git.oblomov.eu Git - git/blob - builtin/checkout.c

   1 #define USE_THE_INDEX_COMPATIBILITY_MACROS
   2 #include "builtin.h"
   3 #include "advice.h"
   4 #include "blob.h"
   5 #include "branch.h"
   6 #include "cache-tree.h"
   7 #include "checkout.h"
   8 #include "commit.h"
   9 #include "config.h"
  10 #include "diff.h"
  11 #include "dir.h"
  12 #include "ll-merge.h"
  13 #include "lockfile.h"
  14 #include "merge-recursive.h"
  15 #include "object-store.h"
  16 #include "parse-options.h"
  17 #include "refs.h"
  18 #include "remote.h"
  19 #include "resolve-undo.h"
  20 #include "revision.h"
  21 #include "run-command.h"
  22 #include "submodule.h"
  23 #include "submodule-config.h"
  24 #include "tree.h"
  25 #include "tree-walk.h"
  26 #include "unpack-trees.h"
  27 #include "wt-status.h"
  28 #include "xdiff-interface.h"
  29
  30 static const char * const checkout_usage[] = {
  31         N_("git checkout [<options>] <branch>"),
  32         N_("git checkout [<options>] [<branch>] -- <file>..."),
  33         NULL,
  34 };
  35
  36 static const char * const switch_branch_usage[] = {
  37         N_("git switch [<options>] [<branch>]"),
  38         NULL,
  39 };
  40
  41 static const char * const restore_usage[] = {
  42         N_("git restore [<options>] [--source=<branch>] <file>..."),
  43         NULL,
  44 };
  45
  46 struct checkout_opts {
  47         int patch_mode;
  48         int quiet;
  49         int merge;
  50         int force;
  51         int force_detach;
  52         int implicit_detach;
  53         int writeout_stage;
  54         int overwrite_ignore;
  55         int ignore_skipworktree;
  56         int ignore_other_worktrees;
  57         int show_progress;
  58         int count_checkout_paths;
  59         int overlay_mode;
  60         int dwim_new_local_branch;
  61         int discard_changes;
  62         int accept_ref;
  63         int accept_pathspec;
  64         int switch_branch_doing_nothing_is_ok;
  65         int only_merge_on_switching_branches;
  66         int can_switch_when_in_progress;
  67         int orphan_from_empty_tree;
  68         int empty_pathspec_ok;
  69         int checkout_index;
  70         int checkout_worktree;
  71         const char *ignore_unmerged_opt;
  72         int ignore_unmerged;
  73
  74         const char *new_branch;
  75         const char *new_branch_force;
  76         const char *new_orphan_branch;
  77         int new_branch_log;
  78         enum branch_track track;
  79         struct diff_options diff_options;
  80         char *conflict_style;
  81
  82         int branch_exists;
  83         const char *prefix;
  84         struct pathspec pathspec;
  85         const char *from_treeish;
  86         struct tree *source_tree;
  87 };
  88
  89 static int post_checkout_hook(struct commit *old_commit, struct commit *new_commit,
  90                               int changed)
  91 {
  92         return run_hook_le(NULL, "post-checkout",
  93                            oid_to_hex(old_commit ? &old_commit->object.oid : &null_oid),
  94                            oid_to_hex(new_commit ? &new_commit->object.oid : &null_oid),
  95                            changed ? "1" : "0", NULL);
  96         /* "new_commit" can be NULL when checking out from the index before
  97            a commit exists. */
  98
  99 }
 100
 101 static int update_some(const struct object_id *oid, struct strbuf *base,
 102                 const char *pathname, unsigned mode, int stage, void *context)
 103 {
 104         int len;
 105         struct cache_entry *ce;
 106         int pos;
 107
 108         if (S_ISDIR(mode))
 109                 return READ_TREE_RECURSIVE;
 110
 111         len = base->len + strlen(pathname);
 112         ce = make_empty_cache_entry(&the_index, len);
 113         oidcpy(&ce->oid, oid);
 114         memcpy(ce->name, base->buf, base->len);
 115         memcpy(ce->name + base->len, pathname, len - base->len);
 116         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
 117         ce->ce_namelen = len;
 118         ce->ce_mode = create_ce_mode(mode);
 119
 120         /*
 121          * If the entry is the same as the current index, we can leave the old
 122          * entry in place. Whether it is UPTODATE or not, checkout_entry will
 123          * do the right thing.
 124          */
 125         pos = cache_name_pos(ce->name, ce->ce_namelen);
 126         if (pos >= 0) {
 127                 struct cache_entry *old = active_cache[pos];
 128                 if (ce->ce_mode == old->ce_mode &&
 129                     oideq(&ce->oid, &old->oid)) {
 130                         old->ce_flags |= CE_UPDATE;
 131                         discard_cache_entry(ce);
 132                         return 0;
 133                 }
 134         }
 135
 136         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 137         return 0;
 138 }
 139
 140 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
 141 {
 142         read_tree_recursive(the_repository, tree, "", 0, 0,
 143                             pathspec, update_some, NULL);
 144
 145         /* update the index with the given tree's info
 146          * for all args, expanding wildcards, and exit
 147          * with any non-zero return code.
 148          */
 149         return 0;
 150 }
 151
 152 static int skip_same_name(const struct cache_entry *ce, int pos)
 153 {
 154         while (++pos < active_nr &&
 155                !strcmp(active_cache[pos]->name, ce->name))
 156                 ; /* skip */
 157         return pos;
 158 }
 159
 160 static int check_stage(int stage, const struct cache_entry *ce, int pos,
 161                        int overlay_mode)
 162 {
 163         while (pos < active_nr &&
 164                !strcmp(active_cache[pos]->name, ce->name)) {
 165                 if (ce_stage(active_cache[pos]) == stage)
 166                         return 0;
 167                 pos++;
 168         }
 169         if (!overlay_mode)
 170                 return 0;
 171         if (stage == 2)
 172                 return error(_("path '%s' does not have our version"), ce->name);
 173         else
 174                 return error(_("path '%s' does not have their version"), ce->name);
 175 }
 176
 177 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
 178 {
 179         unsigned seen = 0;
 180         const char *name = ce->name;
 181
 182         while (pos < active_nr) {
 183                 ce = active_cache[pos];
 184                 if (strcmp(name, ce->name))
 185                         break;
 186                 seen |= (1 << ce_stage(ce));
 187                 pos++;
 188         }
 189         if ((stages & seen) != stages)
 190                 return error(_("path '%s' does not have all necessary versions"),
 191                              name);
 192         return 0;
 193 }
 194
 195 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
 196                           const struct checkout *state, int *nr_checkouts,
 197                           int overlay_mode)
 198 {
 199         while (pos < active_nr &&
 200                !strcmp(active_cache[pos]->name, ce->name)) {
 201                 if (ce_stage(active_cache[pos]) == stage)
 202                         return checkout_entry(active_cache[pos], state,
 203                                               NULL, nr_checkouts);
 204                 pos++;
 205         }
 206         if (!overlay_mode) {
 207                 unlink_entry(ce);
 208                 return 0;
 209         }
 210         if (stage == 2)
 211                 return error(_("path '%s' does not have our version"), ce->name);
 212         else
 213                 return error(_("path '%s' does not have their version"), ce->name);
 214 }
 215
 216 static int checkout_merged(int pos, const struct checkout *state, int *nr_checkouts)
 217 {
 218         struct cache_entry *ce = active_cache[pos];
 219         const char *path = ce->name;
 220         mmfile_t ancestor, ours, theirs;
 221         int status;
 222         struct object_id oid;
 223         mmbuffer_t result_buf;
 224         struct object_id threeway[3];
 225         unsigned mode = 0;
 226
 227         memset(threeway, 0, sizeof(threeway));
 228         while (pos < active_nr) {
 229                 int stage;
 230                 stage = ce_stage(ce);
 231                 if (!stage || strcmp(path, ce->name))
 232                         break;
 233                 oidcpy(&threeway[stage - 1], &ce->oid);
 234                 if (stage == 2)
 235                         mode = create_ce_mode(ce->ce_mode);
 236                 pos++;
 237                 ce = active_cache[pos];
 238         }
 239         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
 240                 return error(_("path '%s' does not have necessary versions"), path);
 241
 242         read_mmblob(&ancestor, &threeway[0]);
 243         read_mmblob(&ours, &threeway[1]);
 244         read_mmblob(&theirs, &threeway[2]);
 245
 246         /*
 247          * NEEDSWORK: re-create conflicts from merges with
 248          * merge.renormalize set, too
 249          */
 250         status = ll_merge(&result_buf, path, &ancestor, "base",
 251                           &ours, "ours", &theirs, "theirs",
 252                           state->istate, NULL);
 253         free(ancestor.ptr);
 254         free(ours.ptr);
 255         free(theirs.ptr);
 256         if (status < 0 || !result_buf.ptr) {
 257                 free(result_buf.ptr);
 258                 return error(_("path '%s': cannot merge"), path);
 259         }
 260
 261         /*
 262          * NEEDSWORK:
 263          * There is absolutely no reason to write this as a blob object
 264          * and create a phony cache entry.  This hack is primarily to get
 265          * to the write_entry() machinery that massages the contents to
 266          * work-tree format and writes out which only allows it for a
 267          * cache entry.  The code in write_entry() needs to be refactored
 268          * to allow us to feed a <buffer, size, mode> instead of a cache
 269          * entry.  Such a refactoring would help merge_recursive as well
 270          * (it also writes the merge result to the object database even
 271          * when it may contain conflicts).
