builtin / checkout.con commit Merge branch 'bp/mv-submodules-with-fsmonitor' (9715f10)
   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", NULL);
 218        free(ancestor.ptr);
 219        free(ours.ptr);
 220        free(theirs.ptr);
 221        if (status < 0 || !result_buf.ptr) {
 222                free(result_buf.ptr);
 223                return error(_("path '%s': cannot merge"), path);
 224        }
 225
 226        /*
 227         * NEEDSWORK:
 228         * There is absolutely no reason to write this as a blob object
 229         * and create a phony cache entry.  This hack is primarily to get
 230         * to the write_entry() machinery that massages the contents to
 231         * work-tree format and writes out which only allows it for a
 232         * cache entry.  The code in write_entry() needs to be refactored
 233         * to allow us to feed a <buffer, size, mode> instead of a cache
 234         * entry.  Such a refactoring would help merge_recursive as well
 235         * (it also writes the merge result to the object database even
 236         * when it may contain conflicts).
 237         */
 238        if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
 239                die(_("Unable to add merge result for '%s'"), path);
 240        free(result_buf.ptr);
 241        ce = make_transient_cache_entry(mode, &oid, path, 2);
 242        if (!ce)
 243                die(_("make_cache_entry failed for path '%s'"), path);
 244        status = checkout_entry(ce, state, NULL);
 245        discard_cache_entry(ce);
 246        return status;
 247}
 248
 249static int checkout_paths(const struct checkout_opts *opts,
 250                          const char *revision)
 251{
 252        int pos;
 253        struct checkout state = CHECKOUT_INIT;
 254        static char *ps_matched;
 255        struct object_id rev;
 256        struct commit *head;
 257        int errs = 0;
 258        struct lock_file lock_file = LOCK_INIT;
 259
 260        if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 261                die(_("'%s' cannot be used with updating paths"), "--track");
 262
 263        if (opts->new_branch_log)
 264                die(_("'%s' cannot be used with updating paths"), "-l");
 265
 266        if (opts->force && opts->patch_mode)
 267                die(_("'%s' cannot be used with updating paths"), "-f");
 268
 269        if (opts->force_detach)
 270                die(_("'%s' cannot be used with updating paths"), "--detach");
 271
 272        if (opts->merge && opts->patch_mode)
 273                die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 274
 275        if (opts->force && opts->merge)
 276                die(_("'%s' cannot be used with %s"), "-f", "-m");
 277
 278        if (opts->new_branch)
 279                die(_("Cannot update paths and switch to branch '%s' at the same time."),
 280                    opts->new_branch);
 281
 282        if (opts->patch_mode)
 283                return run_add_interactive(revision, "--patch=checkout",
 284                                           &opts->pathspec);
 285
 286        hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 287        if (read_cache_preload(&opts->pathspec) < 0)
 288                return error(_("index file corrupt"));
 289
 290        if (opts->source_tree)
 291                read_tree_some(opts->source_tree, &opts->pathspec);
 292
 293        ps_matched = xcalloc(opts->pathspec.nr, 1);
 294
 295        /*
 296         * Make sure all pathspecs participated in locating the paths
 297         * to be checked out.
 298         */
 299        for (pos = 0; pos < active_nr; pos++) {
 300                struct cache_entry *ce = active_cache[pos];
 301                ce->ce_flags &= ~CE_MATCHED;
 302                if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 303                        continue;
 304                if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 305                        /*
 306                         * "git checkout tree-ish -- path", but this entry
 307                         * is in the original index; it will not be checked
 308                         * out to the working tree and it does not matter
 309                         * if pathspec matched this entry.  We will not do
 310                         * anything to this entry at all.
 311                         */
 312                        continue;
 313                /*
 314                 * Either this entry came from the tree-ish we are
 315                 * checking the paths out of, or we are checking out
 316                 * of the index.
 317                 *
 318                 * If it comes from the tree-ish, we already know it
 319                 * matches the pathspec and could just stamp
 320                 * CE_MATCHED to it from update_some(). But we still
 321                 * need ps_matched and read_tree_recursive (and
 322                 * eventually tree_entry_interesting) cannot fill
 323                 * ps_matched yet. Once it can, we can avoid calling
 324                 * match_pathspec() for _all_ entries when
 325                 * opts->source_tree != NULL.
