trace2: add variable description to git.txt

[git/raj.git] / Documentation / RelNotes / 2.22.0.txt

Git 2.22 Release Notes
======================

Updates since v2.21
-------------------

UI, Workflows & Features

 * "git checkout --no-overlay" can be used to trigger a new mode of
   checking out paths out of the tree-ish, that allows paths that
   match the pathspec that are in the current index and working tree
   and are not in the tree-ish.

 * The %(trailers) formatter in "git log --format=..."  now allows to
   optionally pick trailers selectively by keyword, show only values,
   etc.

 * Four new configuration variables {author,committer}.{name,email}
   have been introduced to override user.{name,email} in more specific
   cases.

 * Command-line completion (in contrib/) learned to tab-complete the
   "git submodule absorbgitdirs" subcommand.

 * "git branch" learned a new subcommand "--show-current".

 * Output from "diff --cc" did not show the original paths when the
   merge involved renames.  A new option adds the paths in the
   original trees to the output.

 * The command line completion (in contrib/) has been taught to
   complete more subcommand parameters.

 * The final report from "git bisect" used to show the suspected
   culprit using a raw "diff-tree", with which there is no output for
   a merge commit.  This has been updated to use a more modern and
   human readable output that still is concise enough.

 * "git rebase --rebase-merges" replaces its old "--preserve-merges"
   option; the latter is now marked as deprecated.

 * Error message given while cloning with --recurse-submodules has
   been updated.

 * The completion helper code now pays attention to repository-local
   configuration (when available), which allows --list-cmds to honour
   a repository specific setting of completion.commands, for example.

 * "git mergetool" learned to offer Sublime Merge (smerge) as one of
   its backends.

 * A new hook "post-index-change" is called when the on-disk index
   file changes, which can help e.g. a virtualized working tree
   implementation.

 * "git difftool" can now run outside a repository.

 * "git checkout -m <other>" was about carrying the differences
   between HEAD and the working-tree files forward while checking out
   another branch, and ignored the differences between HEAD and the
   index.  The command has been taught to abort when the index and the
   HEAD are different.

 * A progress indicator has been added to the "index-pack" step, which
   often makes users wait for completion during "git clone".

 * "git submodule" learns "set-branch" subcommand that allows the
   submodule.*.branch settings to be modified.

 * "git merge-recursive" backend recently learned a new heuristics to
   infer file movement based on how other files in the same directory
   moved.  As this is inherently less robust heuristics than the one
   based on the content similarity of the file itself (rather than
   based on what its neighbours are doing), it sometimes gives an
   outcome unexpected by the end users.  This has been toned down to
   leave the renamed paths in higher/conflicted stages in the index so
   that the user can examine and confirm the result.

 * "git tag" learned to give an advice suggesting it might be a
   mistake when creating an annotated or signed tag that points at
   another tag.

 * The "git pack-objects" command learned to report the number of
   objects it packed via the trace2 mechanism.

 * The list of conflicted paths shown in the editor while concluding a
   conflicted merge was shown above the scissors line when the
   clean-up mode is set to "scissors", even though it was commented
   out just like the list of updated paths and other information to
   help the user explain the merge better.

 * The trace2 tracing facility learned to auto-generate a filename
   when told to log to a directory.

 * "git clone" learned a new --server-option option when talking over
   the protocol version 2.


Performance, Internal Implementation, Development Support etc.

 * The diff machinery, one of the oldest parts of the system, which
   long predates the parse-options API, uses fairly long and complex
   handcrafted option parser.  This is being rewritten to use the
   parse-options API.

 * The implementation of pack-redundant has been updated for
   performance in a repository with many packfiles.

 * A more structured way to obtain execution trace has been added.

 * "git prune" has been taught to take advantage of reachability
   bitmap when able.

 * The command line parser of "git commit-tree" has been rewritten to
   use the parse-options API.

 * Suggest GitGitGadget instead of submitGit as a way to submit
   patches based on GitHub PR to us.

