Documentation/RelNotes/2.16.0.txt - jrn/git - Git at Google

 Git 2.16 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 now an error.


 Updates since v2.15
 -------------------

 UI, Workflows & Features

  * An empty string as a pathspec element that means "everything"
    i.e. 'git add ""', is now illegal.  We started this by first
    deprecating and warning a pathspec that has such an element in
    2.11 (Nov 2016).

  * A hook script that is set unexecutable is simply ignored.  Git
    notifies when such a file is ignored, unless the message is
    squelched via advice.ignoredHook configuration.

  * "git pull" has been taught to accept "--[no-]signoff" option and
    pass it down to "git merge".

  * The "--push-option=<string>" option to "git push" now defaults to a
    list of strings configured via push.pushOption variable.

  * "gitweb" checks if a directory is searchable with Perl's "-x"
    operator, which can be enhanced by using "filetest 'access'"
    pragma, which now we do.

  * "git stash save" has been deprecated in favour of "git stash push".

  * The set of paths output from "git status --ignored" was tied
    closely with its "--untracked=<mode>" option, but now it can be
    controlled more flexibly.  Most notably, a directory that is
    ignored because it is listed to be ignored in the ignore/exclude
    mechanism can be handled differently from a directory that ends up
    to be ignored only because all files in it are ignored.

  * The remote-helper for talking to MediaWiki has been updated to
    truncate an overlong pagename so that ".mw" suffix can still be
    added.

  * The remote-helper for talking to MediaWiki has been updated to
    work with mediawiki namespaces.

  * The "--format=..." option "git for-each-ref" takes learned to show
    the name of the 'remote' repository and the ref at the remote side
    that is affected for 'upstream' and 'push' via "%(push:remotename)"
    and friends.

  * Doc and message updates to teach users "bisect view" is a synonym
    for "bisect visualize".

  * "git bisect run" that did not specify any command to run used to go
    ahead and treated all commits to be tested as 'good'.  This has
    been corrected by making the command error out.

  * The SubmittingPatches document has been converted to produce an
    HTML version via AsciiDoc/Asciidoctor.

  * We learned to talk to watchman to speed up "git status" and other
    operations that need to see which paths have been modified.

  * The "diff" family of commands learned to ignore differences in
    carriage return at the end of line.

  * Places that know about "sendemail.to", like documentation and shell
    completion (in contrib/) have been taught about "sendemail.tocmd",
    too.

  * "git add --renormalize ." is a new and safer way to record the fact
    that you are correcting the end-of-line convention and other
    "convert_to_git()" glitches in the in-repository data.

  * "git branch" and "git checkout -b" are now forbidden from creating
    a branch whose name is "HEAD".

  * "git branch --list" learned to show its output through the pager by
    default when the output is going to a terminal, which is controlled
    by the pager.branch configuration variable.  This is similar to a
    recent change to "git tag --list".

  * "git grep -W", "git diff -W" and their friends learned a heuristic
    to extend a pre-context beyond the line that matches the "function
    pattern" (aka "diff.*.xfuncname") to include a comment block, if
    exists, that immediately precedes it.

  * "git config --expiry-date gc.reflogexpire" can read "2.weeks" from
    the configuration and report it as a timestamp, just like "--int"
    would read "1k" and report 1024, to help consumption by scripts.

  * The shell completion (in contrib/) learned that "git pull" can take
    the "--autostash" option.


 Performance, Internal Implementation, Development Support etc.

  * An earlier update made it possible to use an on-stack in-core
    lockfile structure (as opposed to having to deliberately leak an
    on-heap one).  Many codepaths have been updated to take advantage
    of this new facility.

  * Calling cmd_foo() as if it is a general purpose helper function is
    a no-no.  Correct two instances of such to set an example.

  * We try to see if somebody runs our test suite with a shell that
    does not support "local" like bash/dash does.

  * An early part of piece-by-piece rewrite of "git bisect" in C.

  * GSoC to piece-by-piece rewrite "git submodule" in C.

  * Optimize the code to find shortest unique prefix of object names.

  * Pathspec-limited revision traversal was taught not to keep finding
    unneeded differences once it knows two trees are different inside
    given pathspec.

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

  * Code cleanup.

  * A single-word "unsigned flags" in the diff options is being split
    into a structure with many bitfields.

  * TravisCI build updates.

  * Parts of a test to drive the long-running content filter interface
    has been split into its own module, hopefully to eventually become
    reusable.

