doc hash-function-transition: clarify what SHAttered means

[git] / Documentation / RelNotes / 2.17.0.txt

Git 2.17 Release Notes
======================

Updates since v2.16
-------------------

UI, Workflows & Features

 * "diff" family of commands learned "--find-object=<object-id>" option
   to limit the findings to changes that involve the named object.

 * "git format-patch" learned to give 72-cols to diffstat, which is
   consistent with other line length limits the subcommand uses for
   its output meant for e-mails.

 * The log from "git daemon" can be redirected with a new option; one
   relevant use case is to send the log to standard error (instead of
   syslog) when running it from inetd.

 * "git rebase" learned to take "--allow-empty-message" option.

 * "git am" has learned the "--quit" option, in addition to the
   existing "--abort" option; having the pair mirrors a few other
   commands like "rebase" and "cherry-pick".

 * "git worktree add" learned to run the post-checkout hook, just like
   "git clone" runs it upon the initial checkout.

 * "git tag" learned an explicit "--edit" option that allows the
   message given via "-m" and "-F" to be further edited.

 * "git fetch --prune-tags" may be used as a handy short-hand for
   getting rid of stale tags that are locally held.

 * The new "--show-current-patch" option gives an end-user facing way
   to get the diff being applied when "git rebase" (and "git am")
   stops with a conflict.

 * "git add -p" used to offer "/" (look for a matching hunk) as a
   choice, even there was only one hunk, which has been corrected.
   Also the single-key help is now given only for keys that are
   enabled (e.g. help for '/' won't be shown when there is only one
   hunk).

 * Since Git 1.7.9, "git merge" defaulted to --no-ff (i.e. even when
   the side branch being merged is a descendant of the current commit,
   create a merge commit instead of fast-forwarding) when merging a
   tag object.  This was appropriate default for integrators who pull
   signed tags from their downstream contributors, but caused an
   unnecessary merges when used by downstream contributors who
   habitually "catch up" their topic branches with tagged releases
   from the upstream.  Update "git merge" to default to --no-ff only
   when merging a tag object that does *not* sit at its usual place in
   refs/tags/ hierarchy, and allow fast-forwarding otherwise, to
   mitigate the problem.

 * "git status" can spend a lot of cycles to compute the relation
   between the current branch and its upstream, which can now be
   disabled with "--no-ahead-behind" option.

 * "git diff" and friends learned funcname patterns for Go language
   source files.

 * "git send-email" learned "--reply-to=<address>" option.

 * Funcname pattern used for C# now recognizes "async" keyword.

 * In a way similar to how "git tag" learned to honor the pager
   setting only in the list mode, "git config" learned to ignore the
   pager setting when it is used for setting values (i.e. when the
   purpose of the operation is not to "show").


Performance, Internal Implementation, Development Support etc.

 * More perf tests for threaded grep

 * "perf" test output can be sent to codespeed server.

 * The build procedure for perl/ part has been greatly simplified by
   weaning ourselves off of MakeMaker.

 * Perl 5.8 or greater has been required since Git 1.7.4 released in
   2010, but we continued to assume some core modules may not exist and
   used a conditional "eval { require <<module>> }"; we no longer do
   this.  Some platforms (Fedora/RedHat/CentOS, for example) ship Perl
   without all core modules by default (e.g. Digest::MD5, File::Temp,
   File::Spec, Net::Domain, Net::SMTP).  Users on such platforms may
   need to install these additional modules.

 * As a convenience, we install copies of Perl modules we require which
   are not part of the core Perl distribution (e.g. Error and
   Mail::Address).  Users and packagers whose operating system provides
   these modules can set NO_PERL_CPAN_FALLBACKS to avoid installing the
   bundled modules.

 * In preparation for implementing narrow/partial clone, the machinery
   for checking object connectivity used by gc and fsck has been
   taught that a missing object is OK when it is referenced by a
   packfile specially marked as coming from trusted repository that
   promises to make them available on-demand and lazily.

 * The machinery to clone & fetch, which in turn involves packing and
   unpacking objects, has been told how to omit certain objects using
   the filtering mechanism introduced by another topic.  It now knows
   to mark the resulting pack as a promisor pack to tolerate missing
   objects, laying foundation for "narrow" clones.

 * The first step to getting rid of mru API and using the
   doubly-linked list API directly instead.

 * Retire mru API as it does not give enough abstraction over
   underlying list API to be worth it.

