Merge branch 'cb/merge-recursive-fix'
[git] / builtin-checkout.c
1 #include "cache.h"
2 #include "builtin.h"
3 #include "parse-options.h"
4 #include "refs.h"
5 #include "commit.h"
6 #include "tree.h"
7 #include "tree-walk.h"
8 #include "unpack-trees.h"
9 #include "dir.h"
10 #include "run-command.h"
11 #include "merge-recursive.h"
12 #include "branch.h"
13 #include "diff.h"
14 #include "revision.h"
15 #include "remote.h"
16 #include "blob.h"
17 #include "xdiff-interface.h"
18 #include "ll-merge.h"
19
20 static const char * const checkout_usage[] = {
21         "git checkout [options] <branch>",
22         "git checkout [options] [<branch>] -- <file>...",
23         NULL,
24 };
25
26 struct checkout_opts {
27         int quiet;
28         int merge;
29         int force;
30         int writeout_stage;
31         int writeout_error;
32
33         const char *new_branch;
34         int new_branch_log;
35         enum branch_track track;
36 };
37
38 static int post_checkout_hook(struct commit *old, struct commit *new,
39                               int changed)
40 {
41         struct child_process proc;
42         const char *name = git_path("hooks/post-checkout");
43         const char *argv[5];
44
45         if (access(name, X_OK) < 0)
46                 return 0;
47
48         memset(&proc, 0, sizeof(proc));
49         argv[0] = name;
50         argv[1] = xstrdup(sha1_to_hex(old ? old->object.sha1 : null_sha1));
51         argv[2] = xstrdup(sha1_to_hex(new->object.sha1));
52         argv[3] = changed ? "1" : "0";
53         argv[4] = NULL;
54         proc.argv = argv;
55         proc.no_stdin = 1;
56         proc.stdout_to_stderr = 1;
57         return run_command(&proc);
58 }
59
60 static int update_some(const unsigned char *sha1, const char *base, int baselen,
61                 const char *pathname, unsigned mode, int stage, void *context)
62 {
63         int len;
64         struct cache_entry *ce;
65
66         if (S_ISGITLINK(mode))
67                 return 0;
68
69         if (S_ISDIR(mode))
70                 return READ_TREE_RECURSIVE;
71
72         len = baselen + strlen(pathname);
73         ce = xcalloc(1, cache_entry_size(len));
74         hashcpy(ce->sha1, sha1);
75         memcpy(ce->name, base, baselen);
76         memcpy(ce->name + baselen, pathname, len - baselen);
77         ce->ce_flags = create_ce_flags(len, 0);
78         ce->ce_mode = create_ce_mode(mode);
79         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
80         return 0;
81 }
82
83 static int read_tree_some(struct tree *tree, const char **pathspec)
84 {
85         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
86
87         /* update the index with the given tree's info
88          * for all args, expanding wildcards, and exit
89          * with any non-zero return code.
90          */
91         return 0;
92 }
93
94 static int skip_same_name(struct cache_entry *ce, int pos)
95 {
96         while (++pos < active_nr &&
97                !strcmp(active_cache[pos]->name, ce->name))
98                 ; /* skip */
99         return pos;
100 }
101
102 static int check_stage(int stage, struct cache_entry *ce, int pos)
103 {
104         while (pos < active_nr &&
105                !strcmp(active_cache[pos]->name, ce->name)) {
106                 if (ce_stage(active_cache[pos]) == stage)
107                         return 0;
108                 pos++;
109         }
110         return error("path '%s' does not have %s version",
111                      ce->name,
112                      (stage == 2) ? "our" : "their");
113 }
114
115 static int check_all_stages(struct cache_entry *ce, int pos)
116 {
117         if (ce_stage(ce) != 1 ||
118             active_nr <= pos + 2 ||
119             strcmp(active_cache[pos+1]->name, ce->name) ||
120             ce_stage(active_cache[pos+1]) != 2 ||
121             strcmp(active_cache[pos+2]->name, ce->name) ||
122             ce_stage(active_cache[pos+2]) != 3)
123                 return error("path '%s' does not have all three versions",
124                              ce->name);
125         return 0;
126 }
127
128 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
129                           struct checkout *state)
130 {
131         while (pos < active_nr &&
132                !strcmp(active_cache[pos]->name, ce->name)) {
133                 if (ce_stage(active_cache[pos]) == stage)
