@matheusbsbs / matheus-bagliano / commits / 34d607032c

git-apply: skip threeway in add / rename cases

Certain invocations of "git apply --3way" will attempt threeway and fail due to missing objects, even though git is able to fall back on apply_fragments and apply the patch successfully with a return value of 0. To fix, return early from try_threeway() in the following cases: - When the patch is a rename and no lines have changed. In this case, "git diff" doesn't record the blob info, so 3way is neither possible nor necessary. - When the patch is an addition and there is no add/add conflict, i.e. direct_to_threeway is false. In this case, threeway will fail since the preimage is not in cache, but isn't necessary anyway since there is no conflict. This fixes a few unecessary error messages when applying these kinds of patches with --3way. It also fixes a reported issue where applying a concatenation of several git produced patches will fail when those patches involve a deletion followed by creation of the same file. Add a test for this case too. (test provided by <i@zenithal.me>) Signed-off-by: Jerry Zhang <jerry@skydio.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jerry Zhang committed Dec 17, 2021 at 15:29 UTC 34d607032c0db6a6c68754e7a339c3caf08d6a79

2 files changed +21 -1

apply.c

+3 -1

@@ -3582,7 +3582,9 @@ static int try_threeway(struct apply_state *state,

3582

3583 /* No point falling back to 3-way merge in these cases */

3584 if (patch->is_delete ||

3585 - S_ISGITLINK(patch->old_mode) || S_ISGITLINK(patch->new_mode))

3585 + S_ISGITLINK(patch->old_mode) || S_ISGITLINK(patch->new_mode) ||

3586 + (patch->is_new && !patch->direct_to_threeway) ||

3587 + (patch->is_rename && !patch->lines_added && !patch->lines_deleted))

3588 return -1;

3589

3590 /* Preimage the patch was prepared for */

t/t4108-apply-threeway.sh

+18

@@ -275,4 +275,22 @@ test_expect_success 'apply full-index patch with 3way' '

275 git apply --3way --index bin.diff

276 '

277

278 +test_expect_success 'apply delete then new patch with 3way' '

279 + git reset --hard main &&

280 + test_write_lines 2 > delnew &&

281 + git add delnew &&

282 + git diff --cached >> new.patch &&

283 + git reset --hard &&

284 + test_write_lines 1 > delnew &&

285 + git add delnew &&

286 + git commit -m "delnew" &&

287 + rm delnew &&

288 + git diff >> delete-then-new.patch &&

289 + cat new.patch >> delete-then-new.patch &&

290 +

291 + git checkout -- . &&

292 + # Apply must succeed.

293 + git apply --3way delete-then-new.patch

294 +'

295 +

296 test_done