 272          */
 273         if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
 274                 die(_("Unable to add merge result for '%s'"), path);
 275         free(result_buf.ptr);
 276         ce = make_transient_cache_entry(mode, &oid, path, 2);
 277         if (!ce)
 278                 die(_("make_cache_entry failed for path '%s'"), path);
 279         status = checkout_entry(ce, state, NULL, nr_checkouts);
 280         discard_cache_entry(ce);
 281         return status;
 282 }
 283
 284 static void mark_ce_for_checkout_overlay(struct cache_entry *ce,
 285                                          char *ps_matched,
 286                                          const struct checkout_opts *opts)
 287 {
 288         ce->ce_flags &= ~CE_MATCHED;
 289         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 290                 return;
 291         if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 292                 /*
 293                  * "git checkout tree-ish -- path", but this entry
 294                  * is in the original index but is not in tree-ish
 295                  * or does not match the pathspec; it will not be
 296                  * checked out to the working tree.  We will not do
 297                  * anything to this entry at all.
 298                  */
 299                 return;
 300         /*
 301          * Either this entry came from the tree-ish we are
 302          * checking the paths out of, or we are checking out
 303          * of the index.
 304          *
 305          * If it comes from the tree-ish, we already know it
 306          * matches the pathspec and could just stamp
 307          * CE_MATCHED to it from update_some(). But we still
 308          * need ps_matched and read_tree_recursive (and
 309          * eventually tree_entry_interesting) cannot fill
 310          * ps_matched yet. Once it can, we can avoid calling
 311          * match_pathspec() for _all_ entries when
 312          * opts->source_tree != NULL.
 313          */
 314         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched))
 315                 ce->ce_flags |= CE_MATCHED;
 316 }
 317
 318 static void mark_ce_for_checkout_no_overlay(struct cache_entry *ce,
 319                                             char *ps_matched,
 320                                             const struct checkout_opts *opts)
 321 {
 322         ce->ce_flags &= ~CE_MATCHED;
 323         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
 324                 return;
 325         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched)) {
 326                 ce->ce_flags |= CE_MATCHED;
 327                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
 328                         /*
 329                          * In overlay mode, but the path is not in
 330                          * tree-ish, which means we should remove it
 331                          * from the index and the working tree.
 332                          */
 333                         ce->ce_flags |= CE_REMOVE | CE_WT_REMOVE;
 334         }
 335 }
 336
 337 static int checkout_worktree(const struct checkout_opts *opts)
 338 {
 339         struct checkout state = CHECKOUT_INIT;
 340         int nr_checkouts = 0, nr_unmerged = 0;
 341         int errs = 0;
 342         int pos;
 343
 344         state.force = 1;
 345         state.refresh_cache = 1;
 346         state.istate = &the_index;
 347
 348         enable_delayed_checkout(&state);
 349         for (pos = 0; pos < active_nr; pos++) {
 350                 struct cache_entry *ce = active_cache[pos];
 351                 if (ce->ce_flags & CE_MATCHED) {
 352                         if (!ce_stage(ce)) {
 353                                 errs |= checkout_entry(ce, &state,
 354                                                        NULL, &nr_checkouts);
 355                                 continue;
 356                         }
 357                         if (opts->writeout_stage)
 358                                 errs |= checkout_stage(opts->writeout_stage,
 359                                                        ce, pos,
 360                                                        &state,
 361                                                        &nr_checkouts, opts->overlay_mode);
 362                         else if (opts->merge)
 363                                 errs |= checkout_merged(pos, &state,
 364                                                         &nr_unmerged);
 365                         pos = skip_same_name(ce, pos) - 1;
 366                 }
 367         }
 368         remove_marked_cache_entries(&the_index, 1);
 369         remove_scheduled_dirs();
 370         errs |= finish_delayed_checkout(&state, &nr_checkouts);
 371
 372         if (opts->count_checkout_paths) {
 373                 if (nr_unmerged)
 374                         fprintf_ln(stderr, Q_("Recreated %d merge conflict",
 375                                               "Recreated %d merge conflicts",
 376                                               nr_unmerged),
 377                                    nr_unmerged);
 378                 if (opts->source_tree)
 379                         fprintf_ln(stderr, Q_("Updated %d path from %s",
 380                                               "Updated %d paths from %s",
 381                                               nr_checkouts),
 382                                    nr_checkouts,
 383                                    find_unique_abbrev(&opts->source_tree->object.oid,
 384                                                       DEFAULT_ABBREV));
 385                 else if (!nr_unmerged || nr_checkouts)
 386                         fprintf_ln(stderr, Q_("Updated %d path from the index",
 387                                               "Updated %d paths from the index",
 388                                               nr_checkouts),
 389                                    nr_checkouts);
 390         }
 391
 392         return errs;
 393 }
 394
 395 static int checkout_paths(const struct checkout_opts *opts,
 396                           const char *revision)
 397 {
 398         int pos;
 399         static char *ps_matched;
 400         struct object_id rev;
 401         struct commit *head;
 402         int errs = 0;
 403         struct lock_file lock_file = LOCK_INIT;
 404         int checkout_index;
 405
 406         trace2_cmd_mode(opts->patch_mode ? "patch" : "path");
 407
 408         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
 409                 die(_("'%s' cannot be used with updating paths"), "--track");
 410
 411         if (opts->new_branch_log)
 412                 die(_("'%s' cannot be used with updating paths"), "-l");
 413
 414         if (opts->ignore_unmerged && opts->patch_mode)
 415                 die(_("'%s' cannot be used with updating paths"),
 416                     opts->ignore_unmerged_opt);
 417
 418         if (opts->force_detach)
 419                 die(_("'%s' cannot be used with updating paths"), "--detach");
 420
 421         if (opts->merge && opts->patch_mode)
 422                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
 423
 424         if (opts->ignore_unmerged && opts->merge)
 425                 die(_("'%s' cannot be used with %s"),
 426                     opts->ignore_unmerged_opt, "-m");
 427
 428         if (opts->new_branch)
 429                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
 430                     opts->new_branch);
 431
 432         if (!opts->checkout_worktree && !opts->checkout_index)
 433                 die(_("neither '%s' or '%s' is specified"),
 434                     "--staged", "--worktree");
 435
 436         if (!opts->checkout_worktree && !opts->from_treeish)
 437                 die(_("'%s' must be used when '%s' is not specified"),
 438                     "--worktree", "--source");
 439
 440         if (opts->checkout_index && !opts->checkout_worktree &&
 441             opts->writeout_stage)
 442                 die(_("'%s' or '%s' cannot be used with %s"),
 443                     "--ours", "--theirs", "--staged");
 444
 445         if (opts->checkout_index && !opts->checkout_worktree &&
 446             opts->merge)
 447                 die(_("'%s' or '%s' cannot be used with %s"),
 448                     "--merge", "--conflict", "--staged");
 449
 450         if (opts->patch_mode) {
 451                 const char *patch_mode;
 452
 453                 if (opts->checkout_index && opts->checkout_worktree)
 454                         patch_mode = "--patch=checkout";
 455                 else if (opts->checkout_index && !opts->checkout_worktree)
 456                         patch_mode = "--patch=reset";
 457                 else
 458                         die(_("'%s' with only '%s' is not currently supported"),
 459                             "--patch", "--worktree");
 460                 return run_add_interactive(revision, patch_mode, &opts->pathspec);
 461         }
 462
 463         repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 464         if (read_cache_preload(&opts->pathspec) < 0)
 465                 return error(_("index file corrupt"));
 466
 467         if (opts->source_tree)
 468                 read_tree_some(opts->source_tree, &opts->pathspec);
 469
 470         ps_matched = xcalloc(opts->pathspec.nr, 1);
 471
 472         /*
 473          * Make sure all pathspecs participated in locating the paths
 474          * to be checked out.
