options);
1554         free(prevopts);
1555         return newopts;
1556 }
1557
1558 /* create-branch option (either b or c) */
1559 static char cb_option = 'b';
1560
1561 static int checkout_main(int argc, const char **argv, const char *prefix,
1562                          struct checkout_opts *opts, struct option *options,
1563                          const char * const usagestr[])
1564 {
1565         struct branch_info new_branch_info;
1566         int parseopt_flags = 0;
1567
1568         memset(&new_branch_info, 0, sizeof(new_branch_info));
1569         opts->overwrite_ignore = 1;
1570         opts->prefix = prefix;
1571         opts->show_progress = -1;
1572
1573         git_config(git_checkout_config, opts);
1574
1575         opts->track = BRANCH_TRACK_UNSPECIFIED;
1576
1577         if (!opts->accept_pathspec && !opts->accept_ref)
1578                 BUG("make up your mind, you need to take _something_");
1579         if (opts->accept_pathspec && opts->accept_ref)
1580                 parseopt_flags = PARSE_OPT_KEEP_DASHDASH;
1581
1582         argc = parse_options(argc, argv, prefix, options,
1583                              usagestr, parseopt_flags);
1584
1585         if (opts->show_progress < 0) {
1586                 if (opts->quiet)
1587                         opts->show_progress = 0;
1588                 else
1589                         opts->show_progress = isatty(2);
1590         }
1591
1592         if (opts->conflict_style) {
1593                 opts->merge = 1; /* implied */
1594                 git_xmerge_config("merge.conflictstyle", opts->conflict_style, NULL);
1595         }
1596         if (opts->force) {
1597                 opts->discard_changes = 1;
1598                 opts->ignore_unmerged_opt = "--force";
1599                 opts->ignore_unmerged = 1;
1600         }
1601
1602         if ((!!opts->new_branch + !!opts->new_branch_force + !!opts->new_orphan_branch) > 1)
1603                 die(_("-%c, -%c and --orphan are mutually exclusive"),
1604                                 cb_option, toupper(cb_option));
1605
1606         if (opts->overlay_mode == 1 && opts->patch_mode)
1607                 die(_("-p and --overlay are mutually exclusive"));
1608
1609         if (opts->checkout_index >= 0 || opts->checkout_worktree >= 0) {
1610                 if (opts->checkout_index < 0)
1611                         opts->checkout_index = 0;
1612                 if (opts->checkout_worktree < 0)
1613                         opts->checkout_worktree = 0;
1614         } else {
1615                 if (opts->checkout_index < 0)
1616                         opts->checkout_index = -opts->checkout_index - 1;
1617                 if (opts->checkout_worktree < 0)
1618                         opts->checkout_worktree = -opts->checkout_worktree - 1;
1619         }
1620         if (opts->checkout_index < 0 || opts->checkout_worktree < 0)
1621                 BUG("these flags should be non-negative by now");
1622         /*
1623          * convenient shortcut: "git restore --staged [--worktree]" equals
1624          * "git restore --staged [--worktree] --source HEAD"
1625          */
1626         if (!opts->from_treeish && opts->checkout_index)
1627                 opts->from_treeish = "HEAD";
1628
1629         /*
1630          * From here on, new_branch will contain the branch to be checked out,
1631          * and new_branch_force and new_orphan_branch will tell us which one of
1632          * -b/-B/-c/-C/--orphan is being used.
1633          */
1634         if (opts->new_branch_force)
1635                 opts->new_branch = opts->new_branch_force;
1636
1637         if (opts->new_orphan_branch)
1638                 opts->new_branch = opts->new_orphan_branch;
1639
1640         /* --track without -c/-C/-b/-B/--orphan should DWIM */
1641         if (opts->track != BRANCH_TRACK_UNSPECIFIED && !opts->new_branch) {
1642                 const char *argv0 = argv[0];
1643                 if (!argc || !strcmp(argv0, "--"))
1644                         die(_("--track needs a branch name"));
1645                 skip_prefix(argv0, "refs/", &argv0);
1646                 skip_prefix(argv0, "remotes/", &argv0);
1647                 argv0 = strchr(argv0, '/');
1648                 if (!argv0 || !argv0[1])
1649                         die(_("missing branch name; try -%c"), cb_option);
1650                 opts->new_branch = argv0 + 1;
1651         }
1652
1653         /*
1654          * Extract branch name from command line arguments, so
1655          * all that is left is pathspecs.