 * The test framework has been updated to help developers by making it
   easier to run most of the tests under different versions of
   over-the-wire protocols.

 * Dev support update to make it easier to compare two formatted
   results from our documentation.

 * The scripted "git rebase" implementation has been retired.

 * "git multi-pack-index verify" did not scale well with the number of
   packfiles, which is being improved.

 * "git stash" has been rewritten in C.

 * The "check-docs" Makefile target to support developers has been
   updated.

 * The tests have been updated not to rely on the abbreviated option
   names the parse-options API offers, to protect us from an
   abbreviated form of an option that used to be unique within the
   command getting non-unique when a new option that share the same
   prefix is added.

 * The scripted version of "git rebase -i" wrote and rewrote the todo
   list many times during a single step of its operation, and the
   recent C-rewrite made a faithful conversion of the logic to C.  The
   implementation has been updated to carry necessary information
   around in-core to avoid rewriting the same file over and over
   unnecessarily.

 * Test framework update to more robustly clean up leftover files and
   processes after tests are done.

 * Conversion from unsigned char[20] to struct object_id continues.

 * While running "git diff" in a lazy clone, we can upfront know which
   missing blobs we will need, instead of waiting for the on-demand
   machinery to discover them one by one.  The code learned to aim to
   achieve better performance by batching the request for these
   promised blobs.


Fixes since v2.21
-----------------

 * "git prune-packed" did not notice and complain against excess
   arguments given from the command line, which now it does.
   (merge 9b0bd87ed2 rj/prune-packed-excess-args later to maint).

 * Split-index fix.
   (merge 6e37c8ed3c nd/split-index-null-base-fix later to maint).

 * "git diff --no-index" may still want to access Git goodies like
   --ext-diff and --textconv, but so far these have been ignored,
   which has been corrected.
   (merge 287ab28bfa jk/diff-no-index-initialize later to maint).

 * Unify RPC code for smart http in protocol v0/v1 and v2, which fixes
   a bug in the latter (lack of authentication retry) and generally
   improves the code base.
   (merge a97d00799a jt/http-auth-proto-v2-fix later to maint).

 * The include file compat/bswap.h has been updated so that it is safe
   to (accidentally) include it more than once.
   (merge 33aa579a55 jk/guard-bswap-header later to maint).

 * The set of header files used by "make hdr-check" unconditionally
   included sha256/gcrypt.h, even when it is not used, causing the
   make target to fail.  We now skip it when GCRYPT_SHA256 is not in
   use.
   (merge f23aa18e7f rj/hdr-check-gcrypt-fix later to maint).

 * The Makefile uses 'find' utility to enumerate all the *.h header
   files, which is expensive on platforms with slow filesystems; it
   now optionally uses "ls-files" if working within a repository,
   which is a trick similar to how all sources are enumerated to run
   ETAGS on.
   (merge 92b88eba9f js/find-lib-h-with-ls-files-when-possible later to maint).

 * "git rebase" that was reimplemented in C did not set ORIG_HEAD
   correctly, which has been corrected.
   (merge cbd29ead92 js/rebase-orig-head-fix later to maint).

 * Dev support.
   (merge f545737144 js/stress-test-ui-tweak later to maint).

 * CFLAGS now can be tweaked when invoking Make while using
   DEVELOPER=YesPlease; this did not work well before.
   (merge 6d5d4b4e93 ab/makefile-help-devs-more later to maint).

 * "git fsck --connectivity-only" omits computation necessary to sift
   the objects that are not reachable from any of the refs into
   unreachable and dangling.  This is now enabled when dangling
   objects are requested (which is done by default, but can be
   overridden with the "--no-dangling" option).
   (merge 8d8c2a5aef jk/fsck-doc later to maint).

 * On platforms where "git fetch" is killed with SIGPIPE (e.g. OSX),
   the upload-pack that runs on the other end that hangs up after
   detecting an error could cause "git fetch" to die with a signal,
   which led to a flakey test.  "git fetch" now ignores SIGPIPE during
   the network portion of its operation (this is not a problem as we
   check the return status from our write(2)s).
   (merge 143588949c jk/no-sigpipe-during-network-transport later to maint).

