refs: update ref transactions to use struct object_id

[alt-git.git] / Documentation / RelNotes / 2.15.0.txt

Git 2.15 Release Notes
======================

Backward compatibility notes and other notable changes.

 * Use of an empty string as a pathspec element that is used for
   'everything matches' is still warned and Git asks users to use a
   more explicit '.' for that instead.  The hope is that existing
   users will not mind this change, and eventually the warning can be
   turned into a hard error, upgrading the deprecation into removal of
   this (mis)feature.  That is now scheduled to happen in Git v2.16,
   the next major release after this one.

 * Git now avoids blindly falling back to ".git" when the setup
   sequence said we are _not_ in Git repository.  A corner case that
   happens to work right now may be broken by a call to BUG().
   We've tried hard to locate such cases and fixed them, but there
   might still be cases that need to be addressed--bug reports are
   greatly appreciated.

 * "branch --set-upstream" that has been deprecated in Git 1.8 has
   finally been retired.


Updates since v2.14
-------------------

UI, Workflows & Features

 * An example that is now obsolete has been removed from a sample hook,
   and an old example in it that added a sign-off manually has been
   improved to use the interpret-trailers command.

 * The advice message given when "git rebase" stops for conflicting
   changes has been improved.

 * The "rerere-train" script (in contrib/) learned the "--overwrite"
   option to allow overwriting existing recorded resolutions.

 * "git contacts" (in contrib/) now lists the address on the
   "Reported-by:" trailer to its output, in addition to those on
   S-o-b: and other trailers, to make it easier to notify (and thank)
   the original bug reporter.

 * "git rebase", especially when it is run by mistake and ends up
   trying to replay many changes, spent long time in silence.  The
   command has been taught to show progress report when it spends
   long time preparing these many changes to replay (which would give
   the user a chance to abort with ^C).

 * "git merge" learned a "--signoff" option to add the Signed-off-by:
   trailer with the committer's name.

 * "git diff" learned to optionally paint new lines that are the same
   as deleted lines elsewhere differently from genuinely new lines.

 * "git interpret-trailers" learned to take the trailer specifications
   from the command line that overrides the configured values.

 * "git interpret-trailers" has been taught a "--parse" and a few
   other options to make it easier for scripts to grab existing
   trailer lines from a commit log message.

 * The "--format=%(trailers)" option "git log" and its friends take
   learned to take the 'unfold' and 'only' modifiers to normalize its
   output, e.g. "git log --format=%(trailers:only,unfold)".

 * "gitweb" shows a link to visit the 'raw' contents of blbos in the
   history overview page.

 * "[gc] rerereResolved = 5.days" used to be invalid, as the variable
   is defined to take an integer counting the number of days.  It now
   is allowed.

 * The code to acquire a lock on a reference (e.g. while accepting a
   push from a client) used to immediately fail when the reference is
   already locked---now it waits for a very short while and retries,
   which can make it succeed if the lock holder was holding it during
   a read-only operation.

 * "branch --set-upstream" that has been deprecated in Git 1.8 has
   finally been retired.

 * The codepath to call external process filter for smudge/clean
   operation learned to show the progress meter.

 * "git rev-parse" learned "--is-shallow-repository", that is to be
   used in a way similar to existing "--is-bare-repository" and
   friends.

 * "git describe --match <pattern>" has been taught to play well with
   the "--all" option.

 * "git branch" learned "-c/-C" to create a new branch by copying an
   existing one.

 * Some commands (most notably "git status") makes an opportunistic
   update when performing a read-only operation to help optimize later
   operations in the same repository.  The new "--no-optional-locks"
   option can be passed to Git to disable them.

 * "git for-each-ref --format=..." learned a new format element,
   %(trailers), to show only the commit log trailer part of the log
   message.


Performance, Internal Implementation, Development Support etc.

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

 * Start using selected c99 constructs in small, stable and
   essentialpart of the system to catch people who care about
   older compilers that do not grok them.

 * The filter-process interface learned to allow a process with long
   latency give a "delayed" response.

 * Many uses of comparision callback function the hashmap API uses
   cast the callback function type when registering it to
   hashmap_init(), which defeats the compile time type checking when
   the callback interface changes (e.g. gaining more parameters).
   The callback implementations have been updated to take "void *"
   pointers and cast them to the type they expect instead.

 * Because recent Git for Windows do come with a real msgfmt, the
   build procedure for git-gui has been updated to use it instead of a
   hand-rolled substitute.

