rebase -i --root: let the sequencer handle even the initial part

In this developer's earlier attempt to accelerate interactive rebases by
converting large parts from Unix shell script into portable, performant
C, the --root handling was specifically excluded (to simplify the task a
little bit; it still took over a year to get that reduced set of patches
into Git proper).

This patch ties up that loose end: now only --preserve-merges uses the
slow Unix shell script implementation to perform the interactive rebase.

As the rebase--helper reports progress to stderr (unlike the scripted
interactive rebase, which reports it to stdout, of all places), we have
to adjust a couple of tests that did not expect that for `git rebase -i
--root`.

This patch fixes -- at long last! -- the really old bug reported in
6a6bc5bdc4d (add tests for rebasing root, 2013-06-06) that rebasing with
--root *always* rewrote the root commit, even if there were no changes.

The bug still persists in --preserve-merges mode, of course, but that
mode will be deprecated as soon as the new --rebase-merges mode
stabilizes, anyway.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer: learn about the special "fake root commit" handling

When an interactive rebase wants to recreate a root commit, it
- first creates a new, empty root commit,
- checks it out,
- converts the next `pick` command so that it amends the empty root
commit

Introduce support in the sequencer to handle such an empty root commit,
by looking for the file <GIT_DIR>/rebase-merge/squash-onto; if it exists
and contains a commit name, the sequencer will compare the HEAD to said
root commit, and if identical, a new root commit will be created.

While converting scripted code into proper, portable C, we also do away
with the old "amend with an empty commit message, then cherry-pick
without committing, then amend again" dance and replace it with code
that uses the internal API properly to do exactly what we want: create a
new root commit.

To keep the implementation simple, we always spawn `git commit` to create
new root commits.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer: extract helper to update active_cache_tree

This patch extracts the code from is_index_unchanged() to initialize or
update the index' cache tree (i.e. a tree object reflecting the current
index' top-level tree).

The new helper will be used in the upcoming code to support `git rebase
-i --root` via the sequencer.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

rebase -i --rebase-merges: add a section to the man page

The --rebase-merges mode is probably not half as intuitive to use as
its inventor hopes, so let's document it some.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

rebase -i: introduce --rebase-merges=[no-]rebase-cousins

When running `git rebase --rebase-merges` non-interactively with an
ancestor of HEAD as <upstream> (or leaving the todo list unmodified),
we would ideally recreate the exact same commits as before the rebase.

However, if there are commits in the commit range <upstream>.. that do not
have <upstream> as direct ancestor (i.e. if `git log <upstream>..` would
show commits that are omitted by `git log --ancestry-path <upstream>..`),
this is currently not the case: we would turn them into commits that have
<upstream> as direct ancestor.

Let's illustrate that with a diagram:

C
/ \
A - B - E - F
\ /
D

Currently, after running `git rebase -i --rebase-merges B`, the new branch
structure would be (pay particular attention to the commit `D`):

--- C' --
/ \
A - B ------ E' - F'
\ /
D'

This is not really preserving the branch topology from before! The
reason is that the commit `D` does not have `B` as ancestor, and
therefore it gets rebased onto `B`.

This is unintuitive behavior. Even worse, when recreating branch
structure, most use cases would appear to want cousins *not* to be
rebased onto the new base commit. For example, Git for Windows (the
heaviest user of the Git garden shears, which served as the blueprint
for --rebase-merges) frequently merges branches from `next` early, and
these branches certainly do *not* want to be rebased. In the example
above, the desired outcome would look like this:

--- C' --
/ \
A - B ------ E' - F'
\ /
-- D' --

Let's introduce the term "cousins" for such commits ("D" in the
example), and let's not rebase them by default. For hypothetical
use cases where cousins *do* need to be rebased, `git rebase
--rebase=merges=rebase-cousins` needs to be used.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pull: accept --rebase=merges to recreate the branch topology

Similar to the `preserve` mode simply passing the `--preserve-merges`
option to the `rebase` command, the `merges` mode simply passes the
`--rebase-merges` option.

This will allow users to conveniently rebase non-trivial commit
topologies when pulling new commits, without flattening them.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

rebase --rebase-merges: avoid "empty merges"

The `git merge` command does not allow merging commits that are already
reachable from HEAD: `git merge HEAD^`, for example, will report that we
are already up to date and not change a thing.

In an interactive rebase, such a merge could occur previously, e.g. when
competing (or slightly modified) versions of a patch series were applied
upstream, and the user had to `git rebase --skip` all of the local
commits, and the topic branch becomes "empty" as a consequence.

Let's teach the todo command `merge` to behave the same as `git merge`.

Seeing as it requires some low-level trickery to create such merges with
Git's commands in the first place, we do not even have to bother to
introduce an option to force `merge` to create such merge commits.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer: handle post-rewrite for merge commands

In the previous patches, we implemented the basic functionality of the
`git rebase -i --rebase-merges` command, in particular the `merge`
command to create merge commits in the sequencer.

The interactive rebase is a lot more these days, though, than a simple
cherry-pick in a loop. For example, it calls the post-rewrite hook (if
any) after rebasing with a mapping of the old->new commits.

