git.oblomov.eu Git - git/blob - 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, opts->prefix)) {
 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.gently = 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 merge_options o;
 729                         struct strbuf sb = STRBUF_INIT;
 730
 731                         if (!opts->merge)
 732                                 return 1;
 733
 734                         /*
 735                          * Without old_branch_info->commit, the below is the same as
 736                          * the two-tree unpack we already tried and failed.
 737                          */
 738                         if (!old_branch_info->commit)
 739                                 return 1;
 740
 741                         if (repo_index_has_changes(the_repository,
 742                                                    get_commit_tree(old_branch_info->commit),
 743                                                    &sb))
 744                                 warning(_("staged changes in the following files may be lost: %s"),
 745                                         sb.buf);
 746                         strbuf_release(&sb);
 747
 748                         /* Do more real merge */
 749
 750                         /*
 751                          * We update the index fully, then write the
 752                          * tree from the index, then merge the new
 753                          * branch with the current tree, with the old
 754                          * branch as the base. Then we reset the index
 755                          * (but not the working tree) to the new
 756                          * branch, leaving the working tree as the
 757                          * merged version, but skipping unmerged
 758                          * entries in the index.
 759                          */
 760
 761                         add_files_to_cache(NULL, NULL, 0);
 762                         /*
 763                          * NEEDSWORK: carrying over local changes
 764                          * when branches have different end-of-line
 765                          * normalization (or clean+smudge rules) is
 766                          * a pain; plumb in an option to set
 767                          * o.renormalize?
 768                          */
 769                         init_merge_options(&o, the_repository);
 770                         o.verbosity = 0;
 771                         work = write_tree_from_memory(&o);
 772
 773                         ret = reset_tree(get_commit_tree(new_branch_info->commit),
 774                                          opts, 1,
 775                                          writeout_error);
 776                         if (ret)
 777                                 return ret;
 778                         o.ancestor = old_branch_info->name;
 779                         o.branch1 = new_branch_info->name;
 780                         o.branch2 = "local";
 781                         ret = merge_trees(&o,
 782                                           get_commit_tree(new_branch_info->commit),
 783                                           work,
 784                                           get_commit_tree(old_branch_info->commit),
 785                                           &result);
 786                         if (ret < 0)
 787                                 exit(128);
 788                         ret = reset_tree(get_commit_tree(new_branch_info->commit),
 789                                          opts, 0,
 790                                          writeout_error);
 791                         strbuf_release(&o.obuf);
 792                         if (ret)
 793                                 return ret;
 794                 }
 795         }
 796
 797         if (!active_cache_tree)
 798                 active_cache_tree = cache_tree();
 799
 800         if (!cache_tree_fully_valid(active_cache_tree))
 801                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 802
 803         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 804                 die(_("unable to write new index file"));
 805
 806         if (!opts->force && !opts->quiet)
 807                 show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 808
 809         return 0;
 810 }
 811
 812 static void report_tracking(struct branch_info *new_branch_info)
 813 {
 814         struct strbuf sb = STRBUF_INIT;
 815         struct branch *branch = branch_get(new_branch_info->name);
 816
 817         if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 818                 return;
 819         fputs(sb.buf, stdout);
 820         strbuf_release(&sb);
 821 }
 822
 823 static void update_refs_for_switch(const struct checkout_opts *opts,
 824                                    struct branch_info *old_branch_info,
 825                                    struct branch_info *new_branch_info)
 826 {
 827         struct strbuf msg = STRBUF_INIT;
 828         const char *old_desc, *reflog_msg;
 829         if (opts->new_branch) {
 830                 if (opts->new_orphan_branch) {
 831                         char *refname;
 832
 833                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 834                         if (opts->new_branch_log &&
 835                             !should_autocreate_reflog(refname)) {
 836                                 int ret;
 837                                 struct strbuf err = STRBUF_INIT;
 838
 839                                 ret = safe_create_reflog(refname, 1, &err);
 840                                 if (ret) {
 841                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 842                                                 opts->new_orphan_branch, err.buf);
 843                                         strbuf_release(&err);
 844                                         free(refname);
 845                                         return;
 846                                 }
 847                                 strbuf_release(&err);
 848                         }
 849                         free(refname);
 850                 }
 851                 else
 852                         create_branch(the_repository,
 853                                       opts->new_branch, new_branch_info->name,
 854                                       opts->new_branch_force ? 1 : 0,
 855                                       opts->new_branch_force ? 1 : 0,
 856                                       opts->new_branch_log,