1656          *
1657          * Handle
1658          *
1659          *  1) git checkout <tree> -- [<paths>]
1660          *  2) git checkout -- [<paths>]
1661          *  3) git checkout <something> [<paths>]
1662          *
1663          * including "last branch" syntax and DWIM-ery for names of
1664          * remote branches, erroring out for invalid or ambiguous cases.
1665          */
1666         if (argc && opts->accept_ref) {
1667                 struct object_id rev;
1668                 int dwim_ok =
1669                         !opts->patch_mode &&
1670                         opts->dwim_new_local_branch &&
1671                         opts->track == BRANCH_TRACK_UNSPECIFIED &&
1672                         !opts->new_branch;
1673                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1674                                              &new_branch_info, opts, &rev);
1675                 argv += n;
1676                 argc -= n;
1677         } else if (!opts->accept_ref && opts->from_treeish) {
1678                 struct object_id rev;
1679
1680                 if (get_oid_mb(opts->from_treeish, &rev))
1681                         die(_("could not resolve %s"), opts->from_treeish);
1682
1683                 setup_new_branch_info_and_source_tree(&new_branch_info,
1684                                                       opts, &rev,
1685                                                       opts->from_treeish);
1686
1687                 if (!opts->source_tree)
1688                         die(_("reference is not a tree: %s"), opts->from_treeish);
1689         }
1690
1691         if (argc) {
1692                 parse_pathspec(&opts->pathspec, 0,
1693                                opts->patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1694                                prefix, argv);
1695
1696                 if (!opts->pathspec.nr)
1697                         die(_("invalid path specification"));
1698
1699                 /*
1700                  * Try to give more helpful suggestion.
1701                  * new_branch && argc > 1 will be caught later.
1702                  */
1703                 if (opts->new_branch && argc == 1 && !new_branch_info.commit)
1704                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1705                                 argv[0], opts->new_branch);
1706
1707                 if (opts->force_detach)
1708                         die(_("git checkout: --detach does not take a path argument '%s'"),
1709                             argv[0]);
1710         }
1711
1712         if (opts->pathspec_from_file) {
1713                 if (opts->pathspec.nr)
1714                         die(_("--pathspec-from-file is incompatible with pathspec arguments"));
1715
1716                 if (opts->force_detach)
1717                         die(_("--pathspec-from-file is incompatible with --detach"));
1718
1719                 if (opts->patch_mode)
1720                         die(_("--pathspec-from-file is incompatible with --patch"));
1721
1722                 parse_pathspec_file(&opts->pathspec, 0,
1723                                     0,
1724                                     prefix, opts->pathspec_from_file, opts->pathspec_file_nul);
1725         } else if (opts->pathspec_file_nul) {
1726                 die(_("--pathspec-file-nul requires --pathspec-from-file"));
1727         }
1728
1729         opts->pathspec.recursive = 1;
1730
1731         if (opts->pathspec.nr) {
1732                 if (1 < !!opts->writeout_stage + !!opts->force + !!opts->merge)
1733                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1734                               "checking out of the index."));
1735         } else {
1736                 if (opts->accept_pathspec && !opts->empty_pathspec_ok &&
1737                     !opts->patch_mode)  /* patch mode is special */
1738                         die(_("you must specify path(s) to restore"));
1739         }
1740
1741         if (opts->new_branch) {
1742                 struct strbuf buf = STRBUF_INIT;
1743
1744                 if (opts->new_branch_force)
1745                         opts->branch_exists = validate_branchname(opts->new_branch, &buf);
1746                 else
1747                         opts->branch_exists =
1748                                 validate_new_branchname(opts->new_branch, &buf, 0);
1749                 strbuf_release(&buf);
1750         }
1751
1752         UNLEAK(opts);
1753         if (opts->patch_mode || opts->pathspec.nr)
1754                 return checkout_paths(opts, &new_branch_info);
1755         else
1756                 return checkout_branch(opts, &new_branch_info);
1757 }
1758
1759 int cmd_checkout(int argc, const char **argv, const char *prefix)
1760 {
1761         struct checkout_opts opts;
1762         struct option *options;
1763         struct option checkout_options[] = {
1764                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1765                            N_("create and checkout a new branch")),
1766                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1767                            N_("create/reset and checkout a branch")),
1768                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1769                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1770                          N_("second guess 'git checkout <no-such-branch>' (default)")),
1771                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
1772                 OPT_END()
1773         };
1774         int ret;
1775
1776         memset(&opts, 0, sizeof(opts));
1777         opts.dwim_new_local_branch = 1;
1778         opts.switch_branch_doing_nothing_is_ok = 1;
1779         opts.only_merge_on_switching_branches = 0;
1780         opts.accept_ref = 1;
1781         opts.accept_pathspec = 1;
1782         opts.implicit_detach = 1;
1783         opts.can_switch_when_in_progress = 1;
1784         opts.orphan_from_empty_tree = 0;
1785         opts.empty_pathspec_ok = 1;
1786         opts.overlay_mode = -1;
1787         opts.checkout_index = -2;    /* default on */
1788         opts.checkout_worktree = -2; /* default on */
1789
1790         if (argc == 3 && !strcmp(argv[1], "-b")) {
1791                 /*
1792                  * User ran 'git checkout -b <branch>' and expects
1793                  * the same behavior as 'git switch -c <branch>'.
