builtin / checkout.con commit Merge branch 'master' of git://github.com/git-l10n/git-po (1f5a6ca)
   1#include "builtin.h"
   2#include "config.h"
   3#include "checkout.h"
   4#include "lockfile.h"
   5#include "parse-options.h"
   6#include "refs.h"
   7#include "object-store.h"
   8#include "commit.h"
   9#include "tree.h"
  10#include "tree-walk.h"
  11#include "cache-tree.h"
  12#include "unpack-trees.h"
  13#include "dir.h"
  14#include "run-command.h"
  15#include "merge-recursive.h"
  16#include "branch.h"
  17#include "diff.h"
  18#include "revision.h"
  19#include "remote.h"
  20#include "blob.h"
  21#include "xdiff-interface.h"
  22#include "ll-merge.h"
  23#include "resolve-undo.h"
  24#include "submodule-config.h"
  25#include "submodule.h"
  26#include "advice.h"
  27
  28static int checkout_optimize_new_branch;
  29
  30static const char * const checkout_usage[] = {
  31        N_("git checkout [<options>] <branch>"),
  32        N_("git checkout [<options>] [<branch>] -- <file>..."),
  33        NULL,
  34};
  35
  36struct checkout_opts {
  37        int patch_mode;
  38        int quiet;
  39        int merge;
  40        int force;
  41        int force_detach;
  42        int writeout_stage;
  43        int overwrite_ignore;
  44        int ignore_skipworktree;
  45        int ignore_other_worktrees;
  46        int show_progress;
  47        /*
  48         * If new checkout options are added, skip_merge_working_tree
  49         * should be updated accordingly.
  50         */
  51
  52        const char *new_branch;
  53        const char *new_branch_force;
  54        const char *new_orphan_branch;
  55        int new_branch_log;
  56        enum branch_track track;
  57        struct diff_options diff_options;
  58
  59        int branch_exists;
  60        const char *prefix;
  61        struct pathspec pathspec;
  62        struct tree *source_tree;
  63};
  64
  65static int post_checkout_hook(struct commit *old_commit, struct commit *new_commit,
  66                              int changed)
  67{
  68        return run_hook_le(NULL, "post-checkout",
  69                           oid_to_hex(old_commit ? &old_commit->object.oid : &null_oid),
  70                           oid_to_hex(new_commit ? &new_commit->object.oid : &null_oid),
  71                           changed ? "1" : "0", NULL);
  72        /* "new_commit" can be NULL when checking out from the index before
  73           a commit exists. */
  74
  75}
  76
  77static int update_some(const struct object_id *oid, struct strbuf *base,
  78                const char *pathname, unsigned mode, int stage, void *context)
  79{
  80        int len;
  81        struct cache_entry *ce;
  82        int pos;
  83
  84        if (S_ISDIR(mode))
  85                return READ_TREE_RECURSIVE;
  86
  87        len = base->len + strlen(pathname);
  88        ce = make_empty_cache_entry(&the_index, len);
  89        oidcpy(&ce->oid, oid);
  90        memcpy(ce->name, base->buf, base->len);
  91        memcpy(ce->name + base->len, pathname, len - base->len);
  92        ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  93        ce->ce_namelen = len;
  94        ce->ce_mode = create_ce_mode(mode);
  95
  96        /*
  97         * If the entry is the same as the current index, we can leave the old
  98         * entry in place. Whether it is UPTODATE or not, checkout_entry will
  99         * do the right thing.
 100         */
 101        pos = cache_name_pos(ce->name, ce->ce_namelen);
 102        if (pos >= 0) {
 103                struct cache_entry *old = active_cache[pos];
 104                if (ce->ce_mode == old->ce_mode &&
 105                    oideq(&ce->oid, &old->oid)) {
 106                        old->ce_flags |= CE_UPDATE;
 107                        discard_cache_entry(ce);
 108                        return 0;
 109                }
 110        }
 111
 112        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 113        return 0;
 114}
 115
 116static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 117{
 118        read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 119
 120        /* update the index with the given tree's info
 121         * for all args, expanding wildcards, and exit
 122         * with any non-zero return code.
 123         */
 124        return 0;
 125}
 126
 127static int skip_same_name(const struct cache_entry *ce, int pos)
 128{
 129        while (++pos < active_nr &&
 130               !strcmp(active_cache[pos]->name, ce->name))
 131                ; /* skip */
 132        return pos;
 133}
 134
 135static int check_stage(int stage, const struct cache_entry *ce, int pos)
 136{
 137        while (pos < active_nr &&
 138               !strcmp(active_cache[pos]->name, ce->name)) {
 139                if (ce_stage(active_cache[pos]) == stage)
 140                        return 0;
 141                pos++;
 142        }
 143        if (stage == 2)
 144                return error(_("path '%s' does not have our version"), ce->name);
 145        else
 146                return error(_("path '%s' does not have their version"), ce->name);
 147}
 148
 149static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 150{
 151        unsigned seen = 0;
 152        const char *name = ce->name;
 153
 154        while (pos < active_nr) {
 155                ce = active_cache[pos];
 156                if (strcmp(name, ce->name))
 157                        break;
 158                seen |= (1 << ce_stage(ce));
 159                pos++;
 160        }
 161        if ((stages & seen) != stages)
 162                return error(_("path '%s' does not have all necessary versions"),
 163                             name);
 164        return 0;
 165}
 166
 167static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 168                          const struct checkout *state)
 169{
 170        while (pos < active_nr &&
 171               !strcmp(active_cache[pos]->name, ce->name)) {
 172                if (ce_stage(active_cache[pos]) == stage)
 173                        return checkout_entry(active_cache[pos], state, NULL);
 174                pos++;
 175        }
 176        if (stage == 2)
 177                return error(_("path '%s' does not have our version"), ce->name);
 178        else
 179                return error(_("path '%s' does not have their version"), ce->name);
 180}
 181
 182static int checkout_merged(int pos, const struct checkout *state)
 183{