  * Drop (perhaps overly cautious) sanity check before using the index
    read from the filesystem at runtime.

  * The build procedure has been taught to avoid some unnecessary
    instability in the build products.

  * A new mechanism to upgrade the wire protocol in place is proposed
    and demonstrated that it works with the older versions of Git
    without harming them.

 Also contains various documentation updates and code clean-ups.


 Fixes since v2.15
 -----------------

  * "auto" as a value for the columnar output configuration ought to
    judge "is the output consumed by humans?" with the same criteria as
    "auto" for coloured output configuration, i.e. either the standard
    output stream is going to tty, or a pager is in use.  We forgot the
    latter, which has been fixed.

  * The experimental "color moved lines differently in diff output"
    feature was buggy around "ignore whitespace changes" edges, which
    has been corrected.

  * Instead of using custom line comparison and hashing functions to
    implement "moved lines" coloring in the diff output, use the pair
    of these functions from lower-layer xdiff/ code.

  * Some codepaths did not check for errors when asking what branch the
    HEAD points at, which have been fixed.

  * "git commit", after making a commit, did not check for errors when
    asking on what branch it made the commit, which has been corrected.

  * "git status --ignored -u" did not stop at a working tree of a
    separate project that is embedded in an ignored directory and
    listed files in that other project, instead of just showing the
    directory itself as ignored.

  * A broken access to object databases in recent update to "git grep
    --recurse-submodules" has been fixed.

  * A recent regression in "git rebase -i" that broke execution of git
    commands from subdirectories via "exec" instruction has been fixed.

  * A (possibly flakey) test fix.

  * "git check-ref-format --branch @{-1}" bit a "BUG()" when run
    outside a repository for obvious reasons; clarify the documentation
    and make sure we do not even try to expand the at-mark magic in
    such a case, but still call the validation logic for branch names.

  * "git fetch --recurse-submodules" now knows that submodules can be
    moved around in the superproject in addition to getting updated,
    and finds the ones that need to be fetched accordingly.

  * Command line completion (in contrib/) update.

  * Description of blame.{showroot,blankboundary,showemail,date}
    configuration variables have been added to "git config --help".

  * After an error from lstat(), diff_populate_filespec() function
    sometimes still went ahead and used invalid data in struct stat,
    which has been fixed.

  * UNC paths are also relevant in Cygwin builds and they are now
    tested just like Mingw builds.

  * Correct start-up sequence so that a repository could be placed
    immediately under the root directory again (which was broken at
    around Git 2.13).

  * The credential helper for libsecret (in contrib/) has been improved
    to allow possibly prompting the end user to unlock secrets that are
    currently locked (otherwise the secrets may not be loaded).

  * MinGW updates.

  * Error checking in "git imap-send" for empty response has been
    improved.

  * Recent update to the refs infrastructure implementation started
    rewriting packed-refs file more often than before; this has been
    optimized again for most trivial cases.

  * Some error messages did not quote filenames shown in it, which have
    been fixed.

  * "git rebase -i" recently started misbehaving when a submodule that
    is configured with 'submodule.<name>.ignore' is dirty; this has
    been corrected.

  * Building with NO_LIBPCRE1_JIT did not disable it, which has been fixed.

  * We used to add an empty alternate object database to the system
    that does not help anything; it has been corrected.

  * Doc update around use of "format-patch --subject-prefix" etc.

  * A fix for an ancient bug in "git apply --ignore-space-change" codepath.

  * Clarify and enhance documentation for "merge-base --fork-point", as
    it was clear what it computed but not why/what for.

  * A few scripts (both in production and tests) incorrectly redirected
    their error output.  These have been corrected.

  * "git notes" sent its error message to its standard output stream,
    which was corrected.

  * The three-way merge performed by "git cherry-pick" was confused
    when a new submodule was added in the meantime, which has been
    fixed (or "papered over").

  * The sequencer machinery (used by "git cherry-pick A..B", and "git
    rebase -i", among other things) would have lost a commit if stopped
    due to an unlockable index file, which has been fixed.

  * "git apply --inaccurate-eof" when used with "--ignore-space-change"
    triggered an internal sanity check, which has been fixed.

  * Command line completion (in contrib/) has been taught about the
    "--copy" option of "git branch".

  * When "git rebase" prepared an mailbox of changes and fed it to "git
    am" to replay them, it was confused when a stray "From " happened
    to be in the log message of one of the replayed changes.  This has
    been corrected.

