Merge branch 'jk/ci-only-on-selected-branches'
[git] / 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         int pathspec_file_nul;
74         const char *pathspec_from_file;
75
76         const char *new_branch;
77         const char *new_branch_force;
78         const char *new_orphan_branch;
79         int new_branch_log;
80         enum branch_track track;
81         struct diff_options diff_options;
82         char *conflict_style;
83
84         int branch_exists;
85         const char *prefix;
86         struct pathspec pathspec;
87         const char *from_treeish;
88         struct tree *source_tree;
89 };
90
91 struct branch_info {
92         const char *name; /* The short name used */
93         const char *path; /* The full name of a real branch */
94         struct commit *commit; /* The named commit */
95         char *refname; /* The full name of the ref being checked out. */
96         struct object_id oid; /* The object ID of the commit being checked out. */
97         /*
98          * if not null the branch is detached because it's already
99          * checked out in this checkout
100          */
101         char *checkout;
102 };
103
104 static int post_checkout_hook(struct commit *old_commit, struct commit *new_commit,
105                               int changed)
106 {
107         return run_hook_le(NULL, "post-checkout",
108                            oid_to_hex(old_commit ? &old_commit->object.oid : &null_oid),
109                            oid_to_hex(new_commit ? &new_commit->object.oid : &null_oid),
110                            changed ? "1" : "0", NULL);
111         /* "new_commit" can be NULL when checking out from the index before
112            a commit exists. */
113
114 }
115
116 static int update_some(const struct object_id *oid, struct strbuf *base,
117                 const char *pathname, unsigned mode, int stage, void *context)
118 {
119         int len;
120         struct cache_entry *ce;
121         int pos;
122
123         if (S_ISDIR(mode))
124                 return READ_TREE_RECURSIVE;
125
126         len = base->len + strlen(pathname);
127         ce = make_empty_cache_entry(&the_index, len);
128         oidcpy(&ce->oid, oid);
129         memcpy(ce->name, base->buf, base->len);
130         memcpy(ce->name + base->len, pathname, len - base->len);
131         ce->ce_flags = create_ce_flags(0) | CE_UPDATE;
132         ce->ce_namelen = len;
133         ce->ce_mode = create_ce_mode(mode);
134
135         /*
136          * If the entry is the same as the current index, we can leave the old
137          * entry in place. Whether it is UPTODATE or not, checkout_entry will
138          * do the right thing.
139          */
140         pos = cache_name_pos(ce->name, ce->ce_namelen);
141         if (pos >= 0) {
142                 struct cache_entry *old = active_cache[pos];
143                 if (ce->ce_mode == old->ce_mode &&
144                     !ce_intent_to_add(old) &&
145                     oideq(&ce->oid, &old->oid)) {
146                         old->ce_flags |= CE_UPDATE;
147                         discard_cache_entry(ce);
148                         return 0;
149                 }
150         }
151
152         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
153         return 0;
154 }
155
156 static int read_tree_some(struct tree *tree, const struct pathspec *pathspec)
157 {
158         read_tree_recursive(the_repository, tree, "", 0, 0,
159                             pathspec, update_some, NULL);
160
161         /* update the index with the given tree's info
162          * for all args, expanding wildcards, and exit
163          * with any non-zero return code.
164          */
165         return 0;
166 }
167
168 static int skip_same_name(const struct cache_entry *ce, int pos)
169 {
170         while (++pos < active_nr &&
171                !strcmp(active_cache[pos]->name, ce->name))
172                 ; /* skip */
173         return pos;
174 }
175
176 static int check_stage(int stage, const struct cache_entry *ce, int pos,
177                        int overlay_mode)
178 {
179         while (pos < active_nr &&
180                !strcmp(active_cache[pos]->name, ce->name)) {
181                 if (ce_stage(active_cache[pos]) == stage)
182                         return 0;
183                 pos++;
184         }
185         if (!overlay_mode)
186                 return 0;
187         if (stage == 2)
188                 return error(_("path '%s' does not have our version"), ce->name);
189         else
190                 return error(_("path '%s' does not have their version"), ce->name);
191 }
192
193 static int check_stages(unsigned stages, const struct cache_entry *ce, int pos)
194 {
195         unsigned seen = 0;
196         const char *name = ce->name;
197
198         while (pos < active_nr) {
199                 ce = active_cache[pos];
200                 if (strcmp(name, ce->name))
201                         break;
202                 seen |= (1 << ce_stage(ce));
203                 pos++;
204         }
205         if ((stages & seen) != stages)
206                 return error(_("path '%s' does not have all necessary versions"),
207                              name);
208         return 0;
209 }
210
211 static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
212                           const struct checkout *state, int *nr_checkouts,
213                           int overlay_mode)
214 {
215         while (pos < active_nr &&
216                !strcmp(active_cache[pos]->name, ce->name)) {
217                 if (ce_stage(active_cache[pos]) == stage)
218                         return checkout_entry(active_cache[pos], state,
219                                               NULL, nr_checkouts);
220                 pos++;
221         }
222         if (!overlay_mode) {
223                 unlink_entry(ce);
224                 return 0;
225         }
226         if (stage == 2)
227                 return error(_("path '%s' does not have our version"), ce->name);
228         else
229                 return error(_("path '%s' does not have their version"), ce->name);
230 }
231
232 static int checkout_merged(int pos, const struct checkout *state, int *nr_checkouts)
233 {
234         struct cache_entry *ce = active_cache[pos];
235         const char *path = ce->name;
236         mmfile_t ancestor, ours, theirs;
237         int status;
238         struct object_id oid;
239         mmbuffer_t result_buf;
240         struct object_id threeway[3];
241         unsigned mode = 0;
242
243         memset(threeway, 0, sizeof(threeway));
244         while (pos < active_nr) {
245                 int stage;
246                 stage = ce_stage(ce);
247                 if (!stage || strcmp(path, ce->name))
248                         break;
249                 oidcpy(&threeway[stage - 1], &ce->oid);
250                 if (stage == 2)
251                         mode = create_ce_mode(ce->ce_mode);
252                 pos++;
253                 ce = active_cache[pos];
254         }
255         if (is_null_oid(&threeway[1]) || is_null_oid(&threeway[2]))
256                 return error(_("path '%s' does not have necessary versions"), path);
257
258         read_mmblob(&ancestor, &threeway[0]);
259         read_mmblob(&ours, &threeway[1]);
260         read_mmblob(&theirs, &threeway[2]);
261
262         /*
263          * NEEDSWORK: re-create conflicts from merges with
264          * merge.renormalize set, too
265          */
266         status = ll_merge(&result_buf, path, &ancestor, "base",
267                           &ours, "ours", &theirs, "theirs",
268                           state->istate, NULL);
269         free(ancestor.ptr);
270         free(ours.ptr);
271         free(theirs.ptr);
272         if (status < 0 || !result_buf.ptr) {
273                 free(result_buf.ptr);
274                 return error(_("path '%s': cannot merge"), path);
275         }
276
277         /*
278          * NEEDSWORK:
279          * There is absolutely no reason to write this as a blob object
280          * and create a phony cache entry.  This hack is primarily to get
281          * to the write_entry() machinery that massages the contents to
282          * work-tree format and writes out which only allows it for a
283          * cache entry.  The code in write_entry() needs to be refactored
284          * to allow us to feed a <buffer, size, mode> instead of a cache
285          * entry.  Such a refactoring would help merge_recursive as well
286          * (it also writes the merge result to the object database even
287          * when it may contain conflicts).
288          */
289         if (write_object_file(result_buf.ptr, result_buf.size, blob_type, &oid))
290                 die(_("Unable to add merge result for '%s'"), path);
291         free(result_buf.ptr);
292         ce = make_transient_cache_entry(mode, &oid, path, 2);
293         if (!ce)
294                 die(_("make_cache_entry failed for path '%s'"), path);
295         status = checkout_entry(ce, state, NULL, nr_checkouts);
296         discard_cache_entry(ce);
297         return status;
298 }
299
300 static void mark_ce_for_checkout_overlay(struct cache_entry *ce,
301                                          char *ps_matched,
302                                          const struct checkout_opts *opts)
303 {
304         ce->ce_flags &= ~CE_MATCHED;
305         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
306                 return;
307         if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
308                 /*
309                  * "git checkout tree-ish -- path", but this entry
310                  * is in the original index but is not in tree-ish
311                  * or does not match the pathspec; it will not be
312                  * checked out to the working tree.  We will not do
313                  * anything to this entry at all.
314                  */
315                 return;
316         /*
317          * Either this entry came from the tree-ish we are
318          * checking the paths out of, or we are checking out
319          * of the index.
320          *
321          * If it comes from the tree-ish, we already know it
322          * matches the pathspec and could just stamp
323          * CE_MATCHED to it from update_some(). But we still
324          * need ps_matched and read_tree_recursive (and
325          * eventually tree_entry_interesting) cannot fill
326          * ps_matched yet. Once it can, we can avoid calling
327          * match_pathspec() for _all_ entries when
328          * opts->source_tree != NULL.