 857                                       opts->quiet,
 858                                       opts->track);
 859                 new_branch_info->name = opts->new_branch;
 860                 setup_branch_path(new_branch_info);
 861         }
 862
 863         old_desc = old_branch_info->name;
 864         if (!old_desc && old_branch_info->commit)
 865                 old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
 866
 867         reflog_msg = getenv("GIT_REFLOG_ACTION");
 868         if (!reflog_msg)
 869                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 870                         old_desc ? old_desc : "(invalid)", new_branch_info->name);
 871         else
 872                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 873
 874         if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
 875                 /* Nothing to do. */
 876         } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
 877                 update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
 878                            REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 879                 if (!opts->quiet) {
 880                         if (old_branch_info->path &&
 881                             advice_detached_head && !opts->force_detach)
 882                                 detach_advice(new_branch_info->name);
 883                         describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 884                 }
 885         } else if (new_branch_info->path) {     /* Switch branches. */
 886                 if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
 887                         die(_("unable to update HEAD"));
 888                 if (!opts->quiet) {
 889                         if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
 890                                 if (opts->new_branch_force)
 891                                         fprintf(stderr, _("Reset branch '%s'\n"),
 892                                                 new_branch_info->name);
 893                                 else
 894                                         fprintf(stderr, _("Already on '%s'\n"),
 895                                                 new_branch_info->name);
 896                         } else if (opts->new_branch) {
 897                                 if (opts->branch_exists)
 898                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
 899                                 else
 900                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
 901                         } else {
 902                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 903                                         new_branch_info->name);
 904                         }
 905                 }
 906                 if (old_branch_info->path && old_branch_info->name) {
 907                         if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
 908                                 delete_reflog(old_branch_info->path);
 909                 }
 910         }
 911         remove_branch_state(the_repository);
 912         strbuf_release(&msg);
 913         if (!opts->quiet &&
 914             (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
 915                 report_tracking(new_branch_info);
 916 }
 917
 918 static int add_pending_uninteresting_ref(const char *refname,
 919                                          const struct object_id *oid,
 920                                          int flags, void *cb_data)
 921 {
 922         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 923         return 0;
 924 }
 925
 926 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 927 {
 928         strbuf_addstr(sb, "  ");
 929         strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 930         strbuf_addch(sb, ' ');
 931         if (!parse_commit(commit))
 932                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 933         strbuf_addch(sb, '\n');
 934 }
 935
 936 #define ORPHAN_CUTOFF 4
 937 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 938 {
 939         struct commit *c, *last = NULL;
 940         struct strbuf sb = STRBUF_INIT;
 941         int lost = 0;
 942         while ((c = get_revision(revs)) != NULL) {
 943                 if (lost < ORPHAN_CUTOFF)
 944                         describe_one_orphan(&sb, c);
 945                 last = c;
 946                 lost++;
 947         }
 948         if (ORPHAN_CUTOFF < lost) {
 949                 int more = lost - ORPHAN_CUTOFF;
 950                 if (more == 1)
 951                         describe_one_orphan(&sb, last);
 952                 else
 953                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 954         }
 955
 956         fprintf(stderr,
 957                 Q_(
 958                 /* The singular version */
 959                 "Warning: you are leaving %d commit behind, "
 960                 "not connected to\n"
 961                 "any of your branches:\n\n"
 962                 "%s\n",
 963                 /* The plural version */
 964                 "Warning: you are leaving %d commits behind, "
 965                 "not connected to\n"
 966                 "any of your branches:\n\n"
 967                 "%s\n",
 968                 /* Give ngettext() the count */
 969                 lost),
 970                 lost,
 971                 sb.buf);
 972         strbuf_release(&sb);
 973
 974         if (advice_detached_head)
 975                 fprintf(stderr,
 976                         Q_(
 977                         /* The singular version */
 978                         "If you want to keep it by creating a new branch, "
 979                         "this may be a good time\nto do so with:\n\n"
 980                         " git branch <new-branch-name> %s\n\n",
 981                         /* The plural version */
 982                         "If you want to keep them by creating a new branch, "
 983                         "this may be a good time\nto do so with:\n\n"
 984                         " git branch <new-branch-name> %s\n\n",
 985                         /* Give ngettext() the count */
 986                         lost),
 987                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 988 }
 989
 990 /*
 991  * We are about to leave commit that was at the tip of a detached
 992  * HEAD.  If it is not reachable from any ref, this is the last chance
 993  * for the user to do so without resorting to reflog.