This patch implements the post-rewrite handling for the `merge` command
we just introduced. The other commands that were added recently (`label`
and `reset`) do not create new commits, therefore post-rewrite hooks do
not need to handle them.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer: make refs generated by the `label` command worktree-local

This allows for rebases to be run in parallel in separate worktrees
(think: interrupted in the middle of one rebase, being asked to perform
a different rebase, adding a separate worktree just for that job).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

rebase --rebase-merges: add test for --keep-empty

If there are empty commits on the left hand side of $upstream...HEAD
then the empty commits on the right hand side that we want to keep are
being pruned.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

rebase: introduce the --rebase-merges option

Once upon a time, this here developer thought: wouldn't it be nice if,
say, Git for Windows' patches on top of core Git could be represented as
a thicket of branches, and be rebased on top of core Git in order to
maintain a cherry-pick'able set of patch series?

The original attempt to answer this was: git rebase --preserve-merges.

However, that experiment was never intended as an interactive option,
and it only piggy-backed on git rebase --interactive because that
command's implementation looked already very, very familiar: it was
designed by the same person who designed --preserve-merges: yours truly.

Some time later, some other developer (I am looking at you, Andreas!
;-)) decided that it would be a good idea to allow --preserve-merges to
be combined with --interactive (with caveats!) and the Git maintainer
(well, the interim Git maintainer during Junio's absence, that is)
agreed, and that is when the glamor of the --preserve-merges design
started to fall apart rather quickly and unglamorously.

The reason? In --preserve-merges mode, the parents of a merge commit (or
for that matter, of *any* commit) were not stated explicitly, but were
*implied* by the commit name passed to the `pick` command.

This made it impossible, for example, to reorder commits. Not to mention
to move commits between branches or, deity forbid, to split topic branches
into two.

Alas, these shortcomings also prevented that mode (whose original
purpose was to serve Git for Windows' needs, with the additional hope
that it may be useful to others, too) from serving Git for Windows'
needs.

Five years later, when it became really untenable to have one unwieldy,
big hodge-podge patch series of partly related, partly unrelated patches
in Git for Windows that was rebased onto core Git's tags from time to
time (earning the undeserved wrath of the developer of the ill-fated
git-remote-hg series that first obsoleted Git for Windows' competing
approach, only to be abandoned without maintainer later) was really
untenable, the "Git garden shears" were born [*1*/*2*]: a script,
piggy-backing on top of the interactive rebase, that would first
determine the branch topology of the patches to be rebased, create a
pseudo todo list for further editing, transform the result into a real
todo list (making heavy use of the `exec` command to "implement" the
missing todo list commands) and finally recreate the patch series on
top of the new base commit.

That was in 2013. And it took about three weeks to come up with the
design and implement it as an out-of-tree script. Needless to say, the
implementation needed quite a few years to stabilize, all the while the
design itself proved itself sound.

With this patch, the goodness of the Git garden shears comes to `git
rebase -i` itself. Passing the `--rebase-merges` option will generate
a todo list that can be understood readily, and where it is obvious
how to reorder commits. New branches can be introduced by inserting
`label` commands and calling `merge <label>`. And once this mode will
have become stable and universally accepted, we can deprecate the design
mistake that was `--preserve-merges`.

Link *1*:
https://github.com/msysgit/msysgit/blob/master/share/msysGit/shears.sh
Link *2*:
https://github.com/git-for-windows/build-extra/blob/master/shears.sh

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

rebase-helper --make-script: introduce a flag to rebase merges

The sequencer just learned new commands intended to recreate branch
structure (similar in spirit to --preserve-merges, but with a
substantially less-broken design).

Let's allow the rebase--helper to generate todo lists making use of
these commands, triggered by the new --rebase-merges option. For a
commit topology like this (where the HEAD points to C):

- A - B - C
\ /
D

the generated todo list would look like this:

# branch D
pick 0123 A
label branch-point
pick 1234 D
label D

reset branch-point
pick 2345 B
merge -C 3456 D # C

To keep things simple, we first only implement support for merge commits
with exactly two parents, leaving support for octopus merges to a later
patch series.

All merge-rebasing todo lists start with a hard-coded `label onto` line.
This makes it convenient to refer later on to the revision onto which
everything is rebased, e.g. as starting point for branches other than
the very first one.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer: fast-forward `merge` commands, if possible

Just like with regular `pick` commands, if we are trying to rebase a
merge commit, we now test whether the parents of said commit match HEAD
and the commits to be merged, and fast-forward if possible.

This is not only faster, but also avoids unnecessary proliferation of
new objects.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer: introduce the `merge` command

This patch is part of the effort to reimplement `--preserve-merges` with
a substantially improved design, a design that has been developed in the
Git for Windows project to maintain the dozens of Windows-specific patch
series on top of upstream Git.

The previous patch implemented the `label` and `reset` commands to label
commits and to reset to labeled commits. This patch adds the `merge`
command, with the following syntax:

merge [-C <commit>] <rev> # <oneline>

The <commit> parameter in this instance is the *original* merge commit,
whose author and message will be used for the merge commit that is about
to be created.

