t5300, t5302, t5303: Do not use /dev/zero
[alt-git.git] / builtin-checkout.c
blobc315f63398bac5dd3fd465af881caa5f3b9c9184
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"
20 static const char * const checkout_usage[] = {
21 "git checkout [options] <branch>",
22 "git checkout [options] [<branch>] -- <file>...",
23 NULL,
26 struct checkout_opts {
27 int quiet;
28 int merge;
29 int force;
30 int writeout_stage;
31 int writeout_error;
33 const char *new_branch;
34 int new_branch_log;
35 enum branch_track track;
38 static int post_checkout_hook(struct commit *old, struct commit *new,
39 int changed)
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. */
50 static int update_some(const unsigned char *sha1, const char *base, int baselen,
51 const char *pathname, unsigned mode, int stage, void *context)
53 int len;
54 struct cache_entry *ce;
56 if (S_ISGITLINK(mode))
57 return 0;
59 if (S_ISDIR(mode))
60 return READ_TREE_RECURSIVE;
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;
73 static int read_tree_some(struct tree *tree, const char **pathspec)
75 read_tree_recursive(tree, "", 0, 0, pathspec, update_some, NULL);
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.
81 return 0;
84 static int skip_same_name(struct cache_entry *ce, int pos)
86 while (++pos < active_nr &&
87 !strcmp(active_cache[pos]->name, ce->name))
88 ; /* skip */
89 return pos;
92 static int check_stage(int stage, struct cache_entry *ce, int pos)
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++;
100 return error("path '%s' does not have %s version",
101 ce->name,
102 (stage == 2) ? "our" : "their");
105 static int check_all_stages(struct cache_entry *ce, int pos)
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;
118 static int checkout_stage(int stage, struct cache_entry *ce, int pos,
119 struct checkout *state)
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++;
127 return error("path '%s' does not have %s version",
128 ce->name,
129 (stage == 2) ? "our" : "their");
132 /* NEEDSWORK: share with merge-recursive */
133 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
135 unsigned long size;
136 enum object_type type;
138 if (!hashcmp(sha1, null_sha1)) {
139 mm->ptr = xstrdup("");
140 mm->size = 0;
141 return;
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;
150 static int checkout_merged(int pos, struct checkout *state)
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;
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);
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);
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);
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).
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;
205 static int checkout_paths(struct tree *source_tree, const char **pathspec,
206 struct checkout_opts *opts)
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));
220 newfd = hold_locked_index(lock_file, 1);
221 if (read_cache() < 0)
222 return error("corrupt index file");
224 if (source_tree)
225 read_tree_some(source_tree, pathspec);
227 for (pos = 0; pathspec[pos]; pos++)
229 ps_matched = xcalloc(1, pos);
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);
236 if (report_path_error(ps_matched, pathspec, 0))
237 return 1;
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);
255 pos = skip_same_name(ce, pos) - 1;
258 if (errs)
259 return 1;
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;
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;
280 if (write_cache(newfd, active_cache, active_nr) ||
281 commit_locked_index(lock_file))
282 die("unable to write new index file");
284 resolve_ref("HEAD", rev, 0, &flag);
285 head = lookup_commit_reference_gently(rev, 1);
287 errs |= post_checkout_hook(head, head, 0);
288 return errs;
291 static void show_local_changes(struct object *head)
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 if (diff_setup_done(&rev.diffopt) < 0)
299 die("diff_setup_done failed");
300 add_pending_object(&rev, head, NULL);
301 run_diff_index(&rev, 0);
304 static void describe_detached_head(char *msg, struct commit *commit)
306 struct strbuf sb = STRBUF_INIT;
307 parse_commit(commit);
308 pretty_print_commit(CMIT_FMT_ONELINE, commit, &sb, 0, NULL, NULL, 0, 0);
309 fprintf(stderr, "%s %s... %s\n", msg,
310 find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV), sb.buf);
311 strbuf_release(&sb);
314 static int reset_tree(struct tree *tree, struct checkout_opts *o, int worktree)
316 struct unpack_trees_options opts;
317 struct tree_desc tree_desc;
319 memset(&opts, 0, sizeof(opts));
320 opts.head_idx = -1;
321 opts.update = worktree;
322 opts.skip_unmerged = !worktree;
323 opts.reset = 1;
324 opts.merge = 1;
325 opts.fn = oneway_merge;
326 opts.verbose_update = !o->quiet;
327 opts.src_index = &the_index;
328 opts.dst_index = &the_index;
329 parse_tree(tree);
330 init_tree_desc(&tree_desc, tree->buffer, tree->size);
331 switch (unpack_trees(1, &tree_desc, &opts)) {
332 case -2:
333 o->writeout_error = 1;
335 * We return 0 nevertheless, as the index is all right
336 * and more importantly we have made best efforts to
337 * update paths in the work tree, and we cannot revert
338 * them.