 * Rewrite two more "git submodule" subcommands in C.

 * The tracing machinery learned to report tweaking of environment
   variables as well.

 * Update Coccinelle rules to catch and optimize strbuf_addf(&buf, "%s", str)

 * Prevent "clang-format" from breaking line after function return type.

 * The sequencer infrastructure is shared across "git cherry-pick",
   "git rebase -i", etc., and has always spawned "git commit" when it
   needs to create a commit.  It has been taught to do so internally,
   when able, by reusing the codepath "git commit" itself uses, which
   gives performance boost for a few tens of percents in some sample
   scenarios.

 * Push the submodule version of collision-detecting SHA-1 hash
   implementation a bit harder on builders.

 * Avoid mmapping small files while using packed refs (especially ones
   with zero size, which would cause later munmap() to fail).

 * Conversion from uchar[20] to struct object_id continues.

 * More tests for wildmatch functions.

 * The code to binary search starting from a fan-out table (which is
   how the packfile is indexed with object names) has been refactored
   into a reusable helper.

 * We now avoid using identifiers that clash with C++ keywords.  Even
   though it is not a goal to compile Git with C++ compilers, changes
   like this help use of code analysis tools that targets C++ on our
   codebase.

 * The executable is now built in 'script' phase in Travis CI integration,
   to follow the established practice, rather than during 'before_script'
   phase.  This allows the CI categorize the failures better ('failed'
   is project's fault, 'errored' is build environment's).
   (merge 3c93b82920 sg/travis-build-during-script-phase later to maint).

 * Writing out the index file when the only thing that changed in it
   is the untracked cache information is often wasteful, and this has
   been optimized out.

 * Various pieces of Perl code we have have been cleaned up.

 * Internal API clean-up to allow write_locked_index() optionally skip
   writing the in-core index when it is not modified.


Also contains various documentation updates and code clean-ups.


Fixes since v2.16
-----------------

 * An old regression in "git describe --all $annotated_tag^0" has been
   fixed.

 * "git status" after moving a path in the working tree (hence making
   it appear "removed") and then adding with the -N option (hence
   making that appear "added") detected it as a rename, but did not
   report the  old and new pathnames correctly.

 * "git svn dcommit" did not take into account the fact that a
   svn+ssh:// URL with a username@ (typically used for pushing) refers
   to the same SVN repository without the username@ and failed when
   svn.pushmergeinfo option is set.

 * API clean-up around revision traversal.

 * "git merge -Xours/-Xtheirs" learned to use our/their version when
   resolving a conflicting updates to a symbolic link.

 * "git clone $there $here" is allowed even when here directory exists
   as long as it is an empty directory, but the command incorrectly
   removed it upon a failure of the operation.

 * "git commit --fixup" did not allow "-m<message>" option to be used
   at the same time; allow it to annotate resulting commit with more
   text.

 * When resetting the working tree files recursively, the working tree
   of submodules are now also reset to match.

 * "git stash -- <pathspec>" incorrectly blew away untracked files in
   the directory that matched the pathspec, which has been corrected.

 * Instead of maintaining home-grown email address parsing code, ship
   a copy of reasonably recent Mail::Address to be used as a fallback
   in 'git send-email' when the platform lacks it.
   (merge d60be8acab mm/send-email-fallback-to-local-mail-address later to maint).

 * "git add -p" was taught to ignore local changes to submodules as
   they do not interfere with the partial addition of regular changes
   anyway.

 * Avoid showing a warning message in the middle of a line of "git
   diff" output.
   (merge 4e056c989f nd/diff-flush-before-warning later to maint).

 * The http tracing code, often used to debug connection issues,
   learned to redact potentially sensitive information from its output
   so that it can be more safely sharable.
   (merge 8ba18e6fa4 jt/http-redact-cookies later to maint).

 * Crash fix for a corner case where an error codepath tried to unlock
   what it did not acquire lock on.
   (merge 81fcb698e0 mr/packed-ref-store-fix later to maint).

 * The split-index mode had a few corner case bugs fixed.
   (merge ae59a4e44f tg/split-index-fixes later to maint).

 * Assorted fixes to "git daemon".
   (merge ed15e58efe jk/daemon-fixes later to maint).

 * Completion of "git merge -s<strategy>" (in contrib/) did not work
   well in non-C locale.
   (merge 7cc763aaa3 nd/list-merge-strategy later to maint).

