Revision 6aba117d5cf7128e7bc942888263552fe927e13f authored by Elijah Newren on 29 August 2018, 07:06:13 UTC, committed by Junio C Hamano on 30 August 2018, 14:58:59 UTC
Let's say you have the following three trees, where Base is from one commit behind either master or branch: Base : bar_v1, foo/{file1, file2, file3} branch: bar_v2, foo/{file1, file2}, goo/file3 master: bar_v3, foo/{file1, file2, file3} Using git-am (or am-based rebase) to apply the changes from branch onto master results in the following tree: Result: bar_merged, goo/{file1, file2, file3} This is not what users want; they did not rename foo/ -> goo/, they only renamed one file within that directory. The reason this happens is am constructs fake trees (via build_fake_ancestor()) of the following form: Base_bfa : bar_v1, foo/file3 branch_bfa: bar_v2, goo/file3 Combining these two trees with master's tree: master: bar_v3, foo/{file1, file2, file3}, You can see that merge_recursive_generic() would see branch_bfa as renaming foo/ -> goo/, and master as just adding both foo/file1 and foo/file2. As such, it ends up with goo/{file1, file2, file3} The core problem is that am does not have access to the original trees; it can only construct trees using the blobs involved in the patch. As such, it is not safe to perform directory rename detection within am -3. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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merge.c
#include "cache.h"
#include "diff.h"
#include "diffcore.h"
#include "lockfile.h"
#include "commit.h"
#include "run-command.h"
#include "resolve-undo.h"
#include "tree-walk.h"
#include "unpack-trees.h"
#include "dir.h"
static const char *merge_argument(struct commit *commit)
{
return oid_to_hex(commit ? &commit->object.oid : the_hash_algo->empty_tree);
}
int index_has_changes(struct strbuf *sb)
{
struct object_id head;
int i;
if (!get_oid_tree("HEAD", &head)) {
struct diff_options opt;
diff_setup(&opt);
opt.flags.exit_with_status = 1;
if (!sb)
opt.flags.quick = 1;
do_diff_cache(&head, &opt);
diffcore_std(&opt);
for (i = 0; sb && i < diff_queued_diff.nr; i++) {
if (i)
strbuf_addch(sb, ' ');
strbuf_addstr(sb, diff_queued_diff.queue[i]->two->path);
}
diff_flush(&opt);
return opt.flags.has_changes != 0;
} else {
for (i = 0; sb && i < active_nr; i++) {
if (i)
strbuf_addch(sb, ' ');
strbuf_addstr(sb, active_cache[i]->name);
}
return !!active_nr;
}
}
int try_merge_command(const char *strategy, size_t xopts_nr,
const char **xopts, struct commit_list *common,
const char *head_arg, struct commit_list *remotes)
{
struct argv_array args = ARGV_ARRAY_INIT;
int i, ret;
struct commit_list *j;
argv_array_pushf(&args, "merge-%s", strategy);
for (i = 0; i < xopts_nr; i++)
argv_array_pushf(&args, "--%s", xopts[i]);
for (j = common; j; j = j->next)
argv_array_push(&args, merge_argument(j->item));
argv_array_push(&args, "--");
argv_array_push(&args, head_arg);
for (j = remotes; j; j = j->next)
argv_array_push(&args, merge_argument(j->item));
ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
argv_array_clear(&args);
discard_cache();
if (read_cache() < 0)
die(_("failed to read the cache"));
resolve_undo_clear();
return ret;
}
int checkout_fast_forward(const struct object_id *head,
const struct object_id *remote,
int overwrite_ignore)
{
struct tree *trees[MAX_UNPACK_TREES];
struct unpack_trees_options opts;
struct tree_desc t[MAX_UNPACK_TREES];
int i, nr_trees = 0;
struct dir_struct dir;
struct lock_file lock_file = LOCK_INIT;
refresh_cache(REFRESH_QUIET);
if (hold_locked_index(&lock_file, LOCK_REPORT_ON_ERROR) < 0)
return -1;
memset(&trees, 0, sizeof(trees));
memset(&t, 0, sizeof(t));
trees[nr_trees] = parse_tree_indirect(head);
if (!trees[nr_trees++]) {
rollback_lock_file(&lock_file);
return -1;
}
trees[nr_trees] = parse_tree_indirect(remote);
if (!trees[nr_trees++]) {
rollback_lock_file(&lock_file);
return -1;
}
for (i = 0; i < nr_trees; i++) {
parse_tree(trees[i]);
init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
}
memset(&opts, 0, sizeof(opts));
if (overwrite_ignore) {
memset(&dir, 0, sizeof(dir));
dir.flags |= DIR_SHOW_IGNORED;
setup_standard_excludes(&dir);
opts.dir = &dir;
}
opts.head_idx = 1;
opts.src_index = &the_index;
opts.dst_index = &the_index;
opts.update = 1;
opts.verbose_update = 1;
opts.merge = 1;
opts.fn = twoway_merge;
setup_unpack_trees_porcelain(&opts, "merge");
if (unpack_trees(nr_trees, t, &opts)) {
rollback_lock_file(&lock_file);
clear_unpack_trees_porcelain(&opts);
return -1;
}
clear_unpack_trees_porcelain(&opts);
if (write_locked_index(&the_index, &lock_file, COMMIT_LOCK))
return error(_("unable to write new index file"));
return 0;
}
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