[PATCH 0/9] No more adding submodule ODB as alternate

This series is on jt/add-submodule-odb-clean-up.

After this series, the entire test suite runs without ever adding a submodule ODB as an alternate (checked by running with GIT_TEST_FATAL_REGISTER_SUBMODULE_ODB=1). The code to lazily add submodule ODBs as alternates still remains (with a trace message printed if it happens) just in case there is a rare interaction that the test suite doesn't cover.

This is part of my effort to support partial clone in submodules, but the results here are also beneficial for non-partial-clone submodule users in that access to submodule objects are now quicker (because Git no longer needs to linearly search through alternates when accessing these objects). It also improves code health in that it is clearer at the call site when a submodule object is being accessed.

This patch series contains the 2 patches from my previous work on iterating over submodule refs [1], and 7 new patches.

[1] https://lore.kernel.org/git/cover.1629933380.git.jonathantanmy@google.com/

Jonathan Tan (9):
  refs: make _advance() check struct repo, not flag
  refs: add repo paramater to _iterator_peel()
  refs iterator: support non-the_repository advance
  refs: teach refs_for_each_ref() arbitrary repos
  merge-{ort,recursive}: remove add_submodule_odb()
  object-file: only register submodule ODB if needed
  submodule: pass repo to check_has_commit()
  refs: change refs_for_each_ref_in() to take repo
  submodule: trace adding submodule ODB as alternate

 builtin/submodule--helper.c            | 16 +++--
 merge-ort.c                            | 18 ++----
 merge-recursive.c                      | 41 ++++++------
 object-file.c                          |  3 +-
 object-name.c                          |  4 +-
 refs.c                                 | 87 ++++++++++++++------------
 refs.h                                 | 12 ++--
 refs/debug.c                           |  9 +--
 refs/files-backend.c                   | 28 ++++-----
 refs/iterator.c                        | 51 ++++++++++++---
 refs/packed-backend.c                  | 24 +++----
 refs/ref-cache.c                       |  7 ++-
 refs/refs-internal.h                   | 55 +++++++++++-----
 revision.c                             | 12 ++--
 strbuf.c                               | 12 +++-
 strbuf.h                               |  6 +-
 submodule.c                            | 28 +++++++--
 t/helper/test-ref-store.c              | 20 +++---
 t/t5526-fetch-submodules.sh            |  3 +
 t/t5531-deep-submodule-push.sh         |  3 +
 t/t5545-push-options.sh                |  3 +
 t/t5572-pull-submodule.sh              |  3 +
 t/t6437-submodule-merge.sh             |  3 +
 t/t7418-submodule-sparse-gitmodules.sh |  3 +
 24 files changed, 271 insertions(+), 180 deletions(-)