Re: [PATCH 1/3] builtin/backfill: fix flags passed to `odb_has_object()`

> Patrick Steinhardt <ps@pks.im> writes:
>
>> The function `fill_missing_blobs()` receives an array of object IDs and
>> verifies for each of them whether the corresponding object exists. If it
>> doesn't exist, we add it to a set of objects and then batch-fetch all of
>> the objects at once.
>>
>> The check for whether or not we already have the object is broken
>> though: we pass `OBJECT_INFO_FOR_PREFETCH`, but `odb_has_object()`
>> expects us to pass `HAS_OBJECT_*` flags. The flag expands to:
>>
>>   - `OBJECT_INFO_QUICK`, which asks the object database to not reprepare
>>     in case the object wasn't found. This makes sense, as we'd otherwise
>>     reprepare the object database as many times as we have missing
>>     objects.
>>
>>   - `OBJECT_INFO_SKIP_FETCH_OBJECT`, which asks the object database to
>>     not fetch the object in case it's missing. Again, this makes sense,
>>     as we want to batch-fetch the objects.
>>
>> This shows that we indeed want the equivalent of this flag, but of
>> course represented as `HAS_OBJECT_*` flags.
>>
>> Luckily, the code is already working correctly. The `OBJECT_INFO` flag
>> expands to `(1 << 3) | (1 << 4)`, none of which are valid `HAS_OBJECT`
>> flags. And if no flags are passed, `odb_has_object()` ends up calling
>> `odb_read_object_info_extended()` with exactly the above two flags that
>> we wanted to set in the first place.
>>
>> Of course, this is pure luck, and this can break any moment. So let's
>> fix this and correct the code to not pass any flags at all.
>>
>
> We do pass the same equivalent, no? I mean `OBJECT_INFO_FOR_PREFETCH`
> does resolve to `OBJECT_INFO_SKIP_FETCH_OBJECT | OBJECT_INFO_QUICK` and
> calling `odb_has_object(... , 0)` would also eventually set the same
> flags.
>
> I understand the issue, `odb_has_object()` should only take in
> `HAS_OBJECT_*` flags, even though internally it converts them to
> `OBJECT_INFO_*` flags.
>
> Wouldn't it also be nicer to convert the enum for `HAS_OBJECT_*` to no
> longer be anonymous and use that in `odb_has_object()`?
>
> The patch itself looks good!
>
> - Karthik