 475          */
 476         for (pos = 0; pos < active_nr; pos++)
 477                 if (opts->overlay_mode)
 478                         mark_ce_for_checkout_overlay(active_cache[pos],
 479                                                      ps_matched,
 480                                                      opts);
 481                 else
 482                         mark_ce_for_checkout_no_overlay(active_cache[pos],
 483                                                         ps_matched,
 484                                                         opts);
 485
 486         if (report_path_error(ps_matched, &opts->pathspec, opts->prefix)) {
 487                 free(ps_matched);
 488                 return 1;
 489         }
 490         free(ps_matched);
 491
 492         /* "checkout -m path" to recreate conflicted state */
 493         if (opts->merge)
 494                 unmerge_marked_index(&the_index);
 495
 496         /* Any unmerged paths? */
 497         for (pos = 0; pos < active_nr; pos++) {
 498                 const struct cache_entry *ce = active_cache[pos];
 499                 if (ce->ce_flags & CE_MATCHED) {
 500                         if (!ce_stage(ce))
 501                                 continue;
 502                         if (opts->ignore_unmerged) {
 503                                 if (!opts->quiet)
 504                                         warning(_("path '%s' is unmerged"), ce->name);
 505                         } else if (opts->writeout_stage) {
 506                                 errs |= check_stage(opts->writeout_stage, ce, pos, opts->overlay_mode);
 507                         } else if (opts->merge) {
 508                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
 509                         } else {
 510                                 errs = 1;
 511                                 error(_("path '%s' is unmerged"), ce->name);
 512                         }
 513                         pos = skip_same_name(ce, pos) - 1;
 514                 }
 515         }
 516         if (errs)
 517                 return 1;
 518
 519         /* Now we are committed to check them out */
 520         if (opts->checkout_worktree)
 521                 errs |= checkout_worktree(opts);
 522
 523         /*
 524          * Allow updating the index when checking out from the index.
 525          * This is to save new stat info.
 526          */
 527         if (opts->checkout_worktree && !opts->checkout_index && !opts->source_tree)
 528                 checkout_index = 1;
 529         else
 530                 checkout_index = opts->checkout_index;
 531
 532         if (checkout_index) {
 533                 if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 534                         die(_("unable to write new index file"));
 535         } else {
 536                 /*
 537                  * NEEDSWORK: if --worktree is not specified, we
 538                  * should save stat info of checked out files in the
 539                  * index to avoid the next (potentially costly)
 540                  * refresh. But it's a bit tricker to do...
 541                  */
 542                 rollback_lock_file(&lock_file);
 543         }
 544
 545         read_ref_full("HEAD", 0, &rev, NULL);
 546         head = lookup_commit_reference_gently(the_repository, &rev, 1);
 547
 548         errs |= post_checkout_hook(head, head, 0);
 549         return errs;
 550 }
 551
 552 static void show_local_changes(struct object *head,
 553                                const struct diff_options *opts)
 554 {
 555         struct rev_info rev;
 556         /* I think we want full paths, even if we're in a subdirectory. */
 557         repo_init_revisions(the_repository, &rev, NULL);
 558         rev.diffopt.flags = opts->flags;
 559         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
 560         diff_setup_done(&rev.diffopt);
 561         add_pending_object(&rev, head, NULL);
 562         run_diff_index(&rev, 0);
 563 }
 564
 565 static void describe_detached_head(const char *msg, struct commit *commit)
 566 {
 567         struct strbuf sb = STRBUF_INIT;
 568
 569         if (!parse_commit(commit))
 570                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
 571         if (print_sha1_ellipsis()) {
 572                 fprintf(stderr, "%s %s... %s\n", msg,
 573                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 574         } else {
 575                 fprintf(stderr, "%s %s %s\n", msg,
 576                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
 577         }
 578         strbuf_release(&sb);
 579 }
 580
 581 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 582                       int worktree, int *writeout_error)
 583 {
 584         struct unpack_trees_options opts;
 585         struct tree_desc tree_desc;
 586
 587         memset(&opts, 0, sizeof(opts));
 588         opts.head_idx = -1;
 589         opts.update = worktree;
 590         opts.skip_unmerged = !worktree;
 591         opts.reset = 1;
 592         opts.merge = 1;
 593         opts.fn = oneway_merge;
 594         opts.verbose_update = o->show_progress;
 595         opts.src_index = &the_index;
 596         opts.dst_index = &the_index;
 597         parse_tree(tree);
 598         init_tree_desc(&tree_desc, tree->buffer, tree->size);
 599         switch (unpack_trees(1, &tree_desc, &opts)) {
 600         case -2:
 601                 *writeout_error = 1;
 602                 /*
 603                  * We return 0 nevertheless, as the index is all right
 604                  * and more importantly we have made best efforts to
 605                  * update paths in the work tree, and we cannot revert
 606                  * them.
 607                  */
 608                 /* fallthrough */
 609         case 0:
 610                 return 0;
 611         default:
 612                 return 128;
 613         }
 614 }
 615
 616 struct branch_info {
 617         const char *name; /* The short name used */
 618         const char *path; /* The full name of a real branch */
 619         struct commit *commit; /* The named commit */
 620         /*
 621          * if not null the branch is detached because it's already
 622          * checked out in this checkout
 623          */
 624         char *checkout;
 625 };
 626
 627 static void setup_branch_path(struct branch_info *branch)
 628 {
 629         struct strbuf buf = STRBUF_INIT;
 630
 631         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
 632         if (strcmp(buf.buf, branch->name))
 633                 branch->name = xstrdup(buf.buf);
 634         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
 635         branch->path = strbuf_detach(&buf, NULL);
 636 }
 637
 638 static int merge_working_tree(const struct checkout_opts *opts,
 639                               struct branch_info *old_branch_info,
 640                               struct branch_info *new_branch_info,
 641                               int *writeout_error)
 642 {
 643         int ret;
 644         struct lock_file lock_file = LOCK_INIT;
 645         struct tree *new_tree;
 646
 647         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
 648         if (read_cache_preload(NULL) < 0)
 649                 return error(_("index file corrupt"));
 650
 651         resolve_undo_clear();
 652         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
 653                 if (new_branch_info->commit)
 654                         BUG("'switch --orphan' should never accept a commit as starting point");
 655                 new_tree = parse_tree_indirect(the_hash_algo->empty_tree);
 656         } else
 657                 new_tree = get_commit_tree(new_branch_info->commit);
 658         if (opts->discard_changes) {
 659                 ret = reset_tree(new_tree, opts, 1, writeout_error);
 660                 if (ret)
 661                         return ret;
 662         } else {
 663                 struct tree_desc trees[2];
 664                 struct tree *tree;
 665                 struct unpack_trees_options topts;
 666
 667                 memset(&topts, 0, sizeof(topts));
 668                 topts.head_idx = -1;
 669                 topts.src_index = &the_index;
 670                 topts.dst_index = &the_index;
 671
 672                 setup_unpack_trees_porcelain(&topts, "checkout");
 673
 674                 refresh_cache(REFRESH_QUIET);
 675
 676                 if (unmerged_cache()) {
 677                         error(_("you need to resolve your current index first"));
 678                         return 1;
 679                 }
 680
 681                 /* 2-way merge to the new branch */
 682                 topts.initial_checkout = is_cache_unborn();
 683                 topts.update = 1;
 684                 topts.merge = 1;
 685                 topts.gently = opts->merge && old_branch_info->commit;
 686                 topts.verbose_update = opts->show_progress;
 687                 topts.fn = twoway_merge;
 688                 if (opts->overwrite_ignore) {
 689                         topts.dir = xcalloc(1, sizeof(*topts.dir));
 690                         topts.dir->flags |= DIR_SHOW_IGNORED;
 691                         setup_standard_excludes(topts.dir);
 692                 }
 693                 tree = parse_tree_indirect(old_branch_info->commit ?
