Documentation/RelNotes/2.98.0.adoc

Git v2.98 Release Notes
=======================

This is meant to be the antepenultimate release to prepare for the
long anticipated Git 3.0 which has been vaporware for so long.


UI, Workflows & Features
------------------------

 * The experimental 'git history' command has been taught a new 'squash'
   subcommand to fold a range of commits into a single commit, with any
   descendants replayed on top.

 * A new hook 'report' is added to 'git receive-pack', which runs after
   reference updates and allows the server to filter or modify the
   packet-line status report sent back to the client.

 * The terminology regarding reference storage formats has been unified
   across command-line options, environment variables, configuration
   variables, and source code, standardizing on the phrase "ref storage
   format" (e.g., `--ref-storage-format`, `'GIT_REF_STORAGE_FORMAT'`).
   Additionally, the `--ref-storage-format` option has been updated to
   accept payloads in the form `<format>://<payload>`.

 * The build-time knob 'USE_NSEC' for nanosecond stat precision has been
   converted to a runtime configuration 'core.useNanosec', allowing
   distributions to bundle one binary that adapts to filesystem
   capabilities dynamically.

 * The command-line completion script (in 'contrib/') has been taught
   to complete the 'repair' subcommand for 'git worktree'.

 * Various documentation files have been updated to use explicit
   '<<TARGET,TARGET>>' AsciiDoc cross-references instead of plain text
   references.  This improves rendering on the web and avoids broken
   links when manual pages are included into other pages.

 * The 'git var' command has been updated to output individual components
   of the author and committer identities, take multiple keys on the
   command-line, and support NUL-delimited output with the '-z' option.

 * The 'git-contacts' program (in contrib/) has been taught to read
   patches from the standard input stream when an explicit dash ('-') is
   passed in place of a file.

 * The @{upstream} notation had short-hand @{u} from the beginning,
   and @{push} learned corresponding @{p} to match.

 * The 'format-patch' command has been updated with options to
   configure notes specifically for range-diff output, allowing them to
   differ from the notes displayed on the patches themselves.

 * Validation of the 'fetch.followRemoteHEAD' configuration variable
   has been deferred to when it is actually used, preventing irrelevant
   warnings during 'git fetch' invocations that do not consult it.

 * "git status" now suggests to use 'git merge --continue', not 'git commit',
   when done with conflicts during a 'git merge'.


Performance, Internal Implementation, Development Support etc.
--------------------------------------------------------------

 * The setup of alternates has been deferred to object database
   creation time during clone, which drops the unused ad-hoc alternate
   writing API, simplifying the object database backend interface.

 * Updates to Coccinelle semantic patches to correctly handle the
   'FREE_AND_NULL()' macro and avoid generating broken transformations
   for negated pointer checks.

 * The 'Makefile' has been taught to precompile 'git-compat-util.h' to
   speed up overall compilation, while excluding sources that do not
   include the compatibility header.

 * The can_all_from_reach() and can_all_from_reach_with_flag()
   functions have been updated to accept a repository context,
   preventing bugs where submodule merging incorrectly reads from the
   superproject's commit-graph.

 * The error reporting machinery in the WinANSI compatibility layer has
   been simplified to pass the exact Windows error code and correctly
   format arguments for fatal errors.

 * The Debian 12 CI job has been updated to skip a half-auth clone test
   that occasionally fails due to a bug in the packaged curl version
   handling early HTTP/2 responses.

 * The CI script has been updated to check for one-indexed slice numbers
   when deciding to run unit tests on Windows, mirroring the behaviour in
   the modern GitHub and GitLab workflows.

 * The Windows GitLab CI job has been updated to provision and use the
   GCC-targeting Rust toolchain for MinGW builds, fixing job failures
   caused by incomplete Rust setup and missing linker support.

 * The external merge driver in 'git merge' now uses the tempfile API
   to create its temporary files.  This ensures that these temporaries
   are reliably cleaned up even when the merge driver or its parent Git
   process is terminated abruptly.

 * The performance test for `git fetch` pack-dir rescans has been
   updated to use the `--no-deref` option when cleaning up
   remote-tracking branches.  This prevents `git update-ref` from
   failing with a multiple updates error when both a symref and its
   target are deleted in the same transaction.