The <rev> parameter refers to the (possibly rewritten) revision to
merge. Let's see an example of a todo list (the initial `label onto`
command is an auto-generated convenience so that the label `onto` can be
used to refer to the revision onto which we rebase):

label onto

# Branch abc
reset onto
pick deadbeef Hello, world!
label abc

reset onto
pick cafecafe And now for something completely different
merge -C baaabaaa abc # Merge the branch 'abc' into master

To edit the merge commit's message (a "reword" for merges, if you will),
use `-c` (lower-case) instead of `-C`; this convention was borrowed from
`git commit` that also supports `-c` and `-C` with similar meanings.

To create *new* merges, i.e. without copying the commit message from an
existing commit, simply omit the `-C <commit>` parameter (which will
open an editor for the merge message):

merge abc

This comes in handy when splitting a branch into two or more branches.

Note: this patch only adds support for recursive merges, to keep things
simple. Support for octopus merges will be added later in a separate
patch series, support for merges using strategies other than the
recursive merge is left for the future.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer: introduce new commands to reset the revision

In the upcoming commits, we will teach the sequencer to rebase merges.
This will be done in a very different way from the unfortunate design of
`git rebase --preserve-merges` (which does not allow for reordering
commits, or changing the branch topology).

The main idea is to introduce new todo list commands, to support
labeling the current revision with a given name, resetting the current
revision to a previous state, and merging labeled revisions.

This idea was developed in Git for Windows' Git garden shears (that are
used to maintain Git for Windows' "thicket of branches" on top of
upstream Git), and this patch is part of the effort to make it available
to a wider audience, as well as to make the entire process more robust
(by implementing it in a safe and portable language rather than a Unix
shell script).

This commit implements the commands to label, and to reset to, given
revisions. The syntax is:

label <name>
reset <name>

Internally, the `label <name>` command creates the ref
`refs/rewritten/<name>`. This makes it possible to work with the labeled
revisions interactively, or in a scripted fashion (e.g. via the todo
list command `exec`).

These temporary refs are removed upon sequencer_remove_state(), so that
even a `git rebase --abort` cleans them up.

We disallow '#' as label because that character will be used as separator
in the upcoming `merge` command.

Later in this patch series, we will mark the `refs/rewritten/` refs as
worktree-local, to allow for interactive rebases to be run in parallel in
worktrees linked to the same repository.

As typos happen, a failed `label` or `reset` command will be rescheduled
immediately. As the previous code to reschedule a command is embedded
deeply in the pick/fixup/squash code path, we simply duplicate the few
lines. This will allow us to extend the new code path easily for the
upcoming `merge` command.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-rebase--interactive: clarify arguments

Up to now each command took a commit as its first argument and ignored
the rest of the line (usually the subject of the commit)

Now that we are about to introduce commands that take different
arguments, clarify each command by giving the argument list.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer: offer helpful advice when a command was rescheduled

Previously, we did that just magically, and potentially left some users
quite puzzled. Let's err on the safe side instead, telling the user what
is happening, and how they are supposed to continue.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer: refactor how original todo list lines are accessed

Previously, we did a lot of arithmetic gymnastics to get at the line in
the todo list (as stored in todo_list.buf). This might have been fast,
but only in terms of execution speed, not in terms of developer time.

Let's refactor this to make it a lot easier to read, and hence to
reason about the correctness of the code. It is not performance-critical
code anyway.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer: make rearrange_squash() a bit more obvious

There are some commands that have to be skipped from rearranging by virtue
of not handling any commits.

However, the logic was not quite obvious: it skipped commands based on
their position in the enum todo_command.

Instead, let's make it explicit that we skip all commands that do not
handle any commit. With one exception: the `drop` command, because it,
well, drops the commit and is therefore not eligible to rearranging.

Note: this is a bit academic at the moment because the only time we call
`rearrange_squash()` is directly after generating the todo list, when we
have nothing but `pick` commands anyway.

However, the upcoming `merge` command *will* want to be handled by that
function, and it *can* handle commits.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer: avoid using errno clobbered by rollback_lock_file()

As pointed out in a review of the `--rebase-merges` patch series,
`rollback_lock_file()` clobbers errno. Therefore, we have to report the
error message that uses errno before calling said function.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The fourth batch for 2.18

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Merge branch 'jm/mem-pool'

An reusable "memory pool" implementation has been extracted from
fast-import.c, which in turn has become the first user of the
mem-pool API.

* jm/mem-pool:
mem-pool: move reusable parts of memory pool into its own file
fast-import: introduce mem_pool type
fast-import: rename mem_pool type to mp_block

Merge branch 'tg/use-git-contacts'

Doc update.

* tg/use-git-contacts:
SubmittingPatches: mention the git contacts command

Merge branch 'sb/filenames-with-dashes'

Rename bunch of source files to more consistently use dashes
instead of underscores to connect words.

* sb/filenames-with-dashes:
replace_object.c: rename to use dash in file name
sha1_file.c: rename to use dash in file name
sha1_name.c: rename to use dash in file name
exec_cmd: rename to use dash in file name
unicode_width.h: rename to use dash in file name
write_or_die.c: rename to use dashes in file name

Merge branch 'cc/perf-bisect'

Performance measuring framework in t/perf learned to help bisecting
performance regressions.

* cc/perf-bisect:
t/perf: add scripts to bisect performance regressions
perf/run: add --subsection option

Merge branch 'bp/fsmonitor-prime-index'

The index file is updated to record the fsmonitor section after a
full scan was made, to avoid wasting the effort that has already
spent.

