Sync with 1.6.1.2
[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         return run_hook(NULL, "post-checkout",
42                         sha1_to_hex(old ? old->object.sha1 : null_sha1),
43                         sha1_to_hex(new ? new->object.sha1 : null_sha1),
44                         changed ? "1" : "0", NULL);
45         /* "new" can be NULL when checking out from the index before
46            a commit exists. */
47
48 }
49
50 static int update_some(const unsigned char *sha1, const char *base, int baselen,
51                 const char *pathname, unsigned mode, int stage, void *context)
52 {
53         int len;
54         struct cache_entry *ce;
55
56         if (S_ISGITLINK(mode))
57                 return 0;
58
59         if (S_ISDIR(mode))
60                 return READ_TREE_RECURSIVE;
61
62         len = baselen + strlen(pathname);
63         ce = xcalloc(1, cache_entry_size(len));
64         hashcpy(ce->sha1, sha1);
65         memcpy(ce->name, base, baselen);
66         memcpy(ce->name + baselen, pathname, len - baselen);
67         ce->ce_flags = create_ce_flags(len, 0);
68         ce->ce_mode = create_ce_mode(mode);
69         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
70         return 0;
71 }
72
73 static int read_tree_some(struct tree *tree, const char **pathspec)
74 {
75         read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
76
77         /* update the index with the given tree's info
78          * for all args, expanding wildcards, and exit
79          * with any non-zero return code.
80          */
81         return 0;
82 }
83
84 static int skip_same_name(struct cache_entry *ce, int pos)
85 {
86         while (++pos < active_nr &&
87                !strcmp(active_cache[pos]->name, ce->name))
88                 ; /* skip */
89         return pos;
90 }
91
92 static int check_stage(int stage, struct cache_entry *ce, int pos)
93 {
94         while (pos < active_nr &&
95                !strcmp(active_cache[pos]->name, ce->name)) {
96                 if (ce_stage(active_cache[pos]) == stage)
97                         return 0;
98                 pos++;
99         }
100         return error("path '%s' does not have %s version",
101                      ce->name,
102                      (stage == 2) ? "our" : "their");
103 }
104
105 static int check_all_stages(struct cache_entry *ce, int pos)
106 {
107         if (ce_stage(ce) != 1 ||
108             active_nr <= pos + 2 ||
109             strcmp(active_cache[pos+1]->name, ce->name) ||
110             ce_stage(active_cache[pos+1]) != 2 ||
111             strcmp(active_cache[pos+2]->name, ce->name) ||
112             ce_stage(active_cache[pos+2]) != 3)
113                 return error("path '%s' does not have all three versions",
114                              ce->name);
115         return 0;
116 }
117
118 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
119                           struct checkout *state)
120 {
121         while (pos < active_nr &&
122                !strcmp(active_cache[pos]->name, ce->name)) {
123                 if (ce_stage(active_cache[pos]) == stage)
124                         return checkout_entry(active_cache[pos], state, NULL);
125                 pos++;
126         }
127         return error("path '%s' does not have %s version",
128                      ce->name,
129                      (stage == 2) ? "our" : "their");
130 }
131
132 /* NEEDSWORK: share with merge-recursive */
133 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
134 {
135         unsigned long size;
136         enum object_type type;
137
138         if (!hashcmp(sha1, null_sha1)) {
139                 mm->ptr = xstrdup("");
140                 mm->size = 0;
141                 return;
142         }
143
144         mm->ptr = read_sha1_file(sha1, &type, &size);
145         if (!mm->ptr || type != OBJ_BLOB)
146                 die("unable to read blob object %s", sha1_to_hex(sha1));
147         mm->size = size;
148 }
149
150 static int checkout_merged(int pos, struct checkout *state)
151 {
152         struct cache_entry *ce = active_cache[pos];
153         const char *path = ce->name;
154         mmfile_t ancestor, ours, theirs;
155         int status;
156         unsigned char sha1[20];
157         mmbuffer_t result_buf;
158
159         if (ce_stage(ce) != 1 ||
160             active_nr <= pos + 2 ||
161             strcmp(active_cache[pos+1]->name, path) ||
162             ce_stage(active_cache[pos+1]) != 2 ||
163             strcmp(active_cache[pos+2]->name, path) ||
164             ce_stage(active_cache[pos+2]) != 3)
165                 return error("path '%s' does not have all 3 versions", path);
166
167         fill_mm(active_cache[pos]->sha1, &ancestor);
168         fill_mm(active_cache[pos+1]->sha1, &ours);
169         fill_mm(active_cache[pos+2]->sha1, &theirs);
170
171         status = ll_merge(&result_buf, path, &ancestor,
172                           &ours, "ours", &theirs, "theirs", 1);
173         free(ancestor.ptr);
174         free(ours.ptr);
175         free(theirs.ptr);
