Re: git clone of empty repositories doesn't preserve hash

From: Jeff King <peff@peff.net>
Date: Apr 5, 2023, 21:26 UTC
Message-ID: <20230405212617.GB529421@coredump.intra.peff.net>
In-Reply-To: <xmqq355euj2i.fsf@gitster.g>

On Wed, Apr 05, 2023 at 02:15:33PM -0700, Junio C Hamano wrote:

Show 15 quoted lines

> ----- >8 -----
> Subject: [PATCH] clone: propagate object-format when cloning from void
> 
> A user could prepare an empty repository and set it to use SHA256 as
> the object format.  The new repository created by "git clone" from
> such a repository however would not record that it is expecting
> objects in the same SHA256 format.  This works as expected if the
> source repository is not empty.
> 
> Just like we started copying the name of the primary branch from the
> remote repository even if it is unborn in 3d8314f8 (clone: propagate
> empty remote HEAD even with other branches, 2022-07-07), lift the
> code that records the object format out of the block executed only
> when cloning from an instantiated repository, so that it works also
> when cloning from an empty repository.

Heh, our mails just crossed, but I stumbled upon the same patch. So yes, this looks good to me.

I suspect that setting the flag in the_repository might not matter, since we do not have any refs or objects to manipulate, and what we care about here is that initialize_repository_version() is run. But I agree that the two conceptually belong together, and hoisting both out of the block is the right thing to do.

Show 18 quoted lines

> diff --git c/t/t5702-protocol-v2.sh w/t/t5702-protocol-v2.sh
> index 71aabe30b7..6af5c2062f 100755
> --- c/t/t5702-protocol-v2.sh
> +++ w/t/t5702-protocol-v2.sh
> @@ -269,6 +269,17 @@ test_expect_success 'clone propagates unborn HEAD from non-empty repo' '
>  	grep "warning: remote HEAD refers to nonexistent ref" stderr
>  '
>  
> +test_expect_success 'clone propagates object-format from empty repo' '
> +	test_when_finished "rm -fr src256 dst256" &&
> +
> +	echo sha256 >expect &&
> +	git init --object-format=sha256 src256 &&
> +	git clone src256 dst256 &&
> +	git -C dst256 rev-parse --show-object-format >actual &&
> +
> +	test_cmp expect actual
> +'

And this test looks straightforward. Very nice.

-Peff