builtin/checkout.c

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