 326                 */
 327                if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched))
 328                        ce->ce_flags |= CE_MATCHED;
 329        }
 330
 331        if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 332                free(ps_matched);
 333                return 1;
 334        }
 335        free(ps_matched);
 336
 337        /* "checkout -m path" to recreate conflicted state */
 338        if (opts->merge)
 339                unmerge_marked_index(&the_index);
 340
 341        /* Any unmerged paths? */
 342        for (pos = 0; pos < active_nr; pos++) {
 343                const struct cache_entry *ce = active_cache[pos];
 344                if (ce->ce_flags & CE_MATCHED) {
 345                        if (!ce_stage(ce))
 346                                continue;
 347                        if (opts->force) {
 348                                warning(_("path '%s' is unmerged"), ce->name);
 349                        } else if (opts->writeout_stage) {
 350                                errs |= check_stage(opts->writeout_stage, ce, pos);
 351                        } else if (opts->merge) {
 352                                errs |= check_stages((1<<2) | (1<<3), ce, pos);
 353                        } else {
 354                                errs = 1;
 355                                error(_("path '%s' is unmerged"), ce->name);
 356                        }
 357                        pos = skip_same_name(ce, pos) - 1;
 358                }
 359        }
 360        if (errs)
 361                return 1;
 362
 363        /* Now we are committed to check them out */
 364        state.force = 1;
 365        state.refresh_cache = 1;
 366        state.istate = &the_index;
 367
 368        enable_delayed_checkout(&state);
 369        for (pos = 0; pos < active_nr; pos++) {
 370                struct cache_entry *ce = active_cache[pos];
 371                if (ce->ce_flags & CE_MATCHED) {
 372                        if (!ce_stage(ce)) {
 373                                errs |= checkout_entry(ce, &state, NULL);
 374                                continue;
 375                        }
 376                        if (opts->writeout_stage)
 377                                errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 378                        else if (opts->merge)
 379                                errs |= checkout_merged(pos, &state);
 380                        pos = skip_same_name(ce, pos) - 1;
 381                }
 382        }
 383        errs |= finish_delayed_checkout(&state);
 384
 385        if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 386                die(_("unable to write new index file"));
 387
 388        read_ref_full("HEAD", 0, &rev, NULL);
 389        head = lookup_commit_reference_gently(the_repository, &rev, 1);
 390
 391        errs |= post_checkout_hook(head, head, 0);
 392        return errs;
 393}
 394
 395static void show_local_changes(struct object *head,
 396                               const struct diff_options *opts)
 397{
 398        struct rev_info rev;
 399        /* I think we want full paths, even if we're in a subdirectory. */
 400        init_revisions(&rev, NULL);
 401        rev.diffopt.flags = opts->flags;
 402        rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 403        diff_setup_done(&rev.diffopt);
 404        add_pending_object(&rev, head, NULL);
 405        run_diff_index(&rev, 0);
 406}
 407
 408static void describe_detached_head(const char *msg, struct commit *commit)
 409{
 410        struct strbuf sb = STRBUF_INIT;
 411
 412        if (!parse_commit(commit))
 413                pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 414        if (print_sha1_ellipsis()) {
 415                fprintf(stderr, "%s %s... %s\n", msg,
 416                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 417        } else {
 418                fprintf(stderr, "%s %s %s\n", msg,
 419                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 420        }
 421        strbuf_release(&sb);
 422}
 423
 424static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 425                      int worktree, int *writeout_error)
 426{
 427        struct unpack_trees_options opts;
 428        struct tree_desc tree_desc;
 429
 430        memset(&opts, 0, sizeof(opts));
 431        opts.head_idx = -1;
 432        opts.update = worktree;
 433        opts.skip_unmerged = !worktree;
 434        opts.reset = 1;
 435        opts.merge = 1;
 436        opts.fn = oneway_merge;
 437        opts.verbose_update = o->show_progress;
 438        opts.src_index = &the_index;
 439        opts.dst_index = &the_index;
 440        parse_tree(tree);
 441        init_tree_desc(&tree_desc, tree->buffer, tree->size);
 442        switch (unpack_trees(1, &tree_desc, &opts)) {
 443        case -2:
 444                *writeout_error = 1;
 445                /*
 446                 * We return 0 nevertheless, as the index is all right
 447                 * and more importantly we have made best efforts to
 448                 * update paths in the work tree, and we cannot revert
 449                 * them.
 450                 */
 451                /* fallthrough */
 452        case 0:
 453                return 0;
 454        default:
 455                return 128;
 456        }
 457}
 458
 459struct branch_info {
 460        const char *name; /* The short name used */
 461        const char *path; /* The full name of a real branch */
 462        struct commit *commit; /* The named commit */
 463        /*
 464         * if not null the branch is detached because it's already
 465         * checked out in this checkout
 466         */
 467        char *checkout;
 468};
 469
 470static void setup_branch_path(struct branch_info *branch)
 471{
 472        struct strbuf buf = STRBUF_INIT;
 473
 474        strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 475        if (strcmp(buf.buf, branch->name))
 476                branch->name = xstrdup(buf.buf);
 477        strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 478        branch->path = strbuf_detach(&buf, NULL);
 479}
 480
 481/*
 482 * Skip merging the trees, updating the index and working directory if and
 483 * only if we are creating a new branch via "git checkout -b <new_branch>."
 484 */
 485static int skip_merge_working_tree(const struct checkout_opts *opts,
 486        const struct branch_info *old_branch_info,
 487        const struct branch_info *new_branch_info)
 488{
 489        /*
 490         * Do the merge if sparse checkout is on and the user has not opted in
 491         * to the optimized behavior
 492         */
 493        if (core_apply_sparse_checkout && !checkout_optimize_new_branch)
 494                return 0;
 495
 496        /*
 497         * We must do the merge if we are actually moving to a new commit.