176         if (status < 0 || !result_buf.ptr) {
177                 free(result_buf.ptr);
178                 return error("path '%s': cannot merge", path);
179         }
180
181         /*
182          * NEEDSWORK:
183          * There is absolutely no reason to write this as a blob object
184          * and create a phoney cache entry just to leak.  This hack is
185          * primarily to get to the write_entry() machinery that massages
186          * the contents to work-tree format and writes out which only
187          * allows it for a cache entry.  The code in write_entry() needs
188          * to be refactored to allow us to feed a <buffer, size, mode>
189          * instead of a cache entry.  Such a refactoring would help
190          * merge_recursive as well (it also writes the merge result to the
191          * object database even when it may contain conflicts).
192          */
193         if (write_sha1_file(result_buf.ptr, result_buf.size,
194                             blob_type, sha1))
195                 die("Unable to add merge result for '%s'", path);
196         ce = make_cache_entry(create_ce_mode(active_cache[pos+1]->ce_mode),
197                               sha1,
198                               path, 2, 0);
199         if (!ce)
200                 die("make_cache_entry failed for path '%s'", path);
201         status = checkout_entry(ce, state, NULL);
202         return status;
203 }
204
205 static int checkout_paths(struct tree *source_tree, const char **pathspec,
206                           struct checkout_opts *opts)
207 {
208         int pos;
209         struct checkout state;
210         static char *ps_matched;
211         unsigned char rev[20];
212         int flag;
213         struct commit *head;
214         int errs = 0;
215         int stage = opts->writeout_stage;
216         int merge = opts->merge;
217         int newfd;
218         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
219
220         newfd = hold_locked_index(lock_file, 1);
221         if (read_cache() < 0)
222                 return error("corrupt index file");
223
224         if (source_tree)
225                 read_tree_some(source_tree, pathspec);
226
227         for (pos = 0; pathspec[pos]; pos++)
228                 ;
229         ps_matched = xcalloc(1, pos);
230
231         for (pos = 0; pos < active_nr; pos++) {
232                 struct cache_entry *ce = active_cache[pos];
233                 match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, ps_matched);
234         }
235
236         if (report_path_error(ps_matched, pathspec, 0))
237                 return 1;
238
239         /* Any unmerged paths? */
240         for (pos = 0; pos < active_nr; pos++) {
241                 struct cache_entry *ce = active_cache[pos];
242                 if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
243                         if (!ce_stage(ce))
244                                 continue;
245                         if (opts->force) {
246                                 warning("path '%s' is unmerged", ce->name);
247                         } else if (stage) {
248                                 errs |= check_stage(stage, ce, pos);
249                         } else if (opts->merge) {
250                                 errs |= check_all_stages(ce, pos);
251                         } else {
252                                 errs = 1;
253                                 error("path '%s' is unmerged", ce->name);
254                         }
255                         pos = skip_same_name(ce, pos) - 1;
256                 }
257         }
258         if (errs)
259                 return 1;
260
261         /* Now we are committed to check them out */
262         memset(&state, 0, sizeof(state));
263         state.force = 1;
264         state.refresh_cache = 1;
265         for (pos = 0; pos < active_nr; pos++) {
266                 struct cache_entry *ce = active_cache[pos];
267                 if (match_pathspec(pathspec, ce->name, ce_namelen(ce), 0, NULL)) {
268                         if (!ce_stage(ce)) {
269                                 errs |= checkout_entry(ce, &state, NULL);
270                                 continue;
271                         }
272                         if (stage)
273                                 errs |= checkout_stage(stage, ce, pos, &state);
274                         else if (merge)
275                                 errs |= checkout_merged(pos, &state);
276                         pos = skip_same_name(ce, pos) - 1;
277                 }
278         }
279
280         if (write_cache(newfd, active_cache, active_nr) ||
281             commit_locked_index(lock_file))
282                 die("unable to write new index file");
283
284         resolve_ref("HEAD", rev, 0, &flag);
285         head = lookup_commit_reference_gently(rev, 1);
286
287         errs |= post_checkout_hook(head, head, 0);
288         return errs;
289 }
290
291 static void show_local_changes(struct object *head)
292 {
293         struct rev_info rev;