329          */
330         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched))
331                 ce->ce_flags |= CE_MATCHED;
332 }
333
334 static void mark_ce_for_checkout_no_overlay(struct cache_entry *ce,
335                                             char *ps_matched,
336                                             const struct checkout_opts *opts)
337 {
338         ce->ce_flags &= ~CE_MATCHED;
339         if (!opts->ignore_skipworktree && ce_skip_worktree(ce))
340                 return;
341         if (ce_path_match(&the_index, ce, &opts->pathspec, ps_matched)) {
342                 ce->ce_flags |= CE_MATCHED;
343                 if (opts->source_tree && !(ce->ce_flags & CE_UPDATE))
344                         /*
345                          * In overlay mode, but the path is not in
346                          * tree-ish, which means we should remove it
347                          * from the index and the working tree.
348                          */
349                         ce->ce_flags |= CE_REMOVE | CE_WT_REMOVE;
350         }
351 }
352
353 static int checkout_worktree(const struct checkout_opts *opts,
354                              const struct branch_info *info)
355 {
356         struct checkout state = CHECKOUT_INIT;
357         int nr_checkouts = 0, nr_unmerged = 0;
358         int errs = 0;
359         int pos;
360
361         state.force = 1;
362         state.refresh_cache = 1;
363         state.istate = &the_index;
364
365         init_checkout_metadata(&state.meta, info->refname,
366                                info->commit ? &info->commit->object.oid : &info->oid,
367                                NULL);
368
369         enable_delayed_checkout(&state);
370         for (pos = 0; pos < active_nr; pos++) {
371                 struct cache_entry *ce = active_cache[pos];
372                 if (ce->ce_flags & CE_MATCHED) {
373                         if (!ce_stage(ce)) {
374                                 errs |= checkout_entry(ce, &state,
375                                                        NULL, &nr_checkouts);
376                                 continue;
377                         }
378                         if (opts->writeout_stage)
379                                 errs |= checkout_stage(opts->writeout_stage,
380                                                        ce, pos,
381                                                        &state,
382                                                        &nr_checkouts, opts->overlay_mode);
383                         else if (opts->merge)
384                                 errs |= checkout_merged(pos, &state,
385                                                         &nr_unmerged);
386                         pos = skip_same_name(ce, pos) - 1;
387                 }
388         }
389         remove_marked_cache_entries(&the_index, 1);
390         remove_scheduled_dirs();
391         errs |= finish_delayed_checkout(&state, &nr_checkouts);
392
393         if (opts->count_checkout_paths) {
394                 if (nr_unmerged)
395                         fprintf_ln(stderr, Q_("Recreated %d merge conflict",
396                                               "Recreated %d merge conflicts",
397                                               nr_unmerged),
398                                    nr_unmerged);
399                 if (opts->source_tree)
400                         fprintf_ln(stderr, Q_("Updated %d path from %s",
401                                               "Updated %d paths from %s",
402                                               nr_checkouts),
403                                    nr_checkouts,
404                                    find_unique_abbrev(&opts->source_tree->object.oid,
405                                                       DEFAULT_ABBREV));
406                 else if (!nr_unmerged || nr_checkouts)
407                         fprintf_ln(stderr, Q_("Updated %d path from the index",
408                                               "Updated %d paths from the index",
409                                               nr_checkouts),
410                                    nr_checkouts);
411         }
412
413         return errs;
414 }
415
416 static int checkout_paths(const struct checkout_opts *opts,
417                           const struct branch_info *new_branch_info)
418 {
419         int pos;
420         static char *ps_matched;
421         struct object_id rev;
422         struct commit *head;
423         int errs = 0;
424         struct lock_file lock_file = LOCK_INIT;
425         int checkout_index;
426
427         trace2_cmd_mode(opts->patch_mode ? "patch" : "path");
428
429         if (opts->track != BRANCH_TRACK_UNSPECIFIED)
430                 die(_("'%s' cannot be used with updating paths"), "--track");
431
432         if (opts->new_branch_log)
433                 die(_("'%s' cannot be used with updating paths"), "-l");
434
435         if (opts->ignore_unmerged && opts->patch_mode)
436                 die(_("'%s' cannot be used with updating paths"),
437                     opts->ignore_unmerged_opt);
438
439         if (opts->force_detach)
440                 die(_("'%s' cannot be used with updating paths"), "--detach");
441
442         if (opts->merge && opts->patch_mode)
443                 die(_("'%s' cannot be used with %s"), "--merge", "--patch");
444
445         if (opts->ignore_unmerged && opts->merge)
446                 die(_("'%s' cannot be used with %s"),
447                     opts->ignore_unmerged_opt, "-m");
448
449         if (opts->new_branch)
450                 die(_("Cannot update paths and switch to branch '%s' at the same time."),
451                     opts->new_branch);
452
453         if (!opts->checkout_worktree && !opts->checkout_index)
454                 die(_("neither '%s' or '%s' is specified"),
455                     "--staged", "--worktree");
456
457         if (!opts->checkout_worktree && !opts->from_treeish)
458                 die(_("'%s' must be used when '%s' is not specified"),
459                     "--worktree", "--source");
460
461         if (opts->checkout_index && !opts->checkout_worktree &&
462             opts->writeout_stage)
463                 die(_("'%s' or '%s' cannot be used with %s"),
464                     "--ours", "--theirs", "--staged");
465
466         if (opts->checkout_index && !opts->checkout_worktree &&
467             opts->merge)
468                 die(_("'%s' or '%s' cannot be used with %s"),
469                     "--merge", "--conflict", "--staged");
470
471         if (opts->patch_mode) {
472                 const char *patch_mode;
473
474                 if (opts->checkout_index && opts->checkout_worktree)
475                         patch_mode = "--patch=checkout";
476                 else if (opts->checkout_index && !opts->checkout_worktree)
477                         patch_mode = "--patch=reset";
478                 else if (!opts->checkout_index && opts->checkout_worktree)
479                         patch_mode = "--patch=worktree";
480                 else
481                         BUG("either flag must have been set, worktree=%d, index=%d",
482                             opts->checkout_worktree, opts->checkout_index);
483                 return run_add_interactive(new_branch_info->name, patch_mode, &opts->pathspec);
484         }
485
486         repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
487         if (read_cache_preload(&opts->pathspec) < 0)
488                 return error(_("index file corrupt"));
489
490         if (opts->source_tree)
491                 read_tree_some(opts->source_tree, &opts->pathspec);
492
493         ps_matched = xcalloc(opts->pathspec.nr, 1);
494
495         /*
496          * Make sure all pathspecs participated in locating the paths
497          * to be checked out.
498          */
499         for (pos = 0; pos < active_nr; pos++)
500                 if (opts->overlay_mode)
501                         mark_ce_for_checkout_overlay(active_cache[pos],
502                                                      ps_matched,
503                                                      opts);
504                 else
505                         mark_ce_for_checkout_no_overlay(active_cache[pos],
506                                                         ps_matched,
507                                                         opts);
508
509         if (report_path_error(ps_matched, &opts->pathspec)) {
510                 free(ps_matched);
511                 return 1;
512         }
513         free(ps_matched);
514
515         /* "checkout -m path" to recreate conflicted state */
516         if (opts->merge)
517                 unmerge_marked_index(&the_index);
518
519         /* Any unmerged paths? */
520         for (pos = 0; pos < active_nr; pos++) {
521                 const struct cache_entry *ce = active_cache[pos];
522                 if (ce->ce_flags & CE_MATCHED) {
523                         if (!ce_stage(ce))
524                                 continue;
525                         if (opts->ignore_unmerged) {
526                                 if (!opts->quiet)
527                                         warning(_("path '%s' is unmerged"), ce->name);
528                         } else if (opts->writeout_stage) {
529                                 errs |= check_stage(opts->writeout_stage, ce, pos, opts->overlay_mode);
530                         } else if (opts->merge) {
531                                 errs |= check_stages((1<<2) | (1<<3), ce, pos);
532                         } else {
533                                 errs = 1;
534                                 error(_("path '%s' is unmerged"), ce->name);
535                         }
536                         pos = skip_same_name(ce, pos) - 1;
537                 }
538         }
539         if (errs)
540                 return 1;
541
542         /* Now we are committed to check them out */
543         if (opts->checkout_worktree)
544                 errs |= checkout_worktree(opts, new_branch_info);
545         else
546                 remove_marked_cache_entries(&the_index, 1);
547
548         /*
549          * Allow updating the index when checking out from the index.
550          * This is to save new stat info.
551          */
552         if (opts->checkout_worktree && !opts->checkout_index && !opts->source_tree)
553                 checkout_index = 1;
554         else
555                 checkout_index = opts->checkout_index;
556
557         if (checkout_index) {
558                 if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
559                         die(_("unable to write new index file"));
560         } else {
561                 /*
562                  * NEEDSWORK: if --worktree is not specified, we
563                  * should save stat info of checked out files in the
564                  * index to avoid the next (potentially costly)
565                  * refresh. But it's a bit tricker to do...