 498         */
 499        if (!old_branch_info->commit || !new_branch_info->commit ||
 500                oidcmp(&old_branch_info->commit->object.oid, &new_branch_info->commit->object.oid))
 501                return 0;
 502
 503        /*
 504         * opts->patch_mode cannot be used with switching branches so is
 505         * not tested here
 506         */
 507
 508        /*
 509         * opts->quiet only impacts output so doesn't require a merge
 510         */
 511
 512        /*
 513         * Honor the explicit request for a three-way merge or to throw away
 514         * local changes
 515         */
 516        if (opts->merge || opts->force)
 517                return 0;
 518
 519        /*
 520         * --detach is documented as "updating the index and the files in the
 521         * working tree" but this optimization skips those steps so fall through
 522         * to the regular code path.
 523         */
 524        if (opts->force_detach)
 525                return 0;
 526
 527        /*
 528         * opts->writeout_stage cannot be used with switching branches so is
 529         * not tested here
 530         */
 531
 532        /*
 533         * Honor the explicit ignore requests
 534         */
 535        if (!opts->overwrite_ignore || opts->ignore_skipworktree ||
 536                opts->ignore_other_worktrees)
 537                return 0;
 538
 539        /*
 540         * opts->show_progress only impacts output so doesn't require a merge
 541         */
 542
 543        /*
 544         * If we aren't creating a new branch any changes or updates will
 545         * happen in the existing branch.  Since that could only be updating
 546         * the index and working directory, we don't want to skip those steps
 547         * or we've defeated any purpose in running the command.
 548         */
 549        if (!opts->new_branch)
 550                return 0;
 551
 552        /*
 553         * new_branch_force is defined to "create/reset and checkout a branch"
 554         * so needs to go through the merge to do the reset
 555         */
 556        if (opts->new_branch_force)
 557                return 0;
 558
 559        /*
 560         * A new orphaned branch requrires the index and the working tree to be
 561         * adjusted to <start_point>
 562         */
 563        if (opts->new_orphan_branch)
 564                return 0;
 565
 566        /*
 567         * Remaining variables are not checkout options but used to track state
 568         */
 569
 570        return 1;
 571}
 572
 573static int merge_working_tree(const struct checkout_opts *opts,
 574                              struct branch_info *old_branch_info,
 575                              struct branch_info *new_branch_info,
 576                              int *writeout_error)
 577{
 578        int ret;
 579        struct lock_file lock_file = LOCK_INIT;
 580
 581        hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 582        if (read_cache_preload(NULL) < 0)
 583                return error(_("index file corrupt"));
 584
 585        resolve_undo_clear();
 586        if (opts->force) {
 587                ret = reset_tree(get_commit_tree(new_branch_info->commit),
 588                                 opts, 1, writeout_error);
 589                if (ret)
 590                        return ret;
 591        } else {
 592                struct tree_desc trees[2];
 593                struct tree *tree;
 594                struct unpack_trees_options topts;
 595
 596                memset(&topts, 0, sizeof(topts));
 597                topts.head_idx = -1;
 598                topts.src_index = &the_index;
 599                topts.dst_index = &the_index;
 600
 601                setup_unpack_trees_porcelain(&topts, "checkout");
 602
 603                refresh_cache(REFRESH_QUIET);
 604
 605                if (unmerged_cache()) {
 606                        error(_("you need to resolve your current index first"));
 607                        return 1;
 608                }
 609
 610                /* 2-way merge to the new branch */
 611                topts.initial_checkout = is_cache_unborn();
 612                topts.update = 1;
 613                topts.merge = 1;
 614                topts.gently = opts->merge && old_branch_info->commit;
 615                topts.verbose_update = opts->show_progress;
 616                topts.fn = twoway_merge;
 617                if (opts->overwrite_ignore) {
 618                        topts.dir = xcalloc(1, sizeof(*topts.dir));
 619                        topts.dir->flags |= DIR_SHOW_IGNORED;
 620                        setup_standard_excludes(topts.dir);
 621                }
 622                tree = parse_tree_indirect(old_branch_info->commit ?
 623                                           &old_branch_info->commit->object.oid :
 624                                           the_hash_algo->empty_tree);
 625                init_tree_desc(&trees[0], tree->buffer, tree->size);
 626                tree = parse_tree_indirect(&new_branch_info->commit->object.oid);
 627                init_tree_desc(&trees[1], tree->buffer, tree->size);
 628
 629                ret = unpack_trees(2, trees, &topts);
 630                clear_unpack_trees_porcelain(&topts);
 631                if (ret == -1) {
 632                        /*
 633                         * Unpack couldn't do a trivial merge; either
 634                         * give up or do a real merge, depending on
 635                         * whether the merge flag was used.
 636                         */
 637                        struct tree *result;
 638                        struct tree *work;
 639                        struct merge_options o;
 640                        if (!opts->merge)
 641                                return 1;
 642
 643                        /*
 644                         * Without old_branch_info->commit, the below is the same as
 645                         * the two-tree unpack we already tried and failed.
 646                         */
 647                        if (!old_branch_info->commit)
 648                                return 1;
 649
 650                        /* Do more real merge */
 651
 652                        /*
 653                         * We update the index fully, then write the
 654                         * tree from the index, then merge the new
 655                         * branch with the current tree, with the old
 656                         * branch as the base. Then we reset the index
 657                         * (but not the working tree) to the new
 658                         * branch, leaving the working tree as the
 659                         * merged version, but skipping unmerged
 660                         * entries in the index.
