Re: [PATCH v1 1/1] rev-list: add --missing=print-only mode

> On 20/04/2026 08:43, Patrick Steinhardt wrote:
>> On Sun, Apr 19, 2026 at 02:18:40PM +0530, Siddharth Asthana wrote:
>>
>>>   static struct oidmap missing_objects;
>>>   enum missing_action {
>>> -    MA_ERROR = 0,    /* fail if any missing objects are encountered */
>>> -    MA_ALLOW_ANY,    /* silently allow ALL missing objects */
>>> -    MA_PRINT,        /* print ALL missing objects in special section */
>>> -    MA_PRINT_INFO,   /* same as MA_PRINT but also prints missing 
>>> object info */
>>> +    MA_ERROR = 0, /* fail if any missing objects are encountered */
>>> +    MA_ALLOW_ANY, /* silently allow ALL missing objects */
>>> +    MA_PRINT, /* print ALL missing objects in special section */
>>> +    MA_PRINT_INFO, /* same as MA_PRINT but also prints missing 
>>> object info */
>>> +    MA_PRINT_ONLY, /* print ONLY missing objects, without the "?" 
>>> prefix */
>>
>> Makes me wonder whether we'll eventually also want to have
>> `MA_PRINT_INFO_ONLY`.
> 
> Perhaps we'd be better to add a "--missing-only" option that limits the 
> output to missing objects? That would avoid the problem of "-- 

> missing=print-only" not really explaining what it does as well.
> 
>>> +for obj in "HEAD~1" "HEAD~1^{tree}" "HEAD:1.t"
>>> +do
>>> +    test_expect_success "rev-list --missing=print-only with missing 
>>> $obj" '
>>> +        oid="$(git rev-parse $obj)" &&
>>> +        path=".git/objects/$(test_oid_to_path $oid)" &&
>>> +
>>> +        # Capture present OIDs before hiding anything.
>>> +        git rev-list --objects --no-object-names HEAD ^$obj 
>>> >present.raw &&
>>> +
>>> +        mv "$path" "$path.hidden" &&
>>> +        test_when_finished "mv $path.hidden $path" &&
>>> +
>>> +        git rev-list --missing=print-only --objects --no-object-names \
>>> +            HEAD >actual &&
>>> +
>>> +        # Only the missing OID should appear, without the "?" prefix.
>>> +        grep "^$oid$" actual &&
>>> +
>>> +        # Present objects must NOT appear in the output.
>>> +        while read present_oid
>>> +        do
>>> +            ! grep "^$present_oid$" actual || return 1
>>> +        done <present.raw
>>
>> How many present object IDs do we have? I'm a bit worried that we now
>> execute grep(1) hundreds of times. Can we maybe do some tricks with
>> comm(1) instead?
> 
> If we want to verify that it only prints a single oid then
> 
>      echo $oid >expect &&
>      test_cmp expect actual
> 
> would be much simpler more helpful if the test fails