566                  */
567                 rollback_lock_file(&lock_file);
568         }
569
570         read_ref_full("HEAD", 0, &rev, NULL);
571         head = lookup_commit_reference_gently(the_repository, &rev, 1);
572
573         errs |= post_checkout_hook(head, head, 0);
574         return errs;
575 }
576
577 static void show_local_changes(struct object *head,
578                                const struct diff_options *opts)
579 {
580         struct rev_info rev;
581         /* I think we want full paths, even if we're in a subdirectory. */
582         repo_init_revisions(the_repository, &rev, NULL);
583         rev.diffopt.flags = opts->flags;
584         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
585         diff_setup_done(&rev.diffopt);
586         add_pending_object(&rev, head, NULL);
587         run_diff_index(&rev, 0);
588 }
589
590 static void describe_detached_head(const char *msg, struct commit *commit)
591 {
592         struct strbuf sb = STRBUF_INIT;
593
594         if (!parse_commit(commit))
595                 pp_commit_easy(CMIT_FMT_ONELINE, commit, &sb);
596         if (print_sha1_ellipsis()) {
597                 fprintf(stderr, "%s %s... %s\n", msg,
598                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
599         } else {
600                 fprintf(stderr, "%s %s %s\n", msg,
601                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV), sb.buf);
602         }
603         strbuf_release(&sb);
604 }
605
606 static int reset_tree(struct tree *tree, const struct checkout_opts *o,
607                       int worktree, int *writeout_error,
608                       struct branch_info *info)
609 {
610         struct unpack_trees_options opts;
611         struct tree_desc tree_desc;
612
613         memset(&opts, 0, sizeof(opts));
614         opts.head_idx = -1;
615         opts.update = worktree;
616         opts.skip_unmerged = !worktree;
617         opts.reset = 1;
618         opts.merge = 1;
619         opts.fn = oneway_merge;
620         opts.verbose_update = o->show_progress;
621         opts.src_index = &the_index;
622         opts.dst_index = &the_index;
623         init_checkout_metadata(&opts.meta, info->refname,
624                                info->commit ? &info->commit->object.oid :
625                                is_null_oid(&info->oid) ? &tree->object.oid :
626                                &info->oid,
627                                NULL);
628         parse_tree(tree);
629         init_tree_desc(&tree_desc, tree->buffer, tree->size);
630         switch (unpack_trees(1, &tree_desc, &opts)) {
631         case -2:
632                 *writeout_error = 1;
633                 /*
634                  * We return 0 nevertheless, as the index is all right
635                  * and more importantly we have made best efforts to
636                  * update paths in the work tree, and we cannot revert
637                  * them.
638                  */
639                 /* fallthrough */
640         case 0:
641                 return 0;
642         default:
643                 return 128;
644         }
645 }
646
647 static void setup_branch_path(struct branch_info *branch)
648 {
649         struct strbuf buf = STRBUF_INIT;
650
651         /*
652          * If this is a ref, resolve it; otherwise, look up the OID for our
653          * expression.  Failure here is okay.
654          */
655         if (!dwim_ref(branch->name, strlen(branch->name), &branch->oid, &branch->refname))
656                 repo_get_oid_committish(the_repository, branch->name, &branch->oid);
657
658         strbuf_branchname(&buf, branch->name, INTERPRET_BRANCH_LOCAL);
659         if (strcmp(buf.buf, branch->name))
660                 branch->name = xstrdup(buf.buf);
661         strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
662         branch->path = strbuf_detach(&buf, NULL);
663 }
664
665 static int merge_working_tree(const struct checkout_opts *opts,
666                               struct branch_info *old_branch_info,
667                               struct branch_info *new_branch_info,
668                               int *writeout_error)
669 {
670         int ret;
671         struct lock_file lock_file = LOCK_INIT;
672         struct tree *new_tree;
673
674         hold_locked_index(&lock_file, LOCK_DIE_ON_ERROR);
675         if (read_cache_preload(NULL) < 0)
676                 return error(_("index file corrupt"));
677
678         resolve_undo_clear();
679         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
680                 if (new_branch_info->commit)
681                         BUG("'switch --orphan' should never accept a commit as starting point");
682                 new_tree = parse_tree_indirect(the_hash_algo->empty_tree);
683         } else
684                 new_tree = get_commit_tree(new_branch_info->commit);
685         if (opts->discard_changes) {
686                 ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
687                 if (ret)
688                         return ret;
689         } else {
690                 struct tree_desc trees[2];
691                 struct tree *tree;
692                 struct unpack_trees_options topts;
693
694                 memset(&topts, 0, sizeof(topts));
695                 topts.head_idx = -1;
696                 topts.src_index = &the_index;
697                 topts.dst_index = &the_index;
698
699                 setup_unpack_trees_porcelain(&topts, "checkout");
700
701                 refresh_cache(REFRESH_QUIET);
702
703                 if (unmerged_cache()) {
704                         error(_("you need to resolve your current index first"));
705                         return 1;
706                 }
707
708                 /* 2-way merge to the new branch */
709                 topts.initial_checkout = is_cache_unborn();
710                 topts.update = 1;
711                 topts.merge = 1;
712                 topts.quiet = opts->merge && old_branch_info->commit;
713                 topts.verbose_update = opts->show_progress;
714                 topts.fn = twoway_merge;
715                 init_checkout_metadata(&topts.meta, new_branch_info->refname,
716                                        new_branch_info->commit ?
717                                        &new_branch_info->commit->object.oid :
718                                        &new_branch_info->oid, NULL);
719                 if (opts->overwrite_ignore) {
720                         topts.dir = xcalloc(1, sizeof(*topts.dir));
721                         topts.dir->flags |= DIR_SHOW_IGNORED;
722                         setup_standard_excludes(topts.dir);
723                 }
724                 tree = parse_tree_indirect(old_branch_info->commit ?
725                                            &old_branch_info->commit->object.oid :
726                                            the_hash_algo->empty_tree);
727                 init_tree_desc(&trees[0], tree->buffer, tree->size);
728                 parse_tree(new_tree);
729                 tree = new_tree;
730                 init_tree_desc(&trees[1], tree->buffer, tree->size);
731
732                 ret = unpack_trees(2, trees, &topts);
733                 clear_unpack_trees_porcelain(&topts);
734                 if (ret == -1) {
735                         /*
736                          * Unpack couldn't do a trivial merge; either
737                          * give up or do a real merge, depending on
738                          * whether the merge flag was used.
739                          */
740                         struct tree *work;
741                         struct tree *old_tree;
742                         struct merge_options o;
743                         struct strbuf sb = STRBUF_INIT;
744                         struct strbuf old_commit_shortname = STRBUF_INIT;
745
746                         if (!opts->merge)
747                                 return 1;
748
749                         /*
750                          * Without old_branch_info->commit, the below is the same as
751                          * the two-tree unpack we already tried and failed.
752                          */
753                         if (!old_branch_info->commit)
754                                 return 1;
755                         old_tree = get_commit_tree(old_branch_info->commit);
756
757                         if (repo_index_has_changes(the_repository, old_tree, &sb))
758                                 die(_("cannot continue with staged changes in "
759                                       "the following files:\n%s"), sb.buf);
760                         strbuf_release(&sb);
761
762                         /* Do more real merge */
763
764                         /*
765                          * We update the index fully, then write the
766                          * tree from the index, then merge the new
767                          * branch with the current tree, with the old
768                          * branch as the base. Then we reset the index
769                          * (but not the working tree) to the new
770                          * branch, leaving the working tree as the
771                          * merged version, but skipping unmerged
772                          * entries in the index.
773                          */
774
775                         add_files_to_cache(NULL, NULL, 0);
776                         /*
777                          * NEEDSWORK: carrying over local changes
778                          * when branches have different end-of-line
779                          * normalization (or clean+smudge rules) is
780                          * a pain; plumb in an option to set
781                          * o.renormalize?