 661                         */
 662
 663                        add_files_to_cache(NULL, NULL, 0);
 664                        /*
 665                         * NEEDSWORK: carrying over local changes
 666                         * when branches have different end-of-line
 667                         * normalization (or clean+smudge rules) is
 668                         * a pain; plumb in an option to set
 669                         * o.renormalize?
 670                         */
 671                        init_merge_options(&o);
 672                        o.verbosity = 0;
 673                        work = write_tree_from_memory(&o);
 674
 675                        ret = reset_tree(get_commit_tree(new_branch_info->commit),
 676                                         opts, 1,
 677                                         writeout_error);
 678                        if (ret)
 679                                return ret;
 680                        o.ancestor = old_branch_info->name;
 681                        o.branch1 = new_branch_info->name;
 682                        o.branch2 = "local";
 683                        ret = merge_trees(&o,
 684                                          get_commit_tree(new_branch_info->commit),
 685                                          work,
 686                                          get_commit_tree(old_branch_info->commit),
 687                                          &result);
 688                        if (ret < 0)
 689                                exit(128);
 690                        ret = reset_tree(get_commit_tree(new_branch_info->commit),
 691                                         opts, 0,
 692                                         writeout_error);
 693                        strbuf_release(&o.obuf);
 694                        if (ret)
 695                                return ret;
 696                }
 697        }
 698
 699        if (!active_cache_tree)
 700                active_cache_tree = cache_tree();
 701
 702        if (!cache_tree_fully_valid(active_cache_tree))
 703                cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 704
 705        if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 706                die(_("unable to write new index file"));
 707
 708        if (!opts->force && !opts->quiet)
 709                show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 710
 711        return 0;
 712}
 713
 714static void report_tracking(struct branch_info *new_branch_info)
 715{
 716        struct strbuf sb = STRBUF_INIT;
 717        struct branch *branch = branch_get(new_branch_info->name);
 718
 719        if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 720                return;
 721        fputs(sb.buf, stdout);
 722        strbuf_release(&sb);
 723}
 724
 725static void update_refs_for_switch(const struct checkout_opts *opts,
 726                                   struct branch_info *old_branch_info,
 727                                   struct branch_info *new_branch_info)
 728{
 729        struct strbuf msg = STRBUF_INIT;
 730        const char *old_desc, *reflog_msg;
 731        if (opts->new_branch) {
 732                if (opts->new_orphan_branch) {
 733                        char *refname;
 734
 735                        refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 736                        if (opts->new_branch_log &&
 737                            !should_autocreate_reflog(refname)) {
 738                                int ret;
 739                                struct strbuf err = STRBUF_INIT;
 740
 741                                ret = safe_create_reflog(refname, 1, &err);
 742                                if (ret) {
 743                                        fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 744                                                opts->new_orphan_branch, err.buf);
 745                                        strbuf_release(&err);
 746                                        free(refname);
 747                                        return;
 748                                }
 749                                strbuf_release(&err);
 750                        }
 751                        free(refname);
 752                }
 753                else
 754                        create_branch(opts->new_branch, new_branch_info->name,
 755                                      opts->new_branch_force ? 1 : 0,
 756                                      opts->new_branch_force ? 1 : 0,
 757                                      opts->new_branch_log,
 758                                      opts->quiet,
 759                                      opts->track);
 760                new_branch_info->name = opts->new_branch;
 761                setup_branch_path(new_branch_info);
 762        }
 763
 764        old_desc = old_branch_info->name;
 765        if (!old_desc && old_branch_info->commit)
 766                old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
 767
 768        reflog_msg = getenv("GIT_REFLOG_ACTION");
 769        if (!reflog_msg)
 770                strbuf_addf(&msg, "checkout: moving from %s to %s",
 771                        old_desc ? old_desc : "(invalid)", new_branch_info->name);
 772        else
 773                strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 774
 775        if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
 776                /* Nothing to do. */
 777        } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
 778                update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
 779                           REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 780                if (!opts->quiet) {
 781                        if (old_branch_info->path &&
 782                            advice_detached_head && !opts->force_detach)
 783                                detach_advice(new_branch_info->name);
 784                        describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 785                }
 786        } else if (new_branch_info->path) {     /* Switch branches. */
 787                if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
 788                        die(_("unable to update HEAD"));
 789                if (!opts->quiet) {
 790                        if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
 791                                if (opts->new_branch_force)
 792                                        fprintf(stderr, _("Reset branch '%s'\n"),
 793                                                new_branch_info->name);
 794                                else
 795                                        fprintf(stderr, _("Already on '%s'\n"),
 796                                                new_branch_info->name);
 797                        } else if (opts->new_branch) {
 798                                if (opts->branch_exists)
 799                                        fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
 800                                else
 801                                        fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
 802                        } else {
 803                                fprintf(stderr, _("Switched to branch '%s'\n"),
 804                                        new_branch_info->name);
 805                        }
 806                }
 807                if (old_branch_info->path && old_branch_info->name) {