  * There was a recent semantic mismerge in the codepath to write out a
    section of a configuration section, which has been corrected.

  * Mentions of "git-rebase" and "git-am" (dashed form) still remained
    in end-user visible strings emitted by the "git rebase" command;
    they have been corrected.

  * Contrary to the documentation, "git pull -4/-6 other-args" did not
    ask the underlying "git fetch" to go over IPv4/IPv6, which has been
    corrected.

  * "git checkout --recursive" may overwrite and rewind the history of
    the branch that happens to be checked out in submodule
    repositories, which might not be desirable.  Detach the HEAD but
    still allow the recursive checkout to succeed in such a case.
    (merge 57f22bf997 sb/submodule-recursive-checkout-detach-head later to maint).

  * "git branch --set-upstream" has been deprecated and (sort of)
    removed, as "--set-upstream-to" is the preferred one these days.
    The documentation still had "--set-upstream" listed on its
    synopsys section, which has been corrected.
    (merge a060f3d3d8 tz/branch-doc-remove-set-upstream later to maint).

  * Internaly we use 0{40} as a placeholder object name to signal the
    codepath that there is no such object (e.g. the fast-forward check
    while "git fetch" stores a new remote-tracking ref says "we know
    there is no 'old' thing pointed at by the ref, as we are creating
    it anew" by passing 0{40} for the 'old' side), and expect that a
    codepath to locate an in-core object to return NULL as a sign that
    the object does not exist.  A look-up for an object that does not
    exist however is quite costly with a repository with large number
    of packfiles.  This access pattern has been optimized.
    (merge 87b5e236a1 jk/fewer-pack-rescan later to maint).

  * In addition to "git stash -m message", the command learned to
    accept "git stash -mmessage" form.
    (merge 5675473fcb ph/stash-save-m-option-fix later to maint).

  * Other minor doc, test and build updates and code cleanups.
    (merge 1a1fc2d5b5 rd/man-prune-progress later to maint).
    (merge 0ba014035a rd/man-reflog-add-n later to maint).
    (merge e54b63359f rd/doc-notes-prune-fix later to maint).
    (merge ff4c9b413a sp/doc-info-attributes later to maint).
	Git 2.16 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 now an error.


	Updates since v2.15
	-------------------

	UI, Workflows & Features

	* An empty string as a pathspec element that means "everything"
	i.e. 'git add ""', is now illegal. We started this by first
	deprecating and warning a pathspec that has such an element in
	2.11 (Nov 2016).

	* A hook script that is set unexecutable is simply ignored. Git
	notifies when such a file is ignored, unless the message is
	squelched via advice.ignoredHook configuration.

	* "git pull" has been taught to accept "--[no-]signoff" option and
	pass it down to "git merge".

	* The "--push-option=<string>" option to "git push" now defaults to a
	list of strings configured via push.pushOption variable.

	* "gitweb" checks if a directory is searchable with Perl's "-x"
	operator, which can be enhanced by using "filetest 'access'"
	pragma, which now we do.

	* "git stash save" has been deprecated in favour of "git stash push".

	* The set of paths output from "git status --ignored" was tied
	closely with its "--untracked=<mode>" option, but now it can be
	controlled more flexibly. Most notably, a directory that is
	ignored because it is listed to be ignored in the ignore/exclude
	mechanism can be handled differently from a directory that ends up
	to be ignored only because all files in it are ignored.

	* The remote-helper for talking to MediaWiki has been updated to
	truncate an overlong pagename so that ".mw" suffix can still be
	added.

	* The remote-helper for talking to MediaWiki has been updated to
	work with mediawiki namespaces.

	* The "--format=..." option "git for-each-ref" takes learned to show
	the name of the 'remote' repository and the ref at the remote side
	that is affected for 'upstream' and 'push' via "%(push:remotename)"
	and friends.

	* Doc and message updates to teach users "bisect view" is a synonym
	for "bisect visualize".

	* "git bisect run" that did not specify any command to run used to go
	ahead and treated all commits to be tested as 'good'. This has
	been corrected by making the command error out.

	* The SubmittingPatches document has been converted to produce an
	HTML version via AsciiDoc/Asciidoctor.

	* We learned to talk to watchman to speed up "git status" and other
	operations that need to see which paths have been modified.

	* The "diff" family of commands learned to ignore differences in
	carriage return at the end of line.

