A bit more leftover clean-up to deprepcate "rebase -p".

* js/rebase-deprecate-preserve-merges:
  rebase docs: recommend `-r` over `-p`
  docs: say that `--rebase=preserve` is deprecated
  tests: mark a couple more test cases as requiring `rebase -p`

Rename environment variables that are used to control the "trace2"
mechanism to a more readable name.

* sg/trace2-rename:
  trace2: document the supported values of GIT_TRACE2* env variables
  trace2: rename environment variables to GIT_TRACE2*

* jh/trace2:
  trace2: fix tracing when NO_PTHREADS is defined

A brown-paper-bag bugfix to a change already in 'master'.

* nd/diff-parseopt:
  parse-options: check empty value in OPT_INTEGER and OPT_ABBREV
  diff-parseopt: restore -U (no argument) behavior
  diff-parseopt: correct variable types that are used by parseopt

When parsing the argument for OPT_INTEGER and OPT_ABBREV, we check if we
can parse the entire argument to a number with "if (*s)". There is one
missing check: if "arg" is empty to begin with, we fail to notice.

This could happen with long option by writing like

  git diff --inter-hunk-context= blah blah

Before 16ed6c97 (diff-parseopt: convert --inter-hunk-context,
2019-03-24), --inter-hunk-context is handled by a custom parser
opt_arg() and does detect this correctly.

This restores the bahvior for --inter-hunk-context and make sure all
other integer options are handled the same (sane) way. For OPT_ABBREV
this is new behavior. But it makes it consistent with the rest.

PS. OPT_MAGNITUDE has similar code but git_parse_ulong() does detect
empty "arg". So it's good to go.
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Before d473e2e0 (diff.c: convert -U|--unified, 2019-01-27), -U and
--unified are implemented with a custom parser opt_arg() in diff.c. I
didn't check this code carefully and not realize that it's the
equivalent of PARSE_OPT_NONEG | PARSE_OPT_OPTARG.

In other words, if -U is specified without any argument, the option
should be accepted, and the default value should be used. Without
PARSE_OPT_OPTARG, parse_options() will reject this case and cause a
regression.
Reported-by: NBryan Turner <bturner@atlassian.com>
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Most number-related OPT_ macros store the value in an 'int'
variable. Many of the variables in 'struct diff_options' have a
different type, but during the conversion to using parse_options() I
failed to notice and correct.

The problem was reported on s360x which is a big-endian
architechture. The variable to store '-w' option in this case is
xdl_opts, 'long' type, 8 bytes. But since parse_options() assumes
'int' (4 bytes), it will store bits in the wrong part of xdl_opts. The
problem was found on little-endian platforms because parse_options()
will accidentally store at the right part of xdl_opts.

There aren't much to say about the type change (except that 'int' for
xdl_opts should still be big enough, since Windows' long is the same
size as 'int' and nobody has complained so far). Some safety checks may
be implemented in the future to prevent class of bugs.
Reported-by: NTodd Zullinger <tmz@pobox.com>
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The `--preserve-merges` option is now deprecated in favor of
`--rebase-merges`; Let's stop recommending the former.
Signed-off-by: NJohannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

As of Git v2.22.0, the `--preserve-merges` backend of `git rebase` will
be officially deprecated in favor of the `--rebase-merges` backend.
Consequently, `git pull --rebase=preserve` will also be deprected. State
this explicitly.
Signed-off-by: NJohannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The `--preserve-merges` option has been deprecated, and as a consequence
we started to mark test cases that require that option to be supported,
in preparation for removing that support eventually.

Since we marked those test cases, a couple more crept into the test
suite, and with this patch, we mark them, too.
Signed-off-by: NJohannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Teach trace2 TLS code to not rely on pthread_getspecific() when NO_PTHREADS
is defined.  Instead, always assume the context data of the main thread.
Signed-off-by: NJeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The descriptions of the GIT_TRACE2* environment variables link to the
technical docs for further details on the supported values.  However,
a link like this only really works if the docs are viewed in a browser
and the full documentation is available.  OTOH, in 'man git' there are
no links to conveniently click on, and distro-shipped git packages
tend to include only the man pages, while the technical docs and the
docs in html format are in a separate 'git-doc' package.

So let's describe the supported values to make the manpage more
self-contained, but still keep the references to the technical docs
because the details of the SID, and the JSON and perf output formats
are definitely beyond the scope of 'man git'.
Signed-off-by: NSZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

For an environment variable that is supposed to be set by users, the
GIT_TR2* env vars are just too unclear, inconsistent, and ugly.

Most of the established GIT_* environment variables don't use
abbreviations, and in case of the few that do (GIT_DIR,
GIT_COMMON_DIR, GIT_DIFF_OPTS) it's quite obvious what the
abbreviations (DIR and OPTS) stand for.  But what does TR stand for?
Track, traditional, trailer, transaction, transfer, transformation,
transition, translation, transplant, transport, traversal, tree,
trigger, truncate, trust, or ...?!

The trace2 facility, as the '2' suffix in its name suggests, is
supposed to eventually supercede Git's original trace facility.  It's
reasonable to expect that the corresponding environment variables
follow suit, and after the original GIT_TRACE variables they are
called GIT_TRACE2; there is no such thing is 'GIT_TR'.

All trace2-specific config variables are, very sensibly, in the
'trace2' section, not in 'tr2'.

OTOH, we don't gain anything at all by omitting the last three
characters of "trace" from the names of these environment variables.