782                          */
783                         init_merge_options(&o, the_repository);
784                         o.verbosity = 0;
785                         work = write_in_core_index_as_tree(the_repository);
786
787                         ret = reset_tree(new_tree,
788                                          opts, 1,
789                                          writeout_error, new_branch_info);
790                         if (ret)
791                                 return ret;
792                         o.ancestor = old_branch_info->name;
793                         if (old_branch_info->name == NULL) {
794                                 strbuf_add_unique_abbrev(&old_commit_shortname,
795                                                          &old_branch_info->commit->object.oid,
796                                                          DEFAULT_ABBREV);
797                                 o.ancestor = old_commit_shortname.buf;
798                         }
799                         o.branch1 = new_branch_info->name;
800                         o.branch2 = "local";
801                         ret = merge_trees(&o,
802                                           new_tree,
803                                           work,
804                                           old_tree);
805                         if (ret < 0)
806                                 exit(128);
807                         ret = reset_tree(new_tree,
808                                          opts, 0,
809                                          writeout_error, new_branch_info);
810                         strbuf_release(&o.obuf);
811                         strbuf_release(&old_commit_shortname);
812                         if (ret)
813                                 return ret;
814                 }
815         }
816
817         if (!active_cache_tree)
818                 active_cache_tree = cache_tree();
819
820         if (!cache_tree_fully_valid(active_cache_tree))
821                 cache_tree_update(&the_index, WRITE_TREE_SILENT | WRITE_TREE_REPAIR);
822
823         if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
824                 die(_("unable to write new index file"));
825
826         if (!opts->discard_changes && !opts->quiet && new_branch_info->commit)
827                 show_local_changes(&new_branch_info->commit->object, &opts->diff_options);
828
829         return 0;
830 }
831
832 static void report_tracking(struct branch_info *new_branch_info)
833 {
834         struct strbuf sb = STRBUF_INIT;
835         struct branch *branch = branch_get(new_branch_info->name);
836
837         if (!format_tracking_info(branch, &sb, AHEAD_BEHIND_FULL))
838                 return;
839         fputs(sb.buf, stdout);
840         strbuf_release(&sb);
841 }
842
843 static void update_refs_for_switch(const struct checkout_opts *opts,
844                                    struct branch_info *old_branch_info,
845                                    struct branch_info *new_branch_info)
846 {
847         struct strbuf msg = STRBUF_INIT;
848         const char *old_desc, *reflog_msg;
849         if (opts->new_branch) {
850                 if (opts->new_orphan_branch) {
851                         char *refname;
852
853                         refname = mkpathdup("refs/heads/%s", opts->new_orphan_branch);
854                         if (opts->new_branch_log &&
855                             !should_autocreate_reflog(refname)) {
856                                 int ret;
857                                 struct strbuf err = STRBUF_INIT;
858
859                                 ret = safe_create_reflog(refname, 1, &err);
860                                 if (ret) {
861                                         fprintf(stderr, _("Can not do reflog for '%s': %s\n"),
862                                                 opts->new_orphan_branch, err.buf);
863                                         strbuf_release(&err);
864                                         free(refname);
865                                         return;
866                                 }
867                                 strbuf_release(&err);
868                         }
869                         free(refname);
870                 }
871                 else
872                         create_branch(the_repository,
873                                       opts->new_branch, new_branch_info->name,
874                                       opts->new_branch_force ? 1 : 0,
875                                       opts->new_branch_force ? 1 : 0,
876                                       opts->new_branch_log,
877                                       opts->quiet,
878                                       opts->track);
879                 new_branch_info->name = opts->new_branch;
880                 setup_branch_path(new_branch_info);
881         }
882
883         old_desc = old_branch_info->name;
884         if (!old_desc && old_branch_info->commit)
885                 old_desc = oid_to_hex(&old_branch_info->commit->object.oid);
886
887         reflog_msg = getenv("GIT_REFLOG_ACTION");
888         if (!reflog_msg)
889                 strbuf_addf(&msg, "checkout: moving from %s to %s",
890                         old_desc ? old_desc : "(invalid)", new_branch_info->name);
891         else
892                 strbuf_insertstr(&msg, 0, reflog_msg);
893
894         if (!strcmp(new_branch_info->name, "HEAD") && !new_branch_info->path && !opts->force_detach) {
895                 /* Nothing to do. */
896         } else if (opts->force_detach || !new_branch_info->path) {      /* No longer on any branch. */
897                 update_ref(msg.buf, "HEAD", &new_branch_info->commit->object.oid, NULL,
898                            REF_NO_DEREF, UPDATE_REFS_DIE_ON_ERR);
899                 if (!opts->quiet) {
900                         if (old_branch_info->path &&
901                             advice_detached_head && !opts->force_detach)
902                                 detach_advice(new_branch_info->name);
903                         describe_detached_head(_("HEAD is now at"), new_branch_info->commit);
904                 }
905         } else if (new_branch_info->path) {     /* Switch branches. */
906                 if (create_symref("HEAD", new_branch_info->path, msg.buf) < 0)
907                         die(_("unable to update HEAD"));
908                 if (!opts->quiet) {
909                         if (old_branch_info->path && !strcmp(new_branch_info->path, old_branch_info->path)) {
910                                 if (opts->new_branch_force)
911                                         fprintf(stderr, _("Reset branch '%s'\n"),
912                                                 new_branch_info->name);
913                                 else
914                                         fprintf(stderr, _("Already on '%s'\n"),
915                                                 new_branch_info->name);
916                         } else if (opts->new_branch) {
917                                 if (opts->branch_exists)
918                                         fprintf(stderr, _("Switched to and reset branch '%s'\n"), new_branch_info->name);
919                                 else
920                                         fprintf(stderr, _("Switched to a new branch '%s'\n"), new_branch_info->name);
921                         } else {
922                                 fprintf(stderr, _("Switched to branch '%s'\n"),
923                                         new_branch_info->name);
924                         }
925                 }
926                 if (old_branch_info->path && old_branch_info->name) {
927                         if (!ref_exists(old_branch_info->path) && reflog_exists(old_branch_info->path))
928                                 delete_reflog(old_branch_info->path);
929                 }
930         }
931         remove_branch_state(the_repository, !opts->quiet);
932         strbuf_release(&msg);
933         if (!opts->quiet &&
934             (new_branch_info->path || (!opts->force_detach && !strcmp(new_branch_info->name, "HEAD"))))
935                 report_tracking(new_branch_info);
936 }
937
938 static int add_pending_uninteresting_ref(const char *refname,
939                                          const struct object_id *oid,
940                                          int flags, void *cb_data)
941 {
942         add_pending_oid(cb_data, refname, oid, UNINTERESTING);
943         return 0;
944 }
945
946 static void describe_one_orphan(struct strbuf *sb, struct commit *commit)
947 {
948         strbuf_addstr(sb, "  ");
949         strbuf_add_unique_abbrev(sb, &commit->object.oid, DEFAULT_ABBREV);
950         strbuf_addch(sb, ' ');
951         if (!parse_commit(commit))
952                 pp_commit_easy(CMIT_FMT_ONELINE, commit, sb);
953         strbuf_addch(sb, '\n');
954 }
955
956 #define ORPHAN_CUTOFF 4
957 static void suggest_reattach(struct commit *commit, struct rev_info *revs)
958 {
959         struct commit *c, *last = NULL;
960         struct strbuf sb = STRBUF_INIT;
961         int lost = 0;
962         while ((c = get_revision(revs)) != NULL) {
963                 if (lost < ORPHAN_CUTOFF)
964                         describe_one_orphan(&sb, c);
965                 last = c;
966                 lost++;
967         }
968         if (ORPHAN_CUTOFF < lost) {
969                 int more = lost - ORPHAN_CUTOFF;
970                 if (more == 1)
971                         describe_one_orphan(&sb, last);
972                 else
973                         strbuf_addf(&sb, _(" ... and %d more.\n"), more);
974         }
975
976         fprintf(stderr,
977                 Q_(
978                 /* The singular version */
979                 "Warning: you are leaving %d commit behind, "
980                 "not connected to\n"
981                 "any of your branches:\n\n"
982                 "%s\n",
983                 /* The plural version */
984                 "Warning: you are leaving %d commits behind, "
985                 "not connected to\n"
986                 "any of your branches:\n\n"
987                 "%s\n",
988                 /* Give ngettext() the count */
989                 lost),
990                 lost,
991                 sb.buf);
992         strbuf_release(&sb);
993
994         if (advice_detached_head)
995                 fprintf(stderr,
996                         Q_(
997                         /* The singular version */
998                         "If you want to keep it by creating a new branch, "
999                         "this may be a good time\nto do so with:\n\n"
1000                         " git branch <new-branch-name> %s\n\n",
1001                         /* The plural version */
1002                         "If you want to keep them by creating a new branch, "
1003                         "this may be a good time\nto do so with:\n\n"
1004                         " git branch <new-branch-name> %s\n\n",
1005                         /* Give ngettext() the count */
1006                         lost),
1007                         find_unique_abbrev(&commit->object.oid, DEFAULT_ABBREV));
1008 }
1009
1010 /*
1011  * We are about to leave commit that was at the tip of a detached
1012  * HEAD.  If it is not reachable from any ref, this is the last chance
1013  * for the user to do so without resorting to reflog.
