[PATCH 3/4] merge: merge unborn index before setting ref
- From
Jeff King <peff@peff.net>
- Date
- Mar 25, 2011, 18:10 UTC
- Message-ID
- <20110325181038.GC14898@sigill.intra.peff.net>
- In-Reply-To
- <20110325180644.GA30838@sigill.intra.peff.net>
When we merge into an unborn branch, there are basically two steps:
1. Write the sha1 of the new commit into the ref pointed
to by HEAD. 2. Update the index with the new content, and check it out
to the working tree.We currently do them in this order. However, (2) is the step that is much more likely to fail, since it can be blocked by things like untracked working tree files. When it does, the merge fails and we are left with an empty index but an updated HEAD.
This patch switches the order, so that a failure in updating the index leaves us unchanged. Of course, a failure in updating the ref now leaves us with an updated index and mis-matched HEAD. That is arguably not much better, but it is probably less likely to actually happen.
Signed-off-by: Jeff King <peff@peff.net> --- I noticed this while diagnosing the pull problem fixed in 4/4. As discused, this is just trading one set of error conditions for another. The "right" thing to do is probably to rollback, but of course that can fail, too, and it's more effort. I think in practice this is fine.
builtin/merge.c | 2 +- t/t7607-merge-overwrite.sh | 4 ++++ 2 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/builtin/merge.c b/builtin/merge.c index aa3453c..c8d028c 100644 --- a/builtin/merge.c +++ b/builtin/merge.c @@ -1063,9 +1063,9 @@ int cmd_merge(int argc, const char **argv, const char *prefix) remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT); if (!remote_head) die("%s - not something we can merge", argv[0]); + read_empty(remote_head->sha1, 0); update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0, DIE_ON_ERR); - read_empty(remote_head->sha1, 0); return 0; } else { struct strbuf merge_names = STRBUF_INIT; diff --git a/t/t7607-merge-overwrite.sh b/t/t7607-merge-overwrite.sh index c86e298..b54e840 100755 --- a/t/t7607-merge-overwrite.sh +++ b/t/t7607-merge-overwrite.sh @@ -157,6 +157,10 @@ test_expect_success 'will not overwrite untracked file on unborn branch' ' test_cmp important c0.c ' +test_expect_success 'failed merge leaves unborn branch in the womb' ' + test_must_fail git rev-parse --verify HEAD +' + test_expect_success 'set up unborn branch and content' ' git symbolic-ref HEAD refs/heads/unborn && rm -f .git/index &&
-- 1.7.4.33.gb8855.dirty