 184        struct cache_entry *ce = active_cache[pos];
 185        const char *path = ce->name;
 186        mmfile_t ancestor, ours, theirs;
 187        int status;
 188        struct object_id oid;
 189        mmbuffer_t result_buf;
 190        struct object_id threeway[3];
 191        unsigned mode = 0;
 192
 193        memset(threeway, 0, sizeof(threeway));
 194        while (pos < active_nr) {
 195                int stage;
 196                stage = ce_stage(ce);
 197                if (!stage || strcmp(path, ce->name))
 198                        break;
 199                oidcpy(&threeway[stage - 1], &ce->oid);
 200                if (stage == 2)
 201                        mode = create_ce_mode(ce->ce_mode);
 202                pos++;
 203                ce = active_cache[pos];
 204        }
 205        if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 206                return error(_("path '%s' does not have necessary versions"), path);
 207
 208        read_mmblob(&ancestor, &threeway[0]);
 209        read_mmblob(&ours, &threeway[1]);
 210        read_mmblob(&theirs, &threeway[2]);
 211
 212        /*
 213         * NEEDSWORK: re-create conflicts from merges with
 214         * merge.renormalize set, too
 215         */
 216        status = ll_merge(&result_buf, path, &ancestor, "base",
 217                          &ours, "ours", &theirs, "theirs",
 218                          state->istate, NULL);
 219        free(ancestor.ptr);
 220        free(ours.ptr);
 221        free(theirs.ptr);
 222        if (status < 0 || !result_buf.ptr) {
 223                free(result_buf.ptr);
 224                return error(_("path '%s': cannot merge"), path);
 225        }
 226
 227        /*
 228         * NEEDSWORK:
 229         * There is absolutely no reason to write this as a blob object
 230         * and create a phony cache entry.  This hack is primarily to get
 231         * to the write_entry() machinery that massages the contents to
 232         * work-tree format and writes out which only allows it for a
 233         * cache entry.  The code in write_entry() needs to be refactored
 234         * to allow us to feed a <buffer, size, mode> instead of a cache
 235         * entry.  Such a refactoring would help merge_recursive as well
 236         * (it also writes the merge result to the object database even
 237         * when it may contain conflicts).
 238         */
 239        if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
 240                die(_("Unable to add merge result for '%s'"), path);
 241        free(result_buf.ptr);
 242        ce = make_transient_cache_entry(mode, &oid, path, 2);
 243        if (!ce)
 244                die(_("make_cache_entry failed for path '%s'"), path);
 245        status = checkout_entry(ce, state, NULL);
 246        discard_cache_entry(ce);
 247        return status;
 248}
 249
 250static int checkout_paths(const struct checkout_opts *opts,
 251                          const char *revision)
 252{
 253        int pos;
 254        struct checkout state = CHECKOUT_INIT;
 255        static char *ps_matched;
 256        struct object_id rev;
 257        struct commit *head;
 258        int errs = 0;
 259        struct lock_file lock_file = LOCK_INIT;
 260
 261        if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 262                die(_("'%s' cannot be used with updating paths"), "--track");
 263
 264        if (opts->new_branch_log)
 265                die(_("'%s' cannot be used with updating paths"), "-l");
 266
 267        if (opts->force && opts->patch_mode)
 268                die(_("'%s' cannot be used with updating paths"), "-f");
 269
 270        if (opts->force_detach)
 271                die(_("'%s' cannot be used with updating paths"), "--detach");
 272
 273        if (opts->merge && opts->patch_mode)
 274                die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 275
 276        if (opts->force && opts->merge)
 277                die(_("'%s' cannot be used with %s"), "-f", "-m");
 278
 279        if (opts->new_branch)
 280                die(_("Cannot update paths and switch to branch '%s' at the same time."),
 281                    opts->new_branch);
 282
 283        if (opts->patch_mode)
 284                return run_add_interactive(revision, "--patch=checkout",
 285                                           &opts->pathspec);
 286
 287        hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 288        if (read_cache_preload(&opts->pathspec) < 0)
 289                return error(_("index file corrupt"));
 290
 291        if (opts->source_tree)
 292                read_tree_some(opts->source_tree, &opts->pathspec);
 293
 294        ps_matched = xcalloc(opts->pathspec.nr, 1);
 295
 296        /*
 297         * Make sure all pathspecs participated in locating the paths
 298         * to be checked out.
 299         */
 300        for (pos = 0; pos < active_nr; pos++) {
 301                struct cache_entry *ce = active_cache[pos];
 302                ce->ce_flags &= ~CE_MATCHED;
 303                if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 304                        continue;
 305                if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 306                        /*
 307                         * "git checkout tree-ish -- path", but this entry
 308                         * is in the original index; it will not be checked
 309                         * out to the working tree and it does not matter
 310                         * if pathspec matched this entry.  We will not do
 311                         * anything to this entry at all.
 312                         */
 313                        continue;
 314                /*
 315                 * Either this entry came from the tree-ish we are
 316                 * checking the paths out of, or we are checking out
 317                 * of the index.
 318                 *
 319                 * If it comes from the tree-ish, we already know it
 320                 * matches the pathspec and could just stamp
 321                 * CE_MATCHED to it from update_some(). But we still
 322                 * need ps_matched and read_tree_recursive (and
 323                 * eventually tree_entry_interesting) cannot fill
 324                 * ps_matched yet. Once it can, we can avoid calling
 325                 * match_pathspec() for _all_ entries when
 326                 * opts->source_tree != NULL.
