Re: [PATCH] do not overwrite untracked symlinks

[Junio C Hamano <gitster@pobox.com>]

Clemens Buchacher <drizzd@aon.at> writes:

> Git traditionally overwrites untracked symlinks silently. This will
> generally not cause massive data loss, but it is inconsistent with
> the behavior for regular files, which are not silently overwritten.
>
> With this change, git refuses to overwrite untracked symlinks by
> default. If the user really wants to overwrite the untracked
> symlink, he has git-clean and git-checkout -f at his disposal.
>
> Signed-off-by: Clemens Buchacher <drizzd@aon.at>
> ---
>
> I checked and there are no undesireable side-effects. One test had
> to be modified slightly because it does overwrite an untracked
> symlink.
>
>  symlinks.c                      |    2 +-
>  t/t6035-merge-dir-to-symlink.sh |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/symlinks.c b/symlinks.c
> index 3cacebd..034943b 100644
> --- a/symlinks.c
> +++ b/symlinks.c
> @@ -223,7 +223,7 @@ int check_leading_path(const char *name, int len)
>  	int flags;
>  	int match_len = lstat_cache_matchlen(cache, name, len, &flags,
>  			   FL_SYMLINK|FL_NOENT|FL_DIR, USE_ONLY_LSTAT);
> -	if (flags & (FL_SYMLINK|FL_NOENT))
> +	if (flags & FL_NOENT)
>  		return 0;
>  	else if (flags & FL_DIR)
>  		return -1;

> diff --git a/t/t6035-merge-dir-to-symlink.sh b/t/t6035-merge-dir-to-symlink.sh
> index 92e02d5..1de285b 100755
> --- a/t/t6035-merge-dir-to-symlink.sh
> +++ b/t/t6035-merge-dir-to-symlink.sh
> @@ -22,7 +22,7 @@ test_expect_success SYMLINKS 'keep a/b-2/c/d across checkout' '
>  	git reset --hard master &&
>  	git rm --cached a/b &&
>  	git commit -m "untracked symlink remains" &&
> -	 git checkout start^0 &&
> +	 git checkout -f start^0 &&
>  	 test -f a/b-2/c/d
>  '

The title of the test says that checkout must keep a/b-2/c/d; if "git
checkout" without "-f" doesn't do so and you had to change it to "git
checkout -f", it would mean one of two things: (1) you broke "checkout",
or (2) the behaviour the test wanted to keep working turned out to be
unwanted (iow, "git checkout" without "-f" should fail under the initial
condition this test sets up).

I suspect the situation is the latter.

What this test in 6035 does before your patch is:

 0. Prepare a tree with the following path (no intermediate symlinks)

	a/b/c/d
        a/b-2/c/d
        a/x

    and call that "start";

    prepare another tree with the following path

	a/b -> b-2 (symlink)
        a/b-2/c/d
        a/x

    make it a child of the "start".

 1. Detach the head at the second commit (i.e. a/b symlink pointing at
    b-2), and then remove a/b symlink from the index.  Make a commit with
    that index.

    The index at that point has:

	a/b-2/c/d
        a/x

    and in the working tree there is an untracked a/b symlink that point
    at b-2.

 2. Try to switch to "start"'s tree.  To be able to check it out, a
    directory needs to be created at a/b (as we need c/d underneath it),
    but untracked symbolic link in the working tree a/b interferes with
    it, and it _should_ fail.


So instead of testing "with -f, the untracked path is nuked" and still
calling the test to "preserve a/b-2/c/d", shouldn't you rename the test to
make sure the untracked symlink is preserved, and make sure checkout
without "-f" fails?

Of course, in addition to the above, it would be a good idea to add
another test that makes sure that with "checkout -f" the user can get rid
of the untracked symlink and check out what he wanted to check out.

Hmm?