 * The build configurations for Meson have been optimized to avoid
   recompiling HTTP sources multiple times and to utilize precompiled
   headers for test-helpers and unit tests, reducing clean build times.
   Additionally, the shell completion tests and GitLab CI MSVC runner
   jobs have been fixed.

 * The handling of index conflicts in 'git stash apply --index' has
   been optimized.  Instead of relying on expensive external
   subprocesses using 'git diff-tree' and 'git apply', the index is now
   merged in-core using the merge-ort machinery, which fixes a
   concurrent lock file issue with autostash.

 * The parse-options API has been updated to support grouping
   subcommands, and the 'git refs' command has been updated to use this
   new feature to categorize its subcommands in its help output.

 * Fix definition for the "--all" option to use symbolic constant
   in the options[] array passed to parse_options API.

 * The shell quoting of a lazy prereq script was quoted incorrectly and
   allowed variables dereferenced at the wrong moment, breaking the
   curl version detection.

 * The requirement for a 'SYNOPSIS' section in section 7 manual pages
   has been relaxed by updating the linter script, and dummy
   'SYNOPSIS' sections from existing section 7 documentation have been
   removed to improve the rendered output

 * A test script (t0450) has been updated to use the test_path_is_file
   and test_path_is_missing helper functions, which provides better
   diagnostic output on failure.

 * The routine that rewrites the packed-refs file has been optimized to
   directly pass unmodified reference records verbatim to the output
   via fwrite(3p), instead of redundantly re-formatting them with
   fprintf(3p).

 * The fetch.writeCommitGraph behavior has been optimized to
   incrementally update the commit graph using only the newly fetched
   commits as seeds.  This avoids a full reachability scan of all
   references and drastically reduces the post-fetch commit-graph
   update time for repositories with many references.

 * The odb_source API has been refactored to make alternates an
   implementation detail of the files backend instead of managing them
   at the core object database layer.

 * The test for verifying a signed tag with a missing key has been
   updated to point GNUPGHOME to an unused directory rather than
   deleting the active gpghome directory, working around a flaky rm
   failure caused by the background gpg-agent observed on Alpine.


Fixes since v2.56
-----------------

 * Updates to Coccinelle semantic patches to correctly handle the
   'FREE_AND_NULL()' macro and avoid generating broken transformations
   for negated pointer checks.
   (merge 32814b69d0 jc/cocci-free-updates later to maint).

 * The files backend has been updated to avoid unconditionally locking
   the 'packed-refs' file when deleting a root ref (which are never
   packed).
   (merge d8e4585822 ak/refs-files-root-ref-lock later to maint).

 * The server-side protocol v2 response order for 'wanted-refs' and
   'shallow-info' has been swapped to match the client's expectation,
   fixing a fetch failure when the server has 'uploadpack.allowRefInWant'
   enabled and the client performs a shallow fetch.
   (merge 191740edaa rr/upload-pack-swap-shallow-wanted-ref later to maint).

 * Assorted fixes for code paths that are not careful with boundary and
   error conditions.
   (merge c88341b7e1 js/coverity-fixes later to maint).

 * A bug in git diff --no-index that mishandled reverse (-R) output
   when conflicts existed between a file and a directory has been
   fixed.
   (merge 9a13b3742b hd/diff-no-index-reverse-fix later to maint).

 * 'git pull' has been taught to fail more gracefully instead of
   segfaulting when lookup_commit_reference() fails on unparseable
   objects.
   (merge 38bdda17dd jk/pull-null-merge-head later to maint).

 * The sequencer machinery (used by 'git rebase', 'git cherry-pick', and
   'git revert') has been updated to defer automatic maintenance tasks
   until the end of the operation, preventing nested 'git commit', 'git
   merge', and 'exec' commands from triggering GC operations that could
   contend for locks or delete open packs while the sequence is in
   progress.
   (merge eba1a1c5dd tb/rerere-lock-grace later to maint).

 * When 'core.fsyncMethod' is set to 'batch', the ODB transaction
   failed to properly flush large blob packfiles residing in the
   temporary directory before migrating the directory's contents to the
   main object store.  The execution sequence has been corrected by
   performing the packfile flush before the temporary directory
   migration, averting failure.
   (merge ef7faa6350 jt/object-file-batch-fsync-fix later to maint).