 694                                            &old_branch_info->commit->object.oid :
 695                                            the_hash_algo->empty_tree);
 696                 init_tree_desc(&trees[0], tree->buffer, tree->size);
 697                 parse_tree(new_tree);
 698                 tree = new_tree;
 699                 init_tree_desc(&trees[1], tree->buffer, tree->size);
 700
 701                 ret = unpack_trees(2, trees, &topts);
 702                 clear_unpack_trees_porcelain(&topts);
 703                 if (ret == -1) {
 704                         /*
 705                          * Unpack couldn't do a trivial merge; either
 706                          * give up or do a real merge, depending on
 707                          * whether the merge flag was used.
 708                          */
 709                         struct tree *result;
 710                         struct tree *work;
 711                         struct merge_options o;
 712                         if (!opts->merge)
 713                                 return 1;
 714
 715                         /*
 716                          * Without old_branch_info->commit, the below is the same as
 717                          * the two-tree unpack we already tried and failed.
 718                          */
 719                         if (!old_branch_info->commit)
 720                                 return 1;
 721
 722                         /* Do more real merge */
 723
 724                         /*
 725                          * We update the index fully, then write the
 726                          * tree from the index, then merge the new
 727                          * branch with the current tree, with the old
 728                          * branch as the base. Then we reset the index
 729                          * (but not the working tree) to the new
 730                          * branch, leaving the working tree as the
 731                          * merged version, but skipping unmerged
 732                          * entries in the index.
 733                          */
 734
 735                         add_files_to_cache(NULL, NULL, 0);
 736                         /*
 737                          * NEEDSWORK: carrying over local changes
 738                          * when branches have different end-of-line
 739                          * normalization (or clean+smudge rules) is
 740                          * a pain; plumb in an option to set
 741                          * o.renormalize?
 742                          */
 743                         init_merge_options(&o, the_repository);
 744                         o.verbosity = 0;
 745                         work = write_tree_from_memory(&o);
 746
 747                         ret = reset_tree(new_tree,
 748                                          opts, 1,
 749                                          writeout_error);
 750                         if (ret)
 751                                 return ret;
 752                         o.ancestor = old_branch_info->name;
 753                         o.branch1 = new_branch_info->name;
 754                         o.branch2 = "local";
 755                         ret = merge_trees(&o,
 756                                           new_tree,
 757                                           work,
 758                                           get_commit_tree(old_branch_info->commit),
 759                                           &result);
 760                         if (ret < 0)
 761                                 exit(128);
 762                         ret = reset_tree(new_tree,
 763                                          opts, 0,
 764                                          writeout_error);
 765                         strbuf_release(&o.obuf);
 766                         if (ret)
 767                                 return ret;
 768                 }
 769         }
 770
 771         if (!active_cache_tree)
 772                 active_cache_tree = cache_tree();
 773
 774         if (!cache_tree_fully_valid(active_cache_tree))
 775                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
 776
 777         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
 778                 die(_("unable to write new index file"));
 779
 780         if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
 781                 show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
 782
 783         return 0;
 784 }
 785
 786 static void report_tracking(struct branch_info *new_branch_info)
 787 {
 788         struct strbuf sb = STRBUF_INIT;
 789         struct branch *branch = branch_get(new_branch_info->name);
 790
 791         if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
 792                 return;
 793         fputs(sb.buf, stdout);
 794         strbuf_release(&sb);
 795 }
 796
 797 static void update_refs_for_switch(const struct checkout_opts *opts,
 798                                    struct branch_info *old_branch_info,
 799                                    struct branch_info *new_branch_info)
 800 {
 801         struct strbuf msg = STRBUF_INIT;
 802         const char *old_desc, *reflog_msg;
 803         if (opts->new_branch) {
 804                 if (opts->new_orphan_branch) {
 805                         char *refname;
 806
 807                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
 808                         if (opts->new_branch_log &&
 809                             !should_autocreate_reflog(refname)) {
 810                                 int ret;
 811                                 struct strbuf err = STRBUF_INIT;
 812
 813                                 ret = safe_create_reflog(refname, 1, &err);
 814                                 if (ret) {
 815                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
 816                                                 opts->new_orphan_branch, err.buf);
 817                                         strbuf_release(&err);
 818                                         free(refname);
 819                                         return;
 820                                 }
 821                                 strbuf_release(&err);
 822                         }
 823                         free(refname);
 824                 }
 825                 else
 826                         create_branch(the_repository,
 827                                       opts->new_branch, new_branch_info->name,
 828                                       opts->new_branch_force ? 1 : 0,
 829                                       opts->new_branch_force ? 1 : 0,
 830                                       opts->new_branch_log,
 831                                       opts->quiet,
 832                                       opts->track);
 833                 new_branch_info->name = opts->new_branch;
 834                 setup_branch_path(new_branch_info);
 835         }
 836
 837         old_desc = old_branch_info->name;
 838         if (!old_desc && old_branch_info->commit)
 839                 old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
 840
 841         reflog_msg = getenv("GIT_REFLOG_ACTION");
 842         if (!reflog_msg)
 843                 strbuf_addf(&msg, "checkout: moving from %s to %s",
 844                         old_desc ? old_desc : "(invalid)", new_branch_info->name);
 845         else
 846                 strbuf_insert(&msg, 0, reflog_msg, strlen(reflog_msg));
 847
 848         if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
 849                 /* Nothing to do. */
 850         } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
 851                 update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
 852                            REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
 853                 if (!opts->quiet) {
 854                         if (old_branch_info->path &&
 855                             advice_detached_head && !opts->force_detach)
 856                                 detach_advice(new_branch_info->name);
 857                         describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
 858                 }
 859         } else if (new_branch_info->path) {     /* Switch branches. */
 860                 if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
 861                         die(_("unable to update HEAD"));
 862                 if (!opts->quiet) {
 863                         if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
 864                                 if (opts->new_branch_force)
 865                                         fprintf(stderr, _("Reset branch '%s'\n"),
 866                                                 new_branch_info->name);
 867                                 else
 868                                         fprintf(stderr, _("Already on '%s'\n"),
 869                                                 new_branch_info->name);
 870                         } else if (opts->new_branch) {
 871                                 if (opts->branch_exists)
 872                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
 873                                 else
 874                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
 875                         } else {
 876                                 fprintf(stderr, _("Switched to branch '%s'\n"),
 877                                         new_branch_info->name);
 878                         }
 879                 }
 880                 if (old_branch_info->path && old_branch_info->name) {
 881                         if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
 882                                 delete_reflog(old_branch_info->path);
 883                 }
 884         }
 885         remove_branch_state(the_repository, !opts->quiet);
 886         strbuf_release(&msg);
 887         if (!opts->quiet &&
 888             (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
 889                 report_tracking(new_branch_info);
 890 }
 891
 892 static int add_pending_uninteresting_ref(const char *refname,
 893                                          const struct object_id *oid,
 894                                          int flags, void *cb_data)
 895 {
 896         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
 897         return 0;
 898 }
 899
 900 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
 901 {
 902         strbuf_addstr(sb, "  ");
 903         strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
 904         strbuf_addch(sb, ' ');
 905         if (!parse_commit(commit))
 906                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
 907         strbuf_addch(sb, '\n');
 908 }
 909
 910 #define ORPHAN_CUTOFF 4
 911 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
 912 {
 913         struct commit *c, *last = NULL;
 914         struct strbuf sb = STRBUF_INIT;
 915         int lost = 0;
 916         while ((c = get_revision(revs)) != NULL) {
 917                 if (lost < ORPHAN_CUTOFF)
 918                         describe_one_orphan(&sb, c);
 919                 last = c;
 920                 lost++;
 921         }
 922         if (ORPHAN_CUTOFF < lost) {
 923                 int more = lost - ORPHAN_CUTOFF;
 924                 if (more == 1)
 925                         describe_one_orphan(&sb, last);
 926                 else
 927                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
 928         }
 929
 930         fprintf(stderr,
 931                 Q_(
 932                 /* The singular version */
 933                 "Warning: you are leaving %d commit behind, "
 934                 "not connected to\n"
 935                 "any of your branches:\n\n"
 936                 "%s\n",
 937                 /* The plural version */
 938                 "Warning: you are leaving %d commits behind, "
 939                 "not connected to\n"
 940                 "any of your branches:\n\n"
 941                 "%s\n",
 942                 /* Give ngettext() the count */
 943                 lost),
 944                 lost,
 945                 sb.buf);
 946         strbuf_release(&sb);
 947
 948         if (advice_detached_head)
 949                 fprintf(stderr,
 950                         Q_(
 951                         /* The singular version */
 952                         "If you want to keep it by creating a new branch, "
 953                         "this may be a good time\nto do so with:\n\n"
 954                         " git branch <new-branch-name> %s\n\n",
 955                         /* The plural version */
 956                         "If you want to keep them by creating a new branch, "
 957                         "this may be a good time\nto do so with:\n\n"
 958                         " git branch <new-branch-name> %s\n\n",
 959                         /* Give ngettext() the count */
 960                         lost),
 961                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
 962 }
 963
 964 /*
 965  * We are about to leave commit that was at the tip of a detached
 966  * HEAD.  If it is not reachable from any ref, this is the last chance
 967  * for the user to do so without resorting to reflog.