 327                 */
 328                if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched))
 329                        ce->ce_flags |= CE_MATCHED;
 330        }
 331
 332        if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 333                free(ps_matched);
 334                return 1;
 335        }
 336        free(ps_matched);
 337
 338        /* "checkout -m path" to recreate conflicted state */
 339        if (opts->merge)
 340                unmerge_marked_index(&the_index);
 341
 342        /* Any unmerged paths? */
 343        for (pos = 0; pos < active_nr; pos++) {
 344                const struct cache_entry *ce = active_cache[pos];
 345                if (ce->ce_flags & CE_MATCHED) {
 346                        if (!ce_stage(ce))
 347                                continue;
 348                        if (opts->force) {
 349                                warning(_("path '%s' is unmerged"), ce->name);
 350                        } else if (opts->writeout_stage) {
 351                                errs |= check_stage(opts->writeout_stage, ce, pos);
 352                        } else if (opts->merge) {
 353                                errs |= check_stages((1<<2) | (1<<3), ce, pos);
 354                        } else {
 355                                errs = 1;
 356                                error(_("path '%s' is unmerged"), ce->name);
 357                        }
 358                        pos = skip_same_name(ce, pos) - 1;
 359                }
 360        }
 361        if (errs)
 362                return 1;
 363
 364        /* Now we are committed to check them out */
 365        state.force = 1;
 366        state.refresh_cache = 1;
 367        state.istate = &the_index;
 368
 369        enable_delayed_checkout(&state);
 370        for (pos = 0; pos < active_nr; pos++) {
 371                struct cache_entry *ce = active_cache[pos];
 372                if (ce->ce_flags & CE_MATCHED) {
 373                        if (!ce_stage(ce)) {
 374                                errs |= checkout_entry(ce, &state, NULL);
 375                                continue;
 376                        }
 377                        if (opts->writeout_stage)
 378                                errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 379                        else if (opts->merge)
 380                                errs |= checkout_merged(pos, &state);
 381                        pos = skip_same_name(ce, pos) - 1;
 382                }
 383        }
 384        errs |= finish_delayed_checkout(&state);
 385
 386        if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 387                die(_("unable to write new index file"));
 388
 389        read_ref_full("HEAD", 0, &rev, NULL);
 390        head = lookup_commit_reference_gently(the_repository, &rev, 1);
 391
 392        errs |= post_checkout_hook(head, head, 0);
 393        return errs;
 394}
 395
 396static void show_local_changes(struct object *head,
 397                               const struct diff_options *opts)
 398{
 399        struct rev_info rev;
 400        /* I think we want full paths, even if we're in a subdirectory. */
 401        repo_init_revisions(the_repository, &rev, NULL);
 402        rev.diffopt.flags = opts->flags;
 403        rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 404        diff_setup_done(&rev.diffopt);
 405        add_pending_object(&rev, head, NULL);
 406        run_diff_index(&rev, 0);
 407}
 408
 409static void describe_detached_head(const char *msg, struct commit *commit)
 410{
 411        struct strbuf sb = STRBUF_INIT;
 412
 413        if (!parse_commit(commit))
 414                pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 415        if (print_sha1_ellipsis()) {
 416                fprintf(stderr, "%s %s... %s\n", msg,
 417                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 418        } else {
 419                fprintf(stderr, "%s %s %s\n", msg,
 420                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 421        }
 422        strbuf_release(&sb);
 423}
 424
 425static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 426                      int worktree, int *writeout_error)
 427{
 428        struct unpack_trees_options opts;
 429        struct tree_desc tree_desc;
 430
 431        memset(&opts, 0, sizeof(opts));
 432        opts.head_idx = -1;
 433        opts.update = worktree;
 434        opts.skip_unmerged = !worktree;
 435        opts.reset = 1;
 436        opts.merge = 1;
 437        opts.fn = oneway_merge;
 438        opts.verbose_update = o->show_progress;
 439        opts.src_index = &the_index;
 440        opts.dst_index = &the_index;
 441        parse_tree(tree);
 442        init_tree_desc(&tree_desc, tree->buffer, tree->size);
 443        switch (unpack_trees(1, &tree_desc, &opts)) {
 444        case -2:
 445                *writeout_error = 1;
 446                /*
 447                 * We return 0 nevertheless, as the index is all right
 448                 * and more importantly we have made best efforts to
 449                 * update paths in the work tree, and we cannot revert
 450                 * them.
 451                 */
 452                /* fallthrough */
 453        case 0:
 454                return 0;
 455        default:
 456                return 128;
 457        }
 458}
 459
 460struct branch_info {
 461        const char *name; /* The short name used */
 462        const char *path; /* The full name of a real branch */
 463        struct commit *commit; /* The named commit */
 464        /*
 465         * if not null the branch is detached because it's already
 466         * checked out in this checkout
 467         */
 468        char *checkout;
 469};
 470
 471static void setup_branch_path(struct branch_info *branch)
 472{
 473        struct strbuf buf = STRBUF_INIT;
 474
 475        strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 476        if (strcmp(buf.buf, branch->name))
 477                branch->name = xstrdup(buf.buf);
 478        strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 479        branch->path = strbuf_detach(&buf, NULL);
 480}
 481
 482/*
 483 * Skip merging the trees, updating the index and working directory if and
 484 * only if we are creating a new branch via "git checkout -b <new_branch>."
 485 */
 486static int skip_merge_working_tree(const struct checkout_opts *opts,
 487        const struct branch_info *old_branch_info,
 488        const struct branch_info *new_branch_info)
 489{
 490        /*
 491         * Do the merge if sparse checkout is on and the user has not opted in
 492         * to the optimized behavior
 493         */
 494        if (core_apply_sparse_checkout && !checkout_optimize_new_branch)
 495                return 0;
 496
 497        /*
 498         * We must do the merge if we are actually moving to a new commit.
 499         */
 500        if (!old_branch_info->commit || !new_branch_info->commit ||
 501                !oideq(&old_branch_info->commit->object.oid,
 502                       &new_branch_info->commit->object.oid))
 503                return 0;
 504
 505        /*
 506         * opts->patch_mode cannot be used with switching branches so is
 507         * not tested here
 508         */
 509
 510        /*
 511         * opts->quiet only impacts output so doesn't require a merge
 512         */
 513
 514        /*
 515         * Honor the explicit request for a three-way merge or to throw away
 516         * local changes
 517         */
 518        if (opts->merge || opts->force)
 519                return 0;
 520
 521        /*
 522         * --detach is documented as "updating the index and the files in the
 523         * working tree" but this optimization skips those steps so fall through
 524         * to the regular code path.
