[PATCH 00/24] revision.[ch]: add and use release_revisions()

== For Junio ==

This has a trivially resolved conflict with Derrick Stolee's aaf251cdc5c (revision: put object filter into struct rev_info, 2022-03-08) currently in "seen" in builtin/rev-list.c.

The resolution is to just keep the "goto cleanup" in place of "return 0" in the conflicting lines, but to otherwise keep Derrick's version.

It will pass with/without SANITIZE=leak when applied to both "master" and "seen". I omitted one test change (described in a relevant commit message) due to the latter not being true (no fault of "seen", just a new leaking command being added to a test).

== Summary ==

Ever since we started running regular leak testing in CI with 956d2e4639b (tests: add a test mode for SANITIZE=leak, run it in CI, 2021-09-23) a major roadblock for making headway in marking tests as leak-free has been the leaks in the revision.[ch] API.

Since we use it for an revision walking, including "log", "rev-list" etc. we haven't been able to run common test setup in many cases without dying when compiled with SANITIZE=leak, and cases where we genuinely leak memory are often obscured by several concurrent leaks in the revisions API.

This series adds a release_revisions() and works towards fixing those memory leaks one at a time. As the diffstat to t/* shows we can mark a *lot* of tests leak-free as a result, and those are only the the tests that 100% pass with this series.

An approximate count of the total number of memory leaks in the test suite (approximate because some are "hidden" due to SANITIZE=leak causing "git" to die) is, before this series (running with "--tee" and "--verbose-log"):

    $ grep -a "SUMMARY: LeakSanitizer.*leaked in .*allocation" test-results/*.out|wc -l
    12032

After:

    $ grep -a "SUMMARY: LeakSanitizer.*leaked in .*allocation" test-results/*.out|wc -l
    6652

I.e. this recudes the number of times "git" dies due to having any of N number of leaks by around half, and that's severely undercounting the amount of individual memory leaks.

This is a rather large series, but it should be fairly easy to review. I've leaned towards splitting commits up for ease of review, such that when there's repetitive changes (e.g. additions of release_revisions()) that they're split such that each commit has hunks that make the same sort of change, whenever possible.

All of the changes to "t/*" are then just adding "TEST_PASSES_SANITIZE_LEAK=true" lines as we go along.

This doesn't fix all of the leaks in the revision.[ch] API. In particular there's harder edge cases where the ownership of a struct member isn't very straightforward (sometimes revision.c will allocate it, sometimes not). This does fix all of the common cases though, and what's left is best suited for a follow-up series.

Ævar Arnfjörð Bjarmason (24):
  t/helper/test-fast-rebase.c: don't leak "struct strbuf"
  blame: use "goto cleanup" for cleanup_scoreboard()
  format-patch: don't leak "extra_headers" or "ref_message_ids"
  revision.[ch]: split freeing of revs->commit into a function
  revision.[ch]: provide and start using a release_revisions()
  revisions API users: add straightforward release_revisions()
  revisions API users: use release_revisions() needing "{ 0 }" init
  revisions API users: add "goto cleanup" for release_revisions()
  revisions API users: use release_revisions() in http-push.c
  revisions API users: use release_revisions() in builtin/log.c
  revisions API users: use release_revisions() with UNLEAK()
  revisions API users: use release_revisions() in submodule.c edge case
  revisions API users: use release_revisions() in wt-status.c edge case
  revisions API users: use release_revisions() for "prune_data" users
  revisions API: have release_revisions() release "commits"
  revisions API: have release_revisions() release "mailmap"
  revisions API: have release_revisions() release "cmdline"
  revisions API: have release_revisions() release "grep_filter"
  revisions API: have release_revisions() release "prune_data"
  revisions API: clear "boundary_commits" in release_revisions()
  revisions API: release "reflog_info" in release revisions()
  revisions API: call diff_free(&revs->pruning) in revisions_release()
  revisions API: have release_revisions() release "date_mode"
  revisions API: have release_revisions() release "topo_walk_info"