 994  */
 995 static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
 996 {
 997         struct rev_info revs;
 998         struct object *object = &old_commit->object;
 999
1000         repo_init_revisions(the_repository, &revs, NULL);
1001         setup_revisions(0, NULL, &revs, NULL);
1002
1003         object->flags &= ~UNINTERESTING;
1004         add_pending_object(&revs, object, oid_to_hex(&object->oid));
1005
1006         for_each_ref(add_pending_uninteresting_ref, &revs);
1007         add_pending_oid(&revs, "HEAD", &new_commit->object.oid, UNINTERESTING);
1008
1009         if (prepare_revision_walk(&revs))
1010                 die(_("internal error in revision walk"));
1011         if (!(old_commit->object.flags & UNINTERESTING))
1012                 suggest_reattach(old_commit, &revs);
1013         else
1014                 describe_detached_head(_("Previous HEAD position was"), old_commit);
1015
1016         /* Clean up objects used, as they will be reused. */
1017         clear_commit_marks_all(ALL_REV_FLAGS);
1018 }
1019
1020 static int switch_branches(const struct checkout_opts *opts,
1021                            struct branch_info *new_branch_info)
1022 {
1023         int ret = 0;
1024         struct branch_info old_branch_info;
1025         void *path_to_free;
1026         struct object_id rev;
1027         int flag, writeout_error = 0;
1028
1029         trace2_cmd_mode("branch");
1030
1031         memset(&old_branch_info, 0, sizeof(old_branch_info));
1032         old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
1033         if (old_branch_info.path)
1034                 old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
1035         if (!(flag & REF_ISSYMREF))
1036                 old_branch_info.path = NULL;
1037
1038         if (old_branch_info.path)
1039                 skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
1040
1041         if (!new_branch_info->name) {
1042                 new_branch_info->name = "HEAD";
1043                 new_branch_info->commit = old_branch_info.commit;
1044                 if (!new_branch_info->commit)
1045                         die(_("You are on a branch yet to be born"));
1046                 parse_commit_or_die(new_branch_info->commit);
1047         }
1048
1049         /* optimize the "checkout -b <new_branch> path */
1050         if (skip_merge_working_tree(opts, &old_branch_info, new_branch_info)) {
1051                 if (!checkout_optimize_new_branch && !opts->quiet) {
1052                         if (read_cache_preload(NULL) < 0)
1053                                 return error(_("index file corrupt"));
1054                         show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
1055                 }
1056         } else {
1057                 ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
1058                 if (ret) {
1059                         free(path_to_free);
1060                         return ret;
1061                 }
1062         }
1063
1064         if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
1065                 orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
1066
1067         update_refs_for_switch(opts, &old_branch_info, new_branch_info);
1068
1069         ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
1070         free(path_to_free);
1071         return ret || writeout_error;
1072 }
1073
1074 static int git_checkout_config(const char *var, const char *value, void *cb)
1075 {
1076         if (!strcmp(var, "checkout.optimizenewbranch")) {
1077                 checkout_optimize_new_branch = git_config_bool(var, value);
1078                 return 0;
1079         }
1080
1081         if (!strcmp(var, "diff.ignoresubmodules")) {
1082                 struct checkout_opts *opts = cb;
1083                 handle_ignore_submodules_arg(&opts->diff_options, value);
1084                 return 0;
1085         }
1086
1087         if (starts_with(var, "submodule."))
