Jerry ZhangThe apply_fragments() method of "git apply" can silently apply patches incorrectly if a file has repeating contents. In these cases a three-way merge can apply it correctly or show a conflict. However, because the patches apply "successfully" using apply_fragments(), git will never fall back to the merge, even if the "--3way" flag is used, and the user has no way to ensure correctness by forcing the three-way merge method.
Change the behavior so that when "--3way" is used, git will always try the three-way merge first and will only fall back to apply_fragments() in caseswhere blobs are not available or some other error (but not in the case of a merge conflict).
Signed-off-by: Jerry Zhang <jerry@skydio.com> --- Documentation/git-apply.txt | 5 ++--- apply.c | 13 ++++++------- t/t4108-apply-threeway.sh | 20 ++++++++++++++++++++ 3 files changed, 28 insertions(+), 10 deletions(-)
Show changes to 3 files +28 −10
Documentation/git-apply.txt, apply.c, t/t4108-apply-threeway.sh
diff --git a/Documentation/git-apply.txt b/Documentation/git-apply.txt index 91d9a8601c8c316d4649c405af42e531c39991a8..9144575299c264dd299b542b7b5948eef35f211c 100644 --- a/Documentation/git-apply.txt +++ b/Documentation/git-apply.txt @@ -84,9 +84,8 @@ OPTIONS -3:: --3way:: - When the patch does not apply cleanly, fall back on 3-way merge if - the patch records the identity of blobs it is supposed to apply to, - and we have those blobs available locally, possibly leaving the + Attempt 3-way merge if the patch records the identity of blobs it is supposed + to apply to and we have those blobs available locally, possibly leaving the conflict markers in the files in the working tree for the user to resolve. This option implies the `--index` option, and is incompatible with the `--reject` and the `--cached` options. diff --git a/apply.c b/apply.c index 6695a931e979a968b28af88d425d0c76ba17d0d4..62d65ef8d9c0b68857db55198c73db1f41589df1 100644 --- a/apply.c +++ b/apply.c @@ -3569,10 +3569,10 @@ static int try_threeway(struct apply_state *state, write_object_file("", 0, blob_type, &pre_oid); else if (get_oid(patch->old_oid_prefix, &pre_oid) || read_blob_object(&buf, &pre_oid, patch->old_mode)) - return error(_("repository lacks the necessary blob to fall back on 3-way merge.")); + return error(_("repository lacks the necessary blob to do 3-way merge.")); if (state->apply_verbosity > verbosity_silent) - fprintf(stderr, _("Falling back to three-way merge...\n")); + fprintf(stderr, _("Doing three-way merge...\n")); img = strbuf_detach(&buf, &len); prepare_image(&tmp_image, img, len, 1); @@ -3604,7 +3604,7 @@ static int try_threeway(struct apply_state *state, if (status < 0) { if (state->apply_verbosity > verbosity_silent) fprintf(stderr, - _("Failed to fall back on three-way merge...\n")); + _("Failed to do three-way merge...\n")); return status; } @@ -3637,10 +3637,9 @@ static int apply_data(struct apply_state *state, struct patch *patch, if (load_preimage(state, &image, patch, st, ce) < 0) return -1; - if (patch->direct_to_threeway || - apply_fragments(state, &image, patch) < 0) { + if (!state->threeway || try_threeway(state, &image, patch, st, ce) < 0) { /* Note: with --reject, apply_fragments() returns 0 */ - if (!state->threeway || try_threeway(state, &image, patch, st, ce) < 0) + if (patch->direct_to_threeway || apply_fragments(state, &image, patch) < 0) return -1; } patch->result = image.buf; @@ -5017,7 +5016,7 @@ int apply_parse_options(int argc, const char **argv, OPT_BOOL(0, "apply", force_apply, N_("also apply the patch (use with --stat/--summary/--check)")), OPT_BOOL('3', "3way", &state->threeway, - N_( "attempt three-way merge if a patch does not apply")), + N_( "attempt three-way merge, fall back on normal patch if that fails")), OPT_FILENAME(0, "build-fake-ancestor", &state->fake_ancestor, N_("build a temporary index based on embedded index information")), /* Think twice before adding "--nul" synonym to this */ diff --git a/t/t4108-apply-threeway.sh b/t/t4108-apply-threeway.sh index d62db3fbe16f35a625a4a14eebb70034f695d3eb..0a7332fed5f60a8a2c9c25fc6713d513c3f0ace1 100755 --- a/t/t4108-apply-threeway.sh +++ b/t/t4108-apply-threeway.sh @@ -160,4 +160,24 @@ test_expect_success 'apply -3 with add/add conflict (dirty working tree)' ' test_cmp three.save three ' +test_expect_success 'apply -3 with ambiguous repeating file' ' + git reset --hard && + test_write_lines 1 2 1 2 1 2 1 2 1 2 1>one_two_repeat && + git add one_two_repeat && + git commit -m "init one" && + test_write_lines 1 2 1 2 1 2 1 2 one 2 1>one_two_repeat && + git commit -a -m "change one" && + + git diff HEAD~ >Repeat.diff && + git reset --hard HEAD~ && + + test_write_lines 1 2 1 2 1 2 one 2 1 2 one>one_two_repeat && + git commit -a -m "change surrounding one" && + + git apply --index --3way Repeat.diff && + test_write_lines 1 2 1 2 1 2 one 2 one 2 one>expect && + + test_cmp expect one_two_repeat +' + test_done
-- 2.29.0