 add-interactive.c                             |  3 +-
 bisect.c                                      | 20 ++++--
 builtin/add.c                                 |  3 +-
 builtin/am.c                                  |  3 +
 builtin/bisect--helper.c                      |  2 +
 builtin/blame.c                               |  4 +-
 builtin/checkout.c                            |  3 +-
 builtin/commit.c                              |  7 +-
 builtin/describe.c                            |  2 +
 builtin/diff-files.c                          |  8 ++-
 builtin/diff-index.c                          |  5 +-
 builtin/diff.c                                |  2 +-
 builtin/fast-export.c                         |  1 +
 builtin/log.c                                 | 35 +++++++---
 builtin/merge.c                               |  2 +
 builtin/pack-objects.c                        |  2 +
 builtin/prune.c                               |  1 +
 builtin/reflog.c                              |  1 +
 builtin/rev-list.c                            | 19 +++--
 builtin/shortlog.c                            |  2 +
 builtin/stash.c                               | 20 +++---
 builtin/submodule--helper.c                   | 15 ++--
 bundle.c                                      | 12 ++--
 diff-lib.c                                    |  8 ++-
 fmt-merge-msg.c                               |  1 +
 http-push.c                                   |  3 +-
 merge-ort.c                                   |  1 +
 merge-recursive.c                             |  1 +
 midx.c                                        |  1 +
 pack-bitmap-write.c                           |  1 +
 range-diff.c                                  |  2 +-
 ref-filter.c                                  |  1 +
 reflog-walk.c                                 | 26 ++++++-
 reflog-walk.h                                 |  1 +
 remote.c                                      |  1 +
 revision.c                                    | 69 ++++++++++++++++---
 revision.h                                    |  6 ++
 sequencer.c                                   | 26 +++++--
 shallow.c                                     |  1 +
 submodule.c                                   |  5 +-
 t/helper/test-fast-rebase.c                   | 22 ++++--
 t/helper/test-revision-walking.c              |  1 +
 t/lib-git-svn.sh                              |  4 ++
 t/t0056-git-C.sh                              |  1 +
 t/t0062-revision-walking.sh                   |  1 +
 t/t0100-previous.sh                           |  1 +
 t/t0101-at-syntax.sh                          |  2 +
 t/t1060-object-corruption.sh                  |  2 +
 t/t1401-symbolic-ref.sh                       |  2 +
 t/t1411-reflog-show.sh                        |  1 +
 t/t1412-reflog-loop.sh                        |  2 +
 t/t1415-worktree-refs.sh                      |  1 +
 t/t2015-checkout-unborn.sh                    |  1 +
 t/t2016-checkout-patch.sh                     |  1 +
 t/t3408-rebase-multi-line.sh                  |  1 +
 t/t4021-format-patch-numbered.sh              |  1 +
 t/t4028-format-patch-mime-headers.sh          |  2 +
 t/t4036-format-patch-signer-mime.sh           |  1 +
 t/t4039-diff-assume-unchanged.sh              |  1 +
 t/t4055-diff-context.sh                       |  1 +
 t/t4066-diff-emit-delay.sh                    |  1 +
 t/t4122-apply-symlink-inside.sh               |  1 +
 t/t4126-apply-empty.sh                        |  1 -
 t/t4206-log-follow-harder-copies.sh           |  2 +
 t/t4207-log-decoration-colors.sh              |  1 +
 t/t4212-log-corrupt.sh                        |  1 +
 t/t5313-pack-bounds-checks.sh                 |  2 +
 t/t5322-pack-objects-sparse.sh                |  1 +
 t/t5506-remote-groups.sh                      |  1 +
 t/t5513-fetch-track.sh                        |  1 +
 t/t5515-fetch-merge-logic.sh                  |  1 +
 t/t5518-fetch-exit-status.sh                  |  1 +
 t/t5532-fetch-proxy.sh                        |  2 +
 t/t5900-repo-selection.sh                     |  2 +
 t/t6002-rev-list-bisect.sh                    |  1 +
 t/t6003-rev-list-topo-order.sh                |  1 +
 t/t6018-rev-list-glob.sh                      |  1 +
 t/t6019-rev-list-ancestry-path.sh             |  1 +
 t/t6100-rev-list-in-order.sh                  |  1 +
 t/t6101-rev-parse-parents.sh                  |  1 +
 t/t6110-rev-list-sparse.sh                    |  1 +
 t/t6114-keep-packs.sh                         |  2 +
 t/t6131-pathspec-icase.sh                     |  2 +
 t/t7008-filter-branch-null-sha1.sh            |  2 +
 t/t7702-repack-cyclic-alternate.sh            |  2 +
 t/t9001-send-email.sh                         |  1 +
 t/t9100-git-svn-basic.sh                      |  1 +
 t/t9101-git-svn-props.sh                      |  2 +
 t/t9104-git-svn-follow-parent.sh              |  2 +
 t/t9106-git-svn-commit-diff-clobber.sh        |  2 +
 t/t9122-git-svn-author.sh                     |  2 +
 t/t9129-git-svn-i18n-commitencoding.sh        |  1 +
 t/t9139-git-svn-non-utf8-commitencoding.sh    |  1 +
 t/t9148-git-svn-propset.sh                    |  1 +
 t/t9151-svn-mergeinfo.sh                      |  1 +
 t/t9157-git-svn-fetch-merge.sh                |  2 +
 t/t9159-git-svn-no-parent-mergeinfo.sh        |  2 +
 t/t9161-git-svn-mergeinfo-push.sh             |  1 +
 t/t9162-git-svn-dcommit-interactive.sh        |  2 +
 t/t9163-git-svn-reset-clears-caches.sh        |  1 +
 ...65-git-svn-fetch-merge-branch-of-branch.sh |  2 +
 ...6-git-svn-fetch-merge-branch-of-branch2.sh |  2 +
 wt-status.c                                   | 15 ++--
 103 files changed, 359 insertions(+), 90 deletions(-)