builtin / checkout.con commit Merge branch 'kb/i18n-doc' (81bc521)
   1#include "builtin.h"
   2#include "lockfile.h"
   3#include "parse-options.h"
   4#include "refs.h"
   5#include "commit.h"
   6#include "tree.h"
   7#include "tree-walk.h"
   8#include "cache-tree.h"
   9#include "unpack-trees.h"
  10#include "dir.h"
  11#include "run-command.h"
  12#include "merge-recursive.h"
  13#include "branch.h"
  14#include "diff.h"
  15#include "revision.h"
  16#include "remote.h"
  17#include "blob.h"
  18#include "xdiff-interface.h"
  19#include "ll-merge.h"
  20#include "resolve-undo.h"
  21#include "submodule.h"
  22
  23static const char * const checkout_usage[] = {
  24        N_("git checkout [<options>] <branch>"),
  25        N_("git checkout [<options>] [<branch>] -- <file>..."),
  26        NULL,
  27};
  28
  29struct checkout_opts {
  30        int patch_mode;
  31        int quiet;
  32        int merge;
  33        int force;
  34        int force_detach;
  35        int writeout_stage;
  36        int overwrite_ignore;
  37        int ignore_skipworktree;
  38        int ignore_other_worktrees;
  39
  40        const char *new_branch;
  41        const char *new_branch_force;
  42        const char *new_orphan_branch;
  43        int new_branch_log;
  44        enum branch_track track;
  45        struct diff_options diff_options;
  46
  47        int branch_exists;
  48        const char *prefix;
  49        struct pathspec pathspec;
  50        struct tree *source_tree;
  51
  52        int new_worktree_mode;
  53};
  54
  55static int post_checkout_hook(struct commit *old, struct commit *new,
  56                              int changed)
  57{
  58        return run_hook_le(NULL, "post-checkout",
  59                           sha1_to_hex(old ? old->object.sha1 : null_sha1),
  60                           sha1_to_hex(new ? new->object.sha1 : null_sha1),
  61                           changed ? "1" : "0", NULL);
  62        /* "new" can be NULL when checking out from the index before
  63           a commit exists. */
  64
  65}
  66
  67static int update_some(const unsigned char *sha1, struct strbuf *base,
  68                const char *pathname, unsigned mode, int stage, void *context)
  69{
  70        int len;
  71        struct cache_entry *ce;
  72        int pos;
  73
  74        if (S_ISDIR(mode))
  75                return READ_TREE_RECURSIVE;
  76
  77        len = base->len + strlen(pathname);
  78        ce = xcalloc(1, cache_entry_size(len));
  79        hashcpy(ce->sha1, sha1);
  80        memcpy(ce->name, base->buf, base->len);
  81        memcpy(ce->name + base->len, pathname, len - base->len);
  82        ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
  83        ce->ce_namelen = len;
  84        ce->ce_mode = create_ce_mode(mode);
  85
  86        /*
  87         * If the entry is the same as the current index, we can leave the old
  88         * entry in place. Whether it is UPTODATE or not, checkout_entry will
  89         * do the right thing.
  90         */
  91        pos = cache_name_pos(ce->name, ce->ce_namelen);
  92        if (pos >= 0) {
  93                struct cache_entry *old = active_cache[pos];
  94                if (ce->ce_mode == old->ce_mode &&
  95                    !hashcmp(ce->sha1, old->sha1)) {
  96                        old->ce_flags |= CE_UPDATE;
  97                        free(ce);
  98                        return 0;
  99                }
 100        }
 101
 102        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 103        return 0;
 104}
 105
 106static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 107{
 108        read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
 109
 110        /* update the index with the given tree's info
 111         * for all args, expanding wildcards, and exit
 112         * with any non-zero return code.
 113         */
 114        return 0;
 115}
 116
 117static int skip_same_name(const struct cache_entry *ce, int pos)
 118{
 119        while (++pos < active_nr &&
 120               !strcmp(active_cache[pos]->name, ce->name))
 121                ; /* skip */
 122        return pos;
 123}
 124
 125static int check_stage(int stage, const struct cache_entry *ce, int pos)
 126{
 127        while (pos < active_nr &&
 128               !strcmp(active_cache[pos]->name, ce->name)) {
 129                if (ce_stage(active_cache[pos]) == stage)
 130                        return 0;
 131                pos++;
 132        }
 133        if (stage == 2)
 134                return error(_("path '%s' does not have our version"), ce->name);
 135        else
 136                return error(_("path '%s' does not have their version"), ce->name);
 137}
 138
 139static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 140{
 141        unsigned seen = 0;
 142        const char *name = ce->name;
 143
 144        while (pos < active_nr) {
 145                ce = active_cache[pos];
 146                if (strcmp(name, ce->name))
 147                        break;
 148                seen |= (1 << ce_stage(ce));
 149                pos++;
 150        }
 151        if ((stages & seen) != stages)
 152                return error(_("path '%s' does not have all necessary versions"),
 153                             name);
 154        return 0;
 155}
 156
 157static int checkout_stage(int stage, struct cache_entry *ce, int pos,
 158                          struct checkout *state)
 159{
 160        while (pos < active_nr &&
 161               !strcmp(active_cache[pos]->name, ce->name)) {
 162                if (ce_stage(active_cache[pos]) == stage)
 163                        return checkout_entry(active_cache[pos], state, NULL);
 164                pos++;
 165        }
 166        if (stage == 2)
 167                return error(_("path '%s' does not have our version"), ce->name);
 168        else
 169                return error(_("path '%s' does not have their version"), ce->name);
 170}
 171
 172static int checkout_merged(int pos, struct checkout *state)
 173{
 174        struct cache_entry *ce = active_cache[pos];
 175        const char *path = ce->name;
 176        mmfile_t ancestor, ours, theirs;
 177        int status;
 178        unsigned char sha1[20];
 179        mmbuffer_t result_buf;
 180        unsigned char threeway[3][20];
 181        unsigned mode = 0;
 182
 183        memset(threeway, 0, sizeof(threeway));
 184        while (pos < active_nr) {
 185                int stage;
 186                stage = ce_stage(ce);
 187                if (!stage || strcmp(path, ce->name))
 188                        break;
 189                hashcpy(threeway[stage - 1], ce->sha1);
 190                if (stage == 2)
 191                        mode = create_ce_mode(ce->ce_mode);
 192                pos++;
 193                ce = active_cache[pos];
 194        }
 195        if (is_null_sha1(threeway[1]) || is_null_sha1(threeway[2]))
 196                return error(_("path '%s' does not have necessary versions"), path);
 197
 198        read_mmblob(&ancestor, threeway[0]);
 199        read_mmblob(&ours, threeway[1]);
 200        read_mmblob(&theirs, threeway[2]);
 201
 202        /*
 203         * NEEDSWORK: re-create conflicts from merges with
 204         * merge.renormalize set, too
 205         */
 206        status = ll_merge(&result_buf, path, &ancestor, "base",
 207                          &ours, "ours", &theirs, "theirs", NULL);
 208        free(ancestor.ptr);
 209        free(ours.ptr);
 210        free(theirs.ptr);
 211        if (status < 0 || !result_buf.ptr) {
 212                free(result_buf.ptr);
 213                return error(_("path '%s': cannot merge"), path);
 214        }
 215
 216        /*
 217         * NEEDSWORK:
 218         * There is absolutely no reason to write this as a blob object
 219         * and create a phony cache entry just to leak.  This hack is
 220         * primarily to get to the write_entry() machinery that massages
 221         * the contents to work-tree format and writes out which only
 222         * allows it for a cache entry.  The code in write_entry() needs
 223         * to be refactored to allow us to feed a <buffer, size, mode>
 224         * instead of a cache entry.  Such a refactoring would help
 225         * merge_recursive as well (it also writes the merge result to the
 226         * object database even when it may contain conflicts).