134                         return checkout_entry(active_cache[pos], state, NULL);
135                 pos++;
136         }
137         return error("path '%s' does not have %s version",
138                      ce->name,
139                      (stage == 2) ? "our" : "their");
140 }
141
142 /* NEEDSWORK: share with merge-recursive */
143 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
144 {
145         unsigned long size;
146         enum object_type type;
147
148         if (!hashcmp(sha1, null_sha1)) {
149                 mm->ptr = xstrdup("");
150                 mm->size = 0;
151                 return;
152         }
153
154         mm->ptr = read_sha1_file(sha1, &type, &size);
155         if (!mm->ptr || type != OBJ_BLOB)
156                 die("unable to read blob object %s", sha1_to_hex(sha1));
157         mm->size = size;
158 }
159
160 static int checkout_merged(int pos, struct checkout *state)
161 {
162         struct cache_entry *ce = active_cache[pos];
163         const char *path = ce->name;
164         mmfile_t ancestor, ours, theirs;
165         int status;
166         unsigned char sha1[20];
167         mmbuffer_t result_buf;
168
169         if (ce_stage(ce) != 1 ||
170             active_nr <= pos + 2 ||
171             strcmp(active_cache[pos+1]->name, path) ||
172             ce_stage(active_cache[pos+1]) != 2 ||
173             strcmp(active_cache[pos+2]->name, path) ||
174             ce_stage(active_cache[pos+2]) != 3)
175                 return error("path '%s' does not have all 3 versions", path);
176
177         fill_mm(active_cache[pos]->sha1, &ancestor);
178         fill_mm(active_cache[pos+1]->sha1, &ours);
179         fill_mm(active_cache[pos+2]->sha1, &theirs);
180
181         status = ll_merge(&result_buf, path, &ancestor,
182                           &ours, "ours", &theirs, "theirs", 1);
183         free(ancestor.ptr);
184         free(ours.ptr);
185         free(theirs.ptr);
186         if (status < 0 || !result_buf.ptr) {
187                 free(result_buf.ptr);
188                 return error("path '%s': cannot merge", path);
189         }
190
191         /*
192          * NEEDSWORK:
193          * There is absolutely no reason to write this as a blob object
194          * and create a phoney cache entry just to leak.  This hack is
195          * primarily to get to the write_entry() machinery that massages
196          * the contents to work-tree format and writes out which only
197          * allows it for a cache entry.  The code in write_entry() needs
198          * to be refactored to allow us to feed a <buffer, size, mode>
199          * instead of a cache entry.  Such a refactoring would help
200          * merge_recursive as well (it also writes the merge result to the
201          * object database even when it may contain conflicts).
202          */
203         if (write_sha1_file(result_buf.ptr, result_buf.size,
204                             blob_type, sha1))
205                 die("Unable to add merge result for '%s'", path);
206         ce = make_cache_entry(create_ce_mode(active_cache[pos+1]->ce_mode),
207                               sha1,
208                               path, 2, 0);
209         if (!ce)
210                 die("make_cache_entry failed for path '%s'", path);
211         status = checkout_entry(ce, state, NULL);
212         return status;
213 }
214
215 static int checkout_paths(struct tree *source_tree, const char **pathspec,
216                           struct checkout_opts *opts)
217 {
218         int pos;
219         struct checkout state;
220         static char *ps_matched;
221         unsigned char rev[20];
222         int flag;
223         struct commit *head;
224         int errs = 0;
225         int stage = opts->writeout_stage;
226         int merge = opts->merge;
227         int newfd;
228         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
229
230         newfd = hold_locked_index(lock_file, 1);
231         if (read_cache() < 0)
232                 return error("corrupt index file");
233
234         if (source_tree)
235                 read_tree_some(source_tree, pathspec);
236
237         for (pos = 0; pathspec[pos]; pos++)
238                 ;
239         ps_matched = xcalloc(1, pos);
240
241         for (pos = 0; pos < active_nr; pos++) {