 525         */
 526        if (opts->force_detach)
 527                return 0;
 528
 529        /*
 530         * opts->writeout_stage cannot be used with switching branches so is
 531         * not tested here
 532         */
 533
 534        /*
 535         * Honor the explicit ignore requests
 536         */
 537        if (!opts->overwrite_ignore || opts->ignore_skipworktree ||
 538                opts->ignore_other_worktrees)
 539                return 0;
 540
 541        /*
 542         * opts->show_progress only impacts output so doesn't require a merge
 543         */
 544
 545        /*
 546         * If we aren't creating a new branch any changes or updates will
 547         * happen in the existing branch.  Since that could only be updating
 548         * the index and working directory, we don't want to skip those steps
 549         * or we've defeated any purpose in running the command.
 550         */
 551        if (!opts->new_branch)
 552                return 0;
 553
 554        /*
 555         * new_branch_force is defined to "create/reset and checkout a branch"
 556         * so needs to go through the merge to do the reset
 557         */
 558        if (opts->new_branch_force)
 559                return 0;
 560
 561        /*
 562         * A new orphaned branch requrires the index and the working tree to be
 563         * adjusted to <start_point>
 564         */
 565        if (opts->new_orphan_branch)
 566                return 0;
 567
 568        /*
 569         * Remaining variables are not checkout options but used to track state
 570         */
 571
 572        return 1;
 573}
 574
 575static int merge_working_tree(const struct checkout_opts *opts,
 576                              struct branch_info *old_branch_info,
 577                              struct branch_info *new_branch_info,
 578                              int *writeout_error)
 579{
 580        int ret;
 581        struct lock_file lock_file = LOCK_INIT;
 582
 583        hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 584        if (read_cache_preload(NULL) < 0)
 585                return error(_("index file corrupt"));
 586
 587        resolve_undo_clear();
 588        if (opts->force) {
 589                ret = reset_tree(get_commit_tree(new_branch_info->commit),
 590                                 opts, 1, writeout_error);
 591                if (ret)
 592                        return ret;
 593        } else {
 594                struct tree_desc trees[2];
 595                struct tree *tree;
 596                struct unpack_trees_options topts;
 597
 598                memset(&topts, 0, sizeof(topts));
 599                topts.head_idx = -1;
 600                topts.src_index = &the_index;
 601                topts.dst_index = &the_index;
 602
 603                setup_unpack_trees_porcelain(&topts, "checkout");
 604
 605                refresh_cache(REFRESH_QUIET);
 606
 607                if (unmerged_cache()) {
 608                        error(_("you need to resolve your current index first"));
 609                        return 1;
 610                }
 611
 612                /* 2-way merge to the new branch */
 613                topts.initial_checkout = is_cache_unborn();
 614                topts.update = 1;
 615                topts.merge = 1;
 616                topts.gently = opts->merge && old_branch_info->commit;
 617                topts.verbose_update = opts->show_progress;
 618                topts.fn = twoway_merge;
 619                if (opts->overwrite_ignore) {
 620                        topts.dir = xcalloc(1, sizeof(*topts.dir));
 621                        topts.dir->flags |= DIR_SHOW_IGNORED;
 622                        setup_standard_excludes(topts.dir);
 623                }
 624                tree = parse_tree_indirect(old_branch_info->commit ?
 625                                           &old_branch_info->commit->object.oid :
 626                                           the_hash_algo->empty_tree);
 627                init_tree_desc(&trees[0], tree->buffer, tree->size);
 628                tree = parse_tree_indirect(&new_branch_info->commit->object.oid);
 629                init_tree_desc(&trees[1], tree->buffer, tree->size);
 630
 631                ret = unpack_trees(2, trees, &topts);
 632                clear_unpack_trees_porcelain(&topts);
 633                if (ret == -1) {
 634                        /*
 635                         * Unpack couldn't do a trivial merge; either
 636                         * give up or do a real merge, depending on
 637                         * whether the merge flag was used.
 638                         */
 639                        struct tree *result;
 640                        struct tree *work;
 641                        struct merge_options o;
 642                        if (!opts->merge)
 643                                return 1;
 644
 645                        /*
 646                         * Without old_branch_info->commit, the below is the same as
 647                         * the two-tree unpack we already tried and failed.
 648                         */
 649                        if (!old_branch_info->commit)
 650                                return 1;
 651
 652                        /* Do more real merge */
 653
 654                        /*
 655                         * We update the index fully, then write the
 656                         * tree from the index, then merge the new
 657                         * branch with the current tree, with the old
 658                         * branch as the base. Then we reset the index
 659                         * (but not the working tree) to the new
 660                         * branch, leaving the working tree as the
 661                         * merged version, but skipping unmerged
 662                         * entries in the index.
 663                         */
 664
 665                        add_files_to_cache(NULL, NULL, 0);
 666                        /*
 667                         * NEEDSWORK: carrying over local changes
 668                         * when branches have different end-of-line
 669                         * normalization (or clean+smudge rules) is
 670                         * a pain; plumb in an option to set
 671                         * o.renormalize?
