Re: [PATCH v19 5/7] branch: add --delete-merged <branch>

On 19/07/2026 20:22, Junio C Hamano wrote:
> Harald Nordgren <[email protected]> writes:
> 
>> I think I can fix this with
>>
>> ```
>>      -+  if (strset_contains(data->deletable, ref->name))
>>      ++  if (strset_contains(data->deletable, ref->name) ||
>>      ++      strset_contains(data->spared, ref->name))
>> ```
>>
>> I used your example to write a test about it as well.
>>
>>
>> Harald
> 
> I do not claim that the single example I gave covers all the issues
> that arise from failing to analyze the dependency graph, or from
> attempting to solve the problem sequentially, which makes the
> solution depend on the order in which branches are visited.
> 
> I have a suspicion that it may be unavoidable to employ a multi-pass
> approach that iteratively identifies all branches transitively
> needed by any surviving branch, though that is merely a hunch,
> unsupported by any proof.

I think it would certainly be easier to reason about if we did not 
mutate data->deletable in spare_stacked_base() in removed the spared 
branches with

	strset_for_each_entry(&spared, &iter, entry)
		strset_remove(&deletable, entry);

after the call to refs_for_each_branch_ref() returns in 
spare_stacked_branches().

I'll try and have a proper look at this iteration in the comming week.

Thanks

Phillip