1794                  */
1795                 opts.switch_branch_doing_nothing_is_ok = 0;
1796                 opts.only_merge_on_switching_branches = 1;
1797         }
1798
1799         options = parse_options_dup(checkout_options);
1800         options = add_common_options(&opts, options);
1801         options = add_common_switch_branch_options(&opts, options);
1802         options = add_checkout_path_options(&opts, options);
1803
1804         ret = checkout_main(argc, argv, prefix, &opts,
1805                             options, checkout_usage);
1806         FREE_AND_NULL(options);
1807         return ret;
1808 }
1809
1810 int cmd_switch(int argc, const char **argv, const char *prefix)
1811 {
1812         struct checkout_opts opts;
1813         struct option *options = NULL;
1814         struct option switch_options[] = {
1815                 OPT_STRING('c', "create", &opts.new_branch, N_("branch"),
1816                            N_("create and switch to a new branch")),
1817                 OPT_STRING('C', "force-create", &opts.new_branch_force, N_("branch"),
1818                            N_("create/reset and switch to a branch")),
1819                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1820                          N_("second guess 'git switch <no-such-branch>'")),
1821                 OPT_BOOL(0, "discard-changes", &opts.discard_changes,
1822                          N_("throw away local modifications")),
1823                 OPT_END()
1824         };
1825         int ret;
1826
1827         memset(&opts, 0, sizeof(opts));
1828         opts.dwim_new_local_branch = 1;
1829         opts.accept_ref = 1;
1830         opts.accept_pathspec = 0;
1831         opts.switch_branch_doing_nothing_is_ok = 0;
1832         opts.only_merge_on_switching_branches = 1;
1833         opts.implicit_detach = 0;
1834         opts.can_switch_when_in_progress = 0;
1835         opts.orphan_from_empty_tree = 1;
1836         opts.overlay_mode = -1;
1837
1838         options = parse_options_dup(switch_options);
1839         options = add_common_options(&opts, options);
1840         options = add_common_switch_branch_options(&opts, options);
1841
1842         cb_option = 'c';
1843
1844         ret = checkout_main(argc, argv, prefix, &opts,
1845                             options, switch_branch_usage);
1846         FREE_AND_NULL(options);
1847         return ret;
1848 }
1849
1850 int cmd_restore(int argc, const char **argv, const char *prefix)
1851 {
1852         struct checkout_opts opts;
1853         struct option *options;
1854         struct option restore_options[] = {
1855                 OPT_STRING('s', "source", &opts.from_treeish, "<tree-ish>",
1856                            N_("which tree-ish to checkout from")),
1857                 OPT_BOOL('S', "staged", &opts.checkout_index,
1858                            N_("restore the index")),
1859                 OPT_BOOL('W', "worktree", &opts.checkout_worktree,
1860                            N_("restore the working tree (default)")),
1861                 OPT_BOOL(0, "ignore-unmerged", &opts.ignore_unmerged,
1862                          N_("ignore unmerged entries")),
1863                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode")),
1864                 OPT_END()
1865         };
1866         int ret;
1867
1868         memset(&opts, 0, sizeof(opts));
1869         opts.accept_ref = 0;
1870         opts.accept_pathspec = 1;
1871         opts.empty_pathspec_ok = 0;
1872         opts.overlay_mode = 0;
1873         opts.checkout_index = -1;    /* default off */
1874         opts.checkout_worktree = -2; /* default on */
1875         opts.ignore_unmerged_opt = "--ignore-unmerged";
1876
1877         options = parse_options_dup(restore_options);
1878         options = add_common_options(&opts, options);
1879         options = add_checkout_path_options(&opts, options);
1880
1881         ret = checkout_main(argc, argv, prefix, &opts,
1882                             options, restore_usage);
1883         FREE_AND_NULL(options);
1884         return ret;
1885 }