It's a very unexpected behaviour when a user sees a deleted file after a merge with enabled sparse-checkout. Moreover, when the user resolves merge conflicts and commits the changes with the command "git commit -am xxx", a repository can be broken because all the moved files will be deleted. Finally, it's really hard to find a user who deleted these files because "git log file" doesn't show any merge commits by default. I'm not sure that my fix is correct but I checked all tests and I didn't find a better way to prevent files deleting.
12.09.2016, 02:24, "Junio C Hamano" <gitster@pobox.com>:
Show 60 quoted lines
> Mikhail Filippov <mikhail@filippov.me> writes:
>
>> ---
>
> You'd need a lot more explanation on why this is needed
> (i.e. without it what behaviour you would get, and why that
> behaviour is wrong).
>
>> merge-recursive.c | 9 +++++---
>> t/t6042-merge-rename-corner-cases.sh | 42 ++++++++++++++++++++++++++++++++++++
>> 2 files changed, 48 insertions(+), 3 deletions(-)
>>
>> diff --git a/merge-recursive.c b/merge-recursive.c
>> index e349126..25dc701 100644
>> --- a/merge-recursive.c
>> +++ b/merge-recursive.c
>> @@ -1724,9 +1724,12 @@ static int merge_content(struct merge_options *o,
>> */
>> path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
>> if (!path_renamed_outside_HEAD) {
>> - add_cacheinfo(o, mfi.mode, &mfi.oid, path,
>> - 0, (!o->call_depth), 0);
>> - return mfi.clean;
>> + struct stat st;
>> + if (lstat(path, &st) == 0) {
>> + add_cacheinfo(o, mfi.mode, &mfi.oid, path,
>> + 0, (!o->call_depth), 0);
>> + return mfi.clean;
>> + }
>
> I cannot guess what you are trying to achieve without explanation in
> the proposed log message, but I can say that this unconditional
> checking of a working tree file cannot be correct (there may or may
> not be other things that are wrong with this change, which cannot be
> judged without more information).
>
> Imagine your o->call_depth is not zero, i.e. we are making a virtual
> common ancestor with this merge, in which case any of the three
> trees involved may have nothing to do with the current working tree
> files.
>
>> +test_expect_success 'move file/sparse-checkout/merge should not delete moved file' '
>> + git rm -rf . &&
>> + git clean -fdqx &&
>> + rm -rf .git &&
>> + git init &&
>
> Yuck. This is inherited from existing tests but I think they need
> to be cleaned up. It is not your fault, and it is not in the scope
> of this change.
>
>> + git status >output &&
>> + cp output /tmp/a &&
>
> Huh?
>
>> + test_i18ngrep "nothing to commit" output
>> +'
>> +
>> test_doneMikhail Filippov <mikhail@filippov.me>