1014  */
1015 static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
1016 {
1017         struct rev_info revs;
1018         struct object *object = &old_commit->object;
1019
1020         repo_init_revisions(the_repository, &revs, NULL);
1021         setup_revisions(0, NULL, &revs, NULL);
1022
1023         object->flags &= ~UNINTERESTING;
1024         add_pending_object(&revs, object, oid_to_hex(&object->oid));
1025
1026         for_each_ref(add_pending_uninteresting_ref, &revs);
1027         if (new_commit)
1028                 add_pending_oid(&revs, "HEAD",
1029                                 &new_commit->object.oid,
1030                                 UNINTERESTING);
1031
1032         if (prepare_revision_walk(&revs))
1033                 die(_("internal error in revision walk"));
1034         if (!(old_commit->object.flags & UNINTERESTING))
1035                 suggest_reattach(old_commit, &revs);
1036         else
1037                 describe_detached_head(_("Previous HEAD position was"), old_commit);
1038
1039         /* Clean up objects used, as they will be reused. */
1040         clear_commit_marks_all(ALL_REV_FLAGS);
1041 }
1042
1043 static int switch_branches(const struct checkout_opts *opts,
1044                            struct branch_info *new_branch_info)
1045 {
1046         int ret = 0;
1047         struct branch_info old_branch_info;
1048         void *path_to_free;
1049         struct object_id rev;
1050         int flag, writeout_error = 0;
1051         int do_merge = 1;
1052
1053         trace2_cmd_mode("branch");
1054
1055         memset(&old_branch_info, 0, sizeof(old_branch_info));
1056         old_branch_info.path = path_to_free = resolve_refdup("HEAD", 0, &rev, &flag);
1057         if (old_branch_info.path)
1058                 old_branch_info.commit = lookup_commit_reference_gently(the_repository, &rev, 1);
1059         if (!(flag & REF_ISSYMREF))
1060                 old_branch_info.path = NULL;
1061
1062         if (old_branch_info.path)
1063                 skip_prefix(old_branch_info.path, "refs/heads/", &old_branch_info.name);
1064
1065         if (opts->new_orphan_branch && opts->orphan_from_empty_tree) {
1066                 if (new_branch_info->name)
1067                         BUG("'switch --orphan' should never accept a commit as starting point");
1068                 new_branch_info->commit = NULL;
1069                 new_branch_info->name = "(empty)";
1070                 do_merge = 1;
1071         }
1072
1073         if (!new_branch_info->name) {
1074                 new_branch_info->name = "HEAD";
1075                 new_branch_info->commit = old_branch_info.commit;
1076                 if (!new_branch_info->commit)
1077                         die(_("You are on a branch yet to be born"));
1078                 parse_commit_or_die(new_branch_info->commit);
1079
1080                 if (opts->only_merge_on_switching_branches)
1081                         do_merge = 0;
1082         }
1083
1084         if (do_merge) {
1085                 ret = merge_working_tree(opts, &old_branch_info, new_branch_info, &writeout_error);
1086                 if (ret) {
1087                         free(path_to_free);
1088                         return ret;
1089                 }
1090         }
1091
1092         if (!opts->quiet && !old_branch_info.path && old_branch_info.commit && new_branch_info->commit != old_branch_info.commit)
1093                 orphaned_commit_warning(old_branch_info.commit, new_branch_info->commit);
1094
1095         update_refs_for_switch(opts, &old_branch_info, new_branch_info);
1096
1097         ret = post_checkout_hook(old_branch_info.commit, new_branch_info->commit, 1);
1098         free(path_to_free);
1099         return ret || writeout_error;
1100 }
1101
1102 static int git_checkout_config(const char *var, const char *value, void *cb)
1103 {
1104         if (!strcmp(var, "diff.ignoresubmodules")) {
1105                 struct checkout_opts *opts = cb;
1106                 handle_ignore_submodules_arg(&opts->diff_options, value);
1107                 return 0;
1108         }
1109
1110         if (starts_with(var, "submodule."))
1111                 return git_default_submodule_config(var, value, NULL);
1112
1113         return git_xmerge_config(var, value, NULL);
1114 }
1115
1116 static void setup_new_branch_info_and_source_tree(
1117         struct branch_info *new_branch_info,
1118         struct checkout_opts *opts,
1119         struct object_id *rev,
1120         const char *arg)
1121 {
1122         struct tree **source_tree = &opts->source_tree;
1123         struct object_id branch_rev;
1124
1125         new_branch_info->name = arg;
1126         setup_branch_path(new_branch_info);
1127
1128         if (!check_refname_format(new_branch_info->path, 0) &&
1129             !read_ref(new_branch_info->path, &branch_rev))
1130                 oidcpy(rev, &branch_rev);
1131         else
1132                 new_branch_info->path = NULL; /* not an existing branch */
1133
1134         new_branch_info->commit = lookup_commit_reference_gently(the_repository, rev, 1);
1135         if (!new_branch_info->commit) {
1136                 /* not a commit */
1137                 *source_tree = parse_tree_indirect(rev);
1138         } else {
1139                 parse_commit_or_die(new_branch_info->commit);
1140                 *source_tree = get_commit_tree(new_branch_info->commit);
1141         }
1142 }
1143
1144 static const char *parse_remote_branch(const char *arg,
1145                                        struct object_id *rev,
1146                                        int could_be_checkout_paths)
1147 {
1148         int num_matches = 0;
1149         const char *remote = unique_tracking_name(arg, rev, &num_matches);
1150
1151         if (remote && could_be_checkout_paths) {
1152                 die(_("'%s' could be both a local file and a tracking branch.\n"
1153                         "Please use -- (and optionally --no-guess) to disambiguate"),
1154                     arg);
1155         }
1156
1157         if (!remote && num_matches > 1) {
1158             if (advice_checkout_ambiguous_remote_branch_name) {
1159                     advise(_("If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
1160                              "you can do so by fully qualifying the name with the --track option:\n"
1161                              "\n"
1162                              "    git checkout --track origin/<name>\n"
1163                              "\n"
1164                              "If you'd like to always have checkouts of an ambiguous <name> prefer\n"
1165                              "one remote, e.g. the 'origin' remote, consider setting\n"
1166                              "checkout.defaultRemote=origin in your config."));
1167             }
1168
1169             die(_("'%s' matched multiple (%d) remote tracking branches"),
1170                 arg, num_matches);
1171         }
1172
1173         return remote;
1174 }
1175
1176 static int parse_branchname_arg(int argc, const char **argv,
1177                                 int dwim_new_local_branch_ok,
1178                                 struct branch_info *new_branch_info,
1179                                 struct checkout_opts *opts,
1180                                 struct object_id *rev)
1181 {
1182         const char **new_branch = &opts->new_branch;
1183         int argcount = 0;
1184         const char *arg;
1185         int dash_dash_pos;
1186         int has_dash_dash = 0;
1187         int i;
1188
1189         /*
1190          * case 1: git checkout <ref> -- [<paths>]
1191          *
1192          *   <ref> must be a valid tree, everything after the '--' must be
1193          *   a path.
1194          *
1195          * case 2: git checkout -- [<paths>]
1196          *
1197          *   everything after the '--' must be paths.
1198          *
1199          * case 3: git checkout <something> [--]
1200          *
1201          *   (a) If <something> is a commit, that is to
1202          *       switch to the branch or detach HEAD at it.  As a special case,
1203          *       if <something> is A...B (missing A or B means HEAD but you can
1204          *       omit at most one side), and if there is a unique merge base
1205          *       between A and B, A...B names that merge base.
1206          *
1207          *   (b) If <something> is _not_ a commit, either "--" is present
1208          *       or <something> is not a path, no -t or -b was given, and
1209          *       and there is a tracking branch whose name is <something>
1210          *       in one and only one remote (or if the branch exists on the
1211          *       remote named in checkout.defaultRemote), then this is a
1212          *       short-hand to fork local <something> from that
1213          *       remote-tracking branch.
1214          *
1215          *   (c) Otherwise, if "--" is present, treat it like case (1).
1216          *
1217          *   (d) Otherwise :
1218          *       - if it's a reference, treat it like case (1)
1219          *       - else if it's a path, treat it like case (2)
1220          *       - else: fail.
1221          *
1222          * case 4: git checkout <something> <paths>
1223          *
1224          *   The first argument must not be ambiguous.
1225          *   - If it's *only* a reference, treat it like case (1).
1226          *   - If it's only a path, treat it like case (2).
1227          *   - else: fail.
1228          *
1229          */
1230         if (!argc)
1231                 return 0;
1232
1233         if (!opts->accept_pathspec) {
1234                 if (argc > 1)
1235                         die(_("only one reference expected"));
1236                 has_dash_dash = 1; /* helps disambiguate */
1237         }
1238
1239         arg = argv[0];
1240         dash_dash_pos = -1;
1241         for (i = 0; i < argc; i++) {
1242                 if (opts->accept_pathspec && !strcmp(argv[i], "--")) {
1243                         dash_dash_pos = i;
1244                         break;
1245                 }
1246         }
1247         if (dash_dash_pos == 0)
1248                 return 1; /* case (2) */
1249         else if (dash_dash_pos == 1)
1250                 has_dash_dash = 1; /* case (3) or (1) */
1251         else if (dash_dash_pos >= 2)
1252                 die(_("only one reference expected, %d given."), dash_dash_pos);
1253         opts->count_checkout_paths = !opts->quiet && !has_dash_dash;
1254
1255         if (!strcmp(arg, "-"))
1256                 arg = "@{-1}";
1257
1258         if (get_oid_mb(arg, rev)) {
1259                 /*
1260                  * Either case (3) or (4), with <something> not being
1261                  * a commit, or an attempt to use case (1) with an
1262                  * invalid ref.