 227         */
 228        if (write_sha1_file(result_buf.ptr, result_buf.size,
 229                            blob_type, sha1))
 230                die(_("Unable to add merge result for '%s'"), path);
 231        ce = make_cache_entry(mode, sha1, path, 2, 0);
 232        if (!ce)
 233                die(_("make_cache_entry failed for path '%s'"), path);
 234        status = checkout_entry(ce, state, NULL);
 235        return status;
 236}
 237
 238static int checkout_paths(const struct checkout_opts *opts,
 239                          const char *revision)
 240{
 241        int pos;
 242        struct checkout state;
 243        static char *ps_matched;
 244        unsigned char rev[20];
 245        int flag;
 246        struct commit *head;
 247        int errs = 0;
 248        struct lock_file *lock_file;
 249
 250        if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 251                die(_("'%s' cannot be used with updating paths"), "--track");
 252
 253        if (opts->new_branch_log)
 254                die(_("'%s' cannot be used with updating paths"), "-l");
 255
 256        if (opts->force && opts->patch_mode)
 257                die(_("'%s' cannot be used with updating paths"), "-f");
 258
 259        if (opts->force_detach)
 260                die(_("'%s' cannot be used with updating paths"), "--detach");
 261
 262        if (opts->merge && opts->patch_mode)
 263                die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 264
 265        if (opts->force && opts->merge)
 266                die(_("'%s' cannot be used with %s"), "-f", "-m");
 267
 268        if (opts->new_branch)
 269                die(_("Cannot update paths and switch to branch '%s' at the same time."),
 270                    opts->new_branch);
 271
 272        if (opts->patch_mode)
 273                return run_add_interactive(revision, "--patch=checkout",
 274                                           &opts->pathspec);
 275
 276        lock_file = xcalloc(1, sizeof(struct lock_file));
 277
 278        hold_locked_index(lock_file, 1);
 279        if (read_cache_preload(&opts->pathspec) < 0)
 280                return error(_("corrupt index file"));
 281
 282        if (opts->source_tree)
 283                read_tree_some(opts->source_tree, &opts->pathspec);
 284
 285        ps_matched = xcalloc(1, opts->pathspec.nr);
 286
 287        /*
 288         * Make sure all pathspecs participated in locating the paths
 289         * to be checked out.
 290         */
 291        for (pos = 0; pos < active_nr; pos++) {
 292                struct cache_entry *ce = active_cache[pos];
 293                ce->ce_flags &= ~CE_MATCHED;
 294                if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 295                        continue;
 296                if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 297                        /*
 298                         * "git checkout tree-ish -- path", but this entry
 299                         * is in the original index; it will not be checked
 300                         * out to the working tree and it does not matter
 301                         * if pathspec matched this entry.  We will not do
 302                         * anything to this entry at all.
 303                         */
 304                        continue;
 305                /*
 306                 * Either this entry came from the tree-ish we are
 307                 * checking the paths out of, or we are checking out
 308                 * of the index.
 309                 *
 310                 * If it comes from the tree-ish, we already know it
 311                 * matches the pathspec and could just stamp
 312                 * CE_MATCHED to it from update_some(). But we still
 313                 * need ps_matched and read_tree_recursive (and
 314                 * eventually tree_entry_interesting) cannot fill
 315                 * ps_matched yet. Once it can, we can avoid calling
 316                 * match_pathspec() for _all_ entries when
 317                 * opts->source_tree != NULL.