	* Places that know about "sendemail.to", like documentation and shell
	completion (in contrib/) have been taught about "sendemail.tocmd",
	too.

	* "git add --renormalize ." is a new and safer way to record the fact
	that you are correcting the end-of-line convention and other
	"convert_to_git()" glitches in the in-repository data.

	* "git branch" and "git checkout -b" are now forbidden from creating
	a branch whose name is "HEAD".

	* "git branch --list" learned to show its output through the pager by
	default when the output is going to a terminal, which is controlled
	by the pager.branch configuration variable. This is similar to a
	recent change to "git tag --list".

	* "git grep -W", "git diff -W" and their friends learned a heuristic
	to extend a pre-context beyond the line that matches the "function
	pattern" (aka "diff.*.xfuncname") to include a comment block, if
	exists, that immediately precedes it.

	* "git config --expiry-date gc.reflogexpire" can read "2.weeks" from
	the configuration and report it as a timestamp, just like "--int"
	would read "1k" and report 1024, to help consumption by scripts.

	* The shell completion (in contrib/) learned that "git pull" can take
	the "--autostash" option.


	Performance, Internal Implementation, Development Support etc.

	* An earlier update made it possible to use an on-stack in-core
	lockfile structure (as opposed to having to deliberately leak an
	on-heap one). Many codepaths have been updated to take advantage
	of this new facility.

	* Calling cmd_foo() as if it is a general purpose helper function is
	a no-no. Correct two instances of such to set an example.

	* We try to see if somebody runs our test suite with a shell that
	does not support "local" like bash/dash does.

	* An early part of piece-by-piece rewrite of "git bisect" in C.

	* GSoC to piece-by-piece rewrite "git submodule" in C.

	* Optimize the code to find shortest unique prefix of object names.

	* Pathspec-limited revision traversal was taught not to keep finding
	unneeded differences once it knows two trees are different inside
	given pathspec.

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

	* Code cleanup.

	* A single-word "unsigned flags" in the diff options is being split
	into a structure with many bitfields.

	* TravisCI build updates.

	* Parts of a test to drive the long-running content filter interface
	has been split into its own module, hopefully to eventually become
	reusable.

	* Drop (perhaps overly cautious) sanity check before using the index
	read from the filesystem at runtime.

	* The build procedure has been taught to avoid some unnecessary
	instability in the build products.

	* A new mechanism to upgrade the wire protocol in place is proposed
	and demonstrated that it works with the older versions of Git
	without harming them.

	Also contains various documentation updates and code clean-ups.


	Fixes since v2.15
	-----------------

	* "auto" as a value for the columnar output configuration ought to
	judge "is the output consumed by humans?" with the same criteria as
	"auto" for coloured output configuration, i.e. either the standard
	output stream is going to tty, or a pager is in use. We forgot the
	latter, which has been fixed.

	* The experimental "color moved lines differently in diff output"
	feature was buggy around "ignore whitespace changes" edges, which
	has been corrected.

	* Instead of using custom line comparison and hashing functions to
	implement "moved lines" coloring in the diff output, use the pair
	of these functions from lower-layer xdiff/ code.

	* Some codepaths did not check for errors when asking what branch the
	HEAD points at, which have been fixed.

	* "git commit", after making a commit, did not check for errors when
	asking on what branch it made the commit, which has been corrected.

	* "git status --ignored -u" did not stop at a working tree of a
	separate project that is embedded in an ignored directory and
	listed files in that other project, instead of just showing the
	directory itself as ignored.

	* A broken access to object databases in recent update to "git grep
	--recurse-submodules" has been fixed.

	* A recent regression in "git rebase -i" that broke execution of git
	commands from subdirectories via "exec" instruction has been fixed.

	* A (possibly flakey) test fix.

	* "git check-ref-format --branch @{-1}" bit a "BUG()" when run
	outside a repository for obvious reasons; clarify the documentation
	and make sure we do not even try to expand the at-mark magic in
	such a case, but still call the validation logic for branch names.

	* "git fetch --recurse-submodules" now knows that submodules can be
	moved around in the superproject in addition to getting updated,
	and finds the ones that need to be fetched accordingly.

	* Command line completion (in contrib/) update.

	* Description of blame.{showroot,blankboundary,showemail,date}
	configuration variables have been added to "git config --help".