* bp/fsmonitor-prime-index:
fsmonitor: force index write after full scan

Merge branch 'bp/fsmonitor-bufsize-fix'

Fix an unexploitable (because the oversized contents are not under
attacker's control) buffer overflow.

* bp/fsmonitor-bufsize-fix:
fsmonitor: fix incorrect buffer size when printing version number

Merge branch 'cb/bash-completion-ls-files-processing'

Shell completion (in contrib) that gives list of paths have been
optimized somewhat.

* cb/bash-completion-ls-files-processing:
completion: improve ls-files filter performance

Merge branch 'es/worktree-docs'

Doc updates.

* es/worktree-docs:
git-worktree.txt: unify command-line prompt in example blocks
git-worktree.txt: recommend 'git worktree remove' over manual deletion

Merge branch 'es/fread-reads-dir-autoconf-fix'

Small fix to the autoconf build procedure.

* es/fread-reads-dir-autoconf-fix:
configure.ac: fix botched FREAD_READS_DIRECTORIES check

Merge branch 'ps/test-chmtime-get'

Test cleanup.

* ps/test-chmtime-get:
t/helper: 'test-chmtime (--get|-g)' to print only the mtime

Merge branch 'js/t5404-path-fix'

Test fix.

* js/t5404-path-fix:
t5404: relax overzealous test

Merge branch 'jk/ref-array-push'

API clean-up aournd ref-filter code.

* jk/ref-array-push:
ref-filter: factor ref_array pushing into its own function
ref-filter: make ref_array_item allocation more consistent
ref-filter: use "struct object_id" consistently

Merge branch 'en/doc-typoes'

Docfix.

* en/doc-typoes:
Documentation: normalize spelling of 'normalised'
Documentation: fix several one-character-off spelling errors

Merge branch 'lw/daemon-log-destination'

Recent introduction of "--log-destination" option to "git daemon"
did not work well when the daemon was run under "--inetd" mode.

* lw/daemon-log-destination:
daemon.c: fix condition for redirecting stderr

Merge branch 'mn/send-email-credential-doc'

Doc update.

* mn/send-email-credential-doc:
send-email: simplify Gmail example in the documentation

Merge branch 'ak/bisect-doc-typofix'

Docfix.

* ak/bisect-doc-typofix:
Documentation/git-bisect.txt: git bisect term → git bisect terms

Merge branch 'br/mergetools-guiffy'

"git mergetools" learned talking to guiffy.

* br/mergetools-guiffy:
mergetools: add support for guiffy

Merge branch 'nd/worktree-move'

Test update.

* nd/worktree-move:
t2028: tighten grep expression to make "move worktree" test more robust

Merge branch 'ks/branch-list-detached-rebase-i'

"git branch --list" during an interrupted "rebase -i" now lets
users distinguish the case where a detached HEAD is being rebased
and a normal branch is being rebased.

* ks/branch-list-detached-rebase-i:
t3200: verify "branch --list" sanity when rebasing from detached HEAD
branch --list: print useful info whilst interactive rebasing a detached HEAD

Merge branch 'jk/t5561-missing-curl'

Test fixes.

* jk/t5561-missing-curl:
t5561: skip tests if curl is not available
t5561: drop curl stderr redirects

Merge branch 'bw/commit-partial-from-subdirectory-fix'

"cd sub/dir && git commit ../path" ought to record the changes to
the file "sub/path", but this regressed long time ago.

* bw/commit-partial-from-subdirectory-fix:
commit: allow partial commits with relative paths

Merge branch 'jk/relative-directory-fix'

Some codepaths, including the refs API, get and keep relative
paths, that go out of sync when the process does chdir(2). The
chdir-notify API is introduced to let these codepaths adjust these
cached paths to the new current directory.

* jk/relative-directory-fix:
refs: use chdir_notify to update cached relative paths
set_work_tree: use chdir_notify
add chdir-notify API
trace.c: export trace_setup_key
set_git_dir: die when setenv() fails

Merge branch 'jk/flockfile-stdio'

Code clean-up.

* jk/flockfile-stdio:
config: move flockfile() closer to unlocked functions

Merge branch 'pw/rebase-signoff'

"git rebase" has learned to honor "--signoff" option when using
backends other than "am" (but not "--preserve-merges").

* pw/rebase-signoff:
rebase --keep-empty: always use interactive rebase
rebase -p: error out if --signoff is given
rebase: extend --signoff support

Merge branch 'pw/rebase-keep-empty-fixes'

"git rebase --keep-empty" still removed an empty commit if the
other side contained an empty commit (due to the "does an
equivalent patch exist already?" check), which has been corrected.

* pw/rebase-keep-empty-fixes:
rebase: respect --no-keep-empty
rebase -i --keep-empty: don't prune empty commits
rebase --root: stop assuming squash_onto is unset

Merge branch 'cb/git-gui-ttk-style'

"git gui" has been taught to work with old versions of tk (like
8.5.7) that do not support "ttk::style theme use" as a way to query
the current theme.

* cb/git-gui-ttk-style:
git-gui: workaround ttk:style theme use

Merge branch 'bp/git-gui-bind-kp-enter'

"git gui" performs commit upon CTRL/CMD+ENTER but the
CTRL/CMD+KP_ENTER (i.e. enter key on the numpad) did not have the
same key binding. It now does.