 318                 */
 319                if (ce_path_match(ce, &opts->pathspec, ps_matched))
 320                        ce->ce_flags |= CE_MATCHED;
 321        }
 322
 323        if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 324                free(ps_matched);
 325                return 1;
 326        }
 327        free(ps_matched);
 328
 329        /* "checkout -m path" to recreate conflicted state */
 330        if (opts->merge)
 331                unmerge_marked_index(&the_index);
 332
 333        /* Any unmerged paths? */
 334        for (pos = 0; pos < active_nr; pos++) {
 335                const struct cache_entry *ce = active_cache[pos];
 336                if (ce->ce_flags & CE_MATCHED) {
 337                        if (!ce_stage(ce))
 338                                continue;
 339                        if (opts->force) {
 340                                warning(_("path '%s' is unmerged"), ce->name);
 341                        } else if (opts->writeout_stage) {
 342                                errs |= check_stage(opts->writeout_stage, ce, pos);
 343                        } else if (opts->merge) {
 344                                errs |= check_stages((1<<2) | (1<<3), ce, pos);
 345                        } else {
 346                                errs = 1;
 347                                error(_("path '%s' is unmerged"), ce->name);
 348                        }
 349                        pos = skip_same_name(ce, pos) - 1;
 350                }
 351        }
 352        if (errs)
 353                return 1;
 354
 355        /* Now we are committed to check them out */
 356        memset(&state, 0, sizeof(state));
 357        state.force = 1;
 358        state.refresh_cache = 1;
 359        state.istate = &the_index;
 360        for (pos = 0; pos < active_nr; pos++) {
 361                struct cache_entry *ce = active_cache[pos];
 362                if (ce->ce_flags & CE_MATCHED) {
 363                        if (!ce_stage(ce)) {
 364                                errs |= checkout_entry(ce, &state, NULL);
 365                                continue;
 366                        }
 367                        if (opts->writeout_stage)
 368                                errs |= checkout_stage(opts->writeout_stage, ce, pos, &state);
 369                        else if (opts->merge)
 370                                errs |= checkout_merged(pos, &state);
 371                        pos = skip_same_name(ce, pos) - 1;
 372                }
 373        }
 374
 375        if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 376                die(_("unable to write new index file"));
 377
 378        read_ref_full("HEAD", 0, rev, &flag);
 379        head = lookup_commit_reference_gently(rev, 1);
 380
 381        errs |= post_checkout_hook(head, head, 0);
 382        return errs;
 383}
 384
 385static void show_local_changes(struct object *head,
 386                               const struct diff_options *opts)
 387{
 388        struct rev_info rev;
 389        /* I think we want full paths, even if we're in a subdirectory. */
 390        init_revisions(&rev, NULL);
 391        rev.diffopt.flags = opts->flags;
 392        rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 393        diff_setup_done(&rev.diffopt);
 394        add_pending_object(&rev, head, NULL);
 395        run_diff_index(&rev, 0);
 396}
 397
 398static void describe_detached_head(const char *msg, struct commit *commit)
 399{
 400        struct strbuf sb = STRBUF_INIT;
 401        if (!parse_commit(commit))
 402                pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 403        fprintf(stderr, "%s %s... %s\n", msg,
 404                find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
 405        strbuf_release(&sb);
 406}
 407
 408static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 409                      int worktree, int *writeout_error)
 410{
 411        struct unpack_trees_options opts;
 412        struct tree_desc tree_desc;
 413
 414        memset(&opts, 0, sizeof(opts));
 415        opts.head_idx = -1;
 416        opts.update = worktree;
 417        opts.skip_unmerged = !worktree;
 418        opts.reset = 1;
 419        opts.merge = 1;
 420        opts.fn = oneway_merge;
 421        opts.verbose_update = !o->quiet && isatty(2);
 422        opts.src_index = &the_index;
 423        opts.dst_index = &the_index;
 424        parse_tree(tree);
 425        init_tree_desc(&tree_desc, tree->buffer, tree->size);
 426        switch (unpack_trees(1, &tree_desc, &opts)) {
 427        case -2:
 428                *writeout_error = 1;
 429                /*
 430                 * We return 0 nevertheless, as the index is all right
 431                 * and more importantly we have made best efforts to
 432                 * update paths in the work tree, and we cannot revert
 433                 * them.
 434                 */
 435        case 0:
 436                return 0;
 437        default:
 438                return 128;
 439        }
 440}
 441
 442struct branch_info {
 443        const char *name; /* The short name used */
 444        const char *path; /* The full name of a real branch */
 445        struct commit *commit; /* The named commit */
 446        /*
 447         * if not null the branch is detached because it's already
 448         * checked out in this checkout
 449         */
 450        char *checkout;
 451};
 452
 453static void setup_branch_path(struct branch_info *branch)
 454{
 455        struct strbuf buf = STRBUF_INIT;
 456
 457        strbuf_branchname(&buf, branch->name);
 458        if (strcmp(buf.buf, branch->name))
 459                branch->name = xstrdup(buf.buf);
 460        strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 461        branch->path = strbuf_detach(&buf, NULL);
 462}
 463
 464static int merge_working_tree(const struct checkout_opts *opts,
 465                              struct branch_info *old,
 466                              struct branch_info *new,
 467                              int *writeout_error)
 468{
 469        int ret;
 470        struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 471
 472        hold_locked_index(lock_file, 1);
 473        if (read_cache_preload(NULL) < 0)
 474                return error(_("corrupt index file"));
 475
 476        resolve_undo_clear();
 477        if (opts->force) {
 478                ret = reset_tree(new->commit->tree, opts, 1, writeout_error);
 479                if (ret)
 480                        return ret;
 481        } else {
 482                struct tree_desc trees[2];
 483                struct tree *tree;
 484                struct unpack_trees_options topts;
 485
 486                memset(&topts, 0, sizeof(topts));
 487                topts.head_idx = -1;
 488                topts.src_index = &the_index;
 489                topts.dst_index = &the_index;
 490
 491                setup_unpack_trees_porcelain(&topts, "checkout");
 492
 493                refresh_cache(REFRESH_QUIET);
 494
 495                if (unmerged_cache()) {
 496                        error(_("you need to resolve your current index first"));
 497                        return 1;
 498                }
 499
 500                /* 2-way merge to the new branch */
 501                topts.initial_checkout = is_cache_unborn();
 502                topts.update = 1;
 503                topts.merge = 1;
 504                topts.gently = opts->merge && old->commit;
 505                topts.verbose_update = !opts->quiet && isatty(2);
 506                topts.fn = twoway_merge;
 507                if (opts->overwrite_ignore) {
 508                        topts.dir = xcalloc(1, sizeof(*topts.dir));
 509                        topts.dir->flags |= DIR_SHOW_IGNORED;
 510                        setup_standard_excludes(topts.dir);
 511                }
 512                tree = parse_tree_indirect(old->commit && !opts->new_worktree_mode ?
