git/t, branch main

Merge branch 'jk/midx-write-v1-by-default'

2026-04-16T22:43:26Z

As writing version 2 MIDX files by default breaks older versions of Git and its reimplementations, use V2 only when necessary. * jk/midx-write-v1-by-default: MIDX: revert the default version to v1

MIDX: revert the default version to v1

2026-04-16T20:45:53Z

We introduced midx version 2 in b2ec8e90c2 (midx: do not require packs to be sorted in lexicographic order, 2026-02-24) and now write it by default. The rationale was that older versions should ignore the v2 midx and fall back to using the packs (just like we do for other midx errors). Unfortunately this is not the case, as we have a hard die() when we see an unknown midx version. As a result, writing a midx with Git 2.54-rc2 puts the repository into a state that is unusable with Git 2.53. And this midx write may happen behind the scenes as part of normal operations, like fetch. Let's switch back to writing v1 by default to avoid regressing the case where multiple versions of Git are used on the same repository. There is one gotcha, though: the v2 format is required for some new features, like midx compaction, and running "git multi-pack-index compact" will complain when asked to write a v1 index. The user must set midx.version to "2" to make the feature work. So instead of always using v1, we'll base the default on whether the requested feature requires v2. That does mean that running midx compaction will create a repository that can't be read by older versions of Git. But we never do that by default; only people experimenting with the new feature will be affected. We have to adjust the test expectation in t5319, since it will now generate v1 files. And our "auto-select v2" is covered by the tests in t5335, which continue to check that compaction works without having to set midx.version manually (and also explicitly check that asking for v1 with compaction reports the problem). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'ds/rev-list-maximal-only-optim'

2026-04-09T18:21:59Z

"git rev-list --maximal-only" has been optimized by borrowing the logic used by "git show-branch --independent", which computes the same kind of information much more efficiently. * ds/rev-list-maximal-only-optim: rev-list: use reduce_heads() for --maximal-only p6011: add perf test for rev-list --maximal-only t6600: test --maximal-only and --independent

Merge branch 'jt/index-fd-wo-repo-regression-fix-maint'

2026-04-08T17:20:51Z

During Git 2.52 timeframe, we broke streaming computation of object hash outside a repository, which has been corrected. * jt/index-fd-wo-repo-regression-fix-maint: object-file: avoid ODB transaction when not writing objects

Merge branch 'tc/replay-ref'

2026-04-08T17:19:18Z

The experimental `git replay` command learned the `--ref=` option to allow specifying which ref to update, overriding the default behavior. * tc/replay-ref: replay: allow to specify a ref with option --ref replay: use stuck form in documentation and help message builtin/replay: mark options as not negatable

Merge branch 'ng/add-files-to-cache-wo-rename'

2026-04-08T17:19:18Z

add_files_to_cache() used diff_files() to detect only the paths that are different between the index and the working tree and add them, which does not need rename detection, which interfered with unnecessary conflicts. * ng/add-files-to-cache-wo-rename: read-cache: disable renames in add_files_to_cache

Merge branch 'ss/t7004-unhide-git-failures'

2026-04-08T17:19:15Z

Test clean-up. * ss/t7004-unhide-git-failures: t7004: replace wc -l with modern test helpers

t1800: add &&-chains to test helper functions

2026-04-08T17:15:47Z

Add the missing &&'s so we properly propagate failures between commands in the hook helper functions. Also add a missing mkdir -p arg (found by adding the &&). Reported-by: SZEDER Gábor Signed-off-by: Adrian Ratiu Signed-off-by: Junio C Hamano

object-file: avoid ODB transaction when not writing objects

2026-04-08T00:32:36Z

In ce1661f9da (odb: add transaction interface, 2025-09-16), existing ODB transaction logic is adapted to create a transaction interface at the ODB layer. The intent here is for the ODB transaction interface to eventually provide an object source agnostic means to manage transactions. An unintended consequence of this change though is that `object-file.c:index_fd()` may enter the ODB transaction path even when no object write is requested. In non-repository contexts, this can result in a NULL dereference and segfault. One such case occurs when running git-diff(1) outside of a repository with "core.bigFileThreshold" forcing the streaming path in `index_fd()`: $ echo foo >foo $ echo bar >bar $ git -c core.bigFileThreshold=1 diff -- foo bar In this scenario, the caller only needs to compute the object ID. Object hashing does not require an ODB, so starting a transaction is both unnecessary and invalid. Fix the bug by avoiding the use of ODB transactions in `index_fd()` when callers are only interested in computing the object hash. Reported-by: Luca Stefani Signed-off-by: Justin Tobler [jc: adjusted to fd13909e (Merge branch 'jt/odb-transaction', 2025-10-02)] Signed-off-by: Junio C Hamano

Merge branch 'th/backfill-auto-detect-sparseness-fix'

2026-04-07T21:59:28Z

"git backfill" is capable of auto-detecting a sparsely checked out working tree, which was broken. * th/backfill-auto-detect-sparseness-fix: backfill: auto-detect sparse-checkout from config