	* After an error from lstat(), diff_populate_filespec() function
	sometimes still went ahead and used invalid data in struct stat,
	which has been fixed.

	* UNC paths are also relevant in Cygwin builds and they are now
	tested just like Mingw builds.

	* Correct start-up sequence so that a repository could be placed
	immediately under the root directory again (which was broken at
	around Git 2.13).

	* The credential helper for libsecret (in contrib/) has been improved
	to allow possibly prompting the end user to unlock secrets that are
	currently locked (otherwise the secrets may not be loaded).

	* MinGW updates.

	* Error checking in "git imap-send" for empty response has been
	improved.

	* Recent update to the refs infrastructure implementation started
	rewriting packed-refs file more often than before; this has been
	optimized again for most trivial cases.

	* Some error messages did not quote filenames shown in it, which have
	been fixed.

	* "git rebase -i" recently started misbehaving when a submodule that
	is configured with 'submodule.<name>.ignore' is dirty; this has
	been corrected.

	* Building with NO_LIBPCRE1_JIT did not disable it, which has been fixed.

	* We used to add an empty alternate object database to the system
	that does not help anything; it has been corrected.

	* Doc update around use of "format-patch --subject-prefix" etc.

	* A fix for an ancient bug in "git apply --ignore-space-change" codepath.

	* Clarify and enhance documentation for "merge-base --fork-point", as
	it was clear what it computed but not why/what for.

	* A few scripts (both in production and tests) incorrectly redirected
	their error output. These have been corrected.

	* "git notes" sent its error message to its standard output stream,
	which was corrected.

	* The three-way merge performed by "git cherry-pick" was confused
	when a new submodule was added in the meantime, which has been
	fixed (or "papered over").

	* The sequencer machinery (used by "git cherry-pick A..B", and "git
	rebase -i", among other things) would have lost a commit if stopped
	due to an unlockable index file, which has been fixed.

	* "git apply --inaccurate-eof" when used with "--ignore-space-change"
	triggered an internal sanity check, which has been fixed.

	* Command line completion (in contrib/) has been taught about the
	"--copy" option of "git branch".

	* When "git rebase" prepared an mailbox of changes and fed it to "git
	am" to replay them, it was confused when a stray "From " happened
	to be in the log message of one of the replayed changes. This has
	been corrected.

	* There was a recent semantic mismerge in the codepath to write out a
	section of a configuration section, which has been corrected.

	* Mentions of "git-rebase" and "git-am" (dashed form) still remained
	in end-user visible strings emitted by the "git rebase" command;
	they have been corrected.

	* Contrary to the documentation, "git pull -4/-6 other-args" did not
	ask the underlying "git fetch" to go over IPv4/IPv6, which has been
	corrected.

	* "git checkout --recursive" may overwrite and rewind the history of
	the branch that happens to be checked out in submodule
	repositories, which might not be desirable. Detach the HEAD but
	still allow the recursive checkout to succeed in such a case.
	(merge 57f22bf997 sb/submodule-recursive-checkout-detach-head later to maint).

	* "git branch --set-upstream" has been deprecated and (sort of)
	removed, as "--set-upstream-to" is the preferred one these days.
	The documentation still had "--set-upstream" listed on its
	synopsys section, which has been corrected.
	(merge a060f3d3d8 tz/branch-doc-remove-set-upstream later to maint).

	* Internaly we use 0{40} as a placeholder object name to signal the
	codepath that there is no such object (e.g. the fast-forward check
	while "git fetch" stores a new remote-tracking ref says "we know
	there is no 'old' thing pointed at by the ref, as we are creating
	it anew" by passing 0{40} for the 'old' side), and expect that a
	codepath to locate an in-core object to return NULL as a sign that
	the object does not exist. A look-up for an object that does not
	exist however is quite costly with a repository with large number
	of packfiles. This access pattern has been optimized.
	(merge 87b5e236a1 jk/fewer-pack-rescan later to maint).

	* In addition to "git stash -m message", the command learned to
	accept "git stash -mmessage" form.
	(merge 5675473fcb ph/stash-save-m-option-fix later to maint).

	* Other minor doc, test and build updates and code cleanups.
	(merge 1a1fc2d5b5 rd/man-prune-progress later to maint).
	(merge 0ba014035a rd/man-reflog-add-n later to maint).
	(merge e54b63359f rd/doc-notes-prune-fix later to maint).
	(merge ff4c9b413a sp/doc-info-attributes later to maint).