* bp/git-gui-bind-kp-enter:
git-gui: bind CTRL/CMD+numpad ENTER to do_commit

Merge branch 'bb/git-gui-ssh-key-files'

"git gui" learned that "~/.ssh/id_ecdsa.pub" and
"~/.ssh/id_ed25519.pub" are also possible SSH key files.

* bb/git-gui-ssh-key-files:
git-gui: search for all current SSH key types

mem-pool: move reusable parts of memory pool into its own file

This moves the reusable parts of the memory pool logic used by
fast-import.c into its own file for use by other components.

Signed-off-by: Jameson Miller <jamill@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

SubmittingPatches: mention the git contacts command

Instead of just mentioning 'git blame' and 'git shortlog', which make it
quite hard for new contributors to pick out the appropriate list of
people to cc on their patch series, mention the 'git contacts' utility,
which makes it much easier to get a reasonable list of contacts for a
change.

This should help new contributors pick out a reasonable cc list by
simply using a single command.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fast-import: introduce mem_pool type

Introduce the mem_pool type which encapsulates all the information necessary to
manage a pool of memory. This change moves the existing variables in
fast-import used to support the global memory pool to use this structure. It
also renames variables that are no longer used by memory pools to reflect their
more scoped usage.

These changes allow for the multiple instances of a memory pool to
exist and be reused outside of fast-import. In a future commit the
mem_pool type will be moved to its own file.

Signed-off-by: Jameson Miller <jamill@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

fast-import: rename mem_pool type to mp_block

This is part of a patch series to extract the memory pool logic in
fast-import into a more generalized version. The existing mem_pool type
maps more closely to a "block of memory" (mp_block) in the more
generalized memory pool. This commit renames the mem_pool to mp_block to
reduce churn in future patches.

Signed-off-by: Jameson Miller <jamill@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Merge branch 'svn/authors-prog-2' of git://bogomips.org/git-svn

* 'svn/authors-prog-2' of git://bogomips.org/git-svn:
git-svn: allow empty email-address using authors-prog and authors-file
git-svn: search --authors-prog in PATH too

replace_object.c: rename to use dash in file name

This is more consistent with the project style. The majority of
Git's source files use dashes in preference to underscores in their file
names.

Noticed while adding a header corresponding to this file.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>

sha1_file.c: rename to use dash in file name

This is more consistent with the project style. The majority of Git's
source files use dashes in preference to underscores in their file names.

Signed-off-by: Stefan Beller <sbeller@google.com>

sha1_name.c: rename to use dash in file name

This is more consistent with the project style. The majority of Git's
source files use dashes in preference to underscores in their file names.

Signed-off-by: Stefan Beller <sbeller@google.com>

exec_cmd: rename to use dash in file name

This is more consistent with the project style. The majority of Git's
source files use dashes in preference to underscores in their file names.

Signed-off-by: Stefan Beller <sbeller@google.com>

unicode_width.h: rename to use dash in file name

This is more consistent with the project style. The majority of Git's
source files use dashes in preference to underscores in their file names.

Also adjust contrib/update-unicode as well.

Signed-off-by: Stefan Beller <sbeller@google.com>

write_or_die.c: rename to use dashes in file name

This is more consistent with the project style. The majority of Git's
source files use dashes in preference to underscores in their file names.

Signed-off-by: Stefan Beller <sbeller@google.com>

fsmonitor: force index write after full scan

fsmonitor currently only flags the index as dirty if the extension is being
added or removed. This is a performance optimization that recognizes you can
stat() a lot of files in less time than it takes to write out an updated index.

This patch makes a small enhancement and flags the index dirty if we end up
having to stat() all files and scan the entire working directory. The assumption
being that must be expensive or you would not have turned on the feature.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Revert "Merge branch 'en/rename-directory-detection'"

This reverts commit e4bb62fa1eeee689744b413e29a50b4d1dae6886, reversing
changes made to 468165c1d8a442994a825f3684528361727cd8c0.

The topic appears to inflict severe regression in renaming merges,
even though the promise of it was that it would improve them.

We do not yet know which exact change in the topic was wrong, but in
the meantime, let's play it safe and revert it out of 'master'
before real Git-using projects are harmed.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

fsmonitor: fix incorrect buffer size when printing version number

This is a trivial bug fix for passing the incorrect size to snprintf() when
outputting the version. It should be passing the size of the destination buffer
rather than the size of the value being printed.

Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/perf: add scripts to bisect performance regressions

The new bisect_regression script can be used to automatically bisect
performance regressions. It will pass the new bisect_run_script to
`git bisect run`.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

perf/run: add --subsection option

This new option makes it possible to run perf tests as defined
in only one subsection of a config file.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The third batch for 2.18

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Merge branch 'eb/cred-helper-ignore-sigpipe'

When credential helper exits very quickly without reading its
input, it used to cause Git to die with SIGPIPE, which has been
fixed.

* eb/cred-helper-ignore-sigpipe:
credential: ignore SIGPIPE when writing to credential helpers

Merge branch 'lv/tls-1.3'

When built with more recent cURL, GIT_SSL_VERSION can now specify
"tlsv1.3" as its value.

