With the files backend, root refs such as HEAD or ORIG_HEAD are only
added to the loose ref cache if REFS_FOR_EACH_INCLUDE_ROOT_REFS is
passed when the cache is created. If the cache has already been created
for an earlier ref iterator, root refs are silently omitted. Conversely,
once they have been added, any later iterator also yields them, whether
or not they were requested. This has been the case since d0f00c1ac1
(refs: introduce `refs_for_each_include_root_refs()`, 2024-02-23).
For example, `git for-each-ref --include-root-refs --merged=main` omits
root refs that are merged into main, because looking up the given commit
loads the replace refs, which populates the loose ref cache first. The
reftable backend is not affected, as it filters root refs for each
iterator rather than caching them.
Fix this by keeping the root refs out of the loose ref cache. Instead,
read them into a separate, temporary ref cache whenever an iterator is
requested with REFS_FOR_EACH_INCLUDE_ROOT_REFS, and overlay an iterator
over that cache on the loose ref iterator. The cache is freed along with
the iterator.
Alternatively, the root refs could always be added to the loose ref
cache and skipped during iteration unless requested. But that would mean
reading them in every command that uses the loose ref cache, even though
only two call sites actually request them. Also, keeping the root ref
cache for reuse by later iterators is not worthwhile, because those two
call sites only request the root refs once per command.
Signed-off-by: Andy Koppe <andy.koppe@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Andy Koppe
7f4e8cd956