 672                         */
 673                        init_merge_options(&o);
 674                        o.verbosity = 0;
 675                        work = write_tree_from_memory(&o);
 676
 677                        ret = reset_tree(get_commit_tree(new_branch_info->commit),
 678                                         opts, 1,
 679                                         writeout_error);
 680                        if (ret)
 681                                return ret;
 682                        o.ancestor = old_branch_info->name;
 683                        o.branch1 = new_branch_info->name;
 684                        o.branch2 = "local";
 685                        ret = merge_trees(&o,
 686                                          get_commit_tree(new_branch_info->commit),
 687                                          work,
 688                                          get_commit_tree(old_branch_info->commit),
 689                                          &result);
 690                        if (ret < 0)
 691                                exit(128);
 692                        ret = reset_tree(get_commit_tree(new_branch_info->commit),
 693                                         opts, 0,
 694                                         writeout_error);
 695                        strbuf_release(&o.obuf);
 696                        if (ret)
 697                                return ret;
 698                }
 699        }
 700
 701        if (!active_cache_tree)
 702                active_cache_tree = cache_tree();
 703
 704        if (!cache_tree_fully_valid(active_cache_tree))
 705                cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 706
 707        if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 708                die(_("unable to write new index file"));
 709
 710        if (!opts->force && !opts->quiet)
 711                show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 712
 713        return 0;
 714}
 715
 716static void report_tracking(struct branch_info *new_branch_info)
 717{
 718        struct strbuf sb = STRBUF_INIT;
 719        struct branch *branch = branch_get(new_branch_info->name);
 720
 721        if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 722                return;
 723        fputs(sb.buf, stdout);
 724        strbuf_release(&sb);
 725}
 726
 727static void update_refs_for_switch(const struct checkout_opts *opts,
 728                                   struct branch_info *old_branch_info,
 729                                   struct branch_info *new_branch_info)
 730{
 731        struct strbuf msg = STRBUF_INIT;
 732        const char *old_desc, *reflog_msg;
 733        if (opts->new_branch) {
 734                if (opts->new_orphan_branch) {
 735                        char *refname;
 736
 737                        refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 738                        if (opts->new_branch_log &&
 739                            !should_autocreate_reflog(refname)) {
 740                                int ret;
 741                                struct strbuf err = STRBUF_INIT;
 742
 743                                ret = safe_create_reflog(refname, 1, &err);
 744                                if (ret) {
 745                                        fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 746                                                opts->new_orphan_branch, err.buf);
 747                                        strbuf_release(&err);
 748                                        free(refname);
 749                                        return;
 750                                }
 751                                strbuf_release(&err);
 752                        }
 753                        free(refname);
 754                }
 755                else
 756                        create_branch(opts->new_branch, new_branch_info->name,
 757                                      opts->new_branch_force ? 1 : 0,
 758                                      opts->new_branch_force ? 1 : 0,
 759                                      opts->new_branch_log,
 760                                      opts->quiet,
 761                                      opts->track);
 762                new_branch_info->name = opts->new_branch;
 763                setup_branch_path(new_branch_info);
 764        }
 765
 766        old_desc = old_branch_info->name;
 767        if (!old_desc && old_branch_info->commit)
 768                old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
 769
 770        reflog_msg = getenv("GIT_REFLOG_ACTION");
 771        if (!reflog_msg)
 772                strbuf_addf(&msg, "checkout: moving from %s to %s",
 773                        old_desc ? old_desc : "(invalid)", new_branch_info->name);
 774        else
 775                strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 776
 777        if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
 778                /* Nothing to do. */
 779        } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
 780                update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
 781                           REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 782                if (!opts->quiet) {
 783                        if (old_branch_info->path &&
 784                            advice_detached_head && !opts->force_detach)
 785                                detach_advice(new_branch_info->name);
 786                        describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 787                }
 788        } else if (new_branch_info->path) {     /* Switch branches. */
 789                if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
 790                        die(_("unable to update HEAD"));
 791                if (!opts->quiet) {
 792                        if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
 793                                if (opts->new_branch_force)
 794                                        fprintf(stderr, _("Reset branch '%s'\n"),
 795                                                new_branch_info->name);
 796                                else
 797                                        fprintf(stderr, _("Already on '%s'\n"),
 798                                                new_branch_info->name);
 799                        } else if (opts->new_branch) {
 800                                if (opts->branch_exists)
 801                                        fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
 802                                else
 803                                        fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
 804                        } else {
 805                                fprintf(stderr, _("Switched to branch '%s'\n"),
 806                                        new_branch_info->name);
 807                        }
 808                }
 809                if (old_branch_info->path && old_branch_info->name) {
 810                        if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
 811                                delete_reflog(old_branch_info->path);
 812                }
 813        }
 814        remove_branch_state();
 815        strbuf_release(&msg);
 816        if (!opts->quiet &&
 817            (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
 818                report_tracking(new_branch_info);
 819}
 820
 821static int add_pending_uninteresting_ref(const char *refname,
 822                                         const struct object_id *oid,
 823                                         int flags, void *cb_data)
 824{
 825        add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 826        return 0;
 827}
 828
 829static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 830{
 831        strbuf_addstr(sb, "  ");
 832        strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 833        strbuf_addch(sb, ' ');
 834        if (!parse_commit(commit))
 835                pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 836        strbuf_addch(sb, '\n');
 837}
 838
 839#define ORPHAN_CUTOFF 4
 840static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 841{
 842        struct commit *c, *last = NULL;
 843        struct strbuf sb = STRBUF_INIT;
 844        int lost = 0;
 845        while ((c = get_revision(revs)) != NULL) {
 846                if (lost < ORPHAN_CUTOFF)
 847                        describe_one_orphan(&sb, c);
 848                last = c;
 849                lost++;
 850        }
 851        if (ORPHAN_CUTOFF < lost) {
 852                int more = lost - ORPHAN_CUTOFF;
 853                if (more == 1)
 854                        describe_one_orphan(&sb, last);
 855                else
 856                        strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 857        }
 858
 859        fprintf(stderr,
 860                Q_(
 861                /* The singular version */
 862                "Warning: you are leaving %d commit behind, "
 863                "not connected to\n"
 864                "any of your branches:\n\n"
 865                "%s\n",
 866                /* The plural version */
 867                "Warning: you are leaving %d commits behind, "
 868                "not connected to\n"
 869                "any of your branches:\n\n"
 870                "%s\n",
 871                /* Give ngettext() the count */
 872                lost),
 873                lost,
 874                sb.buf);
 875        strbuf_release(&sb);
 876
 877        if (advice_detached_head)
 878                fprintf(stderr,
 879                        Q_(
 880                        /* The singular version */
 881                        "If you want to keep it by creating a new branch, "
 882                        "this may be a good time\nto do so with:\n\n"
 883                        " git branch <new-branch-name> %s\n\n",
 884                        /* The plural version */
 885                        "If you want to keep them by creating a new branch, "
 886                        "this may be a good time\nto do so with:\n\n"
 887                        " git branch <new-branch-name> %s\n\n",
 888                        /* Give ngettext() the count */
 889                        lost),
 890                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 891}
 892
 893/*
 894 * We are about to leave commit that was at the tip of a detached
 895 * HEAD.  If it is not reachable from any ref, this is the last chance
 896 * for the user to do so without resorting to reflog.
