patchrevision: fix --left/right-only use with unrelated histories

> +test_expect_success 'rev-list one-sided unrelated symmetric diff' '
> +	test_tick &&
> +	git commit --allow-empty -m xyz &&
> +	git branch cmp &&
> +	git rebase --force-rebase --root &&
> +
> +	git rev-list --left-only  HEAD...cmp >head &&
> +	git rev-list --right-only HEAD...cmp >cmp  &&
> +
> +	test $(comm -12 <(sort head) <(sort cmp) | wc -l) = "0"

> Thank you for adding a test. We have a helper function test_line_count 
> which provides a helpful debugging message if the comparison fails. 
> Using that and avoiding process substitutions we'd write
>
> 	sort head >sorted_head &&
> 	sort cmp >sorted_cmp &&
> 	comm -12 sorted_head sorted_cmp >actual &&
> 	test_line_count = 0 actual

> On Sun Mar 30, 2025 at 6:11 AM EDT, Phillip Wood wrote:
>> Thank you for adding a test. We have a helper function test_line_count
>> which provides a helpful debugging message if the comparison fails.
>> Using that and avoiding process substitutions we'd write
>>
>> 	sort head >sorted_head &&
>> 	sort cmp >sorted_cmp &&
>> 	comm -12 sorted_head sorted_cmp >actual &&
>> 	test_line_count = 0 actual
> Thanks for that helper tip.  I was just about to send a v2 when your
> message came in, so I'm getting that incorporated now.
> 
> By the way, I had originally wanted to write test assertions that
> checked the actual number of commit ids returned from each of the two
> calls to rev-list - something like:
> 
>      git rev-list --X-only HEAD...cmp >file &&
>      test_line_count = N file
> 
> But since I'm not very familiar with this test harness yet, I couldn't
> actually figure the correct value for N.  It's not 1 (the commit made in
> my test body), and it's not 2 (that commit, plus the one from the setup
> case at the top of the file).  Any appropriate higher value wasn't
> obvious.

> Each test in a given file runs in the same repository (this is a 
> performance optimization) so the number of commits will depend on what 
> the previous tests have done. Usually there is a setup test at the start 
> of the file which creates some commits with tags. Individual tests can 
> then use those tags to establish a known state.

> This is a similar fix as 023756f4eb (revision walker: --cherry-pick is a
> limited operation), but for the --left-only and --right-only options.
>
> When computing a symmetric difference between two unrelated histories,
> no suitable merge base exists, and so no boundary commit is flagged as
> UNINTERESTING.  Previously, we relied on the presence of such boundary
> to trigger limiting and thus consideration of either "revs->left_only"
> or "revs->right_only".
>
> A number of other entries in the option parser have started including
> overrides for "revs->limited = 1".  Do the same for these options.
>
> Signed-off-by: Matt Hunter <m@lfurio.us>
> ---

> Range-diff against v1:
> 1:  1982f14d70 ! 1:  4f5b264b26 revision: fix --left/right-only use with unrelated histories
>     @@ t/t6000-rev-list-misc.sh: test_expect_success 'rev-list --unpacked' '
>      +	git rev-list --left-only  HEAD...cmp >head &&
>      +	git rev-list --right-only HEAD...cmp >cmp  &&
>      +
>     -+	test $(comm -12 <(sort head) <(sort cmp) | wc -l) = "0"
>     ++	sort head >head.sorted &&
>     ++	sort cmp >cmp.sorted &&
>     ++	comm -12 head.sorted cmp.sorted >actual &&
>     ++	test_line_count = 0 actual
>      +'
>      +
>       test_done
>
> base-commit: 683c54c999c301c2cd6f715c411407c413b1d84e
>
>  revision.c               |  2 ++
>  t/t6000-rev-list-misc.sh | 15 +++++++++++++++
>  2 files changed, 17 insertions(+)
>
> diff --git a/revision.c b/revision.c
> index c4390f0938..e045445bc3 100644
> --- a/revision.c
> +++ b/revision.c
> @@ -2488,10 +2488,12 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
>  			die(_("options '%s' and '%s' cannot be used together"),
>  			    "--left-only", "--right-only/--cherry");
>  		revs->left_only = 1;
> +		revs->limited = 1;
>  	} else if (!strcmp(arg, "--right-only")) {
>  		if (revs->left_only)
>  			die(_("options '%s' and '%s' cannot be used together"), "--right-only", "--left-only");
>  		revs->right_only = 1;
> +		revs->limited = 1;
>  	} else if (!strcmp(arg, "--cherry")) {
>  		if (revs->left_only)
>  			die(_("options '%s' and '%s' cannot be used together"), "--cherry", "--left-only");
> diff --git a/t/t6000-rev-list-misc.sh b/t/t6000-rev-list-misc.sh
> index 6289a2e8b0..d338f7ecb4 100755
> --- a/t/t6000-rev-list-misc.sh
> +++ b/t/t6000-rev-list-misc.sh
> @@ -182,4 +182,19 @@ test_expect_success 'rev-list --unpacked' '
>  	test_cmp expect actual
>  '
>  
> +test_expect_success 'rev-list one-sided unrelated symmetric diff' '
> +	test_tick &&
> +	git commit --allow-empty -m xyz &&
> +	git branch cmp &&
> +	git rebase --force-rebase --root &&
> +
> +	git rev-list --left-only  HEAD...cmp >head &&
> +	git rev-list --right-only HEAD...cmp >cmp  &&
> +
> +	sort head >head.sorted &&
> +	sort cmp >cmp.sorted &&
> +	comm -12 head.sorted cmp.sorted >actual &&
> +	test_line_count = 0 actual
> +'
> +
>  test_done