 * Workaround for segfault with more recent versions of SVN.
   (merge 7f6f75e97a ew/svn-branch-segfault-fix later to maint).

 * Plug recently introduced leaks in fsck.
   (merge ba3a08ca0e jt/fsck-code-cleanup later to maint).

 * "git pull --rebase" did not pass verbosity setting down when
   recursing into a submodule.
   (merge a56771a668 sb/pull-rebase-submodule later to maint).

 * The way "git reset --hard" reports the commit the updated HEAD
   points at is made consistent with the way how the commit title is
   generated by the other parts of the system.  This matters when the
   title is spread across physically multiple lines.
   (merge 1cf823fb68 tg/reset-hard-show-head-with-pretty later to maint).

 * Test fixes.
   (merge 63b1a175ee sg/test-i18ngrep later to maint).

 * Some bugs around "untracked cache" feature have been fixed.  This
   will notice corrupt data in the untracked cache left by old and
   buggy code and issue a warning---the index can be fixed by clearing
   the untracked cache from it.
   (merge 0cacebf099 nd/fix-untracked-cache-invalidation later to maint).
   (merge 7bf0be7501 ab/untracked-cache-invalidation-docs later to maint).

 * "git blame HEAD COPYING" in a bare repository failed to run, while
   "git blame HEAD -- COPYING" run just fine.  This has been corrected.

 * "git add" files in the same directory, but spelling the directory
   path in different cases on case insensitive filesystem, corrupted
   the name hash data structure and led to unexpected results.  This
   has been corrected.
   (merge c95525e90d bp/name-hash-dirname-fix later to maint).

 * "git rebase -p" mangled log messages of a merge commit, which is
   now fixed.
   (merge ed5144d7eb js/fix-merge-arg-quoting-in-rebase-p later to maint).

 * Some low level protocol codepath could crash when they get an
   unexpected flush packet, which is now fixed.
   (merge bb1356dc64 js/packet-read-line-check-null later to maint).

 * "git check-ignore" with multiple paths got confused when one is a
   file and the other is a directory, which has been fixed.
   (merge d60771e930 rs/check-ignore-multi later to maint).

 * "git describe $garbage" stopped giving any errors when the garbage
   happens to be a string with 40 hexadecimal letters.
   (merge a8e7a2bf0f sb/describe-blob later to maint).

 * Code to unquote single-quoted string (used in the parser for
   configuration files, etc.) did not diagnose bogus input correctly
   and produced bogus results instead.
   (merge ddbbf8eb25 jk/sq-dequote-on-bogus-input later to maint).

 * Many places in "git apply" knew that "/dev/null" that signals
   "there is no such file on this side of the diff" can be followed by
   whitespace and garbage when parsing a patch, except for one, which
   made an otherwise valid patch (e.g. ones from subversion) rejected.
   (merge e454ad4bec tk/apply-dev-null-verify-name-fix later to maint).

 * We no longer create any *.spec file, so "make clean" should not
   remove it.
   (merge 4321bdcabb tz/do-not-clean-spec-file later to maint).

 * "git push" over http transport did not unquote the push-options
   correctly.
   (merge 90dce21eb0 jk/push-options-via-transport-fix later to maint).

 * "git send-email" learned to complain when the batch-size option is
   not defined when the relogin-delay option is, since these two are
   mutually required.
   (merge 9caa70697b xz/send-email-batch-size later to maint).

 * Y2k20 fix ;-) for our perl scripts.
   (merge a40e06ee33 bw/perl-timegm-timelocal-fix later to maint).

 * Threaded "git grep" has been optimized to avoid allocation in code
   section that is covered under a mutex.
   (merge 38ef24dccf rv/grep-cleanup later to maint).

 * "git subtree" script (in contrib/) scripted around "git log", whose
   output got affected by end-user configuration like log.showsignature
   (merge 8841b5222c sg/subtree-signed-commits later to maint).

 * While finding unique object name abbreviation, the code may
   accidentally have read beyond the end of the array of object names
   in a pack.
   (merge 21abed500c ds/find-unique-abbrev-optim later to maint).

 * Micro optimization in revision traversal code.
   (merge ebbed3ba04 ds/mark-parents-uninteresting-optim later to maint).

 * "git commit" used to run "gc --auto" near the end, which was lost
   when the command was reimplemented in C by mistake.
   (merge 095c741edd ab/gc-auto-in-commit later to maint).