1263                  *
1264                  * It's likely an error, but we need to find out if
1265                  * we should auto-create the branch, case (3).(b).
1266                  */
1267                 int recover_with_dwim = dwim_new_local_branch_ok;
1268
1269                 int could_be_checkout_paths = !has_dash_dash &&
1270                         check_filename(opts->prefix, arg);
1271
1272                 if (!has_dash_dash && !no_wildcard(arg))
1273                         recover_with_dwim = 0;
1274
1275                 /*
1276                  * Accept "git checkout foo", "git checkout foo --"
1277                  * and "git switch foo" as candidates for dwim.
1278                  */
1279                 if (!(argc == 1 && !has_dash_dash) &&
1280                     !(argc == 2 && has_dash_dash) &&
1281                     opts->accept_pathspec)
1282                         recover_with_dwim = 0;
1283
1284                 if (recover_with_dwim) {
1285                         const char *remote = parse_remote_branch(arg, rev,
1286                                                                  could_be_checkout_paths);
1287                         if (remote) {
1288                                 *new_branch = arg;
1289                                 arg = remote;
1290                                 /* DWIMmed to create local branch, case (3).(b) */
1291                         } else {
1292                                 recover_with_dwim = 0;
1293                         }
1294                 }
1295
1296                 if (!recover_with_dwim) {
1297                         if (has_dash_dash)
1298                                 die(_("invalid reference: %s"), arg);
1299                         return argcount;
1300                 }
1301         }
1302
1303         /* we can't end up being in (2) anymore, eat the argument */
1304         argcount++;
1305         argv++;
1306         argc--;
1307
1308         setup_new_branch_info_and_source_tree(new_branch_info, opts, rev, arg);
1309
1310         if (!opts->source_tree)                   /* case (1): want a tree */
1311                 die(_("reference is not a tree: %s"), arg);
1312
1313         if (!has_dash_dash) {   /* case (3).(d) -> (1) */
1314                 /*
1315                  * Do not complain the most common case
1316                  *      git checkout branch
1317                  * even if there happen to be a file called 'branch';
1318                  * it would be extremely annoying.
1319                  */
1320                 if (argc)
1321                         verify_non_filename(opts->prefix, arg);
1322         } else if (opts->accept_pathspec) {
1323                 argcount++;
1324                 argv++;
1325                 argc--;
1326         }
1327
1328         return argcount;
1329 }
1330
1331 static int switch_unborn_to_new_branch(const struct checkout_opts *opts)
1332 {
1333         int status;
1334         struct strbuf branch_ref = STRBUF_INIT;
1335
1336         trace2_cmd_mode("unborn");
1337
1338         if (!opts->new_branch)
1339                 die(_("You are on a branch yet to be born"));
1340         strbuf_addf(&branch_ref, "refs/heads/%s", opts->new_branch);
1341         status = create_symref("HEAD", branch_ref.buf, "checkout -b");
1342         strbuf_release(&branch_ref);
1343         if (!opts->quiet)
1344                 fprintf(stderr, _("Switched to a new branch '%s'\n"),
1345                         opts->new_branch);
1346         return status;
1347 }
1348
1349 static void die_expecting_a_branch(const struct branch_info *branch_info)
1350 {
1351         struct object_id oid;
1352         char *to_free;
1353
1354         if (dwim_ref(branch_info->name, strlen(branch_info->name), &oid, &to_free) == 1) {
1355                 const char *ref = to_free;
1356
1357                 if (skip_prefix(ref, "refs/tags/", &ref))
1358                         die(_("a branch is expected, got tag '%s'"), ref);
1359                 if (skip_prefix(ref, "refs/remotes/", &ref))
1360                         die(_("a branch is expected, got remote branch '%s'"), ref);
1361                 die(_("a branch is expected, got '%s'"), ref);
1362         }
1363         if (branch_info->commit)
1364                 die(_("a branch is expected, got commit '%s'"), branch_info->name);
1365         /*
1366          * This case should never happen because we already die() on
1367          * non-commit, but just in case.
1368          */
1369         die(_("a branch is expected, got '%s'"), branch_info->name);
1370 }
1371
1372 static void die_if_some_operation_in_progress(void)
1373 {
1374         struct wt_status_state state;
1375
1376         memset(&state, 0, sizeof(state));
1377         wt_status_get_state(the_repository, &state, 0);
1378
1379         if (state.merge_in_progress)
1380                 die(_("cannot switch branch while merging\n"
1381                       "Consider \"git merge --quit\" "
1382                       "or \"git worktree add\"."));
1383         if (state.am_in_progress)
1384                 die(_("cannot switch branch in the middle of an am session\n"
1385                       "Consider \"git am --quit\" "
1386                       "or \"git worktree add\"."));
1387         if (state.rebase_interactive_in_progress || state.rebase_in_progress)
1388                 die(_("cannot switch branch while rebasing\n"
1389                       "Consider \"git rebase --quit\" "
1390                       "or \"git worktree add\"."));
1391         if (state.cherry_pick_in_progress)
1392                 die(_("cannot switch branch while cherry-picking\n"
1393                       "Consider \"git cherry-pick --quit\" "
1394                       "or \"git worktree add\"."));
1395         if (state.revert_in_progress)
1396                 die(_("cannot switch branch while reverting\n"
1397                       "Consider \"git revert --quit\" "
1398                       "or \"git worktree add\"."));
1399         if (state.bisect_in_progress)
1400                 warning(_("you are switching branch while bisecting"));
1401 }
1402
1403 static int checkout_branch(struct checkout_opts *opts,
1404                            struct branch_info *new_branch_info)
1405 {
1406         if (opts->pathspec.nr)
1407                 die(_("paths cannot be used with switching branches"));
1408
1409         if (opts->patch_mode)
1410                 die(_("'%s' cannot be used with switching branches"),
1411                     "--patch");
1412
1413         if (opts->overlay_mode != -1)
1414                 die(_("'%s' cannot be used with switching branches"),
1415                     "--[no]-overlay");
1416
1417         if (opts->writeout_stage)
1418                 die(_("'%s' cannot be used with switching branches"),
1419                     "--ours/--theirs");
1420
1421         if (opts->force && opts->merge)
1422                 die(_("'%s' cannot be used with '%s'"), "-f", "-m");
1423
1424         if (opts->discard_changes && opts->merge)
1425                 die(_("'%s' cannot be used with '%s'"), "--discard-changes", "--merge");
1426
1427         if (opts->force_detach && opts->new_branch)
1428                 die(_("'%s' cannot be used with '%s'"),
1429                     "--detach", "-b/-B/--orphan");
1430
1431         if (opts->new_orphan_branch) {
1432                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1433                         die(_("'%s' cannot be used with '%s'"), "--orphan", "-t");
1434                 if (opts->orphan_from_empty_tree && new_branch_info->name)
1435                         die(_("'%s' cannot take <start-point>"), "--orphan");
1436         } else if (opts->force_detach) {
1437                 if (opts->track != BRANCH_TRACK_UNSPECIFIED)
1438                         die(_("'%s' cannot be used with '%s'"), "--detach", "-t");
1439         } else if (opts->track == BRANCH_TRACK_UNSPECIFIED)
1440                 opts->track = git_branch_track;
1441
1442         if (new_branch_info->name && !new_branch_info->commit)
1443                 die(_("Cannot switch branch to a non-commit '%s'"),
1444                     new_branch_info->name);
1445
1446         if (!opts->switch_branch_doing_nothing_is_ok &&
1447             !new_branch_info->name &&
1448             !opts->new_branch &&
1449             !opts->force_detach)
1450                 die(_("missing branch or commit argument"));
1451
1452         if (!opts->implicit_detach &&
1453             !opts->force_detach &&
1454             !opts->new_branch &&
1455             !opts->new_branch_force &&
1456             new_branch_info->name &&
1457             !new_branch_info->path)
1458                 die_expecting_a_branch(new_branch_info);
1459
1460         if (!opts->can_switch_when_in_progress)
1461                 die_if_some_operation_in_progress();
1462
1463         if (new_branch_info->path && !opts->force_detach && !opts->new_branch &&
1464             !opts->ignore_other_worktrees) {
1465                 int flag;
1466                 char *head_ref = resolve_refdup("HEAD", 0, NULL, &flag);