294         /* I think we want full paths, even if we're in a subdirectory. */
295         init_revisions(&rev, NULL);
296         rev.abbrev = 0;
297         rev.diffopt.output_format |= DIFF_FORMAT_NAME_STATUS;
298         add_pending_object(&rev, head, NULL);
299         run_diff_index(&rev, 0);
300 }
301
302 static void describe_detached_head(char *msg, struct commit *commit)
303 {
304         struct strbuf sb = STRBUF_INIT;
305         parse_commit(commit);
306         pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, 0, NULL, NULL, 0, 0);
307         fprintf(stderr, "%s %s... %s\n", msg,
308                 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
309         strbuf_release(&sb);
310 }
311
312 static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
313 {
314         struct unpack_trees_options opts;
315         struct tree_desc tree_desc;
316
317         memset(&opts, 0, sizeof(opts));
318         opts.head_idx = -1;
319         opts.update = worktree;
320         opts.skip_unmerged = !worktree;
321         opts.reset = 1;
322         opts.merge = 1;
323         opts.fn = oneway_merge;
324         opts.verbose_update = !o->quiet;
325         opts.src_index = &the_index;
326         opts.dst_index = &the_index;
327         parse_tree(tree);
328         init_tree_desc(&tree_desc, tree->buffer, tree->size);
329         switch (unpack_trees(1, &tree_desc, &opts)) {
330         case -2:
331                 o->writeout_error = 1;
332                 /*
333                  * We return 0 nevertheless, as the index is all right
334                  * and more importantly we have made best efforts to
335                  * update paths in the work tree, and we cannot revert
336                  * them.
337                  */
338         case 0:
339                 return 0;
340         default:
341                 return 128;
342         }
343 }
344
345 struct branch_info {
346         const char *name; /* The short name used */
347         const char *path; /* The full name of a real branch */
348         struct commit *commit; /* The named commit */
349 };
350
351 static void setup_branch_path(struct branch_info *branch)
352 {
353         struct strbuf buf = STRBUF_INIT;
354         int ret;
355
356         if ((ret = interpret_nth_last_branch(branch->name, &buf))
357             && ret == strlen(branch->name)) {
358                 branch->name = xstrdup(buf.buf);
359                 strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
360         } else {
361                 strbuf_addstr(&buf, "refs/heads/");
362                 strbuf_addstr(&buf, branch->name);
363         }
364         branch->path = strbuf_detach(&buf, NULL);
365 }
366
367 static int merge_working_tree(struct checkout_opts *opts,
368                               struct branch_info *old, struct branch_info *new)
369 {
370         int ret;
371         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
372         int newfd = hold_locked_index(lock_file, 1);
373
374         if (read_cache() < 0)
375                 return error("corrupt index file");
376
377         if (opts->force) {
378                 ret = reset_tree(new->commit->tree, opts, 1);
379                 if (ret)
380                         return ret;
381         } else {
382                 struct tree_desc trees[2];
383                 struct tree *tree;
384                 struct unpack_trees_options topts;
385
386                 memset(&topts, 0, sizeof(topts));
387                 topts.head_idx = -1;
388                 topts.src_index = &the_index;
389                 topts.dst_index = &the_index;
390
391                 topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
392
393                 refresh_cache(REFRESH_QUIET);
394
395                 if (unmerged_cache()) {
396                         error("you need to resolve your current index first");
397                         return 1;
398                 }
399
400                 /* 2-way merge to the new branch */
401                 topts.initial_checkout = is_cache_unborn();
402                 topts.update = 1;
403                 topts.merge = 1;
404                 topts.gently = opts->merge;
405                 topts.verbose_update = !opts->quiet;
406                 topts.fn = twoway_merge;
407                 topts.dir = xcalloc(1, sizeof(*topts.dir));
408                 topts.dir->show_ignored = 1;
409                 topts.dir->exclude_per_dir = ".gitignore";
410                 tree = parse_tree_indirect(old->commit->object.sha1);
411                 init_tree_desc(&trees[0], tree->buffer, tree->size);
412                 tree = parse_tree_indirect(new->commit->object.sha1);
413                 init_tree_desc(&trees[1], tree->buffer, tree->size);
414
415                 ret = unpack_trees(2, trees, &topts);
416                 if (ret == -1) {
417                         /*
418                          * Unpack couldn't do a trivial merge; either
419                          * give up or do a real merge, depending on
420                          * whether the merge flag was used.