So let's rename all GIT_TR2* environment variables to GIT_TRACE2*,
before they make their way into a stable release.
Signed-off-by: NSZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

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

The "--dir-diff" mode of "git difftool" is not useful in "--no-index"
mode; they are now explicitly marked as mutually incompatible.

* js/difftool-no-index:
  difftool --no-index: error out on --dir-diff (and don't crash)

The codepath to parse :<path> that obtains the object name for an
indexed object has been made more robust.

* jk/get-oid-indexed-object-name:
  get_oid: handle NULL repo->index

Code clean-up.

* jc/set-packet-header-signature-fix:
  pkt-line: drop 'const'-ness of a param to set_packet_header()

Code clean-up.

* cb/http-push-null-in-message-fix:
  http-push: prevent format overflow warning with gcc >= 9

Doc update.

* js/stash-in-c-use-builtin-doc:
  stash: document stash.useBuiltin

A prerequiste check in the test suite to see if a working jgit is
available was made more robust.

* tz/test-lib-check-working-jgit:
  test-lib: try harder to ensure a working jgit

Code clean-up.

* js/parseopt-unknown-cb-returns-an-enum:
  parse-options: adjust `parse_opt_unknown_cb()`s declared return type

Update collision-detecting SHA-1 code to build properly on HP-UX.

* ab/sha1dc:
  sha1dc: update from upstream

"git status" did not know that the "label" instruction in the
todo-list "rebase -i -r" uses should not be shown as a hex object
name.

* js/rebase-i-label-shown-in-status-fix:
  status: fix display of rebase -ir's `label` command

Developer support update.

* es/check-non-portable-pre-5.10:
  check-non-portable-shell: support Perl versions older than 5.10

Doc update.

* ds/trace2-document-env-vars:
  trace2: add variable description to git.txt

The fsmonitor interface got out of sync after the in-core index
file gets discarded, which has been corrected.

* js/fsmonitor-refresh-after-discarding-index:
  fsmonitor: force a refresh after the index was discarded
  fsmonitor: demonstrate that it is not refreshed after discard_index()

A stale in-code comment has been updated.

* cm/notes-comment-fix:
  notes: correct documentation of format_display_notes()

Code cleanup.

* tt/no-ipv6-fallback-for-winxp:
  mingw: remove obsolete IPv6-related code

An additional test for MinGW

* js/t5580-unc-alternate-test:
  t5580: verify that alternates can be UNC paths

"git cvsexportcommit" running on msys did not expect cvsnt showed
"cvs status" output with CRLF line endings.

* ds/cvsexportcommit-force-text:
  cvsexportcommit: force crlf translation

To run tests for Git SVN, our scripts for CI used to install the
git-svn package (in the hope that it would bring in the right
dependencies).  This has been updated to install the more direct
dependency, namely, libsvn-perl.

* sg/ci-libsvn-perl:
  ci: install 'libsvn-perl' instead of 'git-svn'

Avoid patterns to pipe output from a git command to feed another
command in tests.

* bl/t4253-exit-code-from-format-patch:
  t4253-am-keep-cr-dos: avoid using pipes

The code to generate the multi-pack idx file was not prepared to
see too many packfiles and ran out of open file descriptor, which
has been corrected.

* ds/midx-too-many-packs:
  midx: add packs to packed_git linked list
  midx: pass a repository pointer

On a filesystem like HFS+, the names of the refs stored as filesystem
entities may become different from what the end-user expects, just
like files in the working tree get "renamed".  Work around the
mismatch by paying attention to the core.precomposeUnicode
configuration.

* en/unicode-in-refnames:
  Honor core.precomposeUnicode in more places

Update "git difftool" and "git mergetool" so that the combinations
of {diff,merge}.{tool,guitool} configuration variables serve as
fallback settings of each other in a sensible order.

* dl/difftool-mergetool:
  difftool: fallback on merge.guitool
  difftool: make --gui, --tool and --extcmd mutually exclusive
  mergetool: fallback to tool when guitool unavailable
  mergetool--lib: create gui_mode function
  mergetool: use get_merge_tool function
  t7610: add mergetool --gui tests
  t7610: unsuppress output

A pair of private functions in http.c that had names similar to
fread/fwrite did not return the number of elements, which was found
to be confusing.

* mh/http-fread-api-fix:
  Make fread/fwrite-like functions in http.c more like fread/fwrite.

Future-proof a test against an update to MSYS2 runtime v3.x series.

* js/t6500-use-windows-pid-on-mingw:
  t6500(mingw): use the Windows PID of the shell

Allow tests that involve httpd to be run under leak sanitizer, just
like we can already do so under address sanitizer.

* jk/apache-lsan:
  t/lib-httpd: pass LSAN_OPTIONS through apache

Attempt to use an abbreviated option in "git clone --recurs" is
responded by a request to disambiguate between --recursive and
--recurse-submodules, which is bad because these two are synonyms.
The parse-options API has been extended to define such synonyms
more easily and not produce an unnecessary failure.

* nd/parse-options-aliases:
  parse-options: don't emit "ambiguous option" for aliases

"git branch new A...B" and "git checkout -b new A...B" have been
taught that in their contexts, the notation A...B means "the merge
base between these two commits", just like "git checkout A...B"
detaches HEAD at that commit.

* dl/branch-from-3dot-merge-base:
  branch: make create_branch accept a merge base rev
  t2018: cleanup in current test