242                 struct cache_entry *ce = active_cache[pos];
243                 pathspec_match(pathspec, ps_matched, ce->name, 0);
244         }
245
246         if (report_path_error(ps_matched, pathspec, 0))
247                 return 1;
248
249         /* Any unmerged paths? */
250         for (pos = 0; pos < active_nr; pos++) {
251                 struct cache_entry *ce = active_cache[pos];
252                 if (pathspec_match(pathspec, NULL, ce->name, 0)) {
253                         if (!ce_stage(ce))
254                                 continue;
255                         if (opts->force) {
256                                 warning("path '%s' is unmerged", ce->name);
257                         } else if (stage) {
258                                 errs |= check_stage(stage, ce, pos);
259                         } else if (opts->merge) {
260                                 errs |= check_all_stages(ce, pos);
261                         } else {
262                                 errs = 1;
263                                 error("path '%s' is unmerged", ce->name);
264                         }
265                         pos = skip_same_name(ce, pos) - 1;
266                 }
267         }
268         if (errs)
269                 return 1;
270
271         /* Now we are committed to check them out */
272         memset(&state, 0, sizeof(state));
273         state.force = 1;
274         state.refresh_cache = 1;
275         for (pos = 0; pos < active_nr; pos++) {
276                 struct cache_entry *ce = active_cache[pos];
277                 if (pathspec_match(pathspec, NULL, ce->name, 0)) {
278                         if (!ce_stage(ce)) {
279                                 errs |= checkout_entry(ce, &state, NULL);
280                                 continue;
281                         }
282                         if (stage)
283                                 errs |= checkout_stage(stage, ce, pos, &state);
284                         else if (merge)
285                                 errs |= checkout_merged(pos, &state);
286                         pos = skip_same_name(ce, pos) - 1;
287                 }
288         }
289
290         if (write_cache(newfd, active_cache, active_nr) ||
291             commit_locked_index(lock_file))
292                 die("unable to write new index file");
293
294         resolve_ref("HEAD", rev, 0, &flag);
295         head = lookup_commit_reference_gently(rev, 1);
296
297         errs |= post_checkout_hook(head, head, 0);
298         return errs;
299 }
300
301 static void show_local_changes(struct object *head)
302 {
303         struct rev_info rev;
304         /* I think we want full paths, even if we're in a subdirectory. */
305         init_revisions(&rev, NULL);
306         rev.abbrev = 0;
307         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
308         add_pending_object(&rev, head, NULL);
309         run_diff_index(&rev, 0);
310 }
311
312 static void describe_detached_head(char *msg, struct commit *commit)
313 {
314         struct strbuf sb = STRBUF_INIT;
315         parse_commit(commit);
316         pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, 0, NULL, NULL, 0, 0);
317         fprintf(stderr, "%s %s... %s\n", msg,
318                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
319         strbuf_release(&sb);
320 }
321
322 static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
323 {
324         struct unpack_trees_options opts;
325         struct tree_desc tree_desc;
326
327         memset(&opts, 0, sizeof(opts));
328         opts.head_idx = -1;
329         opts.update = worktree;
330         opts.skip_unmerged = !worktree;
331         opts.reset = 1;
332         opts.merge = 1;
333         opts.fn = oneway_merge;
334         opts.verbose_update = !o->quiet;
335         opts.src_index = &the_index;
336         opts.dst_index = &the_index;
337         parse_tree(tree);
338         init_tree_desc(&tree_desc, tree->buffer, tree->size);
339         switch (unpack_trees(1, &tree_desc, &opts)) {
340         case -2:
341                 o->writeout_error = 1;
342                 /*
343                  * We return 0 nevertheless, as the index is all right
344                  * and more importantly we have made best efforts to
345                  * update paths in the work tree, and we cannot revert
346                  * them.