 808                        if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
 809                                delete_reflog(old_branch_info->path);
 810                }
 811        }
 812        remove_branch_state();
 813        strbuf_release(&msg);
 814        if (!opts->quiet &&
 815            (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
 816                report_tracking(new_branch_info);
 817}
 818
 819static int add_pending_uninteresting_ref(const char *refname,
 820                                         const struct object_id *oid,
 821                                         int flags, void *cb_data)
 822{
 823        add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 824        return 0;
 825}
 826
 827static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 828{
 829        strbuf_addstr(sb, "  ");
 830        strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 831        strbuf_addch(sb, ' ');
 832        if (!parse_commit(commit))
 833                pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 834        strbuf_addch(sb, '\n');
 835}
 836
 837#define ORPHAN_CUTOFF 4
 838static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 839{
 840        struct commit *c, *last = NULL;
 841        struct strbuf sb = STRBUF_INIT;
 842        int lost = 0;
 843        while ((c = get_revision(revs)) != NULL) {
 844                if (lost < ORPHAN_CUTOFF)
 845                        describe_one_orphan(&sb, c);
 846                last = c;
 847                lost++;
 848        }
 849        if (ORPHAN_CUTOFF < lost) {
 850                int more = lost - ORPHAN_CUTOFF;
 851                if (more == 1)
 852                        describe_one_orphan(&sb, last);
 853                else
 854                        strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 855        }
 856
 857        fprintf(stderr,
 858                Q_(
 859                /* The singular version */
 860                "Warning: you are leaving %d commit behind, "
 861                "not connected to\n"
 862                "any of your branches:\n\n"
 863                "%s\n",
 864                /* The plural version */
 865                "Warning: you are leaving %d commits behind, "
 866                "not connected to\n"
 867                "any of your branches:\n\n"
 868                "%s\n",
 869                /* Give ngettext() the count */
 870                lost),
 871                lost,
 872                sb.buf);
 873        strbuf_release(&sb);
 874
 875        if (advice_detached_head)
 876                fprintf(stderr,
 877                        Q_(
 878                        /* The singular version */
 879                        "If you want to keep it by creating a new branch, "
 880                        "this may be a good time\nto do so with:\n\n"
 881                        " git branch <new-branch-name> %s\n\n",
 882                        /* The plural version */
 883                        "If you want to keep them by creating a new branch, "
 884                        "this may be a good time\nto do so with:\n\n"
 885                        " git branch <new-branch-name> %s\n\n",
 886                        /* Give ngettext() the count */
 887                        lost),
 888                        find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 889}
 890
 891/*
 892 * We are about to leave commit that was at the tip of a detached
 893 * HEAD.  If it is not reachable from any ref, this is the last chance
 894 * for the user to do so without resorting to reflog.
 895 */
 896static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
 897{
 898        struct rev_info revs;
 899        struct object *object = &old_commit->object;
 900
 901        init_revisions(&revs, NULL);
 902        setup_revisions(0, NULL, &revs, NULL);
 903
 904        object->flags &= ~UNINTERESTING;
 905        add_pending_object(&revs, object, oid_to_hex(&object->oid));
 906
 907        for_each_ref(add_pending_uninteresting_ref, &revs);
 908        add_pending_oid(&revs, "HEAD", &new_commit->object.oid, UNINTERESTING);
 909
 910        if (prepare_revision_walk(&revs))
 911                die(_("internal error in revision walk"));
 912        if (!(old_commit->object.flags & UNINTERESTING))
 913                suggest_reattach(old_commit, &revs);
 914        else
 915                describe_detached_head(_("Previous HEAD position was"), old_commit);
 916
 917        /* Clean up objects used, as they will be reused. */
 918        clear_commit_marks_all(ALL_REV_FLAGS);
 919}
 920
 921static int switch_branches(const struct checkout_opts *opts,
 922                           struct branch_info *new_branch_info)
 923{
 924        int ret = 0;
 925        struct branch_info old_branch_info;
 926        void *path_to_free;
 927        struct object_id rev;
 928        int flag, writeout_error = 0;
 929        memset(&old_branch_info, 0, sizeof(old_branch_info));
 930        old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
 931        if (old_branch_info.path)
 932                old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
 933        if (!(flag & REF_ISSYMREF))
 934                old_branch_info.path = NULL;
 935
 936        if (old_branch_info.path)
 937                skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
 938
 939        if (!new_branch_info->name) {
 940                new_branch_info->name = "HEAD";
 941                new_branch_info->commit = old_branch_info.commit;
 942                if (!new_branch_info->commit)
 943                        die(_("You are on a branch yet to be born"));
 944                parse_commit_or_die(new_branch_info->commit);
 945        }
 946
 947        /* optimize the "checkout -b <new_branch> path */
 948        if (skip_merge_working_tree(opts, &old_branch_info, new_branch_info)) {
 949                if (!checkout_optimize_new_branch && !opts->quiet) {
 950                        if (read_cache_preload(NULL) < 0)
 951                                return error(_("index file corrupt"));
 952                        show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 953                }
 954        } else {
 955                ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
 956                if (ret) {
 957                        free(path_to_free);
 958                        return ret;
 959                }
 960        }
 961
 962        if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
 963                orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
 964
 965        update_refs_for_switch(opts, &old_branch_info, new_branch_info);
 966
 967        ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
 968        free(path_to_free);
 969        return ret || writeout_error;
 970}
 971
 972static int git_checkout_config(const char *var, const char *value, void *cb)
 973{
 974        if (!strcmp(var, "checkout.optimizenewbranch")) {
 975                checkout_optimize_new_branch = git_config_bool(var, value);
 976                return 0;
 977        }
 978
 979        if (!strcmp(var, "diff.ignoresubmodules")) {
 980                struct checkout_opts *opts = cb;
 981                handle_ignore_submodules_arg(&opts->diff_options, value);
 982                return 0;
 983        }
 984
 985        if (starts_with(var, "submodule."))