1088                 return git_default_submodule_config(var, value, NULL);
1089
1090         return git_xmerge_config(var, value, NULL);
1091 }
1092
1093 static int parse_branchname_arg(int argc, const char **argv,
1094                                 int dwim_new_local_branch_ok,
1095                                 struct branch_info *new_branch_info,
1096                                 struct checkout_opts *opts,
1097                                 struct object_id *rev,
1098                                 int *dwim_remotes_matched)
1099 {
1100         struct tree **source_tree = &opts->source_tree;
1101         const char **new_branch = &opts->new_branch;
1102         int argcount = 0;
1103         struct object_id branch_rev;
1104         const char *arg;
1105         int dash_dash_pos;
1106         int has_dash_dash = 0;
1107         int i;
1108
1109         /*
1110          * case 1: git checkout <ref> -- [<paths>]
1111          *
1112          *   <ref> must be a valid tree, everything after the '--' must be
1113          *   a path.
1114          *
1115          * case 2: git checkout -- [<paths>]
1116          *
1117          *   everything after the '--' must be paths.
1118          *
1119          * case 3: git checkout <something> [--]
1120          *
1121          *   (a) If <something> is a commit, that is to
1122          *       switch to the branch or detach HEAD at it.  As a special case,
1123          *       if <something> is A...B (missing A or B means HEAD but you can
1124          *       omit at most one side), and if there is a unique merge base
1125          *       between A and B, A...B names that merge base.
1126          *
1127          *   (b) If <something> is _not_ a commit, either "--" is present
1128          *       or <something> is not a path, no -t or -b was given, and
1129          *       and there is a tracking branch whose name is <something>
1130          *       in one and only one remote (or if the branch exists on the
1131          *       remote named in checkout.defaultRemote), then this is a
1132          *       short-hand to fork local <something> from that
1133          *       remote-tracking branch.
1134          *
1135          *   (c) Otherwise, if "--" is present, treat it like case (1).
1136          *
1137          *   (d) Otherwise :
1138          *       - if it's a reference, treat it like case (1)
1139          *       - else if it's a path, treat it like case (2)
1140          *       - else: fail.
1141          *
1142          * case 4: git checkout <something> <paths>
1143          *
1144          *   The first argument must not be ambiguous.
1145          *   - If it's *only* a reference, treat it like case (1).
1146          *   - If it's only a path, treat it like case (2).
1147          *   - else: fail.
1148          *
1149          */
1150         if (!argc)
1151                 return 0;
1152
1153         arg = argv[0];
1154         dash_dash_pos = -1;
1155         for (i = 0; i < argc; i++) {
1156                 if (!strcmp(argv[i], "--")) {
1157                         dash_dash_pos = i;
1158                         break;
1159                 }
1160         }
1161         if (dash_dash_pos == 0)
1162                 return 1; /* case (2) */
1163         else if (dash_dash_pos == 1)
1164                 has_dash_dash = 1; /* case (3) or (1) */
1165         else if (dash_dash_pos >= 2)
1166                 die(_("only one reference expected, %d given."), dash_dash_pos);
1167         opts->count_checkout_paths = !opts->quiet && !has_dash_dash;
1168
1169         if (!strcmp(arg, "-"))
1170                 arg = "@{-1}";
1171
1172         if (get_oid_mb(arg, rev)) {
1173                 /*
1174                  * Either case (3) or (4), with <something> not being
1175                  * a commit, or an attempt to use case (1) with an
1176                  * invalid ref.
1177                  *
1178                  * It's likely an error, but we need to find out if
1179                  * we should auto-create the branch, case (3).(b).
1180                  */
1181                 int recover_with_dwim = dwim_new_local_branch_ok;
1182
1183                 int could_be_checkout_paths = !has_dash_dash &&
1184                         check_filename(opts->prefix, arg);
1185
1186                 if (!has_dash_dash && !no_wildcard(arg))
1187                         recover_with_dwim = 0;
1188
1189                 /*
1190                  * Accept "git checkout foo" and "git checkout foo --"
1191                  * as candidates for dwim.