347                  */
348         case 0:
349                 return 0;
350         default:
351                 return 128;
352         }
353 }
354
355 struct branch_info {
356         const char *name; /* The short name used */
357         const char *path; /* The full name of a real branch */
358         struct commit *commit; /* The named commit */
359 };
360
361 static void setup_branch_path(struct branch_info *branch)
362 {
363         struct strbuf buf = STRBUF_INIT;
364         strbuf_addstr(&buf, "refs/heads/");
365         strbuf_addstr(&buf, branch->name);
366         branch->path = strbuf_detach(&buf, NULL);
367 }
368
369 static int merge_working_tree(struct checkout_opts *opts,
370                               struct branch_info *old, struct branch_info *new)
371 {
372         int ret;
373         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
374         int newfd = hold_locked_index(lock_file, 1);
375
376         if (read_cache() < 0)
377                 return error("corrupt index file");
378
379         if (opts->force) {
380                 ret = reset_tree(new->commit->tree, opts, 1);
381                 if (ret)
382                         return ret;
383         } else {
384                 struct tree_desc trees[2];
385                 struct tree *tree;
386                 struct unpack_trees_options topts;
387
388                 memset(&topts, 0, sizeof(topts));
389                 topts.head_idx = -1;
390                 topts.src_index = &the_index;
391                 topts.dst_index = &the_index;
392
393                 topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
394
395                 refresh_cache(REFRESH_QUIET);
396
397                 if (unmerged_cache()) {
398                         error("you need to resolve your current index first");
399                         return 1;
400                 }
401
402                 /* 2-way merge to the new branch */
403                 topts.initial_checkout = is_cache_unborn();
404                 topts.update = 1;
405                 topts.merge = 1;
406                 topts.gently = opts->merge;
407                 topts.verbose_update = !opts->quiet;
408                 topts.fn = twoway_merge;
409                 topts.dir = xcalloc(1, sizeof(*topts.dir));
410                 topts.dir->show_ignored = 1;
411                 topts.dir->exclude_per_dir = ".gitignore";
412                 tree = parse_tree_indirect(old->commit->object.sha1);
413                 init_tree_desc(&trees[0], tree->buffer, tree->size);
414                 tree = parse_tree_indirect(new->commit->object.sha1);
415                 init_tree_desc(&trees[1], tree->buffer, tree->size);
416
417                 ret = unpack_trees(2, trees, &topts);
418                 if (ret == -1) {
419                         /*
420                          * Unpack couldn't do a trivial merge; either
421                          * give up or do a real merge, depending on
422                          * whether the merge flag was used.
423                          */
424                         struct tree *result;
425                         struct tree *work;
426                         struct merge_options o;
427                         if (!opts->merge)
428                                 return 1;
429                         parse_commit(old->commit);
430
431                         /* Do more real merge */
432
433                         /*
434                          * We update the index fully, then write the
435                          * tree from the index, then merge the new
436                          * branch with the current tree, with the old
437                          * branch as the base. Then we reset the index
438                          * (but not the working tree) to the new
439                          * branch, leaving the working tree as the
440                          * merged version, but skipping unmerged
441                          * entries in the index.
442                          */
443
444                         add_files_to_cache(NULL, NULL, 0);
445                         init_merge_options(&o);
446                         o.verbosity = 0;
447                         work = write_tree_from_memory(&o);
448
449                         ret = reset_tree(new->commit->tree, opts, 1);
450                         if (ret)
451                                 return ret;
452                         o.branch1 = new->name;
453                         o.branch2 = "local";
454                         merge_trees(&o, new->commit->tree, work,
455                                 old->commit->tree, &result);
456                         ret = reset_tree(new->commit->tree, opts, 0);
457                         if (ret)
458                                 return ret;
459                 }
460         }
461
462         if (write_cache(newfd, active_cache, active_nr) ||
463             commit_locked_index(lock_file))
464                 die("unable to write new index file");
465
466         if (!opts->force && !opts->quiet)
467                 show_local_changes(&new->commit->object);
468
469         return 0;
470 }
471
472 static void report_tracking(struct branch_info *new)
473 {
474         struct strbuf sb = STRBUF_INIT;
475         struct branch *branch = branch_get(new->name);
476
477         if (!format_tracking_info(branch, &sb))
478                 return;
479         fputs(sb.buf, stdout);
480         strbuf_release(&sb);
481 }
482
483 static void update_refs_for_switch(struct checkout_opts *opts,
484                                    struct branch_info *old,
485                                    struct branch_info *new)
486 {
487         struct strbuf msg = STRBUF_INIT;
488         const char *old_desc;
489         if (opts->new_branch) {
490                 create_branch(old->name, opts->new_branch, new->name, 0,
491                               opts->new_branch_log, opts->track);
492                 new->name = opts->new_branch;
493                 setup_branch_path(new);
494         }
495
496         old_desc = old->name;
497         if (!old_desc && old->commit)
498                 old_desc = sha1_to_hex(old->commit->object.sha1);
499         strbuf_addf(&msg, "checkout: moving from %s to %s",
500                     old_desc ? old_desc : "(invalid)", new->name);
501