421                          */
422                         struct tree *result;
423                         struct tree *work;
424                         struct merge_options o;
425                         if (!opts->merge)
426                                 return 1;
427                         parse_commit(old->commit);
428
429                         /* Do more real merge */
430
431                         /*
432                          * We update the index fully, then write the
433                          * tree from the index, then merge the new
434                          * branch with the current tree, with the old
435                          * branch as the base. Then we reset the index
436                          * (but not the working tree) to the new
437                          * branch, leaving the working tree as the
438                          * merged version, but skipping unmerged
439                          * entries in the index.
440                          */
441
442                         add_files_to_cache(NULL, NULL, 0);
443                         init_merge_options(&o);
444                         o.verbosity = 0;
445                         work = write_tree_from_memory(&o);
446
447                         ret = reset_tree(new->commit->tree, opts, 1);
448                         if (ret)
449                                 return ret;
450                         o.branch1 = new->name;
451                         o.branch2 = "local";
452                         merge_trees(&o, new->commit->tree, work,
453                                 old->commit->tree, &result);
454                         ret = reset_tree(new->commit->tree, opts, 0);
455                         if (ret)
456                                 return ret;
457                 }
458         }
459
460         if (write_cache(newfd, active_cache, active_nr) ||
461             commit_locked_index(lock_file))
462                 die("unable to write new index file");
463
464         if (!opts->force && !opts->quiet)
465                 show_local_changes(&new->commit->object);
466
467         return 0;
468 }
469
470 static void report_tracking(struct branch_info *new)
471 {
472         struct strbuf sb = STRBUF_INIT;
473         struct branch *branch = branch_get(new->name);
474
475         if (!format_tracking_info(branch, &sb))
476                 return;
477         fputs(sb.buf, stdout);
478         strbuf_release(&sb);
479 }
480
481 static void update_refs_for_switch(struct checkout_opts *opts,
482                                    struct branch_info *old,
483                                    struct branch_info *new)
484 {
485         struct strbuf msg = STRBUF_INIT;
486         const char *old_desc;
487         if (opts->new_branch) {
488                 create_branch(old->name, opts->new_branch, new->name, 0,
489                               opts->new_branch_log, opts->track);
490                 new->name = opts->new_branch;
491                 setup_branch_path(new);
492         }
493
494         old_desc = old->name;
495         if (!old_desc && old->commit)
496                 old_desc = sha1_to_hex(old->commit->object.sha1);
497         strbuf_addf(&msg, "checkout: moving from %s to %s",
498                     old_desc ? old_desc : "(invalid)", new->name);
499
500         if (new->path) {
501                 create_symref("HEAD", new->path, msg.buf);
502                 if (!opts->quiet) {
503                         if (old->path && !strcmp(new->path, old->path))
504                                 fprintf(stderr, "Already on \"%s\"\n",
505                                         new->name);
506                         else
507                                 fprintf(stderr, "Switched to%s branch \"%s\"\n",
508                                         opts->new_branch ? " a new" : "",
509                                         new->name);
510                 }
511         } else if (strcmp(new->name, "HEAD")) {
512                 update_ref(msg.buf, "HEAD", new->commit->object.sha1, NULL,
513                            REF_NODEREF, DIE_ON_ERR);
514                 if (!opts->quiet) {
515                         if (old->path)
516                                 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);
517                         describe_detached_head("HEAD is now at", new->commit);
518                 }
519         }
520         remove_branch_state();
521         strbuf_release(&msg);
522         if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
523                 report_tracking(new);
524 }
525
526 static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
527 {
528         int ret = 0;
529         struct branch_info old;
530         unsigned char rev[20];
