add-patch: fix inverted return code of repo_read_index()

After applying hunks to a file with "add -p", the C patch_update_file() function tries to refresh the index (just like the perl version does). We can only refresh the index if we're able to read it in, so we first check the return value of repo_read_index(). But unlike many functions, where "0" is success, that function is documented to return the number of entries in the index. Hence we should be checking for success with a non-negative return value. Neither the tests nor any users seem to have noticed this, probably due to a combination of: - this affects only the C version, which is not yet the default - following it up with any porcelain command like "git diff" or "git commit" would refresh the index automatically. But you can see the problem by running the plumbing "git diff-files" immediately after "add -p" stages all hunks. Running the new test with GIT_TEST_ADD_I_USE_BUILTIN=1 fails without the matching code change. Signed-off-by: Jeff King <peff@peff.net> Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Sep 7, 2020 at 04:08 UTC dc6264157236fb729ad072e18f14d89549c08555

2 files changed +8 -1

add-patch.c

+1 -1

@@ -1624,7 +1624,7 @@ soft_increment:

1624 NULL, 0, NULL, 0))

1625 error(_("'git apply' failed"));

1626 }

1627 - if (!repo_read_index(s->s.r))

1627 + if (repo_read_index(s->s.r) >= 0)

1628 repo_refresh_and_write_index(s->s.r, REFRESH_QUIET, 0,

1629 1, NULL, NULL, NULL);

1630 }

t/t3701-add-interactive.sh

@@ -560,6 +560,13 @@ test_expect_success 'patch mode ignores unmerged entries' '

560 diff_cmp expected diff

561 '

562

563 +test_expect_success 'index is refreshed after applying patch' '

564 + git reset --hard &&

565 + echo content >test &&

566 + printf y | git add -p &&

567 + git diff-files --exit-code

568 +'

569 +

570 test_expect_success 'diffs can be colorized' '

571 git reset --hard &&

572