 * "git grep --recurse-submodules" has been reworked to give a more
   consistent output across submodule boundary (and do its thing
   without having to fork a separate process).

 * A helper function to read a single whole line into strbuf
   mistakenly triggered OOM error at EOF under certain conditions,
   which has been fixed.
   (merge 642956cf45 rs/strbuf-getwholeline-fix later to maint).

 * The "ref-store" code reorganization continues.

 * "git commit" used to discard the index and re-read from the filesystem
   just in case the pre-commit hook has updated it in the middle; this
   has been optimized out when we know we do not run the pre-commit hook.
   (merge 680ee550d7 kw/commit-keep-index-when-pre-commit-is-not-run later to maint).

 * Updates to the HTTP layer we made recently unconditionally used
   features of libCurl without checking the existence of them, causing
   compilation errors, which has been fixed.  Also migrate the code to
   check feature macros, not version numbers, to cope better with
   libCurl that vendor ships with backported features.

 * The API to start showing progress meter after a short delay has
   been simplified.
   (merge 8aade107dd jc/simplify-progress later to maint).

 * Code clean-up to avoid mixing values read from the .gitmodules file
   and values read from the .git/config file.

 * We used to spend more than necessary cycles allocating and freeing
   piece of memory while writing each index entry out.  This has been
   optimized.

 * Platforms that ship with a separate sha1 with collision detection
   library can link to it instead of using the copy we ship as part of
   our source tree.

 * Code around "notes" have been cleaned up.
   (merge 3964281524 mh/notes-cleanup later to maint).

 * The long-standing rule that an in-core lockfile instance, once it
   is used, must not be freed, has been lifted and the lockfile and
   tempfile APIs have been updated to reduce the chance of programming
   errors.

 * Our hashmap implementation in hashmap.[ch] is not thread-safe when
   adding a new item needs to expand the hashtable by rehashing; add
   an API to disable the automatic rehashing to work it around.

 * Many of our programs consider that it is OK to release dynamic
   storage that is used throughout the life of the program by simply
   exiting, but this makes it harder to leak detection tools to avoid
   reporting false positives.  Plug many existing leaks and introduce
   a mechanism for developers to mark that the region of memory
   pointed by a pointer is not lost/leaking to help these tools.

 * As "git commit" to conclude a conflicted "git merge" honors the
   commit-msg hook, "git merge" that records a merge commit that
   cleanly auto-merges should, but it didn't.

 * The codepath for "git merge-recursive" has been cleaned up.

 * Many leaks of strbuf have been fixed.

 * "git imap-send" has our own implementation of the protocol and also
   can use more recent libCurl with the imap protocol support.  Update
   the latter so that it can use the credential subsystem, and then
   make it the default option to use, so that we can eventually
   deprecate and remove the former.

 * "make style" runs git-clang-format to help developers by pointing
   out coding style issues.

 * A test to demonstrate "git mv" failing to adjust nested submodules
   has been added.
   (merge c514167df2 hv/mv-nested-submodules-test later to maint).

 * On Cygwin, "ulimit -s" does not report failure but it does not work
   at all, which causes an unexpected success of some tests that
   expect failures under a limited stack situation.  This has been
   fixed.

 * Many codepaths have been updated to squelch -Wimplicit-fallthrough
   warnings from Gcc 7 (which is a good code hygiene).

 * Add a helper for DLL loading in anticipation for its need in a
   future topic RSN.

 * "git status --ignored", when noticing that a directory without any
   tracked path is ignored, still enumerated all the ignored paths in
   the directory, which is unnecessary.  The codepath has been
   optimized to avoid this overhead.

 * The final batch to "git rebase -i" updates to move more code from
   the shell script to C has been merged.

 * Operations that do not touch (majority of) packed refs have been
   optimized by making accesses to packed-refs file lazy; we no longer
   pre-parse everything, and an access to a single ref in the
   packed-refs does not touch majority of irrelevant refs, either.

 * Add comment to clarify that the style file is meant to be used with
   clang-5 and the rules are still work in progress.

 * Many variables that points at a region of memory that will live
   throughout the life of the program have been marked with UNLEAK
   marker to help the leak checkers concentrate on real leaks..

 * Plans for weaning us off of SHA-1 has been documented.

 * A new "oidmap" API has been introduced and oidset API has been
   rewritten to use it.


Also contains various documentation updates and code clean-ups.


