Re: How de-duplicate similar repositories with alternates

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

On Tue, Dec 04 2018, Jeff King wrote:

> On Thu, Nov 29, 2018 at 03:59:26PM +0100, Ævar Arnfjörð Bjarmason wrote:
>
>> This is the thing I was wrong about, in retrospect probably because I'd
>> been putting PATH_TO_REPO in objects/info/alternates, but we actually
>> need PATH_TO_REPO/objects, and "git gc" won't warn about this (or "git
>> fsck"). Probably a good idea to patch that at some point, i.e. whine
>> about paths in alternates that don't have objects, or at the very least
>> those that don't exist. #leftoverbits
>
> We do complain about missing directories; see alt_odb_usable().
> Pointing to a real directory that doesn't happen to contain any objects
> is harder. If there are no loose objects, there might not be any hashed
> object directories. For a "real" object database, there should always be
> a "pack/" directory. But technically the object storage directory does
> not even need to have that; it can just be a directory full of loose
> objects that happens not to have any at this moment.
>
> That said, I suspect if we issued a warning for "woah, it looks like
> this doesn't have any objects in it, nor does it even have a pack
> directory" that nobody would complain.

Yeah, although see my <87sgzjyif2.fsf@evledraar.gmail.com>, I also ran
into a different issue.

I think a warning (or even error) like this would be more useful:

    test ! -d $objdir && error... # current behavior
    test -d $objdir/objects && error "Did you mean $objdir/objects, silly?" # new error

I.e. I suspect I'm not the only one who's not read the documentation
carefully enough and thought it was a path to the root of the repo and
wondered why it silently didn't work.