1192                  */
1193                 if (!(argc == 1 && !has_dash_dash) &&
1194                     !(argc == 2 && has_dash_dash))
1195                         recover_with_dwim = 0;
1196
1197                 if (recover_with_dwim) {
1198                         const char *remote = unique_tracking_name(arg, rev,
1199                                                                   dwim_remotes_matched);
1200                         if (remote) {
1201                                 if (could_be_checkout_paths)
1202                                         die(_("'%s' could be both a local file and a tracking branch.\n"
1203                                               "Please use -- (and optionally --no-guess) to disambiguate"),
1204                                             arg);
1205                                 *new_branch = arg;
1206                                 arg = remote;
1207                                 /* DWIMmed to create local branch, case (3).(b) */
1208                         } else {
1209                                 recover_with_dwim = 0;
1210                         }
1211                 }
1212
1213                 if (!recover_with_dwim) {
1214                         if (has_dash_dash)
1215                                 die(_("invalid reference: %s"), arg);
1216                         return argcount;
1217                 }
1218         }
1219
1220         /* we can't end up being in (2) anymore, eat the argument */
1221         argcount++;
1222         argv++;
1223         argc--;
1224
1225         new_branch_info->name = arg;
1226         setup_branch_path(new_branch_info);
1227
1228         if (!check_refname_format(new_branch_info->path, 0) &&
1229             !read_ref(new_branch_info->path, &branch_rev))
1230                 oidcpy(rev, &branch_rev);
1231         else
1232                 new_branch_info->path = NULL; /* not an existing branch */
1233
1234         new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
1235         if (!new_branch_info->commit) {
1236                 /* not a commit */
1237                 *source_tree = parse_tree_indirect(rev);
1238         } else {
1239                 parse_commit_or_die(new_branch_info->commit);
1240                 *source_tree = get_commit_tree(new_branch_info->commit);
1241         }
1242
1243         if (!*source_tree)                   /* case (1): want a tree */
1244                 die(_("reference is not a tree: %s"), arg);
1245         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1246                 /*
1247                  * Do not complain the most common case
1248                  *      git checkout branch
1249                  * even if there happen to be a file called 'branch';
1250                  * it would be extremely annoying.
1251                  */
1252                 if (argc)
1253                         verify_non_filename(opts->prefix, arg);
1254         } else {
1255                 argcount++;
1256                 argv++;
1257                 argc--;
1258         }
1259
1260         return argcount;
1261 }
1262
1263 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1264 {
1265         int status;
1266         struct strbuf branch_ref = STRBUF_INIT;
1267
1268         trace2_cmd_mode("unborn");
1269
1270         if (!opts->new_branch)
1271                 die(_("You are on a branch yet to be born"));
1272         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1273         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1274         strbuf_release(&branch_ref);
1275         if (!opts->quiet)
1276                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1277                         opts->new_branch);
1278         return status;
1279 }
1280
1281 static int checkout_branch(struct checkout_opts *opts,
1282                            struct branch_info *new_branch_info)
1283 {
1284         if (opts->pathspec.nr)
1285                 die(_("paths cannot be used with switching branches"));
1286
1287         if (opts->patch_mode)
1288                 die(_("'%s' cannot be used with switching branches"),
1289                     "--patch");
1290
1291         if (!opts->overlay_mode)
1292                 die(_("'%s' cannot be used with switching branches"),
1293                     "--no-overlay");
1294
1295         if (opts->writeout_stage)
1296                 die(_("'%s' cannot be used with switching branches"),
1297                     "--ours/--theirs");
1298
1299         if (opts->force && opts->merge)
1300                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1301
1302         if (opts->force_detach && opts->new_branch)
1303                 die(_("'%s' cannot be used with '%s'"),
1304                     "--detach", "-b/-B/--orphan");
1305
1306         if (opts->new_orphan_branch) {
1307                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1308                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1309         } else if (opts->force_detach) {
1310                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1311                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1312         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1313                 opts->track = git_branch_track;
1314
1315         if (new_branch_info->name && !new_branch_info->commit)
1316                 die(_("Cannot switch branch to a non-commit '%s'"),
1317                     new_branch_info->name);
1318