Fixes since v2.14
-----------------

 * "%C(color name)" in the pretty print format always produced ANSI
   color escape codes, which was an early design mistake.  They now
   honor the configuration (e.g. "color.ui = never") and also tty-ness
   of the output medium.

 * The http.{sslkey,sslCert} configuration variables are to be
   interpreted as a pathname that honors "~[username]/" prefix, but
   weren't, which has been fixed.

 * Numerous bugs in walking of reflogs via "log -g" and friends have
   been fixed.

 * "git commit" when seeing an totally empty message said "you did not
   edit the message", which is clearly wrong.  The message has been
   corrected.

 * When a directory is not readable, "gitweb" fails to build the
   project list.  Work this around by skipping such a directory.

 * Some versions of GnuPG fails to kill gpg-agent it auto-spawned
   and such a left-over agent can interfere with a test.  Work it
   around by attempting to kill one before starting a new test.

 * A recently added test for the "credential-cache" helper revealed
   that EOF detection done around the time the connection to the cache
   daemon is torn down were flaky.  This was fixed by reacting to
   ECONNRESET and behaving as if we got an EOF.

 * "git log --tag=no-such-tag" showed log starting from HEAD, which
   has been fixed---it now shows nothing.

 * The "tag.pager" configuration variable was useless for those who
   actually create tag objects, as it interfered with the use of an
   editor.  A new mechanism has been introduced for commands to enable
   pager depending on what operation is being carried out to fix this,
   and then "git tag -l" is made to run pager by default.

 * "git push --recurse-submodules $there HEAD:$target" was not
   propagated down to the submodules, but now it is.

 * Commands like "git rebase" accepted the --rerere-autoupdate option
   from the command line, but did not always use it.  This has been
   fixed.

 * "git clone --recurse-submodules --quiet" did not pass the quiet
   option down to submodules.

 * Test portability fix for OBSD.

 * Portability fix for OBSD.

 * "git am -s" has been taught that some input may end with a trailer
   block that is not Signed-off-by: and it should refrain from adding
   an extra blank line before adding a new sign-off in such a case.

 * "git svn" used with "--localtime" option did not compute the tz
   offset for the timestamp in question and instead always used the
   current time, which has been corrected.

 * Memory leak in an error codepath has been plugged.

 * "git stash -u" used the contents of the committed version of the
   ".gitignore" file to decide which paths are ignored, even when the
   file has local changes.  The command has been taught to instead use
   the locally modified contents.

 * bash 4.4 or newer gave a warning on NUL byte in command
   substitution done in "git stash"; this has been squelched.

 * "git grep -L" and "git grep --quiet -L" reported different exit
   codes; this has been corrected.

 * When handshake with a subprocess filter notices that the process
   asked for an unknown capability, Git did not report what program
   the offending subprocess was running.  This has been corrected.

 * "git apply" that is used as a better "patch -p1" failed to apply a
   taken from a file with CRLF line endings to a file with CRLF line
   endings.  The root cause was because it misused convert_to_git()
   that tried to do "safe-crlf" processing by looking at the index
   entry at the same path, which is a nonsense---in that mode, "apply"
   is not working on the data in (or derived from) the index at all.
   This has been fixed.

 * Killing "git merge --edit" before the editor returns control left
   the repository in a state with MERGE_MSG but without MERGE_HEAD,
   which incorrectly tells the subsequent "git commit" that there was
   a squash merge in progress.  This has been fixed.

 * "git archive" did not work well with pathspecs and the
   export-ignore attribute.

 * In addition to "cc: <a@dd.re.ss> # cruft", "cc: a@dd.re.ss # cruft"
   was taught to "git send-email" as a valid way to tell it that it
   needs to also send a carbon copy to <a@dd.re.ss> in the trailer
   section.
   (merge cc90750677 mm/send-email-cc-cruft later to maint).

 * "git branch -M a b" while on a branch that is completely unrelated
   to either branch a or branch b misbehaved when multiple worktree
   was in use.  This has been fixed.
   (merge 31824d180d nd/worktree-kill-parse-ref later to maint).

 * "git gc" and friends when multiple worktrees are used off of a
   single repository did not consider the index and per-worktree refs
   of other worktrees as the root for reachability traversal, making
   objects that are in use only in other worktrees to be subject to
   garbage collection.

 * A regression to "gitk --bisect" by a recent update has been fixed.
   (merge 1d0538e486 mh/packed-ref-store-prep later to maint).

 * "git -c submodule.recurse=yes pull" did not work as if the
   "--recurse-submodules" option was given from the command line.
   This has been corrected.