 * A recent update broke "is this object available to us?" check for
   well-known objects like an empty tree (which should yield "yes",
   even when there is no on-disk object for an empty tree), which has
   been corrected.
   (merge f06ab027ef jk/virtual-objects-do-exist later to maint).

 * The setup code has been cleaned up to avoid leaks around the
   repository_format structure.
   (merge e8805af1c3 ma/clear-repository-format later to maint).

 * "git config --type=color ..." is meant to replace "git config --get-color"
   but there is a slight difference that wasn't documented, which is
   now fixed.
   (merge cd8e7593b9 jk/config-type-color-ends-with-lf later to maint).

 * When the "clean" filter can reduce the size of a huge file in the
   working tree down to a small "token" (a la Git LFS), there is no
   point in allocating a huge scratch area upfront, but the buffer is
   sized based on the original file size.  The convert mechanism now
   allocates very minimum and reallocates as it receives the output
   from the clean filter process.
   (merge 02156ab031 jh/resize-convert-scratch-buffer later to maint).

 * "git rebase" uses the refs/rewritten/ hierarchy to store its
   intermediate states, which inherently makes the hierarchy per
   worktree, but it didn't quite work well.
   (merge b9317d55a3 nd/rewritten-ref-is-per-worktree later to maint).

 * "git log -L<from>,<to>:<path>" with "-s" did not suppress the patch
   output as it should.  This has been corrected.
   (merge 05314efaea jk/line-log-with-patch later to maint).

 * "git worktree add" used to do a "find an available name with stat
   and then mkdir", which is race-prone.  This has been fixed by using
   mkdir and reacting to EEXIST in a loop.
   (merge 7af01f2367 ms/worktree-add-atomic-mkdir later to maint).

 * Build update for SHA-1 with collision detection.
   (merge 07a20f569b jk/sha1dc later to maint).

 * Build procedure has been fixed around use of asciidoctor instead of
   asciidoc.
   (merge 185f9a0ea0 ma/asciidoctor-fixes later to maint).

 * remote-http transport did not anonymize URLs reported in its error
   messages at places.
   (merge c1284b21f2 js/anonymize-remote-curl-diag later to maint).

 * Error messages given from the http transport have been updated so
   that they can be localized.
   (merge ed8b4132c8 js/remote-curl-i18n later to maint).

 * "git init" forgot to read platform-specific repository
   configuration, which made Windows port to ignore settings of
   core.hidedotfiles, for example.

 * A corner-case object name ambiguity while the sequencer machinery
   is working (e.g. "rebase -i -x") has been fixed.

 * "git format-patch" did not diagnose an error while opening the
   output file for the cover-letter, which has been corrected.
   (merge 2fe95f494c jc/format-patch-error-check later to maint).

 * "git checkout -f <branch>" while the index has an unmerged path
   incorrectly left some paths in an unmerged state, which has been
   corrected.

 * A corner case bug in the refs API has been corrected.
   (merge d3322eb28b jk/refs-double-abort later to maint).

 * Unicode update.
   (merge 584b62c37b bb/unicode-12 later to maint).

 * dumb-http walker has been updated to share more error recovery
   strategy with the normal codepath.

 * A buglet in configuration parser has been fixed.
   (merge 19e7fdaa58 nd/include-if-wildmatch later to maint).

 * The documentation for "git read-tree --reset -u" has been updated.
   (merge b5a0bd694c nd/read-tree-reset-doc later to maint).

 * Code clean-up around a much-less-important-than-it-used-to-be
   update_server_info() funtion.
   (merge b3223761c8 jk/server-info-rabbit-hole later to maint).

 * The message given when "git commit -a <paths>" errors out has been
   updated.
   (merge 5a1dbd48bc nd/commit-a-with-paths-msg-update later to maint).

 * "git cherry-pick --options A..B", after giving control back to the
   user to ask help resolving a conflicted step, did not honor the
   options it originally received, which has been corrected.