340 case 0:
341 return 0;
342 default:
343 return 128;
347 struct branch_info {
348 const char *name; /* The short name used */
349 const char *path; /* The full name of a real branch */
350 struct commit *commit; /* The named commit */
353 static void setup_branch_path(struct branch_info *branch)
355 struct strbuf buf = STRBUF_INIT;
356 int ret;
358 if ((ret = interpret_nth_last_branch(branch->name, &buf))
359 && ret == strlen(branch->name)) {
360 branch->name = xstrdup(buf.buf);
361 strbuf_splice(&buf, 0, 0, "refs/heads/", 11);
362 } else {
363 strbuf_addstr(&buf, "refs/heads/");
364 strbuf_addstr(&buf, branch->name);
366 branch->path = strbuf_detach(&buf, NULL);
369 static int merge_working_tree(struct checkout_opts *opts,
370 struct branch_info *old, struct branch_info *new)
372 int ret;
373 struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
374 int newfd = hold_locked_index(lock_file, 1);
376 if (read_cache() < 0)
377 return error("corrupt index file");
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;
388 memset(&topts, 0, sizeof(topts));
389 topts.head_idx = -1;
390 topts.src_index = &the_index;
391 topts.dst_index = &the_index;
393 topts.msgs.not_uptodate_file = "You have local changes to '%s'; cannot switch branches.";
395 refresh_cache(REFRESH_QUIET);
397 if (unmerged_cache()) {
398 error("you need to resolve your current index first");
399 return 1;
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);
417 ret = unpack_trees(2, trees, &topts);
418 if (ret == -1) {
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.
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);
431 /* Do more real merge */
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.
444 add_files_to_cache(NULL, NULL, 0);
445 init_merge_options(&o);
446 o.verbosity = 0;
447 work = write_tree_from_memory(&o);
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;
462 if (write_cache(newfd, active_cache, active_nr) ||
463 commit_locked_index(lock_file))
464 die("unable to write new index file");
466 if (!opts->force && !opts->quiet)
467 show_local_changes(&new->commit->object);
469 return 0;
472 static void report_tracking(struct branch_info *new)
474 struct strbuf sb = STRBUF_INIT;
475 struct branch *branch = branch_get(new->name);
477 if (!format_tracking_info(branch, &sb))
478 return;
479 fputs(sb.buf, stdout);
480 strbuf_release(&sb);
483 static void update_refs_for_switch(struct checkout_opts *opts,
484 struct branch_info *old,
485 struct branch_info *new)
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);
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);
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);
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);
522 remove_branch_state();
523 strbuf_release(&msg);
524 if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
525 report_tracking(new);
528 static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
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;
540 if (old.path && !prefixcmp(old.path, "refs/heads/"))
541 old.name = old.path + strlen("refs/heads/");
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);
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.