* lv/tls-1.3:
http: allow use of TLS 1.3

Merge branch 'pk/test-avoid-pipe-hiding-exit-status'

Test cleanup.

* pk/test-avoid-pipe-hiding-exit-status:
test: avoid pipes in git related commands for test

Merge branch 'rs/status-with-removed-submodule'

"git submodule status" misbehaved on a submodule that has been
removed from the working tree.

* rs/status-with-removed-submodule:
submodule: check for NULL return of get_submodule_ref_store()

Merge branch 'nd/combined-test-helper'

Small test-helper programs have been consolidated into a single
binary.

* nd/combined-test-helper: (36 commits)
t/helper: merge test-write-cache into test-tool
t/helper: merge test-wildmatch into test-tool
t/helper: merge test-urlmatch-normalization into test-tool
t/helper: merge test-subprocess into test-tool
t/helper: merge test-submodule-config into test-tool
t/helper: merge test-string-list into test-tool
t/helper: merge test-strcmp-offset into test-tool
t/helper: merge test-sigchain into test-tool
t/helper: merge test-sha1-array into test-tool
t/helper: merge test-scrap-cache-tree into test-tool
t/helper: merge test-run-command into test-tool
t/helper: merge test-revision-walking into test-tool
t/helper: merge test-regex into test-tool
t/helper: merge test-ref-store into test-tool
t/helper: merge test-read-cache into test-tool
t/helper: merge test-prio-queue into test-tool
t/helper: merge test-path-utils into test-tool
t/helper: merge test-online-cpus into test-tool
t/helper: merge test-mktemp into test-tool
t/helper: merge (unused) test-mergesort into test-tool
...

Merge branch 'sb/packfiles-in-repository'

Refactoring of the internal global data structure continues.

* sb/packfiles-in-repository:
packfile: keep prepare_packed_git() private
packfile: allow find_pack_entry to handle arbitrary repositories
packfile: add repository argument to find_pack_entry
packfile: allow reprepare_packed_git to handle arbitrary repositories
packfile: allow prepare_packed_git to handle arbitrary repositories
packfile: allow prepare_packed_git_one to handle arbitrary repositories
packfile: add repository argument to reprepare_packed_git
packfile: add repository argument to prepare_packed_git
packfile: add repository argument to prepare_packed_git_one
packfile: allow install_packed_git to handle arbitrary repositories
packfile: allow rearrange_packed_git to handle arbitrary repositories
packfile: allow prepare_packed_git_mru to handle arbitrary repositories

Merge branch 'sb/object-store'

Refactoring the internal global data structure to make it possible
to open multiple repositories, work with and then close them.

Rerolled by Duy on top of a separate preliminary clean-up topic.
The resulting structure of the topics looked very sensible.

* sb/object-store: (27 commits)
sha1_file: allow sha1_loose_object_info to handle arbitrary repositories
sha1_file: allow map_sha1_file to handle arbitrary repositories
sha1_file: allow map_sha1_file_1 to handle arbitrary repositories
sha1_file: allow open_sha1_file to handle arbitrary repositories
sha1_file: allow stat_sha1_file to handle arbitrary repositories
sha1_file: allow sha1_file_name to handle arbitrary repositories
sha1_file: add repository argument to sha1_loose_object_info
sha1_file: add repository argument to map_sha1_file
sha1_file: add repository argument to map_sha1_file_1
sha1_file: add repository argument to open_sha1_file
sha1_file: add repository argument to stat_sha1_file
sha1_file: add repository argument to sha1_file_name
sha1_file: allow prepare_alt_odb to handle arbitrary repositories
sha1_file: allow link_alt_odb_entries to handle arbitrary repositories
sha1_file: add repository argument to prepare_alt_odb
sha1_file: add repository argument to link_alt_odb_entries
sha1_file: add repository argument to read_info_alternates
sha1_file: add repository argument to link_alt_odb_entry
sha1_file: add raw_object_store argument to alt_odb_usable
pack: move approximate object count to object store
...

Merge branch 'jc/test-must-be-empty'

Test helper update.

* jc/test-must-be-empty:
test_must_be_empty: simplify file existence check

Merge branch 'cc/perf-aggregate-sort'

Perf-test update.

* cc/perf-aggregate-sort:
perf/aggregate: add --sort-by=regression option
perf/aggregate: add display_dir()

Merge branch 'ab/doc-hash-brokenness'

Doc updates.

* ab/doc-hash-brokenness:
doc hash-function-transition: clarify what SHAttered means
doc hash-function-transition: clarify how older gits die on NewHash

Merge branch 'bc/hash-independent-tests'

Tests that rely on the exact hardcoded values of object names have
been updated in preparation for hash function migration.

* bc/hash-independent-tests:
t2107: abstract away SHA-1-specific constants
t2101: abstract away SHA-1-specific constants
t2101: modernize test style
t2020: abstract away SHA-1 specific constants
t1507: abstract away SHA-1-specific constants
t1411: abstract away SHA-1-specific constants
t1405: sort reflog entries in a hash-independent way
t1300: abstract away SHA-1-specific constants
t1304: abstract away SHA-1-specific constants
t1011: abstract away SHA-1-specific constants

Merge branch 'ab/drop-contrib-examples'

* ab/drop-contrib-examples:
Remove contrib/examples/*

The second batch for 2.18

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Merge branch 'ys/bisect-object-id-missing-conversion-fix'

Code clean-up.