 897 */
 898static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
 899{
 900        struct rev_info revs;
 901        struct object *object = &old_commit->object;
 902
 903        repo_init_revisions(the_repository, &revs, NULL);
 904        setup_revisions(0, NULL, &revs, NULL);
 905
 906        object->flags &= ~UNINTERESTING;
 907        add_pending_object(&revs, object, oid_to_hex(&object->oid));
 908
 909        for_each_ref(add_pending_uninteresting_ref, &revs);
 910        add_pending_oid(&revs, "HEAD", &new_commit->object.oid, UNINTERESTING);
 911
 912        if (prepare_revision_walk(&revs))
 913                die(_("internal error in revision walk"));
 914        if (!(old_commit->object.flags & UNINTERESTING))
 915                suggest_reattach(old_commit, &revs);
 916        else
 917                describe_detached_head(_("Previous HEAD position was"), old_commit);
 918
 919        /* Clean up objects used, as they will be reused. */
 920        clear_commit_marks_all(ALL_REV_FLAGS);
 921}
 922
 923static int switch_branches(const struct checkout_opts *opts,
 924                           struct branch_info *new_branch_info)
 925{
 926        int ret = 0;
 927        struct branch_info old_branch_info;
 928        void *path_to_free;
 929        struct object_id rev;
 930        int flag, writeout_error = 0;
 931        memset(&old_branch_info, 0, sizeof(old_branch_info));
 932        old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
 933        if (old_branch_info.path)
 934                old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
 935        if (!(flag & REF_ISSYMREF))
 936                old_branch_info.path = NULL;
 937
 938        if (old_branch_info.path)
 939                skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
 940
 941        if (!new_branch_info->name) {
 942                new_branch_info->name = "HEAD";
 943                new_branch_info->commit = old_branch_info.commit;
 944                if (!new_branch_info->commit)
 945                        die(_("You are on a branch yet to be born"));
 946                parse_commit_or_die(new_branch_info->commit);
 947        }
 948
 949        /* optimize the "checkout -b <new_branch> path */
 950        if (skip_merge_working_tree(opts, &old_branch_info, new_branch_info)) {
 951                if (!checkout_optimize_new_branch && !opts->quiet) {
 952                        if (read_cache_preload(NULL) < 0)
 953                                return error(_("index file corrupt"));
 954                        show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 955                }
 956        } else {
 957                ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
 958                if (ret) {
 959                        free(path_to_free);
 960                        return ret;
 961                }
 962        }
 963
 964        if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
 965                orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
 966
 967        update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 968
 969        ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 970        free(path_to_free);
 971        return ret || writeout_error;
 972}
 973
 974static int git_checkout_config(const char *var, const char *value, void *cb)
 975{
 976        if (!strcmp(var, "checkout.optimizenewbranch")) {
 977                checkout_optimize_new_branch = git_config_bool(var, value);
 978                return 0;
 979        }
 980
 981        if (!strcmp(var, "diff.ignoresubmodules")) {
 982                struct checkout_opts *opts = cb;
 983                handle_ignore_submodules_arg(&opts->diff_options, value);
 984                return 0;
 985        }
 986
 987        if (starts_with(var, "submodule."))
 988                return git_default_submodule_config(var, value, NULL);
 989
 990        return git_xmerge_config(var, value, NULL);
 991}
 992
 993static int parse_branchname_arg(int argc, const char **argv,
 994                                int dwim_new_local_branch_ok,
 995                                struct branch_info *new_branch_info,
 996                                struct checkout_opts *opts,
 997                                struct object_id *rev,
 998                                int *dwim_remotes_matched)
 999{
1000        struct tree **source_tree = &opts->source_tree;
1001        const char **new_branch = &opts->new_branch;
1002        int argcount = 0;
1003        struct object_id branch_rev;
1004        const char *arg;
1005        int dash_dash_pos;
1006        int has_dash_dash = 0;
1007        int i;
1008
1009        /*
1010         * case 1: git checkout <ref> -- [<paths>]
1011         *
1012         *   <ref> must be a valid tree, everything after the '--' must be
1013         *   a path.
1014         *
1015         * case 2: git checkout -- [<paths>]
1016         *
1017         *   everything after the '--' must be paths.
1018         *
1019         * case 3: git checkout <something> [--]
1020         *
1021         *   (a) If <something> is a commit, that is to
1022         *       switch to the branch or detach HEAD at it.  As a special case,
1023         *       if <something> is A...B (missing A or B means HEAD but you can
1024         *       omit at most one side), and if there is a unique merge base
1025         *       between A and B, A...B names that merge base.
1026         *
1027         *   (b) If <something> is _not_ a commit, either "--" is present
1028         *       or <something> is not a path, no -t or -b was given, and
1029         *       and there is a tracking branch whose name is <something>
1030         *       in one and only one remote (or if the branch exists on the
1031         *       remote named in checkout.defaultRemote), then this is a
1032         *       short-hand to fork local <something> from that
1033         *       remote-tracking branch.
1034         *
1035         *   (c) Otherwise, if "--" is present, treat it like case (1).
1036         *
1037         *   (d) Otherwise :
1038         *       - if it's a reference, treat it like case (1)
1039         *       - else if it's a path, treat it like case (2)
1040         *       - else: fail.
1041         *
1042         * case 4: git checkout <something> <paths>
1043         *
1044         *   The first argument must not be ambiguous.
1045         *   - If it's *only* a reference, treat it like case (1).
1046         *   - If it's only a path, treat it like case (2).
1047         *   - else: fail.
1048         *
1049         */
1050        if (!argc)
1051                return 0;
1052
1053        arg = argv[0];
1054        dash_dash_pos = -1;
1055        for (i = 0; i < argc; i++) {
1056                if (!strcmp(argv[i], "--")) {
1057                        dash_dash_pos = i;
1058                        break;
1059                }
1060        }
1061        if (dash_dash_pos == 0)
1062                return 1; /* case (2) */
1063        else if (dash_dash_pos == 1)
1064                has_dash_dash = 1; /* case (3) or (1) */
1065        else if (dash_dash_pos >= 2)
1066                die(_("only one reference expected, %d given."), dash_dash_pos);
1067
1068        if (!strcmp(arg, "-"))
1069                arg = "@{-1}";
1070
1071        if (get_oid_mb(arg, rev)) {
1072                /*
1073                 * Either case (3) or (4), with <something> not being
1074                 * a commit, or an attempt to use case (1) with an
1075                 * invalid ref.