 * The default expiry periods for both reachable and unreachable reflog
   entries have been corrected from a past regression that swapped
   them.
   (merge 60cf500551 ps/reflog-expiry-fix later to maint).

 * The directory traversal logic has been updated to correctly evaluate
   pathspecs for ignored directories containing nested repositories,
   and has been fortified to gracefully handle null pathspecs during
   checkout operations.
   (merge ebc067f3cc rs/dir-skip-nested-repo-fix later to maint).

 * The command-line parsing of revision options has been updated to
   properly distinguish between malformed and unknown options, and to
   correctly report the name of unknown options after they have been
   moved during the option parsing process.
   (merge da2926c8f5 jk/parse-revision-opt-fixes later to maint).

 * The documentation for 'git-name-rev' has been updated to refer to
   object IDs instead of SHA-1, to more accurately reflect that the
   active hash algorithm is used.
   (merge b2ab8fccc3 jk/name-rev-update-hash-descriptions later to maint).

 * The HTTP transport has been updated to handle changes in recent curl
   versions that strip credentials from the effective URL, preventing
   unnecessary credential prompts during redirects.
   (merge 76524c2604 jk/http-curl-strip-creds later to maint).

 * The timestamp used for checking the reflog of a remote-tracking
   branch during 'git push --force-if-includes' was left uninitialized
   when the reflog was completely empty, which has been corrected.
   (merge c84ed3a0ab as/push-force-if-includes-no-reflog later to maint).

 * CI resource exhaustion during test runs on GitHub Actions has been
   mitigated by switching a comparison of a huge output to use a binary
   comparison, and by capping the parallel jobs on Linux to the number
   of available CPUs.
   (merge 4f956cf43a td/ci-large-test-resources later to maint).

 * The `t5520` test script has been updated to disable reflog expiration.
   This prevents test flakiness caused by the auto-maintenance
   reflog-expire task, which would otherwise immediately expire the
   test's reflogs due to them carrying hardcoded timestamps from 2005.
   (merge a68cca9953 tb/t5520-reflog-expire later to maint).

 * The internal representation of timezones in the reflog for the
   reftable format has been fixed to match the specification, which
   dictates an offset in minutes rather than the parsed "+HHMM" integer
   representation.
   (merge e14e2b6cf2 ps/reftable-reflog-timezone later to maint).

 * The internal diff and merge machinery has been updated to use
   standard size_t types rather than signed longs for buffer
   allocations and offsets, preventing subtle overflow issues on LLP64
   architectures, and plugging uninitialized memory leaks along error
   paths.
   (merge 5b0456361d jk/xdiff-size_t later to maint).

 * The documentation for 'git remote set-head' has been updated to
   clarify that it only modifies the local repository's remote-tracking
   symbolic reference, and does not alter the target remote
   repository's own 'HEAD'.
   (merge c5f8f60719 mg/doc-remote-set-head later to maint).

 * The commit map populated from the state branch in 'git
   filter-branch' has been corrected to parse the map using the
   original-to-rewritten order.
   (merge 4811dabed7 gm/filter-branch-state-map-fix later to maint).

 * The documentation for core.pager has been updated to provide
   examples of overriding the LESS environment variable for custom
   pagers by prefixing the pager command in the configuration.
   (merge c7860da7db tz/doc-override-less-env later to maint).

 * Closing a packfile did not evict the entries belonging to it from
   the delta base cache, which could lead to data corruption when a
   newly allocated packfile happened to reuse the same memory address.
   The cache eviction logic has been updated to remove these stale
   entries upon closing a pack
   (merge 8d596ea8e7 ps/packfile-stale-delta-base-cache-fix later to maint).

 * Other code cleanup, docfix, build fix, etc.
   (merge e638de60bc kz/doc-add-rm-typofix later to maint).
   (merge 778c73948a kz/doc-user-manual-typo later to maint).
   (merge 42017ff979 kh/doc-trailers-cmd-examples later to maint).
   (merge 49e646f1c9 dk/fix-shattered-io-link later to maint).