 968  */
 969 static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
 970 {
 971         struct rev_info revs;
 972         struct object *object = &old_commit->object;
 973
 974         repo_init_revisions(the_repository, &revs, NULL);
 975         setup_revisions(0, NULL, &revs, NULL);
 976
 977         object->flags &= ~UNINTERESTING;
 978         add_pending_object(&revs, object, oid_to_hex(&object->oid));
 979
 980         for_each_ref(add_pending_uninteresting_ref, &revs);
 981         if (new_commit)
 982                 add_pending_oid(&revs, "HEAD",
 983                                 &new_commit->object.oid,
 984                                 UNINTERESTING);
 985
 986         if (prepare_revision_walk(&revs))
 987                 die(_("internal error in revision walk"));
 988         if (!(old_commit->object.flags & UNINTERESTING))
 989                 suggest_reattach(old_commit, &revs);
 990         else
 991                 describe_detached_head(_("Previous HEAD position was"), old_commit);
 992
 993         /* Clean up objects used, as they will be reused. */
 994         clear_commit_marks_all(ALL_REV_FLAGS);
 995 }
 996
 997 static int switch_branches(const struct checkout_opts *opts,
 998                            struct branch_info *new_branch_info)
 999 {
1000         int ret = 0;
1001         struct branch_info old_branch_info;
1002         void *path_to_free;
1003         struct object_id rev;
1004         int flag, writeout_error = 0;
1005         int do_merge = 1;
1006
1007         trace2_cmd_mode("branch");
1008
1009         memset(&old_branch_info, 0, sizeof(old_branch_info));
1010         old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
1011         if (old_branch_info.path)
1012                 old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
1013         if (!(flag & REF_ISSYMREF))
1014                 old_branch_info.path = NULL;
1015
1016         if (old_branch_info.path)
1017                 skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
1018
1019         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
1020                 if (new_branch_info->name)
1021                         BUG("'switch --orphan' should never accept a commit as starting point");
1022                 new_branch_info->commit = NULL;
1023                 new_branch_info->name = "(empty)";
1024                 do_merge = 1;
1025         }
1026
1027         if (!new_branch_info->name) {
1028                 new_branch_info->name = "HEAD";
1029                 new_branch_info->commit = old_branch_info.commit;
1030                 if (!new_branch_info->commit)
1031                         die(_("You are on a branch yet to be born"));
1032                 parse_commit_or_die(new_branch_info->commit);
1033
1034                 if (opts->only_merge_on_switching_branches)
1035                         do_merge = 0;
1036         }
1037
1038         if (do_merge) {
1039                 ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
1040                 if (ret) {
1041                         free(path_to_free);
1042                         return ret;
1043                 }
1044         }
1045
1046         if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
1047                 orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
1048
1049         update_refs_for_switch(opts, &old_branch_info, new_branch_info);
1050
1051         ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
1052         free(path_to_free);
1053         return ret || writeout_error;
1054 }
1055
1056 static int git_checkout_config(const char *var, const char *value, void *cb)
1057 {
1058         if (!strcmp(var, "diff.ignoresubmodules")) {
1059                 struct checkout_opts *opts = cb;
1060                 handle_ignore_submodules_arg(&opts->diff_options, value);
1061                 return 0;
1062         }
1063
1064         if (starts_with(var, "submodule."))
1065                 return git_default_submodule_config(var, value, NULL);
1066
1067         return git_xmerge_config(var, value, NULL);
1068 }
1069
1070 static void setup_new_branch_info_and_source_tree(
1071         struct branch_info *new_branch_info,
1072         struct checkout_opts *opts,
1073         struct object_id *rev,
1074         const char *arg)
1075 {
1076         struct tree **source_tree = &opts->source_tree;
1077         struct object_id branch_rev;
1078
1079         new_branch_info->name = arg;
1080         setup_branch_path(new_branch_info);
1081
1082         if (!check_refname_format(new_branch_info->path, 0) &&
1083             !read_ref(new_branch_info->path, &branch_rev))
1084                 oidcpy(rev, &branch_rev);
1085         else
1086                 new_branch_info->path = NULL; /* not an existing branch */
1087
1088         new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
1089         if (!new_branch_info->commit) {
1090                 /* not a commit */
1091                 *source_tree = parse_tree_indirect(rev);
1092         } else {
1093                 parse_commit_or_die(new_branch_info->commit);
1094                 *source_tree = get_commit_tree(new_branch_info->commit);
1095         }
1096 }
1097
1098 static int parse_branchname_arg(int argc, const char **argv,
1099                                 int dwim_new_local_branch_ok,
1100                                 struct branch_info *new_branch_info,
1101                                 struct checkout_opts *opts,
1102                                 struct object_id *rev,
1103                                 int *dwim_remotes_matched)
1104 {
1105         const char **new_branch = &opts->new_branch;
1106         int argcount = 0;
1107         const char *arg;
1108         int dash_dash_pos;
1109         int has_dash_dash = 0;
1110         int i;
1111
1112         /*
1113          * case 1: git checkout <ref> -- [<paths>]
1114          *
1115          *   <ref> must be a valid tree, everything after the '--' must be
1116          *   a path.
1117          *
1118          * case 2: git checkout -- [<paths>]
1119          *
1120          *   everything after the '--' must be paths.
1121          *
1122          * case 3: git checkout <something> [--]
1123          *
1124          *   (a) If <something> is a commit, that is to
1125          *       switch to the branch or detach HEAD at it.  As a special case,
1126          *       if <something> is A...B (missing A or B means HEAD but you can
1127          *       omit at most one side), and if there is a unique merge base
1128          *       between A and B, A...B names that merge base.
1129          *
1130          *   (b) If <something> is _not_ a commit, either "--" is present
1131          *       or <something> is not a path, no -t or -b was given, and
1132          *       and there is a tracking branch whose name is <something>
1133          *       in one and only one remote (or if the branch exists on the
1134          *       remote named in checkout.defaultRemote), then this is a
1135          *       short-hand to fork local <something> from that
1136          *       remote-tracking branch.
1137          *
1138          *   (c) Otherwise, if "--" is present, treat it like case (1).
1139          *
1140          *   (d) Otherwise :
1141          *       - if it's a reference, treat it like case (1)
1142          *       - else if it's a path, treat it like case (2)
1143          *       - else: fail.
1144          *
1145          * case 4: git checkout <something> <paths>
1146          *
1147          *   The first argument must not be ambiguous.
1148          *   - If it's *only* a reference, treat it like case (1).
1149          *   - If it's only a path, treat it like case (2).
1150          *   - else: fail.