 * Unlike "git commit-tree < file", "git commit-tree -F file" did not
   pass the contents of the file verbatim and instead completed an
   incomplete line at the end, if exists.  The latter has been updated
   to match the behaviour of the former.
   (merge c818e74332 rk/commit-tree-make-F-verbatim later to maint).

 * Many codepaths did not diagnose write failures correctly when disks
   go full, due to their misuse of write_in_full() helper function,
   which have been corrected.
   (merge f48ecd38cb jk/write-in-full-fix later to maint).

 * "git help co" now says "co is aliased to ...", not "git co is".
   (merge b3a8076e0d ks/help-alias-label later to maint).

 * "git archive", especially when used with pathspec, stored an empty
   directory in its output, even though Git itself never does so.
   This has been fixed.
   (merge 4318094047 rs/archive-excluded-directory later to maint).

 * API error-proofing which happens to also squelch warnings from GCC.
   (merge c788c54cde tg/refs-allowed-flags later to maint).

 * The explanation of the cut-line in the commit log editor has been
   slightly tweaked.
   (merge 8c4b1a3593 ks/commit-do-not-touch-cut-line later to maint).

 * "git gc" tries to avoid running two instances at the same time by
   reading and writing pid/host from and to a lock file; it used to
   use an incorrect fscanf() format when reading, which has been
   corrected.
   (merge afe2fab72c aw/gc-lockfile-fscanf-fix later to maint).

 * The scripts to drive TravisCI has been reorganized and then an
   optimization to avoid spending cycles on a branch whose tip is
   tagged has been implemented.
   (merge 8376eb4a8f ls/travis-scriptify later to maint).

 * The test linter has been taught that we do not like "echo -e".
   (merge 1a6d46895d tb/test-lint-echo-e later to maint).

 * Code cmp.std.c nitpick.
   (merge ac7da78ede mh/for-each-string-list-item-empty-fix later to maint).

 * A regression fix for 2.11 that made the code to read the list of
   alternate object stores overrun the end of the string.
   (merge f0f7bebef7 jk/info-alternates-fix later to maint).

 * "git describe --match" learned to take multiple patterns in v2.13
   series, but the feature ignored the patterns after the first one
   and did not work at all.  This has been fixed.
   (merge da769d2986 jk/describe-omit-some-refs later to maint).

 * "git filter-branch" cannot reproduce a history with a tag without
   the tagger field, which only ancient versions of Git allowed to be
   created.  This has been corrected.
   (merge b2c1ca6b4b ic/fix-filter-branch-to-handle-tag-without-tagger later to maint).

 * "git cat-file --textconv" started segfaulting recently, which
   has been corrected.
   (merge cc0ea7c9e5 jk/diff-blob later to maint).

 * The built-in pattern to detect the "function header" for HTML did
   not match <H1>..<H6> elements without any attributes, which has
   been fixed.
   (merge 9c03caca2c ik/userdiff-html-h-element-fix later to maint).

 * "git mailinfo" was loose in decoding quoted printable and produced
   garbage when the two letters after the equal sign are not
   hexadecimal.  This has been fixed.
   (merge c8cf423eab rs/mailinfo-qp-decode-fix later to maint).

 * The machinery to create xdelta used in pack files received the
   sizes of the data in size_t, but lost the higher bits of them by
   storing them in "unsigned int" during the computation, which is
   fixed.

 * The delta format used in the packfile cannot reference data at
   offset larger than what can be expressed in 4-byte, but the
   generator for the data failed to make sure the offset does not
   overflow.  This has been corrected.

 * The documentation for '-X<option>' for merges was misleadingly
   written to suggest that "-s theirs" exists, which is not the case.
   (merge c25d98b2a7 jc/merge-x-theirs-docfix later to maint).

 * "git fast-export" with -M/-C option issued "copy" instruction on a
   path that is simultaneously modified, which was incorrect.
   (merge b3e8ca89cf jt/fast-export-copy-modify-fix later to maint).

 * Many codepaths have been updated to squelch -Wsign-compare
   warnings.
   (merge 071bcaab64 rj/no-sign-compare later to maint).

 * Memory leaks in various codepaths have been plugged.
   (merge 4d01a7fa65 ma/leakplugs later to maint).

 * Recent versions of "git rev-parse --parseopt" did not parse the
   option specification that does not have the optional flags (*=?!)
   correctly, which has been corrected.
   (merge a6304fa4c2 bc/rev-parse-parseopt-fix later to maint).