 986                return git_default_submodule_config(var, value, NULL);
 987
 988        return git_xmerge_config(var, value, NULL);
 989}
 990
 991static int parse_branchname_arg(int argc, const char **argv,
 992                                int dwim_new_local_branch_ok,
 993                                struct branch_info *new_branch_info,
 994                                struct checkout_opts *opts,
 995                                struct object_id *rev,
 996                                int *dwim_remotes_matched)
 997{
 998        struct tree **source_tree = &opts->source_tree;
 999        const char **new_branch = &opts->new_branch;
1000        int argcount = 0;
1001        struct object_id branch_rev;
1002        const char *arg;
1003        int dash_dash_pos;
1004        int has_dash_dash = 0;
1005        int i;
1006
1007        /*
1008         * case 1: git checkout <ref> -- [<paths>]
1009         *
1010         *   <ref> must be a valid tree, everything after the '--' must be
1011         *   a path.
1012         *
1013         * case 2: git checkout -- [<paths>]
1014         *
1015         *   everything after the '--' must be paths.
1016         *
1017         * case 3: git checkout <something> [--]
1018         *
1019         *   (a) If <something> is a commit, that is to
1020         *       switch to the branch or detach HEAD at it.  As a special case,
1021         *       if <something> is A...B (missing A or B means HEAD but you can
1022         *       omit at most one side), and if there is a unique merge base
1023         *       between A and B, A...B names that merge base.
1024         *
1025         *   (b) If <something> is _not_ a commit, either "--" is present
1026         *       or <something> is not a path, no -t or -b was given, and
1027         *       and there is a tracking branch whose name is <something>
1028         *       in one and only one remote (or if the branch exists on the
1029         *       remote named in checkout.defaultRemote), then this is a
1030         *       short-hand to fork local <something> from that
1031         *       remote-tracking branch.
1032         *
1033         *   (c) Otherwise, if "--" is present, treat it like case (1).
1034         *
1035         *   (d) Otherwise :
1036         *       - if it's a reference, treat it like case (1)
1037         *       - else if it's a path, treat it like case (2)
1038         *       - else: fail.
1039         *
1040         * case 4: git checkout <something> <paths>
1041         *
1042         *   The first argument must not be ambiguous.
1043         *   - If it's *only* a reference, treat it like case (1).
1044         *   - If it's only a path, treat it like case (2).
1045         *   - else: fail.
1046         *
1047         */
1048        if (!argc)
1049                return 0;
1050
1051        arg = argv[0];
1052        dash_dash_pos = -1;
1053        for (i = 0; i < argc; i++) {
1054                if (!strcmp(argv[i], "--")) {
1055                        dash_dash_pos = i;
1056                        break;
1057                }
1058        }
1059        if (dash_dash_pos == 0)
1060                return 1; /* case (2) */
1061        else if (dash_dash_pos == 1)
1062                has_dash_dash = 1; /* case (3) or (1) */
1063        else if (dash_dash_pos >= 2)
1064                die(_("only one reference expected, %d given."), dash_dash_pos);
1065
1066        if (!strcmp(arg, "-"))
1067                arg = "@{-1}";
1068
1069        if (get_oid_mb(arg, rev)) {
1070                /*
1071                 * Either case (3) or (4), with <something> not being
1072                 * a commit, or an attempt to use case (1) with an
1073                 * invalid ref.
1074                 *
1075                 * It's likely an error, but we need to find out if
1076                 * we should auto-create the branch, case (3).(b).
1077                 */
1078                int recover_with_dwim = dwim_new_local_branch_ok;
1079
1080                if (!has_dash_dash &&
1081                    (check_filename(opts->prefix, arg) || !no_wildcard(arg)))
1082                        recover_with_dwim = 0;
1083                /*
1084                 * Accept "git checkout foo" and "git checkout foo --"
1085                 * as candidates for dwim.