1151          *
1152          */
1153         if (!argc)
1154                 return 0;
1155
1156         if (!opts->accept_pathspec) {
1157                 if (argc > 1)
1158                         die(_("only one reference expected"));
1159                 has_dash_dash = 1; /* helps disambiguate */
1160         }
1161
1162         arg = argv[0];
1163         dash_dash_pos = -1;
1164         for (i = 0; i < argc; i++) {
1165                 if (opts->accept_pathspec && !strcmp(argv[i], "--")) {
1166                         dash_dash_pos = i;
1167                         break;
1168                 }
1169         }
1170         if (dash_dash_pos == 0)
1171                 return 1; /* case (2) */
1172         else if (dash_dash_pos == 1)
1173                 has_dash_dash = 1; /* case (3) or (1) */
1174         else if (dash_dash_pos >= 2)
1175                 die(_("only one reference expected, %d given."), dash_dash_pos);
1176         opts->count_checkout_paths = !opts->quiet && !has_dash_dash;
1177
1178         if (!strcmp(arg, "-"))
1179                 arg = "@{-1}";
1180
1181         if (get_oid_mb(arg, rev)) {
1182                 /*
1183                  * Either case (3) or (4), with <something> not being
1184                  * a commit, or an attempt to use case (1) with an
1185                  * invalid ref.
1186                  *
1187                  * It's likely an error, but we need to find out if
1188                  * we should auto-create the branch, case (3).(b).
1189                  */
1190                 int recover_with_dwim = dwim_new_local_branch_ok;
1191
1192                 int could_be_checkout_paths = !has_dash_dash &&
1193                         check_filename(opts->prefix, arg);
1194
1195                 if (!has_dash_dash && !no_wildcard(arg))
1196                         recover_with_dwim = 0;
1197
1198                 /*
1199                  * Accept "git checkout foo", "git checkout foo --"
1200                  * and "git switch foo" as candidates for dwim.
1201                  */
1202                 if (!(argc == 1 && !has_dash_dash) &&
1203                     !(argc == 2 && has_dash_dash) &&
1204                     opts->accept_pathspec)
1205                         recover_with_dwim = 0;
1206
1207                 if (recover_with_dwim) {
1208                         const char *remote = unique_tracking_name(arg, rev,
1209                                                                   dwim_remotes_matched);
1210                         if (remote) {
1211                                 if (could_be_checkout_paths)
1212                                         die(_("'%s' could be both a local file and a tracking branch.\n"
1213                                               "Please use -- (and optionally --no-guess) to disambiguate"),
1214                                             arg);
1215                                 *new_branch = arg;
1216                                 arg = remote;
1217                                 /* DWIMmed to create local branch, case (3).(b) */
1218                         } else {
1219                                 recover_with_dwim = 0;
1220                         }
1221                 }
1222
1223                 if (!recover_with_dwim) {
1224                         if (has_dash_dash)
1225                                 die(_("invalid reference: %s"), arg);
1226                         return argcount;
1227                 }
1228         }
1229
1230         /* we can't end up being in (2) anymore, eat the argument */
1231         argcount++;
1232         argv++;
1233         argc--;
1234
1235         setup_new_branch_info_and_source_tree(new_branch_info, opts, rev, arg);
1236
1237         if (!opts->source_tree)                   /* case (1): want a tree */
1238                 die(_("reference is not a tree: %s"), arg);
1239
1240         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1241                 /*
1242                  * Do not complain the most common case
1243                  *      git checkout branch
1244                  * even if there happen to be a file called 'branch';
1245                  * it would be extremely annoying.
1246                  */
1247                 if (argc)
1248                         verify_non_filename(opts->prefix, arg);
1249         } else if (opts->accept_pathspec) {
1250                 argcount++;
1251                 argv++;
1252                 argc--;
1253         }
1254
1255         return argcount;
1256 }
1257
1258 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1259 {
1260         int status;
1261         struct strbuf branch_ref = STRBUF_INIT;
1262
1263         trace2_cmd_mode("unborn");
1264
1265         if (!opts->new_branch)
1266                 die(_("You are on a branch yet to be born"));
1267         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1268         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1269         strbuf_release(&branch_ref);
1270         if (!opts->quiet)
1271                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1272                         opts->new_branch);
1273         return status;
1274 }
1275
1276 static void die_expecting_a_branch(const struct branch_info *branch_info)
1277 {
1278         struct object_id oid;
1279         char *to_free;
1280
1281         if (dwim_ref(branch_info->name, strlen(branch_info->name), &oid, &to_free) == 1) {
1282                 const char *ref = to_free;
1283
1284                 if (skip_prefix(ref, "refs/tags/", &ref))
1285                         die(_("a branch is expected, got tag '%s'"), ref);
1286                 if (skip_prefix(ref, "refs/remotes/", &ref))
1287                         die(_("a branch is expected, got remote branch '%s'"), ref);
1288                 die(_("a branch is expected, got '%s'"), ref);
1289         }
1290         if (branch_info->commit)
1291                 die(_("a branch is expected, got commit '%s'"), branch_info->name);
1292         /*
1293          * This case should never happen because we already die() on
1294          * non-commit, but just in case.
1295          */
1296         die(_("a branch is expected, got '%s'"), branch_info->name);
1297 }
1298
1299 static void die_if_some_operation_in_progress(void)
1300 {
1301         struct wt_status_state state;
1302
1303         memset(&state, 0, sizeof(state));
1304         wt_status_get_state(the_repository, &state, 0);
1305
1306         if (state.merge_in_progress)
1307                 die(_("cannot switch branch while merging\n"
1308                       "Consider \"git merge --quit\" "
1309                       "or \"git worktree add\"."));
1310         if (state.am_in_progress)
1311                 die(_("cannot switch branch in the middle of an am session\n"
1312                       "Consider \"git am --quit\" "
1313                       "or \"git worktree add\"."));
1314         if (state.rebase_interactive_in_progress || state.rebase_in_progress)
1315                 die(_("cannot switch branch while rebasing\n"
1316                       "Consider \"git rebase --quit\" "
1317                       "or \"git worktree add\"."));
1318         if (state.cherry_pick_in_progress)
1319                 die(_("cannot switch branch while cherry-picking\n"
1320                       "Consider \"git cherry-pick --quit\" "
1321                       "or \"git worktree add\"."));
1322         if (state.revert_in_progress)
1323                 die(_("cannot switch branch while reverting\n"
1324                       "Consider \"git revert --quit\" "
1325                       "or \"git worktree add\"."));
1326         if (state.bisect_in_progress)
1327                 die(_("cannot switch branch while bisecting\n"
1328                       "Consider \"git bisect reset HEAD\" "
1329                       "or \"git worktree add\"."));
1330 }
1331
1332 static int checkout_branch(struct checkout_opts *opts,
1333                            struct branch_info *new_branch_info)
1334 {
1335         if (opts->pathspec.nr)
1336                 die(_("paths cannot be used with switching branches"));
1337
1338         if (opts->patch_mode)
1339                 die(_("'%s' cannot be used with switching branches"),
1340                     "--patch");
1341
1342         if (opts->overlay_mode != -1)
1343                 die(_("'%s' cannot be used with switching branches"),
1344                     "--[no]-overlay");
1345
1346         if (opts->writeout_stage)
1347                 die(_("'%s' cannot be used with switching branches"),
1348                     "--ours/--theirs");
1349
1350         if (opts->force && opts->merge)
1351                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1352
1353         if (opts->discard_changes && opts->merge)
1354                 die(_("'%s' cannot be used with '%s'"), "--discard-changes", "--merge");
1355
1356         if (opts->force_detach && opts->new_branch)
1357                 die(_("'%s' cannot be used with '%s'"),
1358                     "--detach", "-b/-B/--orphan");
1359
1360         if (opts->new_orphan_branch) {
1361                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1362                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1363                 if (opts->orphan_from_empty_tree && new_branch_info->name)
1364                         die(_("'%s' cannot take <start-point>"), "--orphan");
1365         } else if (opts->force_detach) {
1366                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1367                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1368         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1369                 opts->track = git_branch_track;
1370
1371         if (new_branch_info->name && !new_branch_info->commit)