 * The checkpoint command "git fast-import" did not flush updates to
   refs and marks unless at least one object was created since the
   last checkpoint, which has been corrected, as these things can
   happen without any new object getting created.
   (merge 30e215a65c er/fast-import-dump-refs-on-checkpoint later to maint).

 * Spell the name of our system as "Git" in the output from
   request-pull script.
   (merge e66d7c37a5 ar/request-pull-phrasofix later to maint).

 * Fixes for a handful memory access issues identified by valgrind.
   (merge 2944a94c6b tg/memfixes later to maint).

 * Backports a moral equivalent of 2015 fix to the poll() emulation
   from the upstream gnulib to fix occasional breakages on HPE NonStop.
   (merge 61b2a1acaa rb/compat-poll-fix later to maint).

 * Users with "color.ui = always" in their configuration were broken
   by a recent change that made plumbing commands to pay attention to
   them as the patch created internally by "git add -p" were colored
   (heh) and made unusable.  Fix this regression by redefining
   'always' to mean the same thing as 'auto'.
   (merge 6be4595edb jk/ui-color-always-to-auto-maint later to maint).

 * In the "--format=..." option of the "git for-each-ref" command (and
   its friends, i.e. the listing mode of "git branch/tag"), "%(atom:)"
   (e.g. "%(refname:)", "%(body:)" used to error out.  Instead, treat
   them as if the colon and an empty string that follows it were not
   there.
   (merge bea4dbeafd tb/ref-filter-empty-modifier later to maint).

 * An ancient bug that made Git misbehave with creation/renaming of
   refs has been fixed.

 * Other minor doc, test and build updates and code cleanups.
   (merge f094b89a4d ma/parse-maybe-bool later to maint).
   (merge 39b00fa4d4 jk/drop-sha1-entry-pos later to maint).
   (merge 6cdf8a7929 ma/ts-cleanups later to maint).
   (merge 7560f547e6 ma/up-to-date later to maint).
   (merge 0db3dc75f3 rs/apply-epoch later to maint).
   (merge 74f1bd912b dw/diff-highlight-makefile-fix later to maint).
   (merge f991761eb8 jk/config-lockfile-leak-fix later to maint).
   (merge 150efef1e7 ma/pkt-line-leakfix later to maint).
   (merge 5554451de6 mg/timestamp-t-fix later to maint).
   (merge 276d0e35c0 ma/split-symref-update-fix later to maint).
   (merge 3bc4b8f7c7 bb/doc-eol-dirty later to maint).
   (merge c1bb33c99c jk/system-path-cleanup later to maint).
   (merge ab46e6fc72 cc/subprocess-handshake-missing-capabilities later to maint).
   (merge f7a32dd97f kd/doc-for-each-ref later to maint).
   (merge be94568bc7 ez/doc-duplicated-words-fix later to maint).
   (merge 01e4be6c3d ks/test-readme-phrasofix later to maint).
   (merge 217bb56d4f hn/typofix later to maint).
   (merge c08fd6388c jk/doc-read-tree-table-asciidoctor-fix later to maint).
   (merge c3342b362e ks/doc-use-camelcase-for-config-name later to maint).
   (merge 0bca165fdb jk/validate-headref-fix later to maint).
   (merge 93dbefb389 mr/doc-negative-pathspec later to maint).
   (merge 5e633326e4 ad/doc-markup-fix later to maint).
   (merge 9ca356fa8b rs/cocci-de-paren-call-params later to maint).
   (merge 7099153e8d rs/tag-null-pointer-arith-fix later to maint).
   (merge 0e187d758c rs/run-command-use-alloc-array later to maint).
   (merge e0222159fa jn/strbuf-doc-re-reuse later to maint).
   (merge 97487ea11a rs/qsort-s later to maint).
   (merge a9155c50bd sb/branch-avoid-repeated-strbuf-release later to maint).
   (merge f777623514 ks/branch-tweak-error-message-for-extra-args later to maint).
   (merge 33f3c683ec ks/verify-filename-non-option-error-message-tweak later to maint).
   (merge b3ea7dd32d jk/sha1-loose-object-info-fix later to maint).
   (merge 2720f6db5d rs/fsck-null-return-from-lookup later to maint).
   (merge 99b7b687a6 rs/rs-mailmap later to maint).
   (merge 7823655082 tb/complete-describe later to maint).
   (merge 7cbbf9d6a2 ls/filter-process-delayed later to maint).