Subject: Re: [PATCH 03/10] builtin: use default hash when outside a repository

From: Junio C Hamano <[email-masked]>
Date: Fri, 20 Jun 2025 07:19:41 -0700

"brian m. carlson" <[email-masked]> writes:

> We have some commands that can operate inside or outside a repository.
> If we're operating outside a repository, we clearly cannot use the
> repository's hash algorithm as a default since it doesn't exist, so
> instead, let's pick the default instead of specifically SHA-1.  Right
> now this results in no functional change since the default is SHA-1, but
> that may change in the future.

Nicely explained and this step shows why having GIT_HASH_DEFAULT
makes sense very well.

>
> Signed-off-by: brian m. carlson <[email-masked]>
> ---
>  builtin/apply.c       | 2 +-
>  builtin/diff.c        | 2 +-
>  builtin/hash-object.c | 2 +-
>  builtin/index-pack.c  | 2 +-
>  builtin/ls-remote.c   | 2 +-
>  builtin/patch-id.c    | 2 +-
>  builtin/shortlog.c    | 2 +-
>  builtin/show-index.c  | 2 +-
>  8 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/builtin/apply.c b/builtin/apply.c
> index a1e20c593d..d642a40251 100644
> --- a/builtin/apply.c
> +++ b/builtin/apply.c
> @@ -29,7 +29,7 @@ int cmd_apply(int argc,
>  	 * cf. https://lore.kernel.org/git/[email-masked]/
>  	 */
>  	if (!the_hash_algo)
> -		repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
> +		repo_set_hash_algo(the_repository, GIT_HASH_DEFAULT);
>  
>  	argc = apply_parse_options(argc, argv,
>  				   &state, &force_apply, &options,
> diff --git a/builtin/diff.c b/builtin/diff.c
> index c6231edce4..eebffe36cc 100644
> --- a/builtin/diff.c
> +++ b/builtin/diff.c
> @@ -483,7 +483,7 @@ int cmd_diff(int argc,
>  	 * configurable via a command line option.
>  	 */
>  	if (nongit)
> -		repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
> +		repo_set_hash_algo(the_repository, GIT_HASH_DEFAULT);
>  
>  	init_diff_ui_defaults();
>  	git_config(git_diff_ui_config, NULL);
> diff --git a/builtin/hash-object.c b/builtin/hash-object.c
> index 6a99ec250d..213a302e05 100644
> --- a/builtin/hash-object.c
> +++ b/builtin/hash-object.c
> @@ -104,7 +104,7 @@ int cmd_hash_object(int argc,
>  		prefix = setup_git_directory_gently(&nongit);
>  
>  	if (nongit && !the_hash_algo)
> -		repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
> +		repo_set_hash_algo(the_repository, GIT_HASH_DEFAULT);
>  
>  	if (vpath && prefix) {
>  		vpath_free = prefix_filename(prefix, vpath);
> diff --git a/builtin/index-pack.c b/builtin/index-pack.c
> index bb7925bd29..352ce7f88a 100644
> --- a/builtin/index-pack.c
> +++ b/builtin/index-pack.c
> @@ -2034,7 +2034,7 @@ int cmd_index_pack(int argc,
>  	 * choice but to guess the object hash.
>  	 */
>  	if (!the_repository->hash_algo)
> -		repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
> +		repo_set_hash_algo(the_repository, GIT_HASH_DEFAULT);
>  
>  	opts.flags &= ~(WRITE_REV | WRITE_REV_VERIFY);
>  	if (rev_index) {
> diff --git a/builtin/ls-remote.c b/builtin/ls-remote.c
> index 01a4d4daa1..df09000b30 100644
> --- a/builtin/ls-remote.c
> +++ b/builtin/ls-remote.c
> @@ -112,7 +112,7 @@ int cmd_ls_remote(int argc,
>  	 * depending on what object hash the remote uses.
>  	 */
>  	if (!the_repository->hash_algo)
> -		repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
> +		repo_set_hash_algo(the_repository, GIT_HASH_DEFAULT);
>  
>  	packet_trace_identity("ls-remote");
>  
> diff --git a/builtin/patch-id.c b/builtin/patch-id.c
> index cdef2ec10a..26f04b0335 100644
> --- a/builtin/patch-id.c
> +++ b/builtin/patch-id.c
> @@ -254,7 +254,7 @@ int cmd_patch_id(int argc,
>  	 * the code that computes patch IDs to always use SHA1.
>  	 */
>  	if (!the_hash_algo)
> -		repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
> +		repo_set_hash_algo(the_repository, GIT_HASH_DEFAULT);
>  
>  	generate_id_list(opts ? opts > 1 : config.stable,
>  			 opts ? opts == 3 : config.verbatim);
> diff --git a/builtin/shortlog.c b/builtin/shortlog.c
> index fe15e11497..60adc5e7a5 100644
> --- a/builtin/shortlog.c
> +++ b/builtin/shortlog.c
> @@ -419,7 +419,7 @@ int cmd_shortlog(int argc,
>  	 * git/nongit so that we do not have to do this.
>  	 */
>  	if (nongit && !the_hash_algo)
> -		repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
> +		repo_set_hash_algo(the_repository, GIT_HASH_DEFAULT);
>  
>  	git_config(git_default_config, NULL);
>  	shortlog_init(&log);
> diff --git a/builtin/show-index.c b/builtin/show-index.c
> index 9d4ecf5e7b..2c3e2940ce 100644
> --- a/builtin/show-index.c
> +++ b/builtin/show-index.c
> @@ -47,7 +47,7 @@ int cmd_show_index(int argc,
>  	 *       the index file passed in and use that instead.
>  	 */
>  	if (!the_hash_algo)
> -		repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
> +		repo_set_hash_algo(the_repository, GIT_HASH_DEFAULT);
>  
>  	hashsz = the_hash_algo->rawsz;
>