1076                 *
1077                 * It's likely an error, but we need to find out if
1078                 * we should auto-create the branch, case (3).(b).
1079                 */
1080                int recover_with_dwim = dwim_new_local_branch_ok;
1081
1082                if (!has_dash_dash &&
1083                    (check_filename(opts->prefix, arg) || !no_wildcard(arg)))
1084                        recover_with_dwim = 0;
1085                /*
1086                 * Accept "git checkout foo" and "git checkout foo --"
1087                 * as candidates for dwim.
1088                 */
1089                if (!(argc == 1 && !has_dash_dash) &&
1090                    !(argc == 2 && has_dash_dash))
1091                        recover_with_dwim = 0;
1092
1093                if (recover_with_dwim) {
1094                        const char *remote = unique_tracking_name(arg, rev,
1095                                                                  dwim_remotes_matched);
1096                        if (remote) {
1097                                *new_branch = arg;
1098                                arg = remote;
1099                                /* DWIMmed to create local branch, case (3).(b) */
1100                        } else {
1101                                recover_with_dwim = 0;
1102                        }
1103                }
1104
1105                if (!recover_with_dwim) {
1106                        if (has_dash_dash)
1107                                die(_("invalid reference: %s"), arg);
1108                        return argcount;
1109                }
1110        }
1111
1112        /* we can't end up being in (2) anymore, eat the argument */
1113        argcount++;
1114        argv++;
1115        argc--;
1116
1117        new_branch_info->name = arg;
1118        setup_branch_path(new_branch_info);
1119
1120        if (!check_refname_format(new_branch_info->path, 0) &&
1121            !read_ref(new_branch_info->path, &branch_rev))
1122                oidcpy(rev, &branch_rev);
1123        else
1124                new_branch_info->path = NULL; /* not an existing branch */
1125
1126        new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
1127        if (!new_branch_info->commit) {
1128                /* not a commit */
1129                *source_tree = parse_tree_indirect(rev);
1130        } else {
1131                parse_commit_or_die(new_branch_info->commit);
1132                *source_tree = get_commit_tree(new_branch_info->commit);
1133        }
1134
1135        if (!*source_tree)                   /* case (1): want a tree */
1136                die(_("reference is not a tree: %s"), arg);
1137        if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1138                /*
1139                 * Do not complain the most common case
1140                 *      git checkout branch
1141                 * even if there happen to be a file called 'branch';
1142                 * it would be extremely annoying.
1143                 */
1144                if (argc)
1145                        verify_non_filename(opts->prefix, arg);
1146        } else {
1147                argcount++;
1148                argv++;
1149                argc--;
1150        }
1151
1152        return argcount;
1153}
1154
1155static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1156{
1157        int status;
1158        struct strbuf branch_ref = STRBUF_INIT;
1159
1160        if (!opts->new_branch)
1161                die(_("You are on a branch yet to be born"));
1162        strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1163        status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1164        strbuf_release(&branch_ref);
1165        if (!opts->quiet)
1166                fprintf(stderr, _("Switched to a new branch '%s'\n"),
1167                        opts->new_branch);
1168        return status;
1169}
1170
1171static int checkout_branch(struct checkout_opts *opts,
1172                           struct branch_info *new_branch_info)
1173{
1174        if (opts->pathspec.nr)
1175                die(_("paths cannot be used with switching branches"));
1176
1177        if (opts->patch_mode)
1178                die(_("'%s' cannot be used with switching branches"),
1179                    "--patch");
1180
1181        if (opts->writeout_stage)
1182                die(_("'%s' cannot be used with switching branches"),
1183                    "--ours/--theirs");
1184
1185        if (opts->force && opts->merge)
1186                die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1187
1188        if (opts->force_detach && opts->new_branch)
1189                die(_("'%s' cannot be used with '%s'"),
1190                    "--detach", "-b/-B/--orphan");
1191
1192        if (opts->new_orphan_branch) {
1193                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1194                        die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1195        } else if (opts->force_detach) {
1196                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1197                        die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1198        } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1199                opts->track = git_branch_track;
1200
1201        if (new_branch_info->name && !new_branch_info->commit)
1202                die(_("Cannot switch branch to a non-commit '%s'"),
1203                    new_branch_info->name);
1204
1205        if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1206            !opts->ignore_other_worktrees) {
1207                int flag;
1208                char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1209                if (head_ref &&
1210                    (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1211                        die_if_checked_out(new_branch_info->path, 1);
1212                free(head_ref);
1213        }
1214
1215        if (!new_branch_info->commit && opts->new_branch) {
1216                struct object_id rev;
1217                int flag;
1218
1219                if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1220                    (flag & REF_ISSYMREF) && is_null_oid(&rev))
1221                        return switch_unborn_to_new_branch(opts);
1222        }
1223        return switch_branches(opts, new_branch_info);
1224}
1225
1226int cmd_checkout(int argc, const char **argv, const char *prefix)
1227{
1228        struct checkout_opts opts;
1229        struct branch_info new_branch_info;
1230        char *conflict_style = NULL;
1231        int dwim_new_local_branch = 1;
1232        int dwim_remotes_matched = 0;
1233        struct option options[] = {
1234                OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1235                OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1236                           N_("create and checkout a new branch")),
1237                OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1238                           N_("create/reset and checkout a branch")),
1239                OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1240                OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1241                OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1242                        BRANCH_TRACK_EXPLICIT),
1243                OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1244                OPT_SET_INT_F('2', "ours", &opts.writeout_stage,
1245                              N_("checkout our version for unmerged files"),
1246                              2, PARSE_OPT_NONEG),
1247                OPT_SET_INT_F('3', "theirs", &opts.writeout_stage,
1248                              N_("checkout their version for unmerged files"),
1249                              3, PARSE_OPT_NONEG),