556 if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
557 describe_detached_head("Previous HEAD position was", old.commit);
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);
564 opts->force = 1;
567 ret = merge_working_tree(opts, &old, new);
568 if (ret)
569 return ret;
571 update_refs_for_switch(opts, &old, new);
573 ret = post_checkout_hook(old.commit, new->commit, 1);
574 return ret || opts->writeout_error;
577 static int git_checkout_config(const char *var, const char *value, void *cb)
579 return git_xmerge_config(var, value, cb);
582 int cmd_checkout(int argc, const char **argv, const char *prefix)
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",
598 OPT_SET_INT('3', "theirs", &opts.writeout_stage, "stage",
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(),
606 int has_dash_dash;
608 memset(&opts, 0, sizeof(opts));
609 memset(&new, 0, sizeof(new));
611 git_config(git_checkout_config, NULL);
613 opts.track = BRANCH_TRACK_UNSPECIFIED;
615 argc = parse_options(argc, argv, options, checkout_usage,
616 PARSE_OPT_KEEP_DASHDASH);
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;
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);
640 if (opts.force && opts.merge)
641 die("git checkout: -f and -m are incompatible");
644 * case 1: git checkout <ref> -- [<paths>]
646 * <ref> must be a valid tree, everything after the '--' must be
647 * a path.
649 * case 2: git checkout -- [<paths>]
651 * everything after the '--' must be paths.
653 * case 3: git checkout <something> [<paths>]
655 * With no paths, if <something> is a commit, that is to
656 * switch to the branch or detach HEAD at it.
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.
664 if (argc) {
665 if (!strcmp(argv[0], "--")) { /* case (2) */
666 argv++;
667 argc--;
668 goto no_reference;
671 arg = argv[0];
672 has_dash_dash = (argc > 1) && !strcmp(argv[1], "--");
674 if (!strcmp(arg, "-"))
675 arg = "@{-1}";
677 if (get_sha1(arg, rev)) {
678 if (has_dash_dash) /* case (1) */
679 die("invalid reference: %s", arg);
680 goto no_reference; /* case (3 -> 2) */
683 /* we can't end up being in (2) anymore, eat the argument */
684 argv++;
685 argc--;
687 new.name = arg;
688 if ((new.commit = lookup_commit_reference_gently(rev, 1))) {
689 setup_branch_path(&new);
690 if (resolve_ref(new.path, rev, 1, NULL))
691 new.commit = lookup_commit_reference(rev);
692 else
693 new.path = NULL;
694 parse_commit(new.commit);
695 source_tree = new.commit->tree;
696 } else
697 source_tree = parse_tree_indirect(rev);
699 if (!source_tree) /* case (1): want a tree */
700 die("reference is not a tree: %s", arg);
701 if (!has_dash_dash) {/* case (3 -> 1) */
703 * Do not complain the most common case
704 * git checkout branch
705 * even if there happen to be a file called 'branch';
706 * it would be extremely annoying.
708 if (argc)
709 verify_non_filename(NULL, arg);
711 else {
712 argv++;
713 argc--;
717 no_reference:
718 if (argc) {
719 const char **pathspec = get_pathspec(prefix, argv);
721 if (!pathspec)
722 die("invalid path specification");
724 /* Checkout paths */
725 if (opts.new_branch) {
726 if (argc == 1) {
727 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]);
728 } else {
729 die("git checkout: updating paths is incompatible with switching branches.");
733 if (1 < !!opts.writeout_stage + !!opts.force + !!opts.merge)
734 die("git checkout: --ours/--theirs, --force and --merge are incompatible when\nchecking out of the index.");
736 return checkout_paths(source_tree, pathspec, &opts);
739 if (opts.new_branch) {
740 struct strbuf buf = STRBUF_INIT;
741 strbuf_addstr(&buf, "refs/heads/");
742 strbuf_addstr(&buf, opts.new_branch);
743 if (!get_sha1(buf.buf, rev))
744 die("git checkout: branch %s already exists", opts.new_branch);
745 if (check_ref_format(buf.buf))
746 die("git checkout: we do not like '%s' as a branch name.", opts.new_branch);
747 strbuf_release(&buf);
750 if (new.name && !new.commit) {
751 die("Cannot switch branch to a non-commit.");
753 if (opts.writeout_stage)
754 die("--ours/--theirs is incompatible with switching branches.");
756 return switch_branches(&opts, &new);