 513                                           old->commit->object.sha1 :
 514                                           EMPTY_TREE_SHA1_BIN);
 515                init_tree_desc(&trees[0], tree->buffer, tree->size);
 516                tree = parse_tree_indirect(new->commit->object.sha1);
 517                init_tree_desc(&trees[1], tree->buffer, tree->size);
 518
 519                ret = unpack_trees(2, trees, &topts);
 520                if (ret == -1) {
 521                        /*
 522                         * Unpack couldn't do a trivial merge; either
 523                         * give up or do a real merge, depending on
 524                         * whether the merge flag was used.
 525                         */
 526                        struct tree *result;
 527                        struct tree *work;
 528                        struct merge_options o;
 529                        if (!opts->merge)
 530                                return 1;
 531
 532                        /*
 533                         * Without old->commit, the below is the same as
 534                         * the two-tree unpack we already tried and failed.
 535                         */
 536                        if (!old->commit)
 537                                return 1;
 538
 539                        /* Do more real merge */
 540
 541                        /*
 542                         * We update the index fully, then write the
 543                         * tree from the index, then merge the new
 544                         * branch with the current tree, with the old
 545                         * branch as the base. Then we reset the index
 546                         * (but not the working tree) to the new
 547                         * branch, leaving the working tree as the
 548                         * merged version, but skipping unmerged
 549                         * entries in the index.
 550                         */
 551
 552                        add_files_to_cache(NULL, NULL, 0);
 553                        /*
 554                         * NEEDSWORK: carrying over local changes
 555                         * when branches have different end-of-line
 556                         * normalization (or clean+smudge rules) is
 557                         * a pain; plumb in an option to set
 558                         * o.renormalize?
 559                         */
 560                        init_merge_options(&o);
 561                        o.verbosity = 0;
 562                        work = write_tree_from_memory(&o);
 563
 564                        ret = reset_tree(new->commit->tree, opts, 1,
 565                                         writeout_error);
 566                        if (ret)
 567                                return ret;
 568                        o.ancestor = old->name;
 569                        o.branch1 = new->name;
 570                        o.branch2 = "local";
 571                        merge_trees(&o, new->commit->tree, work,
 572                                old->commit->tree, &result);
 573                        ret = reset_tree(new->commit->tree, opts, 0,
 574                                         writeout_error);
 575                        if (ret)
 576                                return ret;
 577                }
 578        }
 579
 580        if (!active_cache_tree)
 581                active_cache_tree = cache_tree();
 582
 583        if (!cache_tree_fully_valid(active_cache_tree))
 584                cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 585
 586        if (write_locked_index(&the_index, lock_file, COMMIT_LOCK))
 587                die(_("unable to write new index file"));
 588
 589        if (!opts->force && !opts->quiet)
 590                show_local_changes(&new->commit->object, &opts->diff_options);
 591
 592        return 0;
 593}
 594
 595static void report_tracking(struct branch_info *new)
 596{
 597        struct strbuf sb = STRBUF_INIT;
 598        struct branch *branch = branch_get(new->name);
 599
 600        if (!format_tracking_info(branch, &sb))
 601                return;
 602        fputs(sb.buf, stdout);
 603        strbuf_release(&sb);
 604}
 605
 606static void update_refs_for_switch(const struct checkout_opts *opts,
 607                                   struct branch_info *old,
 608                                   struct branch_info *new)
 609{
 610        struct strbuf msg = STRBUF_INIT;
 611        const char *old_desc, *reflog_msg;
 612        if (opts->new_branch) {
 613                if (opts->new_orphan_branch) {
 614                        if (opts->new_branch_log && !log_all_ref_updates) {
 615                                int temp;
 616                                struct strbuf log_file = STRBUF_INIT;
 617                                int ret;
 618                                const char *ref_name;
 619
 620                                ref_name = mkpath("refs/heads/%s", opts->new_orphan_branch);
 621                                temp = log_all_ref_updates;
 622                                log_all_ref_updates = 1;
 623                                ret = log_ref_setup(ref_name, &log_file);
 624                                log_all_ref_updates = temp;
 625                                strbuf_release(&log_file);
 626                                if (ret) {
 627                                        fprintf(stderr, _("Can not do reflog for '%s'\n"),
 628                                            opts->new_orphan_branch);
 629                                        return;
 630                                }
 631                        }
 632                }
 633                else
 634                        create_branch(old->name, opts->new_branch, new->name,
 635                                      opts->new_branch_force ? 1 : 0,
 636                                      opts->new_branch_log,
 637                                      opts->new_branch_force ? 1 : 0,
 638                                      opts->quiet,
 639                                      opts->track);
 640                new->name = opts->new_branch;
 641                setup_branch_path(new);
 642        }
 643
 644        old_desc = old->name;
 645        if (!old_desc && old->commit)
 646                old_desc = sha1_to_hex(old->commit->object.sha1);
 647
 648        reflog_msg = getenv("GIT_REFLOG_ACTION");
 649        if (!reflog_msg)
 650                strbuf_addf(&msg, "checkout: moving from %s to %s",
 651                        old_desc ? old_desc : "(invalid)", new->name);
 652        else
 653                strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 654
 655        if (!strcmp(new->name, "HEAD") && !new->path && !opts->force_detach) {
 656                /* Nothing to do. */
 657        } else if (opts->force_detach || !new->path) {  /* No longer on any branch. */
 658                update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
 659                           REF_NODEREF, UPDATE_REFS_DIE_ON_ERR);
 660                if (!opts->quiet) {
 661                        if (old->path && advice_detached_head)
 662                                detach_advice(new->name);
 663                        describe_detached_head(_("HEAD is now at"), new->commit);
 664                }
 665        } else if (new->path) { /* Switch branches. */
 666                create_symref("HEAD", new->path, msg.buf);
 667                if (!opts->quiet) {
 668                        if (old->path && !strcmp(new->path, old->path)) {
 669                                if (opts->new_branch_force)