 * Allow running a couple of tests with "sh -x".
   (merge c20bf94abc sg/cvs-tests-with-x later to maint).

 * The codepath to replace an existing entry in the index had a bug in
   updating the name hash structure, which has been fixed.
   (merge 0e267b7a24 bp/refresh-cache-ent-rehash-fix later to maint).

 * The transfer.fsckobjects configuration tells "git fetch" to
   validate the data and connected-ness of objects in the received
   pack; the code to perform this check has been taught about the
   narrow clone's convention that missing objects that are reachable
   from objects in a pack that came from a promissor remote is OK.

 * There was an unused file-scope static variable left in http.c when
   building for versions of libCURL that is older than 7.19.4, which
   has been fixed.
   (merge b8fd6008ec rj/http-code-cleanup later to maint).

 * Shell script portability fix.
   (merge 206a6ae013 ml/filter-branch-portability-fix later to maint).

 * Other minor doc, test and build updates and code cleanups.
   (merge e2a5a028c7 bw/oidmap-autoinit later to maint).
   (merge ec3b4b06f8 cl/t9001-cleanup later to maint).
   (merge e1b3f3dd38 ks/submodule-doc-updates later to maint).
   (merge fbac558a9b rs/describe-unique-abbrev later to maint).
   (merge 8462ff43e4 tb/crlf-conv-flags later to maint).
   (merge 7d68bb0766 rb/hashmap-h-compilation-fix later to maint).
   (merge 3449847168 cc/sha1-file-name later to maint).
   (merge ad622a256f ds/use-get-be64 later to maint).
   (merge f919ffebed sg/cocci-move-array later to maint).
   (merge 4e801463c7 jc/mailinfo-cleanup-fix later to maint).
   (merge ef5b3a6c5e nd/shared-index-fix later to maint).
   (merge 9f5258cbb8 tz/doc-show-defaults-to-head later to maint).
   (merge b780e4407d jc/worktree-add-short-help later to maint).
   (merge ae239fc8e5 rs/cocci-strbuf-addf-to-addstr later to maint).
   (merge 2e22a85e5c nd/ignore-glob-doc-update later to maint).
   (merge 3738031581 jk/gettext-poison later to maint).
   (merge 54360a1956 rj/sparse-updates later to maint).
   (merge 12e31a6b12 sg/doc-test-must-fail-args later to maint).
   (merge 760f1ad101 bc/doc-interpret-trailers-grammofix later to maint).
   (merge 4ccf461f56 bp/fsmonitor later to maint).
   (merge a6119f82b1 jk/test-hashmap-updates later to maint).
   (merge 5aea9fe6cc rd/typofix later to maint).
   (merge e4e5da2796 sb/status-doc-fix later to maint).
   (merge 7976e901c8 gs/test-unset-xdg-cache-home later to maint).
   (merge d023df1ee6 tg/worktree-create-tracking later to maint).
   (merge 4cbe92fd41 sm/mv-dry-run-update later to maint).
   (merge 75e5e9c3f7 sb/color-h-cleanup later to maint).
   (merge 2708ef4af6 sg/t6300-modernize later to maint).
   (merge d88e92d4e0 bw/doc-submodule-recurse-config-with-clone later to maint).
   (merge f74bbc8dd2 jk/cached-commit-buffer later to maint).
   (merge 1316416903 ms/non-ascii-ticks later to maint).
   (merge 878056005e rs/strbuf-read-file-or-whine later to maint).
   (merge 79f0ba1547 jk/strbuf-read-file-close-error later to maint).
   (merge edfb8ba068 ot/ref-filter-cleanup later to maint).
   (merge 11395a3b4b jc/test-must-be-empty later to maint).
   (merge 768b9d6db7 mk/doc-pretty-fill later to maint).
   (merge 2caa7b8d27 ab/man-sec-list later to maint).
   (merge 40c17eb184 ks/t3200-typofix later to maint).
   (merge bd9958c358 dp/merge-strategy-doc-fix later to maint).
   (merge 9ee0540a40 js/ming-strftime later to maint).
   (merge 1775e990f7 tz/complete-tag-delete-tagname later to maint).
   (merge 00a4b03501 rj/warning-uninitialized-fix later to maint).
   (merge b635ed97a0 jk/attributes-path-doc later to maint).