1319         if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1320             !opts->ignore_other_worktrees) {
1321                 int flag;
1322                 char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1323                 if (head_ref &&
1324                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1325                         die_if_checked_out(new_branch_info->path, 1);
1326                 free(head_ref);
1327         }
1328
1329         if (!new_branch_info->commit && opts->new_branch) {
1330                 struct object_id rev;
1331                 int flag;
1332
1333                 if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1334                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1335                         return switch_unborn_to_new_branch(opts);
1336         }
1337         return switch_branches(opts, new_branch_info);
1338 }
1339
1340 int cmd_checkout(int argc, const char **argv, const char *prefix)
1341 {
1342         struct checkout_opts opts;
1343         struct branch_info new_branch_info;
1344         char *conflict_style = NULL;
1345         int dwim_new_local_branch, no_dwim_new_local_branch = 0;
1346         int dwim_remotes_matched = 0;
1347         struct option options[] = {
1348                 OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1349                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1350                            N_("create and checkout a new branch")),
1351                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1352                            N_("create/reset and checkout a branch")),
1353                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1354                 OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1355                 OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1356                         BRANCH_TRACK_EXPLICIT),
1357                 OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1358                 OPT_SET_INT_F('2', "ours", &opts.writeout_stage,
1359                               N_("checkout our version for unmerged files"),
1360                               2, PARSE_OPT_NONEG),
1361                 OPT_SET_INT_F('3', "theirs", &opts.writeout_stage,
1362                               N_("checkout their version for unmerged files"),
1363                               3, PARSE_OPT_NONEG),
1364                 OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)"),
1365                            PARSE_OPT_NOCOMPLETE),
1366                 OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1367                 OPT_BOOL_F(0, "overwrite-ignore", &opts.overwrite_ignore,
1368                            N_("update ignored files (default)"),
1369                            PARSE_OPT_NOCOMPLETE),
1370                 OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1371                            N_("conflict style (merge or diff3)")),
1372                 OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1373                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1374                          N_("do not limit pathspecs to sparse entries only")),
1375                 OPT_BOOL(0, "no-guess", &no_dwim_new_local_branch,
1376                          N_("do not second guess 'git checkout <no-such-branch>'")),
1377                 OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1378                          N_("do not check if another worktree is holding the given ref")),
1379                 { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1380                             "checkout", "control recursive updating of submodules",
1381                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1382                 OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1383                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
1384                 OPT_END(),
1385         };
1386
1387         memset(&opts, 0, sizeof(opts));
1388         memset(&new_branch_info, 0, sizeof(new_branch_info));
1389         opts.overwrite_ignore = 1;
1390         opts.prefix = prefix;
1391         opts.show_progress = -1;
1392         opts.overlay_mode = -1;
1393
1394         git_config(git_checkout_config, &opts);
1395
1396         opts.track = BRANCH_TRACK_UNSPECIFIED;
1397
1398         argc = parse_options(argc, argv, prefix, options, checkout_usage,
1399                              PARSE_OPT_KEEP_DASHDASH);
1400
1401         dwim_new_local_branch = !no_dwim_new_local_branch;
1402         if (opts.show_progress < 0) {
1403                 if (opts.quiet)
1404                         opts.show_progress = 0;
1405                 else
1406                         opts.show_progress = isatty(2);
1407         }
1408
1409         if (conflict_style) {
1410                 opts.merge = 1; /* implied */
1411                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1412         }
1413
1414         if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1415                 die(_("-b, -B and --orphan are mutually exclusive"));
1416
1417         if (opts.overlay_mode == 1 && opts.patch_mode)
1418                 die(_("-p and --overlay are mutually exclusive"));
1419
1420         /*
1421          * From here on, new_branch will contain the branch to be checked out,
1422          * and new_branch_force and new_orphan_branch will tell us which one of
1423          * -b/-B/--orphan is being used.