 670                                        fprintf(stderr, _("Reset branch '%s'\n"),
 671                                                new->name);
 672                                else
 673                                        fprintf(stderr, _("Already on '%s'\n"),
 674                                                new->name);
 675                        } else if (opts->new_branch) {
 676                                if (opts->branch_exists)
 677                                        fprintf(stderr, _("Switched to and reset branch '%s'\n"), new->name);
 678                                else
 679                                        fprintf(stderr, _("Switched to a new branch '%s'\n"), new->name);
 680                        } else {
 681                                fprintf(stderr, _("Switched to branch '%s'\n"),
 682                                        new->name);
 683                        }
 684                }
 685                if (old->path && old->name) {
 686                        if (!ref_exists(old->path) && reflog_exists(old->path))
 687                                delete_reflog(old->path);
 688                }
 689        }
 690        remove_branch_state();
 691        strbuf_release(&msg);
 692        if (!opts->quiet &&
 693            (new->path || (!opts->force_detach && !strcmp(new->name, "HEAD"))))
 694                report_tracking(new);
 695}
 696
 697static int add_pending_uninteresting_ref(const char *refname,
 698                                         const struct object_id *oid,
 699                                         int flags, void *cb_data)
 700{
 701        add_pending_sha1(cb_data, refname, oid->hash, UNINTERESTING);
 702        return 0;
 703}
 704
 705static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 706{
 707        strbuf_addstr(sb, "  ");
 708        strbuf_addstr(sb,
 709                find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 710        strbuf_addch(sb, ' ');
 711        if (!parse_commit(commit))
 712                pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 713        strbuf_addch(sb, '\n');
 714}
 715
 716#define ORPHAN_CUTOFF 4
 717static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 718{
 719        struct commit *c, *last = NULL;
 720        struct strbuf sb = STRBUF_INIT;
 721        int lost = 0;
 722        while ((c = get_revision(revs)) != NULL) {
 723                if (lost < ORPHAN_CUTOFF)
 724                        describe_one_orphan(&sb, c);
 725                last = c;
 726                lost++;
 727        }
 728        if (ORPHAN_CUTOFF < lost) {
 729                int more = lost - ORPHAN_CUTOFF;
 730                if (more == 1)
 731                        describe_one_orphan(&sb, last);
 732                else
 733                        strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 734        }
 735
 736        fprintf(stderr,
 737                Q_(
 738                /* The singular version */
 739                "Warning: you are leaving %d commit behind, "
 740                "not connected to\n"
 741                "any of your branches:\n\n"
 742                "%s\n",
 743                /* The plural version */
 744                "Warning: you are leaving %d commits behind, "
 745                "not connected to\n"
 746                "any of your branches:\n\n"
 747                "%s\n",
 748                /* Give ngettext() the count */
 749                lost),
 750                lost,
 751                sb.buf);
 752        strbuf_release(&sb);
 753
 754        if (advice_detached_head)
 755                fprintf(stderr,
 756                        Q_(
 757                        /* The singular version */
 758                        "If you want to keep it by creating a new branch, "
 759                        "this may be a good time\nto do so with:\n\n"
 760                        " git branch <new-branch-name> %s\n\n",
 761                        /* The plural version */
 762                        "If you want to keep them by creating a new branch, "
 763                        "this may be a good time\nto do so with:\n\n"
 764                        " git branch <new-branch-name> %s\n\n",
 765                        /* Give ngettext() the count */
 766                        lost),
 767                        find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 768}
 769
 770/*
 771 * We are about to leave commit that was at the tip of a detached
 772 * HEAD.  If it is not reachable from any ref, this is the last chance
 773 * for the user to do so without resorting to reflog.
 774 */
 775static void orphaned_commit_warning(struct commit *old, struct commit *new)
 776{
 777        struct rev_info revs;
 778        struct object *object = &old->object;
 779        struct object_array refs;
 780
 781        init_revisions(&revs, NULL);
 782        setup_revisions(0, NULL, &revs, NULL);
 783
 784        object->flags &= ~UNINTERESTING;
 785        add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 786
 787        for_each_ref(add_pending_uninteresting_ref, &revs);
 788        add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
 789
 790        refs = revs.pending;
 791        revs.leak_pending = 1;
 792
 793        if (prepare_revision_walk(&revs))
 794                die(_("internal error in revision walk"));
 795        if (!(old->object.flags & UNINTERESTING))
 796                suggest_reattach(old, &revs);
 797        else
 798                describe_detached_head(_("Previous HEAD position was"), old);
 799
 800        clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 801        free(refs.objects);
 802}
 803
 804static int switch_branches(const struct checkout_opts *opts,
 805                           struct branch_info *new)
 806{
 807        int ret = 0;
 808        struct branch_info old;
 809        void *path_to_free;
 810        unsigned char rev[20];
 811        int flag, writeout_error = 0;
 812        memset(&old, 0, sizeof(old));
 813        old.path = path_to_free = resolve_refdup("HEAD", 0, rev, &flag);
 814        old.commit = lookup_commit_reference_gently(rev, 1);
 815        if (!(flag & REF_ISSYMREF))
 816                old.path = NULL;
 817
 818        if (old.path)
 819                skip_prefix(old.path, "refs/heads/", &old.name);
 820
 821        if (!new->name) {
 822                new->name = "HEAD";
 823                new->commit = old.commit;
 824                if (!new->commit)
 825                        die(_("You are on a branch yet to be born"));
 826                parse_commit_or_die(new->commit);
 827        }
 828
 829        ret = merge_working_tree(opts, &old, new, &writeout_error);
 830        if (ret) {
 831                free(path_to_free);
 832                return ret;
 833        }
 834
 835        if (!opts->quiet && !old.path && old.commit &&
 836            new->commit != old.commit && !opts->new_worktree_mode)
 837                orphaned_commit_warning(old.commit, new->commit);
 838
 839        update_refs_for_switch(opts, &old, new);
 840
 841        ret = post_checkout_hook(old.commit, new->commit, 1);
 842        free(path_to_free);
 843        return ret || writeout_error;
 844}
 845
 846static int git_checkout_config(const char *var, const char *value, void *cb)
 847{
 848        if (!strcmp(var, "diff.ignoresubmodules")) {
 849                struct checkout_opts *opts = cb;
 850                handle_ignore_submodules_arg(&opts->diff_options, value);
 851                return 0;
 852        }
 853
 854        if (starts_with(var, "submodule."))