1372                 die(_("Cannot switch branch to a non-commit '%s'"),
1373                     new_branch_info->name);
1374
1375         if (!opts->switch_branch_doing_nothing_is_ok &&
1376             !new_branch_info->name &&
1377             !opts->new_branch &&
1378             !opts->force_detach)
1379                 die(_("missing branch or commit argument"));
1380
1381         if (!opts->implicit_detach &&
1382             !opts->force_detach &&
1383             !opts->new_branch &&
1384             !opts->new_branch_force &&
1385             new_branch_info->name &&
1386             !new_branch_info->path)
1387                 die_expecting_a_branch(new_branch_info);
1388
1389         if (!opts->can_switch_when_in_progress)
1390                 die_if_some_operation_in_progress();
1391
1392         if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1393             !opts->ignore_other_worktrees) {
1394                 int flag;
1395                 char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1396                 if (head_ref &&
1397                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1398                         die_if_checked_out(new_branch_info->path, 1);
1399                 free(head_ref);
1400         }
1401
1402         if (!new_branch_info->commit && opts->new_branch) {
1403                 struct object_id rev;
1404                 int flag;
1405
1406                 if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1407                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1408                         return switch_unborn_to_new_branch(opts);
1409         }
1410         return switch_branches(opts, new_branch_info);
1411 }
1412
1413 static struct option *add_common_options(struct checkout_opts *opts,
1414                                          struct option *prevopts)
1415 {
1416         struct option options[] = {
1417                 OPT__QUIET(&opts->quiet, N_("suppress progress reporting")),
1418                 { OPTION_CALLBACK, 0, "recurse-submodules", NULL,
1419                             "checkout", "control recursive updating of submodules",
1420                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
1421                 OPT_BOOL(0, "progress", &opts->show_progress, N_("force progress reporting")),
1422                 OPT_BOOL('m', "merge", &opts->merge, N_("perform a 3-way merge with the new branch")),
1423                 OPT_STRING(0, "conflict", &opts->conflict_style, N_("style"),
1424                            N_("conflict style (merge or diff3)")),
1425                 OPT_END()
1426         };
1427         struct option *newopts = parse_options_concat(prevopts, options);
1428         free(prevopts);
1429         return newopts;
1430 }
1431
1432 static struct option *add_common_switch_branch_options(
1433         struct checkout_opts *opts, struct option *prevopts)
1434 {
1435         struct option options[] = {
1436                 OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
1437                 OPT_SET_INT('t', "track",  &opts->track, N_("set upstream info for new branch"),
1438                         BRANCH_TRACK_EXPLICIT),
1439                 OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
1440                            PARSE_OPT_NOCOMPLETE),
1441                 OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1442                 OPT_BOOL_F(0, "overwrite-ignore", &opts->overwrite_ignore,
1443                            N_("update ignored files (default)"),
1444                            PARSE_OPT_NOCOMPLETE),
1445                 OPT_BOOL(0, "ignore-other-worktrees", &opts->ignore_other_worktrees,
1446                          N_("do not check if another worktree is holding the given ref")),
1447                 OPT_END()
1448         };
1449         struct option *newopts = parse_options_concat(prevopts, options);
1450         free(prevopts);
1451         return newopts;
1452 }
1453
1454 static struct option *add_checkout_path_options(struct checkout_opts *opts,
1455                                                 struct option *prevopts)
1456 {
1457         struct option options[] = {
1458                 OPT_SET_INT_F('2', "ours", &opts->writeout_stage,
1459                               N_("checkout our version for unmerged files"),
1460                               2, PARSE_OPT_NONEG),
1461                 OPT_SET_INT_F('3', "theirs", &opts->writeout_stage,
1462                               N_("checkout their version for unmerged files"),
1463                               3, PARSE_OPT_NONEG),
1464                 OPT_BOOL('p', "patch", &opts->patch_mode, N_("select hunks interactively")),
1465                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts->ignore_skipworktree,
1466                          N_("do not limit pathspecs to sparse entries only")),
1467                 OPT_END()
1468         };
1469         struct option *newopts = parse_options_concat(prevopts, options);
1470         free(prevopts);
1471         return newopts;
1472 }
1473
1474 static int checkout_main(int argc, const char **argv, const char *prefix,
1475                          struct checkout_opts *opts, struct option *options,
1476                          const char * const usagestr[])
1477 {
1478         struct branch_info new_branch_info;
1479         int dwim_remotes_matched = 0;
1480         int parseopt_flags = 0;
1481
1482         memset(&new_branch_info, 0, sizeof(new_branch_info));
1483         opts->overwrite_ignore = 1;
1484         opts->prefix = prefix;
1485         opts->show_progress = -1;
1486
1487         git_config(git_checkout_config, opts);
1488
1489         opts->track = BRANCH_TRACK_UNSPECIFIED;
1490
1491         if (!opts->accept_pathspec && !opts->accept_ref)
1492                 BUG("make up your mind, you need to take _something_");
1493         if (opts->accept_pathspec && opts->accept_ref)
1494                 parseopt_flags = PARSE_OPT_KEEP_DASHDASH;
1495
1496         argc = parse_options(argc, argv, prefix, options,
1497                              usagestr, parseopt_flags);
1498
1499         if (opts->show_progress < 0) {
1500                 if (opts->quiet)
1501                         opts->show_progress = 0;
1502                 else
1503                         opts->show_progress = isatty(2);
1504         }
1505
1506         if (opts->conflict_style) {
1507                 opts->merge = 1; /* implied */
1508                 git_xmerge_config("merge.conflictstyle", opts->conflict_style, NULL);
1509         }
1510         if (opts->force) {
1511                 opts->discard_changes = 1;
1512                 opts->ignore_unmerged_opt = "--force";
1513                 opts->ignore_unmerged = 1;
1514         }
1515
1516         if ((!!opts->new_branch + !!opts->new_branch_force + !!opts->new_orphan_branch) > 1)
1517                 die(_("-b, -B and --orphan are mutually exclusive"));
1518
1519         if (opts->overlay_mode == 1 && opts->patch_mode)
1520                 die(_("-p and --overlay are mutually exclusive"));
1521
1522         if (opts->checkout_index >= 0 || opts->checkout_worktree >= 0) {
1523                 if (opts->checkout_index < 0)
1524                         opts->checkout_index = 0;
1525                 if (opts->checkout_worktree < 0)
1526                         opts->checkout_worktree = 0;
1527         } else {
1528                 if (opts->checkout_index < 0)
1529                         opts->checkout_index = -opts->checkout_index - 1;
1530                 if (opts->checkout_worktree < 0)
1531                         opts->checkout_worktree = -opts->checkout_worktree - 1;
1532         }
1533         if (opts->checkout_index < 0 || opts->checkout_worktree < 0)
1534                 BUG("these flags should be non-negative by now");
1535         /*
1536          * convenient shortcut: "git restore --staged" equals
1537          * "git restore --staged --source HEAD"
1538          */
1539         if (!opts->from_treeish && opts->checkout_index && !opts->checkout_worktree)
1540                 opts->from_treeish = "HEAD";
1541
1542         /*
1543          * From here on, new_branch will contain the branch to be checked out,
1544          * and new_branch_force and new_orphan_branch will tell us which one of
1545          * -b/-B/--orphan is being used.
1546          */
1547         if (opts->new_branch_force)
1548                 opts->new_branch = opts->new_branch_force;
1549
1550         if (opts->new_orphan_branch)
1551                 opts->new_branch = opts->new_orphan_branch;
1552
1553         /* --track without -b/-B/--orphan should DWIM */
1554         if (opts->track != BRANCH_TRACK_UNSPECIFIED && !opts->new_branch) {
1555                 const char *argv0 = argv[0];
1556                 if (!argc || !strcmp(argv0, "--"))
1557                         die(_("--track needs a branch name"));
1558                 skip_prefix(argv0, "refs/", &argv0);
1559                 skip_prefix(argv0, "remotes/", &argv0);
1560                 argv0 = strchr(argv0, '/');
1561                 if (!argv0 || !argv0[1])
1562                         die(_("missing branch name; try -b"));
1563                 opts->new_branch = argv0 + 1;
1564         }
1565
1566         /*
1567          * Extract branch name from command line arguments, so
1568          * all that is left is pathspecs.
1569          *
1570          * Handle
1571          *
1572          *  1) git checkout <tree> -- [<paths>]
1573          *  2) git checkout -- [<paths>]
1574          *  3) git checkout <something> [<paths>]
1575          *
1576          * including "last branch" syntax and DWIM-ery for names of
1577          * remote branches, erroring out for invalid or ambiguous cases.