1424          */
1425         if (opts.new_branch_force)
1426                 opts.new_branch = opts.new_branch_force;
1427
1428         if (opts.new_orphan_branch)
1429                 opts.new_branch = opts.new_orphan_branch;
1430
1431         /* --track without -b/-B/--orphan should DWIM */
1432         if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1433                 const char *argv0 = argv[0];
1434                 if (!argc || !strcmp(argv0, "--"))
1435                         die(_("--track needs a branch name"));
1436                 skip_prefix(argv0, "refs/", &argv0);
1437                 skip_prefix(argv0, "remotes/", &argv0);
1438                 argv0 = strchr(argv0, '/');
1439                 if (!argv0 || !argv0[1])
1440                         die(_("missing branch name; try -b"));
1441                 opts.new_branch = argv0 + 1;
1442         }
1443
1444         /*
1445          * Extract branch name from command line arguments, so
1446          * all that is left is pathspecs.
1447          *
1448          * Handle
1449          *
1450          *  1) git checkout <tree> -- [<paths>]
1451          *  2) git checkout -- [<paths>]
1452          *  3) git checkout <something> [<paths>]
1453          *
1454          * including "last branch" syntax and DWIM-ery for names of
1455          * remote branches, erroring out for invalid or ambiguous cases.
1456          */
1457         if (argc) {
1458                 struct object_id rev;
1459                 int dwim_ok =
1460                         !opts.patch_mode &&
1461                         dwim_new_local_branch &&
1462                         opts.track == BRANCH_TRACK_UNSPECIFIED &&
1463                         !opts.new_branch;
1464                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1465                                              &new_branch_info, &opts, &rev,
1466                                              &dwim_remotes_matched);
1467                 argv += n;
1468                 argc -= n;
1469         }
1470
1471         if (argc) {
1472                 parse_pathspec(&opts.pathspec, 0,
1473                                opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1474                                prefix, argv);
1475
1476                 if (!opts.pathspec.nr)
1477                         die(_("invalid path specification"));
1478
1479                 /*
1480                  * Try to give more helpful suggestion.
1481                  * new_branch && argc > 1 will be caught later.
1482                  */
1483                 if (opts.new_branch && argc == 1)
1484                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1485                                 argv[0], opts.new_branch);
1486
1487                 if (opts.force_detach)
1488                         die(_("git checkout: --detach does not take a path argument '%s'"),
1489                             argv[0]);
1490
1491                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1492                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1493                               "checking out of the index."));
1494         }
1495
1496         if (opts.new_branch) {
1497                 struct strbuf buf = STRBUF_INIT;
1498
1499                 if (opts.new_branch_force)
1500                         opts.branch_exists = validate_branchname(opts.new_branch, &buf);
1501                 else
1502                         opts.branch_exists =
1503                                 validate_new_branchname(opts.new_branch, &buf, 0);
1504                 strbuf_release(&buf);
1505         }
1506
1507         UNLEAK(opts);
1508         if (opts.patch_mode || opts.pathspec.nr) {
1509                 int ret = checkout_paths(&opts, new_branch_info.name);
1510                 if (ret && dwim_remotes_matched > 1 &&
1511                     advice_checkout_ambiguous_remote_branch_name)
1512                         advise(_("'%s' matched more than one remote tracking branch.\n"
1513                                  "We found %d remotes with a reference that matched. So we fell back\n"
1514                                  "on trying to resolve the argument as a path, but failed there too!\n"
1515                                  "\n"
1516                                  "If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
1517                                  "you can do so by fully qualifying the name with the --track option:\n"
1518                                  "\n"
1519                                  "    git checkout --track origin/<name>\n"
1520                                  "\n"
1521                                  "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
1522                                  "one remote, e.g. the 'origin' remote, consider setting\n"
1523                                  "checkout.defaultRemote=origin in your config."),
1524                                argv[0],
1525                                dwim_remotes_matched);
1526                 return ret;
1527         } else {
1528                 return checkout_branch(&opts, &new_branch_info);
1529         }
1530 }