 855                return parse_submodule_config_option(var, value);
 856
 857        return git_xmerge_config(var, value, NULL);
 858}
 859
 860struct tracking_name_data {
 861        /* const */ char *src_ref;
 862        char *dst_ref;
 863        unsigned char *dst_sha1;
 864        int unique;
 865};
 866
 867static int check_tracking_name(struct remote *remote, void *cb_data)
 868{
 869        struct tracking_name_data *cb = cb_data;
 870        struct refspec query;
 871        memset(&query, 0, sizeof(struct refspec));
 872        query.src = cb->src_ref;
 873        if (remote_find_tracking(remote, &query) ||
 874            get_sha1(query.dst, cb->dst_sha1)) {
 875                free(query.dst);
 876                return 0;
 877        }
 878        if (cb->dst_ref) {
 879                free(query.dst);
 880                cb->unique = 0;
 881                return 0;
 882        }
 883        cb->dst_ref = query.dst;
 884        return 0;
 885}
 886
 887static const char *unique_tracking_name(const char *name, unsigned char *sha1)
 888{
 889        struct tracking_name_data cb_data = { NULL, NULL, NULL, 1 };
 890        char src_ref[PATH_MAX];
 891        snprintf(src_ref, PATH_MAX, "refs/heads/%s", name);
 892        cb_data.src_ref = src_ref;
 893        cb_data.dst_sha1 = sha1;
 894        for_each_remote(check_tracking_name, &cb_data);
 895        if (cb_data.unique)
 896                return cb_data.dst_ref;
 897        free(cb_data.dst_ref);
 898        return NULL;
 899}
 900
 901static void check_linked_checkout(struct branch_info *new, const char *id)
 902{
 903        struct strbuf sb = STRBUF_INIT;
 904        struct strbuf path = STRBUF_INIT;
 905        struct strbuf gitdir = STRBUF_INIT;
 906        const char *start, *end;
 907
 908        if (id)
 909                strbuf_addf(&path, "%s/worktrees/%s/HEAD", get_git_common_dir(), id);
 910        else
 911                strbuf_addf(&path, "%s/HEAD", get_git_common_dir());
 912
 913        if (strbuf_read_file(&sb, path.buf, 0) < 0 ||
 914            !skip_prefix(sb.buf, "ref:", &start))
 915                goto done;
 916        while (isspace(*start))
 917                start++;
 918        end = start;
 919        while (*end && !isspace(*end))
 920                end++;
 921        if (strncmp(start, new->path, end - start) || new->path[end - start] != '\0')
 922                goto done;
 923        if (id) {
 924                strbuf_reset(&path);
 925                strbuf_addf(&path, "%s/worktrees/%s/gitdir", get_git_common_dir(), id);
 926                if (strbuf_read_file(&gitdir, path.buf, 0) <= 0)
 927                        goto done;
 928                strbuf_rtrim(&gitdir);
 929        } else
 930                strbuf_addstr(&gitdir, get_git_common_dir());
 931        die(_("'%s' is already checked out at '%s'"), new->name, gitdir.buf);
 932done:
 933        strbuf_release(&path);
 934        strbuf_release(&sb);
 935        strbuf_release(&gitdir);
 936}
 937
 938static void check_linked_checkouts(struct branch_info *new)
 939{
 940        struct strbuf path = STRBUF_INIT;
 941        DIR *dir;
 942        struct dirent *d;
 943
 944        strbuf_addf(&path, "%s/worktrees", get_git_common_dir());
 945        if ((dir = opendir(path.buf)) == NULL) {
 946                strbuf_release(&path);
 947                return;
 948        }
 949
 950        /*
 951         * $GIT_COMMON_DIR/HEAD is practically outside
 952         * $GIT_DIR so resolve_ref_unsafe() won't work (it
 953         * uses git_path). Parse the ref ourselves.
 954         */
 955        check_linked_checkout(new, NULL);
 956
 957        while ((d = readdir(dir)) != NULL) {
 958                if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
 959                        continue;
 960                check_linked_checkout(new, d->d_name);
 961        }
 962        strbuf_release(&path);
 963        closedir(dir);
 964}
 965
 966static int parse_branchname_arg(int argc, const char **argv,
 967                                int dwim_new_local_branch_ok,
 968                                struct branch_info *new,
 969                                struct checkout_opts *opts,
 970                                unsigned char rev[20])
 971{
 972        struct tree **source_tree = &opts->source_tree;
 973        const char **new_branch = &opts->new_branch;
 974        int argcount = 0;
 975        unsigned char branch_rev[20];
 976        const char *arg;
 977        int dash_dash_pos;
 978        int has_dash_dash = 0;
 979        int i;
 980
 981        /*
 982         * case 1: git checkout <ref> -- [<paths>]
 983         *
 984         *   <ref> must be a valid tree, everything after the '--' must be
 985         *   a path.
 986         *
 987         * case 2: git checkout -- [<paths>]
 988         *
 989         *   everything after the '--' must be paths.
 990         *
 991         * case 3: git checkout <something> [--]
 992         *
 993         *   (a) If <something> is a commit, that is to
 994         *       switch to the branch or detach HEAD at it.  As a special case,
 995         *       if <something> is A...B (missing A or B means HEAD but you can
 996         *       omit at most one side), and if there is a unique merge base
 997         *       between A and B, A...B names that merge base.
 998         *
 999         *   (b) If <something> is _not_ a commit, either "--" is present
1000         *       or <something> is not a path, no -t or -b was given, and
1001         *       and there is a tracking branch whose name is <something>
1002         *       in one and only one remote, then this is a short-hand to
1003         *       fork local <something> from that remote-tracking branch.
1004         *
1005         *   (c) Otherwise, if "--" is present, treat it like case (1).
1006         *
1007         *   (d) Otherwise :
1008         *       - if it's a reference, treat it like case (1)
1009         *       - else if it's a path, treat it like case (2)
1010         *       - else: fail.
1011         *
1012         * case 4: git checkout <something> <paths>
1013         *
1014         *   The first argument must not be ambiguous.
1015         *   - If it's *only* a reference, treat it like case (1).
1016         *   - If it's only a path, treat it like case (2).
1017         *   - else: fail.
