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merge-recursive: Fix modify/delete resolution in the recursive case

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When o->call_depth>0 and we have conflicts, we try to find "middle ground"
when creating the virtual merge base.  In the case of content conflicts,
this can be done by doing a three-way content merge and using the result.
In all parts where the three-way content merge is clean, it is the correct
middle ground, and in parts where it conflicts there is no middle ground
but the conflict markers provide a good compromise since they are unlikely
to accidentally match any further changes.

In the case of a modify/delete conflict, we cannot do the same thing.
Accepting either endpoint as the resolution for the virtual merge base
runs the risk that when handling the non-recursive case we will silently
accept one person's resolution over another without flagging a conflict.
In this case, the closest "middle ground" we have is actually the merge
base of the candidate merge bases.  (We could alternatively attempt a
three way content merge using an empty file in place of the deleted file,
but that seems to be more work than necessary.)

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Elijah Newren 2011-08-11 23:20:11 -06:00 committed by Junio C Hamano
parent 5b448b8530
commit ec61d14963
2 changed files with 26 additions and 16 deletions
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38
merge-recursive.c
View file

@ -1322,27 +1322,42 @@ static int blob_unchanged(const unsigned char *o_sha,
static void handle_delete_modify(struct merge_options *o,
const char *path,
const char *new_path,
unsigned char *o_sha, int o_mode,
unsigned char *a_sha, int a_mode,
unsigned char *b_sha, int b_mode)
{
if (!a_sha) {
char *renamed = NULL;
if (dir_in_way(path, !o->call_depth)) {
renamed = unique_path(o, path, a_sha ? o->branch1 : o->branch2);
}
if (o->call_depth) {
/*
* We cannot arbitrarily accept either a_sha or b_sha as
* correct; since there is no true "middle point" between
* them, simply reuse the base version for virtual merge base.
*/
remove_file_from_cache(path);
update_file(o, 0, o_sha, o_mode, renamed ? renamed : path);
} else if (!a_sha) {
output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
"and modified in %s. Version %s of %s left in tree%s%s.",
path, o->branch1,
o->branch2, o->branch2, path,
NULL == new_path ? "" : " at ",
NULL == new_path ? "" : new_path);
update_file(o, 0, b_sha, b_mode, new_path ? new_path : path);
NULL == renamed ? "" : " at ",
NULL == renamed ? "" : renamed);
update_file(o, 0, b_sha, b_mode, renamed ? renamed : path);
} else {
output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
"and modified in %s. Version %s of %s left in tree%s%s.",
path, o->branch2,
o->branch1, o->branch1, path,
NULL == new_path ? "" : " at ",
NULL == new_path ? "" : new_path);
update_file(o, 0, a_sha, a_mode, new_path ? new_path : path);
NULL == renamed ? "" : " at ",
NULL == renamed ? "" : renamed);
update_file(o, 0, a_sha, a_mode, renamed ? renamed : path);
}
free(renamed);
}
static int merge_content(struct merge_options *o,
@ -1512,14 +1527,9 @@ static int process_entry(struct merge_options *o,
remove_file(o, 1, path, !a_sha);
} else {
/* Modify/delete; deleted side may have put a directory in the way */
char *renamed = NULL;
clean_merge = 0;
if (dir_in_way(path, !o->call_depth)) {
renamed = unique_path(o, path, a_sha ? o->branch1 : o->branch2);
}
handle_delete_modify(o, path, renamed,
handle_delete_modify(o, path, o_sha, o_mode,
a_sha, a_mode, b_sha, b_mode);
free(renamed);
}
} else if ((!o_sha && a_sha && !b_sha) ||
(!o_sha && !a_sha && b_sha)) {

4
t/t6036-recursive-corner-cases.sh
View file

@ -296,7 +296,7 @@ test_expect_success 'setup criss-cross + modify/delete resolved differently' '
git tag E
'
test_expect_failure 'git detects conflict merging criss-cross+modify/delete' '
test_expect_success 'git detects conflict merging criss-cross+modify/delete' '
git checkout D^0 &&
test_must_fail git merge -s recursive E^0 &&
@ -308,7 +308,7 @@ test_expect_failure 'git detects conflict merging criss-cross+modify/delete' '
test $(git rev-parse :2:file) = $(git rev-parse B:file)
'
test_expect_failure 'git detects conflict merging criss-cross+modify/delete, reverse direction' '
test_expect_success 'git detects conflict merging criss-cross+modify/delete, reverse direction' '
git reset --hard &&
git checkout E^0 &&