1467                 if (head_ref &&
1468                     (!(flag & REF_ISSYMREF) || strcmp(head_ref, new_branch_info->path)))
1469                         die_if_checked_out(new_branch_info->path, 1);
1470                 free(head_ref);
1471         }
1472
1473         if (!new_branch_info->commit && opts->new_branch) {
1474                 struct object_id rev;
1475                 int flag;
1476
1477                 if (!read_ref_full("HEAD", 0, &rev, &flag) &&
1478                     (flag & REF_ISSYMREF) && is_null_oid(&rev))
1479                         return switch_unborn_to_new_branch(opts);
1480         }
1481         return switch_branches(opts, new_branch_info);
1482 }
1483
1484 static struct option *add_common_options(struct checkout_opts *opts,
1485                                          struct option *prevopts)
1486 {
1487         struct option options[] = {
1488                 OPT__QUIET(&opts->quiet, N_("suppress progress reporting")),
1489                 OPT_CALLBACK_F(0, "recurse-submodules", NULL,
1490                             "checkout", "control recursive updating of submodules",
1491                             PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater),
1492                 OPT_BOOL(0, "progress", &opts->show_progress, N_("force progress reporting")),
1493                 OPT_BOOL('m', "merge", &opts->merge, N_("perform a 3-way merge with the new branch")),
1494                 OPT_STRING(0, "conflict", &opts->conflict_style, N_("style"),
1495                            N_("conflict style (merge or diff3)")),
1496                 OPT_END()
1497         };
1498         struct option *newopts = parse_options_concat(prevopts, options);
1499         free(prevopts);
1500         return newopts;
1501 }
1502
1503 static struct option *add_common_switch_branch_options(
1504         struct checkout_opts *opts, struct option *prevopts)
1505 {
1506         struct option options[] = {
1507                 OPT_BOOL('d', "detach", &opts->force_detach, N_("detach HEAD at named commit")),
1508                 OPT_SET_INT('t', "track",  &opts->track, N_("set upstream info for new branch"),
1509                         BRANCH_TRACK_EXPLICIT),
1510                 OPT__FORCE(&opts->force, N_("force checkout (throw away local modifications)"),
1511                            PARSE_OPT_NOCOMPLETE),
1512                 OPT_STRING(0, "orphan", &opts->new_orphan_branch, N_("new-branch"), N_("new unparented branch")),
1513                 OPT_BOOL_F(0, "overwrite-ignore", &opts->overwrite_ignore,
1514                            N_("update ignored files (default)"),
1515                            PARSE_OPT_NOCOMPLETE),
1516                 OPT_BOOL(0, "ignore-other-worktrees", &opts->ignore_other_worktrees,
1517                          N_("do not check if another worktree is holding the given ref")),
1518                 OPT_END()
1519         };
1520         struct option *newopts = parse_options_concat(prevopts, options);
1521         free(prevopts);
1522         return newopts;
1523 }
1524
1525 static struct option *add_checkout_path_options(struct checkout_opts *opts,
1526                                                 struct option *prevopts)
1527 {
1528         struct option options[] = {
1529                 OPT_SET_INT_F('2', "ours", &opts->writeout_stage,
1530                               N_("checkout our version for unmerged files"),
1531                               2, PARSE_OPT_NONEG),
1532                 OPT_SET_INT_F('3', "theirs", &opts->writeout_stage,
1533                               N_("checkout their version for unmerged files"),
1534                               3, PARSE_OPT_NONEG),
1535                 OPT_BOOL('p', "patch", &opts->patch_mode, N_("select hunks interactively")),
1536                 OPT_BOOL(0, "ignore-skip-worktree-bits", &opts->ignore_skipworktree,
1537                          N_("do not limit pathspecs to sparse entries only")),
1538                 OPT_PATHSPEC_FROM_FILE(&opts->pathspec_from_file),
1539                 OPT_PATHSPEC_FILE_NUL(&opts->pathspec_file_nul),
1540                 OPT_END()
1541         };
1542         struct option *newopts = parse_options_concat(prevopts, options);
1543         free(prevopts);
1544         return newopts;
1545 }
1546
1547 /* create-branch option (either b or c) */
1548 static char cb_option = 'b';
1549
1550 static int checkout_main(int argc, const char **argv, const char *prefix,
1551                          struct checkout_opts *opts, struct option *options,
1552                          const char * const usagestr[])
1553 {
1554         struct branch_info new_branch_info;
1555         int parseopt_flags = 0;
1556
1557         memset(&new_branch_info, 0, sizeof(new_branch_info));
1558         opts->overwrite_ignore = 1;
1559         opts->prefix = prefix;
1560         opts->show_progress = -1;
1561
1562         git_config(git_checkout_config, opts);
1563
1564         opts->track = BRANCH_TRACK_UNSPECIFIED;
1565
1566         if (!opts->accept_pathspec && !opts->accept_ref)
1567                 BUG("make up your mind, you need to take _something_");
1568         if (opts->accept_pathspec && opts->accept_ref)
1569                 parseopt_flags = PARSE_OPT_KEEP_DASHDASH;
1570
1571         argc = parse_options(argc, argv, prefix, options,
1572                              usagestr, parseopt_flags);
1573
1574         if (opts->show_progress < 0) {
1575                 if (opts->quiet)
1576                         opts->show_progress = 0;
1577                 else
1578                         opts->show_progress = isatty(2);
1579         }
1580
1581         if (opts->conflict_style) {
1582                 opts->merge = 1; /* implied */
1583                 git_xmerge_config("merge.conflictstyle", opts->conflict_style, NULL);
1584         }
1585         if (opts->force) {
1586                 opts->discard_changes = 1;
1587                 opts->ignore_unmerged_opt = "--force";
1588                 opts->ignore_unmerged = 1;
1589         }
1590
1591         if ((!!opts->new_branch + !!opts->new_branch_force + !!opts->new_orphan_branch) > 1)
1592                 die(_("-%c, -%c and --orphan are mutually exclusive"),
1593                                 cb_option, toupper(cb_option));
1594
1595         if (opts->overlay_mode == 1 && opts->patch_mode)
1596                 die(_("-p and --overlay are mutually exclusive"));
1597
1598         if (opts->checkout_index >= 0 || opts->checkout_worktree >= 0) {
1599                 if (opts->checkout_index < 0)
1600                         opts->checkout_index = 0;
1601                 if (opts->checkout_worktree < 0)
1602                         opts->checkout_worktree = 0;
1603         } else {
1604                 if (opts->checkout_index < 0)
1605                         opts->checkout_index = -opts->checkout_index - 1;
1606                 if (opts->checkout_worktree < 0)
1607                         opts->checkout_worktree = -opts->checkout_worktree - 1;
1608         }
1609         if (opts->checkout_index < 0 || opts->checkout_worktree < 0)
1610                 BUG("these flags should be non-negative by now");
1611         /*
1612          * convenient shortcut: "git restore --staged [--worktree]" equals
1613          * "git restore --staged [--worktree] --source HEAD"
1614          */
1615         if (!opts->from_treeish && opts->checkout_index)
1616                 opts->from_treeish = "HEAD";
1617
1618         /*
1619          * From here on, new_branch will contain the branch to be checked out,
1620          * and new_branch_force and new_orphan_branch will tell us which one of
1621          * -b/-B/-c/-C/--orphan is being used.
1622          */
1623         if (opts->new_branch_force)
1624                 opts->new_branch = opts->new_branch_force;
1625
1626         if (opts->new_orphan_branch)
1627                 opts->new_branch = opts->new_orphan_branch;
1628
1629         /* --track without -c/-C/-b/-B/--orphan should DWIM */
1630         if (opts->track != BRANCH_TRACK_UNSPECIFIED && !opts->new_branch) {
1631                 const char *argv0 = argv[0];
1632                 if (!argc || !strcmp(argv0, "--"))
1633                         die(_("--track needs a branch name"));
1634                 skip_prefix(argv0, "refs/", &argv0);
1635                 skip_prefix(argv0, "remotes/", &argv0);
1636                 argv0 = strchr(argv0, '/');
1637                 if (!argv0 || !argv0[1])
1638                         die(_("missing branch name; try -%c"), cb_option);
1639                 opts->new_branch = argv0 + 1;
1640         }
1641
1642         /*
1643          * Extract branch name from command line arguments, so
1644          * all that is left is pathspecs.
1645          *
1646          * Handle
1647          *
1648          *  1) git checkout <tree> -- [<paths>]
1649          *  2) git checkout -- [<paths>]
1650          *  3) git checkout <something> [<paths>]
1651          *
1652          * including "last branch" syntax and DWIM-ery for names of
1653          * remote branches, erroring out for invalid or ambiguous cases.