1018         *
1019         */
1020        if (!argc)
1021                return 0;
1022
1023        arg = argv[0];
1024        dash_dash_pos = -1;
1025        for (i = 0; i < argc; i++) {
1026                if (!strcmp(argv[i], "--")) {
1027                        dash_dash_pos = i;
1028                        break;
1029                }
1030        }
1031        if (dash_dash_pos == 0)
1032                return 1; /* case (2) */
1033        else if (dash_dash_pos == 1)
1034                has_dash_dash = 1; /* case (3) or (1) */
1035        else if (dash_dash_pos >= 2)
1036                die(_("only one reference expected, %d given."), dash_dash_pos);
1037
1038        if (!strcmp(arg, "-"))
1039                arg = "@{-1}";
1040
1041        if (get_sha1_mb(arg, rev)) {
1042                /*
1043                 * Either case (3) or (4), with <something> not being
1044                 * a commit, or an attempt to use case (1) with an
1045                 * invalid ref.
1046                 *
1047                 * It's likely an error, but we need to find out if
1048                 * we should auto-create the branch, case (3).(b).
1049                 */
1050                int recover_with_dwim = dwim_new_local_branch_ok;
1051
1052                if (check_filename(NULL, arg) && !has_dash_dash)
1053                        recover_with_dwim = 0;
1054                /*
1055                 * Accept "git checkout foo" and "git checkout foo --"
1056                 * as candidates for dwim.
1057                 */
1058                if (!(argc == 1 && !has_dash_dash) &&
1059                    !(argc == 2 && has_dash_dash))
1060                        recover_with_dwim = 0;
1061
1062                if (recover_with_dwim) {
1063                        const char *remote = unique_tracking_name(arg, rev);
1064                        if (remote) {
1065                                *new_branch = arg;
1066                                arg = remote;
1067                                /* DWIMmed to create local branch, case (3).(b) */
1068                        } else {
1069                                recover_with_dwim = 0;
1070                        }
1071                }
1072
1073                if (!recover_with_dwim) {
1074                        if (has_dash_dash)
1075                                die(_("invalid reference: %s"), arg);
1076                        return argcount;
1077                }
1078        }
1079
1080        /* we can't end up being in (2) anymore, eat the argument */
1081        argcount++;
1082        argv++;
1083        argc--;
1084
1085        new->name = arg;
1086        setup_branch_path(new);
1087
1088        if (!check_refname_format(new->path, 0) &&
1089            !read_ref(new->path, branch_rev))
1090                hashcpy(rev, branch_rev);
1091        else
1092                new->path = NULL; /* not an existing branch */
1093
1094        new->commit = lookup_commit_reference_gently(rev, 1);
1095        if (!new->commit) {
1096                /* not a commit */
1097                *source_tree = parse_tree_indirect(rev);
1098        } else {
1099                parse_commit_or_die(new->commit);
1100                *source_tree = new->commit->tree;
1101        }
1102
1103        if (!*source_tree)                   /* case (1): want a tree */
1104                die(_("reference is not a tree: %s"), arg);
1105        if (!has_dash_dash) {/* case (3).(d) -> (1) */
1106                /*
1107                 * Do not complain the most common case
1108                 *      git checkout branch
1109                 * even if there happen to be a file called 'branch';
1110                 * it would be extremely annoying.
1111                 */
1112                if (argc)
1113                        verify_non_filename(NULL, arg);
1114        } else {
1115                argcount++;
1116                argv++;
1117                argc--;
1118        }
1119
1120        return argcount;
1121}
1122
1123static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1124{
1125        int status;
1126        struct strbuf branch_ref = STRBUF_INIT;
1127
1128        if (!opts->new_branch)
1129                die(_("You are on a branch yet to be born"));
1130        strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1131        status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1132        strbuf_release(&branch_ref);
1133        if (!opts->quiet)
1134                fprintf(stderr, _("Switched to a new branch '%s'\n"),
1135                        opts->new_branch);
1136        return status;
1137}
1138
1139static int checkout_branch(struct checkout_opts *opts,
1140                           struct branch_info *new)
1141{
1142        if (opts->pathspec.nr)
1143                die(_("paths cannot be used with switching branches"));
1144
1145        if (opts->patch_mode)
1146                die(_("'%s' cannot be used with switching branches"),
1147                    "--patch");
1148
1149        if (opts->writeout_stage)
1150                die(_("'%s' cannot be used with switching branches"),
1151                    "--ours/--theirs");
1152
1153        if (opts->force && opts->merge)
1154                die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1155
1156        if (opts->force_detach && opts->new_branch)
1157                die(_("'%s' cannot be used with '%s'"),
1158                    "--detach", "-b/-B/--orphan");
1159
1160        if (opts->new_orphan_branch) {
1161                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1162                        die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1163        } else if (opts->force_detach) {
1164                if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1165                        die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1166        } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1167                opts->track = git_branch_track;
1168
1169        if (new->name && !new->commit)
1170                die(_("Cannot switch branch to a non-commit '%s'"),
1171                    new->name);
1172
1173        if (new->path && !opts->force_detach && !opts->new_branch) {
1174                unsigned char sha1[20];
1175                int flag;
1176                char *head_ref = resolve_refdup("HEAD", 0, sha1, &flag);
1177                if (head_ref &&
1178                    (!(flag & REF_ISSYMREF) || strcmp(head_ref, new->path)) &&
1179                    !opts->ignore_other_worktrees)
1180                        check_linked_checkouts(new);
1181                free(head_ref);
1182        }
1183
1184        if (!new->commit && opts->new_branch) {
1185                unsigned char rev[20];
1186                int flag;
1187
1188                if (!read_ref_full("HEAD", 0, rev, &flag) &&
1189                    (flag & REF_ISSYMREF) && is_null_sha1(rev))
1190                        return switch_unborn_to_new_branch(opts);
1191        }
1192        return switch_branches(opts, new);
1193}
1194
1195int cmd_checkout(int argc, const char **argv, const char *prefix)
1196{
1197        struct checkout_opts opts;
1198        struct branch_info new;
1199        char *conflict_style = NULL;