502         if (new->path) {
503                 create_symref("HEAD", new->path, msg.buf);
504                 if (!opts->quiet) {
505                         if (old->path && !strcmp(new->path, old->path))
506                                 fprintf(stderr, "Already on \"%s\"\n",
507                                         new->name);
508                         else
509                                 fprintf(stderr, "Switched to%s branch \"%s\"\n",
510                                         opts->new_branch ? " a new" : "",
511                                         new->name);
512                 }
513         } else if (strcmp(new->name, "HEAD")) {
514                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
515                            REF_NODEREF, DIE_ON_ERR);
516                 if (!opts->quiet) {
517                         if (old->path)
518                                 fprintf(stderr, "Note: moving to \"%s\" which isn't a local branch\nIf you want to create a new branch from this checkout, you may do so\n(now or later) by using -b with the checkout command again. Example:\n  git checkout -b <new_branch_name>\n", new->name);
519                         describe_detached_head("HEAD is now at", new->commit);
520                 }
521         }
522         remove_branch_state();
523         strbuf_release(&msg);
524         if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
525                 report_tracking(new);
526 }
527
528 static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
529 {
530         int ret = 0;
531         struct branch_info old;
532         unsigned char rev[20];
533         int flag;
534         memset(&old, 0, sizeof(old));
535         old.path = resolve_ref("HEAD", rev, 0, &flag);
536         old.commit = lookup_commit_reference_gently(rev, 1);
537         if (!(flag & REF_ISSYMREF))
538                 old.path = NULL;
539
540         if (old.path && !prefixcmp(old.path, "refs/heads/"))
541                 old.name = old.path + strlen("refs/heads/");
542
543         if (!new->name) {
544                 new->name = "HEAD";
545                 new->commit = old.commit;
546                 if (!new->commit)
547                         die("You are on a branch yet to be born");
548                 parse_commit(new->commit);
549         }
550
551         /*
552          * If we were on a detached HEAD, but we are now moving to
553          * a new commit, we want to mention the old commit once more
554          * to remind the user that it might be lost.
555          */
556         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
557                 describe_detached_head("Previous HEAD position was", old.commit);
558
559         if (!old.commit && !opts->force) {
560                 if (!opts->quiet) {
561                         fprintf(stderr, "warning: You appear to be on a branch yet to be born.\n");
562                         fprintf(stderr, "warning: Forcing checkout of %s.\n", new->name);
563                 }
564                 opts->force = 1;
565         }
566
567         ret = merge_working_tree(opts, &old, new);
568         if (ret)
569                 return ret;
570
571         update_refs_for_switch(opts, &old, new);
572
573         ret = post_checkout_hook(old.commit, new->commit, 1);
574         return ret || opts->writeout_error;
575 }
576
577 static int git_checkout_config(const char *var, const char *value, void *cb)
578 {
579         return git_xmerge_config(var, value, cb);
580 }
581
582 int cmd_checkout(int argc, const char **argv, const char *prefix)
583 {
584         struct checkout_opts opts;
585         unsigned char rev[20];
586         const char *arg;
587         struct branch_info new;
588         struct tree *source_tree = NULL;
589         char *conflict_style = NULL;
590         struct option options[] = {
591                 OPT__QUIET(&opts.quiet),
592                 OPT_STRING('b', NULL, &opts.new_branch, "new branch", "branch"),
593                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
594                 OPT_SET_INT('t', "track",  &opts.track, "track",
595                         BRANCH_TRACK_EXPLICIT),
596                 OPT_SET_INT('2', "ours", &opts.writeout_stage, "stage",
597                             2),
598                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, "stage",
599                             3),
600                 OPT_BOOLEAN('f', NULL, &opts.force, "force"),
601                 OPT_BOOLEAN('m', "merge", &opts.merge, "merge"),
602                 OPT_STRING(0, "conflict", &conflict_style, "style",
603                            "conflict style (merge or diff3)"),
604                 OPT_END(),
605         };
606         int has_dash_dash;
607
608         memset(&opts, 0, sizeof(opts));
609         memset(&new, 0, sizeof(new));
610
611         git_config(git_checkout_config, NULL);
612
613         opts.track = BRANCH_TRACK_UNSPECIFIED;
614
615         argc = parse_options(argc, argv, options, checkout_usage,
616                              PARSE_OPT_KEEP_DASHDASH);
617
618         /* --track without -b should DWIM */
619         if (0 < opts.track && !opts.new_branch) {
620                 const char *argv0 = argv[0];
621                 if (!argc || !strcmp(argv0, "--"))
622                         die ("--track needs a branch name");
623                 if (!prefixcmp(argv0, "refs/"))
624                         argv0 += 5;
625                 if (!prefixcmp(argv0, "remotes/"))
626                         argv0 += 8;
627                 argv0 = strchr(argv0, '/');
628                 if (!argv0 || !argv0[1])
629                         die ("Missing branch name; try -b");
630                 opts.new_branch = argv0 + 1;
631         }
632
633         if (opts.track == BRANCH_TRACK_UNSPECIFIED)
634                 opts.track = git_branch_track;
635         if (conflict_style) {
636                 opts.merge = 1; /* implied */
637                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
638         }
639
640         if (opts.force && opts.merge)
641                 die("git checkout: -f and -m are incompatible");
642
643         /*
644          * case 1: git checkout <ref> -- [<paths>]
645          *
646          *   <ref> must be a valid tree, everything after the '--' must be
647          *   a path.