1250                OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)"),
1251                           PARSE_OPT_NOCOMPLETE),
1252                OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1253                OPT_BOOL_F(0, "overwrite-ignore", &opts.overwrite_ignore,
1254                           N_("update ignored files (default)"),
1255                           PARSE_OPT_NOCOMPLETE),
1256                OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1257                           N_("conflict style (merge or diff3)")),
1258                OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1259                OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1260                         N_("do not limit pathspecs to sparse entries only")),
1261                OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1262                                N_("second guess 'git checkout <no-such-branch>'")),
1263                OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1264                         N_("do not check if another worktree is holding the given ref")),
1265                { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1266                            "checkout", "control recursive updating of submodules",
1267                            PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1268                OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1269                OPT_END(),
1270        };
1271
1272        memset(&opts, 0, sizeof(opts));
1273        memset(&new_branch_info, 0, sizeof(new_branch_info));
1274        opts.overwrite_ignore = 1;
1275        opts.prefix = prefix;
1276        opts.show_progress = -1;
1277
1278        git_config(git_checkout_config, &opts);
1279
1280        opts.track = BRANCH_TRACK_UNSPECIFIED;
1281
1282        argc = parse_options(argc, argv, prefix, options, checkout_usage,
1283                             PARSE_OPT_KEEP_DASHDASH);
1284
1285        if (opts.show_progress < 0) {
1286                if (opts.quiet)
1287                        opts.show_progress = 0;
1288                else
1289                        opts.show_progress = isatty(2);
1290        }
1291
1292        if (conflict_style) {
1293                opts.merge = 1; /* implied */
1294                git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1295        }
1296
1297        if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1298                die(_("-b, -B and --orphan are mutually exclusive"));
1299
1300        /*
1301         * From here on, new_branch will contain the branch to be checked out,
1302         * and new_branch_force and new_orphan_branch will tell us which one of
1303         * -b/-B/--orphan is being used.
1304         */
1305        if (opts.new_branch_force)
1306                opts.new_branch = opts.new_branch_force;
1307
1308        if (opts.new_orphan_branch)
1309                opts.new_branch = opts.new_orphan_branch;
1310
1311        /* --track without -b/-B/--orphan should DWIM */
1312        if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1313                const char *argv0 = argv[0];
1314                if (!argc || !strcmp(argv0, "--"))
1315                        die(_("--track needs a branch name"));
1316                skip_prefix(argv0, "refs/", &argv0);
1317                skip_prefix(argv0, "remotes/", &argv0);
1318                argv0 = strchr(argv0, '/');
1319                if (!argv0 || !argv0[1])
1320                        die(_("missing branch name; try -b"));
1321                opts.new_branch = argv0 + 1;
1322        }
1323
1324        /*
1325         * Extract branch name from command line arguments, so
1326         * all that is left is pathspecs.
1327         *
1328         * Handle
1329         *
1330         *  1) git checkout <tree> -- [<paths>]
1331         *  2) git checkout -- [<paths>]
1332         *  3) git checkout <something> [<paths>]
1333         *
1334         * including "last branch" syntax and DWIM-ery for names of
1335         * remote branches, erroring out for invalid or ambiguous cases.
1336         */
1337        if (argc) {
1338                struct object_id rev;
1339                int dwim_ok =
1340                        !opts.patch_mode &&
1341                        dwim_new_local_branch &&
1342                        opts.track == BRANCH_TRACK_UNSPECIFIED &&
1343                        !opts.new_branch;
1344                int n = parse_branchname_arg(argc, argv, dwim_ok,
1345                                             &new_branch_info, &opts, &rev,
1346                                             &dwim_remotes_matched);
1347                argv += n;
1348                argc -= n;
1349        }
1350
1351        if (argc) {
1352                parse_pathspec(&opts.pathspec, 0,
1353                               opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1354                               prefix, argv);
1355
1356                if (!opts.pathspec.nr)
1357                        die(_("invalid path specification"));
1358
1359                /*
1360                 * Try to give more helpful suggestion.
1361                 * new_branch && argc > 1 will be caught later.
1362                 */
1363                if (opts.new_branch && argc == 1)
1364                        die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1365                                argv[0], opts.new_branch);
1366
1367                if (opts.force_detach)
1368                        die(_("git checkout: --detach does not take a path argument '%s'"),
1369                            argv[0]);
1370
1371                if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1372                        die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1373                              "checking out of the index."));
1374        }
1375
1376        if (opts.new_branch) {
1377                struct strbuf buf = STRBUF_INIT;
1378
1379                if (opts.new_branch_force)
1380                        opts.branch_exists = validate_branchname(opts.new_branch, &buf);
1381                else
1382                        opts.branch_exists =
1383                                validate_new_branchname(opts.new_branch, &buf, 0);
1384                strbuf_release(&buf);
1385        }
1386
1387        UNLEAK(opts);
1388        if (opts.patch_mode || opts.pathspec.nr) {
1389                int ret = checkout_paths(&opts, new_branch_info.name);
1390                if (ret && dwim_remotes_matched > 1 &&
1391                    advice_checkout_ambiguous_remote_branch_name)
1392                        advise(_("'%s' matched more than one remote tracking branch.\n"
1393                                 "We found %d remotes with a reference that matched. So we fell back\n"
1394                                 "on trying to resolve the argument as a path, but failed there too!\n"
1395                                 "\n"
1396                                 "If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
1397                                 "you can do so by fully qualifying the name with the --track option:\n"
1398                                 "\n"
1399                                 "    git checkout --track origin/<name>\n"
1400                                 "\n"
1401                                 "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
1402                                 "one remote, e.g. the 'origin' remote, consider setting\n"
1403                                 "checkout.defaultRemote=origin in your config."),
1404                               argv[0],
1405                               dwim_remotes_matched);
1406                return ret;
1407        } else {
1408                return checkout_branch(&opts, &new_branch_info);
1409        }
1410}