1200        int dwim_new_local_branch = 1;
1201        struct option options[] = {
1202                OPT__QUIET(&opts.quiet, N_("suppress progress reporting")),
1203                OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1204                           N_("create and checkout a new branch")),
1205                OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1206                           N_("create/reset and checkout a branch")),
1207                OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1208                OPT_BOOL(0, "detach", &opts.force_detach, N_("detach the HEAD at named commit")),
1209                OPT_SET_INT('t', "track",  &opts.track, N_("set upstream info for new branch"),
1210                        BRANCH_TRACK_EXPLICIT),
1211                OPT_STRING(0, "orphan", &opts.new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1212                OPT_SET_INT('2', "ours", &opts.writeout_stage, N_("checkout our version for unmerged files"),
1213                            2),
1214                OPT_SET_INT('3', "theirs", &opts.writeout_stage, N_("checkout their version for unmerged files"),
1215                            3),
1216                OPT__FORCE(&opts.force, N_("force checkout (throw away local modifications)")),
1217                OPT_BOOL('m', "merge", &opts.merge, N_("perform a 3-way merge with the new branch")),
1218                OPT_BOOL(0, "overwrite-ignore", &opts.overwrite_ignore, N_("update ignored files (default)")),
1219                OPT_STRING(0, "conflict", &conflict_style, N_("style"),
1220                           N_("conflict style (merge or diff3)")),
1221                OPT_BOOL('p', "patch", &opts.patch_mode, N_("select hunks interactively")),
1222                OPT_BOOL(0, "ignore-skip-worktree-bits", &opts.ignore_skipworktree,
1223                         N_("do not limit pathspecs to sparse entries only")),
1224                OPT_HIDDEN_BOOL(0, "guess", &dwim_new_local_branch,
1225                                N_("second guess 'git checkout <no-such-branch>'")),
1226                OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
1227                         N_("do not check if another worktree is holding the given ref")),
1228                OPT_END(),
1229        };
1230
1231        memset(&opts, 0, sizeof(opts));
1232        memset(&new, 0, sizeof(new));
1233        opts.overwrite_ignore = 1;
1234        opts.prefix = prefix;
1235
1236        gitmodules_config();
1237        git_config(git_checkout_config, &opts);
1238
1239        opts.track = BRANCH_TRACK_UNSPECIFIED;
1240
1241        argc = parse_options(argc, argv, prefix, options, checkout_usage,
1242                             PARSE_OPT_KEEP_DASHDASH);
1243
1244        opts.new_worktree_mode = getenv("GIT_CHECKOUT_NEW_WORKTREE") != NULL;
1245
1246        if (conflict_style) {
1247                opts.merge = 1; /* implied */
1248                git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
1249        }
1250
1251        if ((!!opts.new_branch + !!opts.new_branch_force + !!opts.new_orphan_branch) > 1)
1252                die(_("-b, -B and --orphan are mutually exclusive"));
1253
1254        /*
1255         * From here on, new_branch will contain the branch to be checked out,
1256         * and new_branch_force and new_orphan_branch will tell us which one of
1257         * -b/-B/--orphan is being used.
1258         */
1259        if (opts.new_branch_force)
1260                opts.new_branch = opts.new_branch_force;
1261
1262        if (opts.new_orphan_branch)
1263                opts.new_branch = opts.new_orphan_branch;
1264
1265        /* --track without -b/-B/--orphan should DWIM */
1266        if (opts.track != BRANCH_TRACK_UNSPECIFIED && !opts.new_branch) {
1267                const char *argv0 = argv[0];
1268                if (!argc || !strcmp(argv0, "--"))
1269                        die (_("--track needs a branch name"));
1270                skip_prefix(argv0, "refs/", &argv0);
1271                skip_prefix(argv0, "remotes/", &argv0);
1272                argv0 = strchr(argv0, '/');
1273                if (!argv0 || !argv0[1])
1274                        die (_("Missing branch name; try -b"));
1275                opts.new_branch = argv0 + 1;
1276        }
1277
1278        /*
1279         * Extract branch name from command line arguments, so
1280         * all that is left is pathspecs.
1281         *
1282         * Handle
1283         *
1284         *  1) git checkout <tree> -- [<paths>]
1285         *  2) git checkout -- [<paths>]
1286         *  3) git checkout <something> [<paths>]
1287         *
1288         * including "last branch" syntax and DWIM-ery for names of
1289         * remote branches, erroring out for invalid or ambiguous cases.
1290         */
1291        if (argc) {
1292                unsigned char rev[20];
1293                int dwim_ok =
1294                        !opts.patch_mode &&
1295                        dwim_new_local_branch &&
1296                        opts.track == BRANCH_TRACK_UNSPECIFIED &&
1297                        !opts.new_branch;
1298                int n = parse_branchname_arg(argc, argv, dwim_ok,
1299                                             &new, &opts, rev);
1300                argv += n;
1301                argc -= n;
1302        }
1303
1304        if (argc) {
1305                parse_pathspec(&opts.pathspec, 0,
1306                               opts.patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1307                               prefix, argv);
1308
1309                if (!opts.pathspec.nr)
1310                        die(_("invalid path specification"));
1311
1312                /*
1313                 * Try to give more helpful suggestion.
1314                 * new_branch && argc > 1 will be caught later.
1315                 */
1316                if (opts.new_branch && argc == 1)
1317                        die(_("Cannot update paths and switch to branch '%s' at the same time.\n"
1318                              "Did you intend to checkout '%s' which can not be resolved as commit?"),
1319                            opts.new_branch, argv[0]);
1320
1321                if (opts.force_detach)
1322                        die(_("git checkout: --detach does not take a path argument '%s'"),
1323                            argv[0]);
1324
1325                if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
1326                        die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1327                              "checking out of the index."));
1328        }
1329
1330        if (opts.new_branch) {
1331                struct strbuf buf = STRBUF_INIT;
1332
1333                opts.branch_exists =
1334                        validate_new_branchname(opts.new_branch, &buf,
1335                                                !!opts.new_branch_force,
1336                                                !!opts.new_branch_force);
1337
1338                strbuf_release(&buf);
1339        }
1340
1341        if (opts.patch_mode || opts.pathspec.nr)
1342                return checkout_paths(&opts, new.name);
1343        else
1344                return checkout_branch(&opts, &new);
1345}