1086                 */
1087                if (!(argc == 1 && !has_dash_dash) &&
1088                    !(argc == 2 && has_dash_dash))
1089                        recover_with_dwim = 0;
1090
1091                if (recover_with_dwim) {
1092                        const char *remote = unique_tracking_name(arg, rev,
1093                                                                  dwim_remotes_matched);
1094                        if (remote) {
1095                                *new_branch = arg;
1096                                arg = remote;
1097                                /* DWIMmed to create local branch, case (3).(b) */
1098                        } else {
1099                                recover_with_dwim = 0;
1100                        }
1101                }
1102
1103                if (!recover_with_dwim) {
1104                        if (has_dash_dash)
1105                                die(_("invalid reference: %s"), arg);
1106                        return argcount;
1107                }
1108        }
1109
1110        /* we can't end up being in (2) anymore, eat the argument */
1111        argcount++;
1112        argv++;
1113        argc--;
1114
1115        new_branch_info->name = arg;
1116        setup_branch_path(new_branch_info);
1117
1118        if (!check_refname_format(new_branch_info->path, 0) &&
1119            !read_ref(new_branch_info->path, &branch_rev))
1120                oidcpy(rev, &branch_rev);
1121        else
1122                new_branch_info->path = NULL; /* not an existing branch */
1123
1124        new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
1125        if (!new_branch_info->commit) {
1126                /* not a commit */
1127                *source_tree = parse_tree_indirect(rev);
1128        } else {
1129                parse_commit_or_die(new_branch_info->commit);
1130                *source_tree = get_commit_tree(new_branch_info->commit);
1131        }
1132
1133        if (!*source_tree)                   /* case (1): want a tree */
1134                die(_("reference is not a tree: %s"), arg);
1135        if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1136                /*
1137                 * Do not complain the most common case
1138                 *      git checkout branch
1139                 * even if there happen to be a file called 'branch';
1140                 * it would be extremely annoying.
1141                 */
1142                if (argc)
1143                        verify_non_filename(opts->prefix, arg);
1144        } else {
1145                argcount++;
1146                argv++;
1147                argc--;
1148        }
1149
1150        return argcount;
1151}
1152
1153static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1154{
1155        int status;
1156        struct strbuf branch_ref = STRBUF_INIT;
1157
1158        if (!opts->new_branch)
1159                die(_("You are on a branch yet to be born"));
1160        strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1161        status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1162        strbuf_release(&branch_ref);
1163        if (!opts->quiet)
1164                fprintf(stderr, _("Switched to a new branch '%s'\n"),
1165                        opts->new_branch);
1166        return status;
1167}
1168
1169static int checkout_branch(struct checkout_opts *opts,
1170                           struct branch_info *new_branch_info)
1171{
1172        if (opts->pathspec.nr)
1173                die(_("paths cannot be used with switching branches"));
1174
1175        if (opts->patch_mode)
1176                die(_("'%s' cannot be used with switching branches"),
1177                    "--patch");
1178
1179        if (opts->writeout_stage)
1180                die(_("'%s' cannot be used with switching branches"),
1181                    "--ours/--theirs");
1182
1183        if (opts->force && opts->merge)
1184                die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1185
1186        if (opts->force_detach && opts->new_branch)
1187                die(_("'%s' cannot be used with '%s'"),
1188                    "--detach", "-b/-B/--orphan");
1189
1190        if (opts->new_orphan_branch) {
1191                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1192                        die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1193        } else if (opts->force_detach) {
1194                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1195                        die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1196        } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1197                opts->track = git_branch_track;
1198
1199        if (new_branch_info->name && !new_branch_info->commit)
1200                die(_("Cannot switch branch to a non-commit '%s'"),
1201                    new_branch_info->name);
1202
1203        if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1204            !opts->ignore_other_worktrees) {
1205                int flag;
1206                char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1207                if (head_ref &&
1208                    (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1209                        die_if_checked_out(new_branch_info->path, 1);
1210                free(head_ref);
1211        }
1212
1213        if (!new_branch_info->commit && opts->new_branch) {
1214                struct object_id rev;
1215                int flag;
1216
1217                if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1218                    (flag & REF_ISSYMREF) && is_null_oid(&rev))
1219                        return switch_unborn_to_new_branch(opts);
1220        }
1221        return switch_branches(opts, new_branch_info);
1222}
1223
1224int cmd_checkout(int argc, const char **argv, const char *prefix)
1225{
1226        struct checkout_opts opts;
1227        struct branch_info new_branch_info;
1228        char *conflict_style = NULL;
1229        int dwim_new_local_branch = 1;
1230        int dwim_remotes_matched = 0;
1231        struct option options[] = {
1232                OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1233                OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1234                           N_("create and checkout a new branch")),
1235                OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1236                           N_("create/reset and checkout a branch")),
1237                OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1238                OPT_BOOL(0, "detach", &opts.force_detach, N_("detach HEAD at named commit")),
1239                OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1240                        BRANCH_TRACK_EXPLICIT),
1241                OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1242                OPT_SET_INT_F('2', "ours", &opts.writeout_stage,
1243                              N_("checkout our version for unmerged files"),
1244                              2, PARSE_OPT_NONEG),
1245                OPT_SET_INT_F('3', "theirs", &opts.writeout_stage,
1246                              N_("checkout their version for unmerged files"),
1247                              3, PARSE_OPT_NONEG),
1248                OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)"),
1249                           PARSE_OPT_NOCOMPLETE),
1250                OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1251                OPT_BOOL_F(0, "overwrite-ignore", &opts.overwrite_ignore,
1252                           N_("update ignored files (default)"),
1253                           PARSE_OPT_NOCOMPLETE),
1254                OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1255                           N_("conflict style (merge or diff3)")),
1256                OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1257                OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1258                         N_("do not limit pathspecs to sparse entries only")),
1259                OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1260                                N_("second guess 'git checkout <no-such-branch>'")),
1261                OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1262                         N_("do not check if another worktree is holding the given ref")),
1263                { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1264                            "checkout", "control recursive updating of submodules",
1265                            PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1266                OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
1267                OPT_END(),
1268        };
1269
1270        memset(&opts, 0, sizeof(opts));
1271        memset(&new_branch_info, 0, sizeof(new_branch_info));
1272        opts.overwrite_ignore = 1;
1273        opts.prefix = prefix;
1274        opts.show_progress = -1;
1275
1276        git_config(git_checkout_config, &opts);
1277
1278        opts.track = BRANCH_TRACK_UNSPECIFIED;
1279
1280        argc = parse_options(argc, argv, prefix, options, checkout_usage,
1281                             PARSE_OPT_KEEP_DASHDASH);
1282
1283        if (opts.show_progress < 0) {
1284                if (opts.quiet)
1285                        opts.show_progress = 0;
1286                else
1287                        opts.show_progress = isatty(2);
1288        }
1289
1290        if (conflict_style) {
1291                opts.merge = 1; /* implied */
1292                git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1293        }
1294
1295        if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1296                die(_("-b, -B and --orphan are mutually exclusive"));
1297
1298        /*
1299         * From here on, new_branch will contain the branch to be checked out,
1300         * and new_branch_force and new_orphan_branch will tell us which one of
1301         * -b/-B/--orphan is being used.