648          *
649          * case 2: git checkout -- [<paths>]
650          *
651          *   everything after the '--' must be paths.
652          *
653          * case 3: git checkout <something> [<paths>]
654          *
655          *   With no paths, if <something> is a commit, that is to
656          *   switch to the branch or detach HEAD at it.
657          *
658          *   Otherwise <something> shall not be ambiguous.
659          *   - If it's *only* a reference, treat it like case (1).
660          *   - If it's only a path, treat it like case (2).
661          *   - else: fail.
662          *
663          */
664         if (argc) {
665                 if (!strcmp(argv[0], "--")) {       /* case (2) */
666                         argv++;
667                         argc--;
668                         goto no_reference;
669                 }
670
671                 arg = argv[0];
672                 has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
673
674                 if (get_sha1(arg, rev)) {
675                         if (has_dash_dash)          /* case (1) */
676                                 die("invalid reference: %s", arg);
677                         goto no_reference;          /* case (3 -> 2) */
678                 }
679
680                 /* we can't end up being in (2) anymore, eat the argument */
681                 argv++;
682                 argc--;
683
684                 new.name = arg;
685                 if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
686                         setup_branch_path(&new);
687                         if (resolve_ref(new.path, rev, 1, NULL))
688                                 new.commit = lookup_commit_reference(rev);
689                         else
690                                 new.path = NULL;
691                         parse_commit(new.commit);
692                         source_tree = new.commit->tree;
693                 } else
694                         source_tree = parse_tree_indirect(rev);
695
696                 if (!source_tree)                   /* case (1): want a tree */
697                         die("reference is not a tree: %s", arg);
698                 if (!has_dash_dash) {/* case (3 -> 1) */
699                         /*
700                          * Do not complain the most common case
701                          *      git checkout branch
702                          * even if there happen to be a file called 'branch';
703                          * it would be extremely annoying.
704                          */
705                         if (argc)
706                                 verify_non_filename(NULL, arg);
707                 }
708                 else {
709                         argv++;
710                         argc--;
711                 }
712         }
713
714 no_reference:
715         if (argc) {
716                 const char **pathspec = get_pathspec(prefix, argv);
717
718                 if (!pathspec)
719                         die("invalid path specification");
720
721                 /* Checkout paths */
722                 if (opts.new_branch) {
723                         if (argc == 1) {
724                                 die("git checkout: updating paths is incompatible with switching branches.\nDid you intend to checkout '%s' which can not be resolved as commit?", argv[0]);
725                         } else {
726                                 die("git checkout: updating paths is incompatible with switching branches.");
727                         }
728                 }
729
730                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
731                         die("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index.");
732
733                 return checkout_paths(source_tree, pathspec, &opts);
734         }
735
736         if (opts.new_branch) {
737                 struct strbuf buf = STRBUF_INIT;
738                 strbuf_addstr(&buf, "refs/heads/");
739                 strbuf_addstr(&buf, opts.new_branch);
740                 if (!get_sha1(buf.buf, rev))
741                         die("git checkout: branch %s already exists", opts.new_branch);
742                 if (check_ref_format(buf.buf))
743                         die("git checkout: we do not like '%s' as a branch name.", opts.new_branch);
744                 strbuf_release(&buf);
745         }
746
747         if (new.name && !new.commit) {
748                 die("Cannot switch branch to a non-commit.");
749         }
750         if (opts.writeout_stage)
751                 die("--ours/--theirs is incompatible with switching branches.");
752
753         return switch_branches(&opts, &new);
754 }