531         int flag;
532         memset(&old, 0, sizeof(old));
533         old.path = resolve_ref("HEAD", rev, 0, &flag);
534         old.commit = lookup_commit_reference_gently(rev, 1);
535         if (!(flag & REF_ISSYMREF))
536                 old.path = NULL;
537
538         if (old.path && !prefixcmp(old.path, "refs/heads/"))
539                 old.name = old.path + strlen("refs/heads/");
540
541         if (!new->name) {
542                 new->name = "HEAD";
543                 new->commit = old.commit;
544                 if (!new->commit)
545                         die("You are on a branch yet to be born");
546                 parse_commit(new->commit);
547         }
548
549         /*
550          * If we were on a detached HEAD, but we are now moving to
551          * a new commit, we want to mention the old commit once more
552          * to remind the user that it might be lost.
553          */
554         if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
555                 describe_detached_head("Previous HEAD position was", old.commit);
556
557         if (!old.commit && !opts->force) {
558                 if (!opts->quiet) {
559                         fprintf(stderr, "warning: You appear to be on a branch yet to be born.\n");
560                         fprintf(stderr, "warning: Forcing checkout of %s.\n", new->name);
561                 }
562                 opts->force = 1;
563         }
564
565         ret = merge_working_tree(opts, &old, new);
566         if (ret)
567                 return ret;
568
569         update_refs_for_switch(opts, &old, new);
570
571         ret = post_checkout_hook(old.commit, new->commit, 1);
572         return ret || opts->writeout_error;
573 }
574
575 static int git_checkout_config(const char *var, const char *value, void *cb)
576 {
577         return git_xmerge_config(var, value, cb);
578 }
579
580 int cmd_checkout(int argc, const char **argv, const char *prefix)
581 {
582         struct checkout_opts opts;
583         unsigned char rev[20];
584         const char *arg;
585         struct branch_info new;
586         struct tree *source_tree = NULL;
587         char *conflict_style = NULL;
588         struct option options[] = {
589                 OPT__QUIET(&opts.quiet),
590                 OPT_STRING('b', NULL, &opts.new_branch, "new branch", "branch"),
591                 OPT_BOOLEAN('l', NULL, &opts.new_branch_log, "log for new branch"),
592                 OPT_SET_INT('t', "track",  &opts.track, "track",
593                         BRANCH_TRACK_EXPLICIT),
594                 OPT_SET_INT('2', "ours", &opts.writeout_stage, "stage",
595                             2),
596                 OPT_SET_INT('3', "theirs", &opts.writeout_stage, "stage",
597                             3),
598                 OPT_BOOLEAN('f', NULL, &opts.force, "force"),
599                 OPT_BOOLEAN('m', "merge", &opts.merge, "merge"),
600                 OPT_STRING(0, "conflict", &conflict_style, "style",
601                            "conflict style (merge or diff3)"),
602                 OPT_END(),
603         };
604         int has_dash_dash;
605
606         memset(&opts, 0, sizeof(opts));
607         memset(&new, 0, sizeof(new));
608
609         git_config(git_checkout_config, NULL);
610
611         opts.track = BRANCH_TRACK_UNSPECIFIED;
612
613         argc = parse_options(argc, argv, options, checkout_usage,
614                              PARSE_OPT_KEEP_DASHDASH);
615
616         /* --track without -b should DWIM */
617         if (0 < opts.track && !opts.new_branch) {
618                 const char *argv0 = argv[0];
619                 if (!argc || !strcmp(argv0, "--"))
620                         die ("--track needs a branch name");
621                 if (!prefixcmp(argv0, "refs/"))
622                         argv0 += 5;
623                 if (!prefixcmp(argv0, "remotes/"))
624                         argv0 += 8;
625                 argv0 = strchr(argv0, '/');
626                 if (!argv0 || !argv0[1])
627                         die ("Missing branch name; try -b");
628                 opts.new_branch = argv0 + 1;
629         }
630
631         if (opts.track == BRANCH_TRACK_UNSPECIFIED)
632                 opts.track = git_branch_track;
633         if (conflict_style) {
634                 opts.merge = 1; /* implied */
635                 git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
636         }
637
638         if (opts.force && opts.merge)
639                 die("git checkout: -f and -m are incompatible");
640
641         /*
642          * case 1: git checkout <ref> -- [<paths>]
643          *
644          *   <ref> must be a valid tree, everything after the '--' must be
645          *   a path.