1302         */
1303        if (opts.new_branch_force)
1304                opts.new_branch = opts.new_branch_force;
1305
1306        if (opts.new_orphan_branch)
1307                opts.new_branch = opts.new_orphan_branch;
1308
1309        /* --track without -b/-B/--orphan should DWIM */
1310        if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1311                const char *argv0 = argv[0];
1312                if (!argc || !strcmp(argv0, "--"))
1313                        die(_("--track needs a branch name"));
1314                skip_prefix(argv0, "refs/", &argv0);
1315                skip_prefix(argv0, "remotes/", &argv0);
1316                argv0 = strchr(argv0, '/');
1317                if (!argv0 || !argv0[1])
1318                        die(_("missing branch name; try -b"));
1319                opts.new_branch = argv0 + 1;
1320        }
1321
1322        /*
1323         * Extract branch name from command line arguments, so
1324         * all that is left is pathspecs.
1325         *
1326         * Handle
1327         *
1328         *  1) git checkout <tree> -- [<paths>]
1329         *  2) git checkout -- [<paths>]
1330         *  3) git checkout <something> [<paths>]
1331         *
1332         * including "last branch" syntax and DWIM-ery for names of
1333         * remote branches, erroring out for invalid or ambiguous cases.
1334         */
1335        if (argc) {
1336                struct object_id rev;
1337                int dwim_ok =
1338                        !opts.patch_mode &&
1339                        dwim_new_local_branch &&
1340                        opts.track == BRANCH_TRACK_UNSPECIFIED &&
1341                        !opts.new_branch;
1342                int n = parse_branchname_arg(argc, argv, dwim_ok,
1343                                             &new_branch_info, &opts, &rev,
1344                                             &dwim_remotes_matched);
1345                argv += n;
1346                argc -= n;
1347        }
1348
1349        if (argc) {
1350                parse_pathspec(&opts.pathspec, 0,
1351                               opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1352                               prefix, argv);
1353
1354                if (!opts.pathspec.nr)
1355                        die(_("invalid path specification"));
1356
1357                /*
1358                 * Try to give more helpful suggestion.
1359                 * new_branch && argc > 1 will be caught later.
1360                 */
1361                if (opts.new_branch && argc == 1)
1362                        die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1363                                argv[0], opts.new_branch);
1364
1365                if (opts.force_detach)
1366                        die(_("git checkout: --detach does not take a path argument '%s'"),
1367                            argv[0]);
1368
1369                if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1370                        die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1371                              "checking out of the index."));
1372        }
1373
1374        if (opts.new_branch) {
1375                struct strbuf buf = STRBUF_INIT;
1376
1377                if (opts.new_branch_force)
1378                        opts.branch_exists = validate_branchname(opts.new_branch, &buf);
1379                else
1380                        opts.branch_exists =
1381                                validate_new_branchname(opts.new_branch, &buf, 0);
1382                strbuf_release(&buf);
1383        }
1384
1385        UNLEAK(opts);
1386        if (opts.patch_mode || opts.pathspec.nr) {
1387                int ret = checkout_paths(&opts, new_branch_info.name);
1388                if (ret && dwim_remotes_matched > 1 &&
1389                    advice_checkout_ambiguous_remote_branch_name)
1390                        advise(_("'%s' matched more than one remote tracking branch.\n"
1391                                 "We found %d remotes with a reference that matched. So we fell back\n"
1392                                 "on trying to resolve the argument as a path, but failed there too!\n"
1393                                 "\n"
1394                                 "If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
1395                                 "you can do so by fully qualifying the name with the --track option:\n"
1396                                 "\n"
1397                                 "    git checkout --track origin/<name>\n"
1398                                 "\n"
1399                                 "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
1400                                 "one remote, e.g. the 'origin' remote, consider setting\n"
1401                                 "checkout.defaultRemote=origin in your config."),
1402                               argv[0],
1403                               dwim_remotes_matched);
1404                return ret;
1405        } else {
1406                return checkout_branch(&opts, &new_branch_info);
1407        }
1408}