1654          */
1655         if (argc && opts->accept_ref) {
1656                 struct object_id rev;
1657                 int dwim_ok =
1658                         !opts->patch_mode &&
1659                         opts->dwim_new_local_branch &&
1660                         opts->track == BRANCH_TRACK_UNSPECIFIED &&
1661                         !opts->new_branch;
1662                 int n = parse_branchname_arg(argc, argv, dwim_ok,
1663                                              &new_branch_info, opts, &rev);
1664                 argv += n;
1665                 argc -= n;
1666         } else if (!opts->accept_ref && opts->from_treeish) {
1667                 struct object_id rev;
1668
1669                 if (get_oid_mb(opts->from_treeish, &rev))
1670                         die(_("could not resolve %s"), opts->from_treeish);
1671
1672                 setup_new_branch_info_and_source_tree(&new_branch_info,
1673                                                       opts, &rev,
1674                                                       opts->from_treeish);
1675
1676                 if (!opts->source_tree)
1677                         die(_("reference is not a tree: %s"), opts->from_treeish);
1678         }
1679
1680         if (argc) {
1681                 parse_pathspec(&opts->pathspec, 0,
1682                                opts->patch_mode ? PATHSPEC_PREFIX_ORIGIN : 0,
1683                                prefix, argv);
1684
1685                 if (!opts->pathspec.nr)
1686                         die(_("invalid path specification"));
1687
1688                 /*
1689                  * Try to give more helpful suggestion.
1690                  * new_branch && argc > 1 will be caught later.
1691                  */
1692                 if (opts->new_branch && argc == 1)
1693                         die(_("'%s' is not a commit and a branch '%s' cannot be created from it"),
1694                                 argv[0], opts->new_branch);
1695
1696                 if (opts->force_detach)
1697                         die(_("git checkout: --detach does not take a path argument '%s'"),
1698                             argv[0]);
1699         }
1700
1701         if (opts->pathspec_from_file) {
1702                 if (opts->pathspec.nr)
1703                         die(_("--pathspec-from-file is incompatible with pathspec arguments"));
1704
1705                 if (opts->force_detach)
1706                         die(_("--pathspec-from-file is incompatible with --detach"));
1707
1708                 if (opts->patch_mode)
1709                         die(_("--pathspec-from-file is incompatible with --patch"));
1710
1711                 parse_pathspec_file(&opts->pathspec, 0,
1712                                     0,
1713                                     prefix, opts->pathspec_from_file, opts->pathspec_file_nul);
1714         } else if (opts->pathspec_file_nul) {
1715                 die(_("--pathspec-file-nul requires --pathspec-from-file"));
1716         }
1717
1718         if (opts->pathspec.nr) {
1719                 if (1 < !!opts->writeout_stage + !!opts->force + !!opts->merge)
1720                         die(_("git checkout: --ours/--theirs, --force and --merge are incompatible when\n"
1721                               "checking out of the index."));
1722         } else {
1723                 if (opts->accept_pathspec && !opts->empty_pathspec_ok &&
1724                     !opts->patch_mode)  /* patch mode is special */
1725                         die(_("you must specify path(s) to restore"));
1726         }
1727
1728         if (opts->new_branch) {
1729                 struct strbuf buf = STRBUF_INIT;
1730
1731                 if (opts->new_branch_force)
1732                         opts->branch_exists = validate_branchname(opts->new_branch, &buf);
1733                 else
1734                         opts->branch_exists =
1735                                 validate_new_branchname(opts->new_branch, &buf, 0);
1736                 strbuf_release(&buf);
1737         }
1738
1739         UNLEAK(opts);
1740         if (opts->patch_mode || opts->pathspec.nr)
1741                 return checkout_paths(opts, &new_branch_info);
1742         else
1743                 return checkout_branch(opts, &new_branch_info);
1744 }
1745
1746 int cmd_checkout(int argc, const char **argv, const char *prefix)
1747 {
1748         struct checkout_opts opts;
1749         struct option *options;
1750         struct option checkout_options[] = {
1751                 OPT_STRING('b', NULL, &opts.new_branch, N_("branch"),
1752                            N_("create and checkout a new branch")),
1753                 OPT_STRING('B', NULL, &opts.new_branch_force, N_("branch"),
1754                            N_("create/reset and checkout a branch")),
1755                 OPT_BOOL('l', NULL, &opts.new_branch_log, N_("create reflog for new branch")),
1756                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1757                          N_("second guess 'git checkout <no-such-branch>' (default)")),
1758                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode (default)")),
1759                 OPT_END()
1760         };
1761         int ret;
1762
1763         memset(&opts, 0, sizeof(opts));
1764         opts.dwim_new_local_branch = 1;
1765         opts.switch_branch_doing_nothing_is_ok = 1;
1766         opts.only_merge_on_switching_branches = 0;
1767         opts.accept_ref = 1;
1768         opts.accept_pathspec = 1;
1769         opts.implicit_detach = 1;
1770         opts.can_switch_when_in_progress = 1;
1771         opts.orphan_from_empty_tree = 0;
1772         opts.empty_pathspec_ok = 1;
1773         opts.overlay_mode = -1;
1774         opts.checkout_index = -2;    /* default on */
1775         opts.checkout_worktree = -2; /* default on */
1776
1777         if (argc == 3 && !strcmp(argv[1], "-b")) {
1778                 /*
1779                  * User ran 'git checkout -b <branch>' and expects
1780                  * the same behavior as 'git switch -c <branch>'.
1781                  */
1782                 opts.switch_branch_doing_nothing_is_ok = 0;
1783                 opts.only_merge_on_switching_branches = 1;
1784         }
1785
1786         options = parse_options_dup(checkout_options);
1787         options = add_common_options(&opts, options);
1788         options = add_common_switch_branch_options(&opts, options);
1789         options = add_checkout_path_options(&opts, options);
1790
1791         ret = checkout_main(argc, argv, prefix, &opts,
1792                             options, checkout_usage);
1793         FREE_AND_NULL(options);
1794         return ret;
1795 }
1796
1797 int cmd_switch(int argc, const char **argv, const char *prefix)
1798 {
1799         struct checkout_opts opts;
1800         struct option *options = NULL;
1801         struct option switch_options[] = {
1802                 OPT_STRING('c', "create", &opts.new_branch, N_("branch"),
1803                            N_("create and switch to a new branch")),
1804                 OPT_STRING('C', "force-create", &opts.new_branch_force, N_("branch"),
1805                            N_("create/reset and switch to a branch")),
1806                 OPT_BOOL(0, "guess", &opts.dwim_new_local_branch,
1807                          N_("second guess 'git switch <no-such-branch>'")),
1808                 OPT_BOOL(0, "discard-changes", &opts.discard_changes,
1809                          N_("throw away local modifications")),
1810                 OPT_END()
1811         };
1812         int ret;
1813
1814         memset(&opts, 0, sizeof(opts));
1815         opts.dwim_new_local_branch = 1;
1816         opts.accept_ref = 1;
1817         opts.accept_pathspec = 0;
1818         opts.switch_branch_doing_nothing_is_ok = 0;
1819         opts.only_merge_on_switching_branches = 1;
1820         opts.implicit_detach = 0;
1821         opts.can_switch_when_in_progress = 0;
1822         opts.orphan_from_empty_tree = 1;
1823         opts.overlay_mode = -1;
1824
1825         options = parse_options_dup(switch_options);
1826         options = add_common_options(&opts, options);
1827         options = add_common_switch_branch_options(&opts, options);
1828
1829         cb_option = 'c';
1830
1831         ret = checkout_main(argc, argv, prefix, &opts,
1832                             options, switch_branch_usage);
1833         FREE_AND_NULL(options);
1834         return ret;
1835 }
1836
1837 int cmd_restore(int argc, const char **argv, const char *prefix)
1838 {
1839         struct checkout_opts opts;
1840         struct option *options;
1841         struct option restore_options[] = {
1842                 OPT_STRING('s', "source", &opts.from_treeish, "<tree-ish>",
1843                            N_("which tree-ish to checkout from")),
1844                 OPT_BOOL('S', "staged", &opts.checkout_index,
1845                            N_("restore the index")),
1846                 OPT_BOOL('W', "worktree", &opts.checkout_worktree,
1847                            N_("restore the working tree (default)")),
1848                 OPT_BOOL(0, "ignore-unmerged", &opts.ignore_unmerged,
1849                          N_("ignore unmerged entries")),
1850                 OPT_BOOL(0, "overlay", &opts.overlay_mode, N_("use overlay mode")),
1851                 OPT_END()
1852         };
1853         int ret;
1854
1855         memset(&opts, 0, sizeof(opts));
1856         opts.accept_ref = 0;
1857         opts.accept_pathspec = 1;
1858         opts.empty_pathspec_ok = 0;
1859         opts.overlay_mode = 0;
1860         opts.checkout_index = -1;    /* default off */
1861         opts.checkout_worktree = -2; /* default on */
1862         opts.ignore_unmerged_opt = "--ignore-unmerged";
1863
1864         options = parse_options_dup(restore_options);
1865         options = add_common_options(&opts, options);
1866         options = add_checkout_path_options(&opts, options);
1867
1868         ret = checkout_main(argc, argv, prefix, &opts,
1869                             options, restore_usage);
1870         FREE_AND_NULL(options);
1871         return ret;
1872 }