* ys/bisect-object-id-missing-conversion-fix:
bisect: use oid_to_hex() for converting object_id hashes to hex strings

Merge branch 'yk/filter-branch-non-committish-refs'

when refs that do not point at committish are given, "git
filter-branch" gave a misleading error messages. This has been
corrected.

* yk/filter-branch-non-committish-refs:
filter-branch: fix errors caused by refs that point at non-committish

Merge branch 'nd/trace-with-env'

Code cleanup.

* nd/trace-with-env:
run-command: use strbuf_addstr() for adding a string to a strbuf

Merge branch 'nd/parseopt-completion-more'

The mechanism to use parse-options API to automate the command line
completion continues to get extended and polished.

* nd/parseopt-completion-more:
completion: use __gitcomp_builtin in _git_cherry
completion: use __gitcomp_builtin in _git_ls_tree
completion: delete option-only completion commands
completion: add --option completion for most builtin commands
completion: factor out _git_xxx calling code
completion: mention the oldest version we need to support
git.c: add hidden option --list-parseopt-builtins
git.c: move cmd_struct declaration up

Merge branch 'ds/bsearch-hash'

Code to find the length to uniquely abbreviate object names based
on packfile content, which is a relatively recent addtion, has been
optimized to use the same fan-out table.

* ds/bsearch-hash:
sha1_name: use bsearch_pack() in unique_in_pack()
sha1_name: use bsearch_pack() for abbreviations
packfile: define and use bsearch_pack()
sha1_name: convert struct min_abbrev_data to object_id

Merge branch 'ws/rebase-p'

Code clean-up.

* ws/rebase-p:
rebase: remove merges_option and a blank line
rebase: remove unused code paths from git_rebase__interactive__preserve_merges
rebase: remove unused code paths from git_rebase__interactive
rebase: add and use git_rebase__interactive__preserve_merges
rebase: extract functions out of git_rebase__interactive
rebase: reindent function git_rebase__interactive
rebase: update invocation of rebase dot-sourced scripts
rebase-interactive: simplify pick_on_preserving_merges

Merge branch 'jk/diff-highlight-graph-fix'

"diff-highlight" filter (in contrib/) learned to undertand "git log
--graph" output better.

* jk/diff-highlight-graph-fix:
diff-highlight: detect --graph by indent
diff-highlight: use flush() helper consistently
diff-highlight: test graphs with --color
diff-highlight: test interleaved parallel lines of history
diff-highlight: prefer "echo" to "cat" in tests
diff-highlight: use test_tick in graph test
diff-highlight: correct test graph diagram

Merge branch 'nd/remove-ignore-env-field'

Code clean-up for the "repository" abstraction.

* nd/remove-ignore-env-field:
repository.h: add comment and clarify repo_set_gitdir
repository: delete ignore_env member
sha1_file.c: move delayed getenv(altdb) back to setup_git_env()
repository.c: delete dead functions
repository.c: move env-related setup code back to environment.c
repository: initialize the_repository in main()

Merge branch 'ps/contains-id-error-message'

"git tag --contains no-such-commit" gave a full list of options
after giving an error message.

* ps/contains-id-error-message:
parse-options: do not show usage upon invalid option value

completion: improve ls-files filter performance

From the output of ls-files, we remove all but the leftmost path
component and then we eliminate duplicates. We do this in a while loop,
which is a performance bottleneck when the number of iterations is large
(e.g. for 60000 files in linux.git).

$ COMP_WORDS=(git status -- ar) COMP_CWORD=3; time _git

real 0m11.876s
user 0m4.685s
sys 0m6.808s

Replacing the loop with the cut command improves performance
significantly:

$ COMP_WORDS=(git status -- ar) COMP_CWORD=3; time _git

real 0m1.372s
user 0m0.263s
sys 0m0.167s

The measurements were done with Msys2 bash, which is used by Git for
Windows.

When filtering the ls-files output we take care not to touch absolute
paths. This is redundant, because ls-files will never output absolute
paths. Remove the unnecessary operations.

The issue was reported here:
https://github.com/git-for-windows/git/issues/1533

Signed-off-by: Clemens Buchacher <drizzd@gmx.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The first batch for 2.18 cycle

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Merge branch 'tg/stash-untracked-with-pathspec-fix'

"git stash push -u -- <pathspec>" gave an unnecessary and confusing
error message when there was no tracked files that match the
<pathspec>, which has been fixed.

* tg/stash-untracked-with-pathspec-fix:
stash: drop superfluos pathspec parameter
stash push -u: don't create empty stash
stash push: avoid printing errors
stash: fix nonsense pipeline

Merge branch 'nd/worktree-prune'

The way "git worktree prune" worked internally has been simplified,
by assuming how "git worktree move" moves an existing worktree to a
different place.

* nd/worktree-prune:
worktree prune: improve prune logic when worktree is moved
worktree: delete dead code
gc.txt: more details about what gc does

Merge branch 'bc/object-id'

Conversion from uchar[20] to struct object_id continues.