1578          */
1579         if (argc && opts->accept_ref) {
1580                 struct object_id rev;
1581                 int dwim_ok =
1582                         !opts->patch_mode &&
1583                         opts->dwim_new_local_branch &&
1584                         opts->track == BRANCH_TRACK_UNSPECIFIED &&
1585                         !opts->new_branch;
1586                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1587                                              &new_branch_info, opts, &rev,
1588                                              &dwim_remotes_matched);
1589                 argv += n;
1590                 argc -= n;
1591         } else if (!opts->accept_ref && opts->from_treeish) {
1592                 struct object_id rev;
1593
1594                 if (get_oid_mb(opts->from_treeish, &rev))
1595                         die(_("could not resolve %s"), opts->from_treeish);
1596
1597                 setup_new_branch_info_and_source_tree(&new_branch_info,
1598                                                       opts, &rev,
1599                                                       opts->from_treeish);
1600
1601                 if (!opts->source_tree)
1602                         die(_("reference is not a tree: %s"), opts->from_treeish);
1603         }
1604
1605         if (opts->accept_pathspec && !opts->empty_pathspec_ok && !argc &&
1606             !opts->patch_mode)  /* patch mode is special */
1607                 die(_("you must specify path(s) to restore"));
1608
1609         if (argc) {
1610                 parse_pathspec(&opts->pathspec, 0,
1611                                opts->patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1612                                prefix, argv);
1613
1614                 if (!opts->pathspec.nr)
1615                         die(_("invalid path specification"));
1616
1617                 /*
1618                  * Try to give more helpful suggestion.
1619                  * new_branch && argc > 1 will be caught later.
1620                  */
1621                 if (opts->new_branch && argc == 1)
1622                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1623                                 argv[0], opts->new_branch);
1624
1625                 if (opts->force_detach)
1626                         die(_("git checkout: --detach does not take a path argument '%s'"),
1627                             argv[0]);
1628
1629                 if (1 < !!opts->writeout_stage + !!opts->force + !!opts->merge)
1630                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1631                               "checking out of the index."));
1632         }
1633
1634         if (opts->new_branch) {
1635                 struct strbuf buf = STRBUF_INIT;
1636
1637                 if (opts->new_branch_force)
1638                         opts->branch_exists = validate_branchname(opts->new_branch, &buf);
1639                 else
1640                         opts->branch_exists =
1641                                 validate_new_branchname(opts->new_branch, &buf, 0);
1642                 strbuf_release(&buf);
1643         }
1644
1645         UNLEAK(opts);
1646         if (opts->patch_mode || opts->pathspec.nr) {
1647                 int ret = checkout_paths(opts, new_branch_info.name);
1648                 if (ret && dwim_remotes_matched > 1 &&
1649                     advice_checkout_ambiguous_remote_branch_name)
1650                         advise(_("'%s' matched more than one remote tracking branch.\n"
1651                                  "We found %d remotes with a reference that matched. So we fell back\n"
1652                                  "on trying to resolve the argument as a path, but failed there too!\n"
1653                                  "\n"
1654                                  "If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
1655                                  "you can do so by fully qualifying the name with the --track option:\n"
1656                                  "\n"
1657                                  "    git checkout --track origin/<name>\n"
1658                                  "\n"
1659                                  "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
1660                                  "one remote, e.g. the 'origin' remote, consider setting\n"
1661                                  "checkout.defaultRemote=origin in your config."),
1662                                argv[0],
1663                                dwim_remotes_matched);
1664                 return ret;
1665         } else {
1666                 return checkout_branch(opts, &new_branch_info);
1667         }
1668 }
1669
1670 int cmd_checkout(int argc, const char **argv, const char *prefix)
1671 {
1672         struct checkout_opts opts;
1673         struct option *options;
1674         struct option checkout_options[] = {
1675                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1676                            N_("create and checkout a new branch")),
1677                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1678                            N_("create/reset and checkout a branch")),
1679                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1680                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1681                          N_("second guess 'git checkout <no-such-branch>' (default)")),
1682                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
1683                 OPT_END()
1684         };
1685         int ret;
1686
1687         memset(&opts, 0, sizeof(opts));
1688         opts.dwim_new_local_branch = 1;
1689         opts.switch_branch_doing_nothing_is_ok = 1;
1690         opts.only_merge_on_switching_branches = 0;
1691         opts.accept_ref = 1;
1692         opts.accept_pathspec = 1;
1693         opts.implicit_detach = 1;
1694         opts.can_switch_when_in_progress = 1;
1695         opts.orphan_from_empty_tree = 0;
1696         opts.empty_pathspec_ok = 1;
1697         opts.overlay_mode = -1;
1698         opts.checkout_index = -2;    /* default on */
1699         opts.checkout_worktree = -2; /* default on */
1700
1701         options = parse_options_dup(checkout_options);
1702         options = add_common_options(&opts, options);
1703         options = add_common_switch_branch_options(&opts, options);
1704         options = add_checkout_path_options(&opts, options);
1705
1706         ret = checkout_main(argc, argv, prefix, &opts,
1707                             options, checkout_usage);
1708         FREE_AND_NULL(options);
1709         return ret;
1710 }
1711
1712 int cmd_switch(int argc, const char **argv, const char *prefix)
1713 {
1714         struct checkout_opts opts;
1715         struct option *options = NULL;
1716         struct option switch_options[] = {
1717                 OPT_STRING('c', "create", &opts.new_branch, N_("branch"),
1718                            N_("create and switch to a new branch")),
1719                 OPT_STRING('C', "force-create", &opts.new_branch_force, N_("branch"),
1720                            N_("create/reset and switch to a branch")),
1721                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1722                          N_("second guess 'git switch <no-such-branch>'")),
1723                 OPT_BOOL(0, "discard-changes", &opts.discard_changes,
1724                          N_("throw away local modifications")),
1725                 OPT_END()
1726         };
1727         int ret;
1728
1729         memset(&opts, 0, sizeof(opts));
1730         opts.dwim_new_local_branch = 1;
1731         opts.accept_ref = 1;
1732         opts.accept_pathspec = 0;
1733         opts.switch_branch_doing_nothing_is_ok = 0;
1734         opts.only_merge_on_switching_branches = 1;
1735         opts.implicit_detach = 0;
1736         opts.can_switch_when_in_progress = 0;
1737         opts.orphan_from_empty_tree = 1;
1738         opts.overlay_mode = -1;
1739
1740         options = parse_options_dup(switch_options);
1741         options = add_common_options(&opts, options);
1742         options = add_common_switch_branch_options(&opts, options);
1743
1744         ret = checkout_main(argc, argv, prefix, &opts,
1745                             options, switch_branch_usage);
1746         FREE_AND_NULL(options);
1747         return ret;
1748 }
1749
1750 int cmd_restore(int argc, const char **argv, const char *prefix)
1751 {
1752         struct checkout_opts opts;
1753         struct option *options;
1754         struct option restore_options[] = {
1755                 OPT_STRING('s', "source", &opts.from_treeish, "<tree-ish>",
1756                            N_("where the checkout from")),
1757                 OPT_BOOL('S', "staged", &opts.checkout_index,
1758                            N_("restore the index")),
1759                 OPT_BOOL('W', "worktree", &opts.checkout_worktree,
1760                            N_("restore the working tree (default)")),
1761                 OPT_BOOL(0, "ignore-unmerged", &opts.ignore_unmerged,
1762                          N_("ignore unmerged entries")),
1763                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode")),
1764                 OPT_END()
1765         };
1766         int ret;
1767
1768         memset(&opts, 0, sizeof(opts));
1769         opts.accept_ref = 0;
1770         opts.accept_pathspec = 1;
1771         opts.empty_pathspec_ok = 0;
1772         opts.overlay_mode = 0;
1773         opts.checkout_index = -1;    /* default off */
1774         opts.checkout_worktree = -2; /* default on */
1775         opts.ignore_unmerged_opt = "--ignore-unmerged";
1776
1777         options = parse_options_dup(restore_options);
1778         options = add_common_options(&opts, options);
1779         options = add_checkout_path_options(&opts, options);
1780
1781         ret = checkout_main(argc, argv, prefix, &opts,
1782                             options, restore_usage);
1783         FREE_AND_NULL(options);
1784         return ret;
1785 }