 * Various glitches in "git gc" around reflog handling have been fixed.

 * The code to read from commit-graph file has been cleanup with more
   careful error checking before using data read from it.

 * Performance fix around "git fetch" that grabs many refs.
   (merge b764300912 jt/fetch-pack-wanted-refs-optim later to maint).

 * Protocol v2 support in "git fetch-pack" of shallow clones has been
   corrected.

 * Performance fix around "git blame", especially in a linear history
   (which is the norm we should optimize for).
   (merge f892014943 dk/blame-keep-origin-blob later to maint).

 * Performance fix for "rev-list --parents -- pathspec".
   (merge 8320b1dbe7 jk/revision-rewritten-parents-in-prio-queue later to maint).

 * Updating the display with progress message has been cleaned up to
   deal better with overlong messages.
   (merge 545dc345eb sg/overlong-progress-fix later to maint).

 * "git blame -- path" in a non-bare repository starts blaming from
   the working tree, and the same command in a bare repository errors
   out because there is no working tree by definition.  The command
   has been taught to instead start blaming from the commit at HEAD,
   which is more useful.
   (merge a544fb08f8 sg/blame-in-bare-start-at-head later to maint).

 * An underallocation in the code to read the untracked cache
   extension has been corrected.
   (merge 3a7b45a623 js/untracked-cache-allocfix later to maint).

 * The code is updated to check the result of memory allocation before
   it is used in more places, by using xmalloc and/or xcalloc calls.
   (merge 999b951b28 jk/xmalloc later to maint).

 * The GETTEXT_POISON test option has been quite broken ever since it
   was made runtime-tunable, which has been fixed.
   (merge f88b9cb603 jc/gettext-test-fix later to maint).

 * Test fix on APFS that is incapable of store paths in Latin-1.
   (merge 3889149619 js/iso8895-test-on-apfs later to maint).

 * "git submodule foreach <command> --quiet" did not pass the option
   down correctly, which has been corrected.
   (merge a282f5a906 nd/submodule-foreach-quiet later to maint).

 * "git send-email" has been taught to use quoted-printable when the
   payload contains carriage-return.  The use of the mechanism is in
   line with the design originally added the codepath that chooses QP
   when the payload has overly long lines.
   (merge 74d76a1701 bc/send-email-qp-cr later to maint).

 * The recently added feature to add addresses that are on
   anything-by: trailers in 'git send-email' was found to be way too
   eager and considered nonsense strings as if they can be legitimate
   beginning of *-by: trailer.  This has been tightened.

 * Builds with gettext broke on recent macOS w/ Homebrew, which
   seems to have stopped including from /usr/local/include; this
   has been corrected.
   (merge 92a1377a2a js/macos-gettext-build later to maint).

 * Running "git add" on a repository created inside the current
   repository is an explicit indication that the user wants to add it
   as a submodule, but when the HEAD of the inner repository is on an
   unborn branch, it cannot be added as a submodule.  Worse, the files
   in its working tree can be added as if they are a part of the outer
   repository, which is not what the user wants.  These problems are
   being addressed.
   (merge f937bc2f86 km/empty-repo-is-still-a-repo later to maint).

 * "git cherry-pick" run with the "-x" or the "--signoff" option used
   to (and more importantly, ought to) clean up the commit log message
   with the --cleanup=space option by default, but this has been
   broken since late 2017.  This has been fixed.

 * When given a tag that points at a commit-ish, "git replace --graft"
   failed to peel the tag before writing a replace ref, which did not
   make sense because the old graft mechanism the feature wants to
   mimick only allowed to replace one commit object with another.
   This has been fixed.
   (merge ee521ec4cb cc/replace-graft-peel-tags later to maint).

 * Code tightening against a "wrong" object appearing where an object
   of a different type is expected, instead of blindly assuming that
   the connection between objects are correctly made.
   (merge 97dd512af7 tb/unexpected later to maint).