646          *
647          * case 2: git checkout -- [<paths>]
648          *
649          *   everything after the '--' must be paths.
650          *
651          * case 3: git checkout <something> [<paths>]
652          *
653          *   With no paths, if <something> is a commit, that is to
654          *   switch to the branch or detach HEAD at it.
655          *
656          *   Otherwise <something> shall not be ambiguous.
657          *   - If it's *only* a reference, treat it like case (1).
658          *   - If it's only a path, treat it like case (2).
659          *   - else: fail.
660          *
661          */
662         if (argc) {
663                 if (!strcmp(argv[0], "--")) {       /* case (2) */
664                         argv++;
665                         argc--;
666                         goto no_reference;
667                 }
668
669                 arg = argv[0];
670                 has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
671
672                 if (!strcmp(arg, "-"))
673                         arg = "@{-1}";
674
675                 if (get_sha1(arg, rev)) {
676                         if (has_dash_dash)          /* case (1) */
677                                 die("invalid reference: %s", arg);
678                         goto no_reference;          /* case (3 -> 2) */
679                 }
680
681                 /* we can't end up being in (2) anymore, eat the argument */
682                 argv++;
683                 argc--;
684
685                 new.name = arg;
686                 if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
687                         setup_branch_path(&new);
688                         if (resolve_ref(new.path, rev, 1, NULL))
689                                 new.commit = lookup_commit_reference(rev);
690                         else
691                                 new.path = NULL;
692                         parse_commit(new.commit);
693                         source_tree = new.commit->tree;
694                 } else
695                         source_tree = parse_tree_indirect(rev);
696
697                 if (!source_tree)                   /* case (1): want a tree */
698                         die("reference is not a tree: %s", arg);
699                 if (!has_dash_dash) {/* case (3 -> 1) */
700                         /*
701                          * Do not complain the most common case
702                          *      git checkout branch
703                          * even if there happen to be a file called 'branch';
704                          * it would be extremely annoying.
705                          */
706                         if (argc)
707                                 verify_non_filename(NULL, arg);
708                 }
709                 else {
710                         argv++;
711                         argc--;
712                 }
713         }
714
715 no_reference:
716         if (argc) {
717                 const char **pathspec = get_pathspec(prefix, argv);
718
719                 if (!pathspec)
720                         die("invalid path specification");
721
722                 /* Checkout paths */
723                 if (opts.new_branch) {
724                         if (argc == 1) {
725                                 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]);
726                         } else {
727                                 die("git checkout: updating paths is incompatible with switching branches.");
728                         }
729                 }
730
731                 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
732                         die("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index.");
733
734                 return checkout_paths(source_tree, pathspec, &opts);
735         }
736
737         if (opts.new_branch) {
738                 struct strbuf buf = STRBUF_INIT;
739                 strbuf_addstr(&buf, "refs/heads/");
740                 strbuf_addstr(&buf, opts.new_branch);
741                 if (!get_sha1(buf.buf, rev))
742                         die("git checkout: branch %s already exists", opts.new_branch);
743                 if (check_ref_format(buf.buf))
744                         die("git checkout: we do not like '%s' as a branch name.", opts.new_branch);
745                 strbuf_release(&buf);
746         }
747
748         if (new.name && !new.commit) {
749                 die("Cannot switch branch to a non-commit.");
750         }
751         if (opts.writeout_stage)
752                 die("--ours/--theirs is incompatible with switching branches.");
753
754         return switch_branches(&opts, &new);
755 }