* bc/object-id: (36 commits)
convert: convert to struct object_id
sha1_file: introduce a constant for max header length
Convert lookup_replace_object to struct object_id
sha1_file: convert read_sha1_file to struct object_id
sha1_file: convert read_object_with_reference to object_id
tree-walk: convert tree entry functions to object_id
streaming: convert istream internals to struct object_id
tree-walk: convert get_tree_entry_follow_symlinks internals to object_id
builtin/notes: convert static functions to object_id
builtin/fmt-merge-msg: convert remaining code to object_id
sha1_file: convert sha1_object_info* to object_id
Convert remaining callers of sha1_object_info_extended to object_id
packfile: convert unpack_entry to struct object_id
sha1_file: convert retry_bad_packed_offset to struct object_id
sha1_file: convert assert_sha1_type to object_id
builtin/mktree: convert to struct object_id
streaming: convert open_istream to use struct object_id
sha1_file: convert check_sha1_signature to struct object_id
sha1_file: convert read_loose_object to use struct object_id
builtin/index-pack: convert struct ref_delta_entry to object_id
...

Merge branch 'ma/shortlog-revparse'

"git shortlog cruft" aborted with a BUG message when run outside a
Git repository. The command has been taught to complain about
extra and unwanted arguments on its command line instead in such a
case.

* ma/shortlog-revparse:
shortlog: disallow left-over arguments outside repo
shortlog: add usage-string for stdin-reading
git-shortlog.txt: reorder usages

Merge branch 'ab/install-symlinks'

The build procedure learned to optionally use symbolic links
(instead of hardlinks and copies) to install "git-foo" for built-in
commands, whose binaries are all identical.

* ab/install-symlinks:
Makefile: optionally symlink libexec/git-core binaries to bin/git
Makefile: add a gitexecdir_relative variable
Makefile: fix broken bindir_relative variable

Merge branch 'ml/filter-branch-no-op-error'

"git filter-branch" learned to use a different exit code to allow
the callers to tell the case where there was no new commits to
rewrite from other error cases.

* ml/filter-branch-no-op-error:
filter-branch: return 2 when nothing to rewrite

Merge branch 'ab/pcre-v2'

Git can be built to use either v1 or v2 of the PCRE library, and so
far, the build-time configuration USE_LIBPCRE=YesPlease instructed
the build procedure to use v1, but now it means v2. USE_LIBPCRE1
and USE_LIBPCRE2 can be used to explicitly choose which version to
use, as before.

* ab/pcre-v2:
Makefile: make USE_LIBPCRE=YesPlease mean v2, not v1
configure: detect redundant --with-libpcre & --with-libpcre1
configure: fix a regression in PCRE v1 detection

Merge branch 'ti/fetch-everything-local-optim'

A "git fetch" from a repository with insane number of refs into a
repository that is already up-to-date still wasted too many cycles
making many lstat(2) calls to see if these objects at the tips
exist as loose objects locally. These lstat(2) calls are optimized
away by enumerating all loose objects beforehand.

It is unknown if the new strategy negatively affects existing use
cases, fetching into a repository with many loose objects from a
repository with small number of refs.

* ti/fetch-everything-local-optim:
fetch-pack.c: use oidset to check existence of loose object

Merge branch 'en/rename-directory-detection'

Rename detection logic in "diff" family that is used in "merge" has
learned to guess when all of x/a, x/b and x/c have moved to z/a,
z/b and z/c, it is likely that x/d added in the meantime would also
want to move to z/d by taking the hint that the entire directory
'x' moved to 'z'. A bug causing dirty files involved in a rename
to be overwritten during merge has also been fixed as part of this
work.

* en/rename-directory-detection: (29 commits)
merge-recursive: ensure we write updates for directory-renamed file
merge-recursive: avoid spurious rename/rename conflict from dir renames
directory rename detection: new testcases showcasing a pair of bugs
merge-recursive: fix remaining directory rename + dirty overwrite cases
merge-recursive: fix overwriting dirty files involved in renames
merge-recursive: avoid clobbering untracked files with directory renames
merge-recursive: apply necessary modifications for directory renames
merge-recursive: when comparing files, don't include trees
merge-recursive: check for file level conflicts then get new name
merge-recursive: add computation of collisions due to dir rename & merging
merge-recursive: check for directory level conflicts
merge-recursive: add get_directory_renames()
merge-recursive: make a helper function for cleanup for handle_renames
merge-recursive: split out code for determining diff_filepairs
merge-recursive: make !o->detect_rename codepath more obvious
merge-recursive: fix leaks of allocated renames and diff_filepairs
merge-recursive: introduce new functions to handle rename logic
merge-recursive: move the get_renames() function
directory rename detection: tests for handling overwriting dirty files
directory rename detection: tests for handling overwriting untracked files
...

configure.ac: fix botched FREAD_READS_DIRECTORIES check

3adf9fdecf (configure.ac: loosen FREAD_READS_DIRECTORIES test program,
2017-06-14) broke the test program for the FREAD_READS_DIRECTORIES check
by making it syntactically invalid (a dangling ")") and by botching the
type returned from 'main' (a FILE* rather than int). As a consequence,
the test program won't even compile, thus the check fails
unconditionally. Fix these problems.

Reported-by: Jonathan Primrose <jprimros@gmail.com>
Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>