 * An earlier update for MinGW and Cygwin accidentally broke MSVC build,
   which has been fixed.
   (merge 22c3634c0f ss/msvc-path-utils-fix later to maint).

 * %(push:track) token used in the --format option to "git
   for-each-ref" and friends was not showing the right branch, which
   has been fixed.
   (merge c646d0934e dr/ref-filter-push-track-fix later to maint).

 * "make check-docs", "git help -a", etc. did not account for cases
   where a particular build may deliberately omit some subcommands,
   which has been corrected.

 * The logic to tell if a Git repository has a working tree protects
   "git branch -D" from removing the branch that is currently checked
   out by mistake.  The implementation of this logic was broken for
   repositories with unusual name, which unfortunately is the norm for
   submodules these days.  This has been fixed.
   (merge f3534c98e4 jt/submodule-repo-is-with-worktree later to maint).

 * AIX shared the same build issues with other BSDs around fileno(fp),
   which has been corrected.
   (merge ee662bf5c6 cc/aix-has-fileno-as-a-macro later to maint).

 * The autoconf generated configure script failed to use the right
   gettext() implementations from -libintl by ignoring useless stub
   implementations shipped in some C library, which has been
   corrected.
   (merge b71e56a683 vk/autoconf-gettext later to maint).

 * Code cleanup, docfix, build fix, etc.
   (merge 11f470aee7 jc/test-yes-doc later to maint).
   (merge 90503a240b js/doc-symref-in-proto-v1 later to maint).
   (merge 5c326d1252 jk/unused-params later to maint).
   (merge 68cabbfda3 dl/doc-submodule-wo-subcommand later to maint).
   (merge 9903623761 ab/receive-pack-use-after-free-fix later to maint).
   (merge 1ede45e44b en/merge-options-doc later to maint).
   (merge 3e14dd2c8e rd/doc-hook-used-in-sample later to maint).
   (merge c271dc28fd nd/no-more-check-racy later to maint).
   (merge e6e15194a8 yb/utf-16le-bom-spellfix later to maint).
   (merge bb101aaf0c rd/attr.c-comment-typofix later to maint).
   (merge 716a5af812 rd/gc-prune-doc-fix later to maint).
   (merge 50b206371d js/untravis-windows later to maint).
   (merge dbf47215e3 js/rebase-recreate-merge later to maint).
   (merge 56cb2d30f8 dl/reset-doc-no-wrt-abbrev later to maint).
   (merge 64eca306a2 ja/dir-rename-doc-markup-fix later to maint).
   (merge af91b0230c dl/ignore-docs later to maint).
   (merge 59a06e947b ra/t3600-test-path-funcs later to maint).
   (merge e041d0781b ar/t4150-remove-cruft later to maint).
   (merge 8d75a1d183 ma/asciidoctor-fixes-more later to maint).
   (merge 74cc547b0f mh/pack-protocol-doc-fix later to maint).
   (merge ed31851fa6 ab/doc-misc-typofixes later to maint).
   (merge a7256debd4 nd/checkout-m-doc-update later to maint).
   (merge 3a9e1ad78d jt/t5551-protocol-v2-does-not-have-half-auth later to maint).
   (merge 0b918b75af sg/t5318-cleanup later to maint).
   (merge 68ed71b53c cb/doco-mono later to maint).
   (merge a34dca2451 nd/interpret-trailers-docfix later to maint).
   (merge cf7b857a77 en/fast-import-parsing-fix later to maint).
   (merge fe61ccbc35 po/rerere-doc-fmt later to maint).
   (merge ffea0248bf po/describe-not-necessarily-7 later to maint).
   (merge 7cb7283adb tg/ls-files-debug-format-fix later to maint).
   (merge f64a21bd82 tz/doc-apostrophe-no-longer-needed later to maint).
   (merge dbe7b41019 js/t3301-unbreak-notes-test later to maint).
   (merge d8083e4180 km/t3000-retitle later to maint).
   (merge 9e4cbccbd7 tz/git-svn-doc-markup-fix later to maint).