last-modified: support sparse checkouts

[dscho]

Cc: Toon Claes toon@iotcl.com
cc: Derrick Stolee stolee@gmail.com

[dscho]

/submit

[gitgitgadget]

Submitted as pull.2013.git.1764423826908.gitgitgadget@gmail.com

To fetch this version into FETCH_HEAD:

git fetch https://github.com/gitgitgadget/git/ pr-2013/dscho/last-modified-vs-sparse-checkouts-v1

To fetch this version to local tag pr-2013/dscho/last-modified-vs-sparse-checkouts-v1:

git fetch --no-tags https://github.com/gitgitgadget/git/ tag pr-2013/dscho/last-modified-vs-sparse-checkouts-v1

[gitgitgadget]

On the Git mailing list, Derrick Stolee wrote (reply to this):

On 11/29/2025 8:43 AM, Johannes Schindelin via GitGitGadget wrote:
> From: Johannes Schindelin <johannes.schindelin@gmx.de>
> 
> In a sparse checkout, a user might want to run `last-modified` on a
> directory outside the worktree.
> 
> And even in non-sparse checkouts, a user might need to run that command
> on a directory that does not exist in the worktree.
> 
> These use cases should be supported via the `--` separator between
> revision and file arguments, which is even advertised in the
> documentation. This patch fixes a tiny bug that prevents that from
> working.

>  	argc = parse_options(argc, argv, prefix, last_modified_options,
>  			     last_modified_usage,
> -			     PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN_OPT);
> +			     PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN_OPT |
> +			     PARSE_OPT_KEEP_DASHDASH);

I'm intrigued that this is the only fix that was required.

> +test_expect_success 'last-modified in sparse checkout' '
> +	test_when_finished "git sparse-checkout disable" &&
> +	git sparse-checkout set b &&
> +	check_last_modified -- a <<-\EOF

Would we expect this to work without the '--'? Should it
fail for a directory that exists at HEAD but is outside of
the sparse-checkout?

Thanks,
-Stolee

[gitgitgadget]

User Derrick Stolee <stolee@gmail.com> has been added to the cc: list.

[gitgitgadget]

On the Git mailing list, Toon Claes wrote (reply to this):

Derrick Stolee <stolee@gmail.com> writes:

> On 11/29/2025 8:43 AM, Johannes Schindelin via GitGitGadget wrote:
>> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>> 
>> In a sparse checkout, a user might want to run `last-modified` on a
>> directory outside the worktree.
>> 
>> And even in non-sparse checkouts, a user might need to run that command
>> on a directory that does not exist in the worktree.
>> 
>> These use cases should be supported via the `--` separator between
>> revision and file arguments, which is even advertised in the
>> documentation. This patch fixes a tiny bug that prevents that from
>> working.
>
>>  	argc = parse_options(argc, argv, prefix, last_modified_options,
>>  			     last_modified_usage,
>> -			     PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN_OPT);
>> +			     PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN_OPT |
>> +			     PARSE_OPT_KEEP_DASHDASH);
>
> I'm intrigued that this is the only fix that was required.

I like it!

>> +test_expect_success 'last-modified in sparse checkout' '
>> +	test_when_finished "git sparse-checkout disable" &&
>> +	git sparse-checkout set b &&
>> +	check_last_modified -- a <<-\EOF
>
> Would we expect this to work without the '--'? Should it
> fail for a directory that exists at HEAD but is outside of
> the sparse-checkout?

I don't think we need to complicate things that much. Arguments after
the '--' are handled as pathspecs. If no paths match that pathspec, the
output is simply nothing.

Just to demonstrate:

On 'master':

    $ git last-modified a
    fatal: ambiguous argument 'a': unknown revision or path not in the working tree.
    Use '--' to separate paths from revisions, like this:
    'git <command> [<revision>...] -- [<file>...]'

    $ git last-modified -- a
    fatal: ambiguous argument 'a': unknown revision or path not in the working tree.
    Use '--' to separate paths from revisions, like this:
    'git <command> [<revision>...] -- [<file>...]'

With this patch applied:

    $ git last-modified a
    fatal: ambiguous argument 'a': unknown revision or path not in the working tree.
    Use '--' to separate paths from revisions, like this:
    'git <command> [<revision>...] -- [<file>...]'

    $ git last-modified -- a

    $ echo $?
    0

I agree this behavior is better. Thanks for this fix. I approve.

-- 
Cheers,
Toon