branch: introduce --set-upstream-to

The existing --set-uptream option can cause confusion, as it uses the
usual branch convention of assuming a starting point of HEAD if none
is specified, causing

    git branch --set-upstream origin/master

to create a new local branch 'origin/master' that tracks the current
branch. As --set-upstream already exists, we can't simply change its
behaviour. To work around this, introduce --set-upstream-to which
accepts a compulsory argument indicating what the new upstream branch
should be and one optinal argument indicating which branch to change,
defaulting to HEAD.

The new options allows us to type

    git branch --set-upstream-to origin/master

to set the current branch's upstream to be origin's master.

Signed-off-by: Carlos Martín Nieto <cmn@elego.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
contrib: add credential helper for GnomeKeyring

With this installed in your $PATH, you can store
git-over-http passwords in your keyring by doing:

git config credential.helper gnome-keyring

The code is based in large part on the work of John Szakmeister
who wrote the helper originally for the initial, unpublished
version of the credential helper protocol.

This version will pass t0303 if you do:

  GIT_TEST_CREDENTIAL_HELPER=gnome-keyring \
  ./t0303-credential-external.sh

Signed-off-by: Philipp A. Hartmann <pah@qo.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
in_merge_bases(): support only one "other" commit

In early days of its life, I planned to make it possible to compute
"is a commit contained in all of these other commits?" with this
function, but it turned out that no caller needed it.

Just make it take two commit objects and add a comment to say what
these two functions do.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
receive-pack: use in_merge_bases() for fast-forward check

The original computed merge-base between the old commit and the new
commit and checked if the old commit was a merge base between them,
in order to make sure we are fast-forwarding.

Instead, call in_merge_bases(old, new) which does the same.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
http-push: use in_merge_bases() for fast-forward check

The original computed merge-base between HEAD and the remote ref and
checked if the remote ref is a merge base between them, in order to
make sure that we are fast-forwarding.

Instead, call in_merge_bases(remote, HEAD) which does the same.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
in_merge_bases(): omit unnecessary redundant common ancestor reduction

The function get_merge_bases() needs to postprocess the result from
merge_bases_many() in order to make sure none of the commit is a
true ancestor of another commit, which is expensive.  However, when
checking if a commit is an ancestor of another commit, we only need
to see if the commit is a common ancestor between the two, and do
not have to care if other common ancestors merge_bases_many() finds
are true merge bases or an ancestor of another merge base.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
log: fix --quiet synonym for -s

Originally the "--quiet" option was parsed by the
diff-option parser into the internal QUICK option. This had
the effect of silencing diff output from the log (which was
not intended, but happened to work and people started to
use it). But it also had other odd side effects at the diff
level (for example, it would suppress the second commit in
"git show A B").

To fix this, commit 1c40c36 converted log to parse-options
and handled the "quiet" option separately, not passing it
on to the diff code. However, it simply ignored the option,
which was a regression for people using it as a synonym for
"-s". Commit 01771a8 then fixed that by interpreting the
option to add DIFF_FORMAT_NO_OUTPUT to the list of output
formats.

However, that commit did not fix it in all cases. It sets
the flag after setup_revisions is called. Naively, this
makes sense because you would expect the setup_revisions
parser to overwrite our output format flag if "-p" or
another output format flag is seen.

However, that is not how the NO_OUTPUT flag works. We
actually store it in the bit-field as just another format.
At the end of setup_revisions, we call diff_setup_done,
which post-processes the bitfield and clears any other
formats if we have set NO_OUTPUT. By setting the flag after
setup_revisions is done, diff_setup_done does not have a
chance to make this tweak, and we end up with other format
options still set.

As a result, the flag would have no effect in "git log -p
--quiet" or "git show --quiet".  Fix it by setting the
format flag before the call to setup_revisions.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
branch: add --unset-upstream option

We have ways of setting the upstream information, but if we want to
unset it, we need to resort to modifying the configuration manually.

Teach branch an --unset-upstream option that unsets this information.

Signed-off-by: Carlos Martín Nieto <cmn@elego.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
branch: deprecate --set-upstream and show help if we detect possible mistaken use

This interface is error prone, and a better one (--set-upstream-to)
exists. Add a message listing the alternatives and suggest how to fix
a --set-upstream invocation in case the user only gives one argument
which causes a local branch with the same name as a remote-tracking
one to be created. The typical case is

    git branch --set-upstream origin/master

when the user meant

    git branch --set-upstream master origin/master

assuming that the current branch is master. Show a message telling the
user how to undo their action and get what they wanted. For the
command above, the message would be

The --set-upstream flag is deprecated and will be removed. Consider using --track or --set-upstream-to
Branch origin/master set up to track local branch master.

If you wanted to make 'master' track 'origin/master', do this:

    git branch -d origin/master
    git branch --set-upstream-to origin/master

Signed-off-by: Carlos Martín Nieto <cmn@elego.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
teach log --no-walk=unsorted, which avoids sorting

When 'git log' is passed the --no-walk option, no revision walk takes
place, naturally. Perhaps somewhat surprisingly, however, the provided
revisions still get sorted by commit date. So e.g 'git log --no-walk
HEAD HEAD~1' and 'git log --no-walk HEAD~1 HEAD' give the same result
(unless the two revisions share the commit date, in which case they
will retain the order given on the command line). As the commit that
introduced --no-walk (8e64006 (Teach revision machinery about
--no-walk, 2007-07-24)) points out, the sorting is intentional, to
allow things like

 git log --abbrev-commit --pretty=oneline --decorate --all --no-walk

to show all refs in order by commit date.

But there are also other cases where the sorting is not wanted, such
as

 <command producing revisions in order> |
       git log --oneline --no-walk --stdin

To accomodate both cases, leave the decision of whether or not to sort
up to the caller, by allowing --no-walk={sorted,unsorted}, defaulting
to 'sorted' for backward-compatibility reasons.

Signed-off-by: Martin von Zweigbergk <martinvonz@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
demonstrate broken 'git cherry-pick three one two'

Cherry-picking commits out of order (w.r.t. commit time stamp) doesn't
currently work. Add a test case to demonstrate it.

Signed-off-by: Martin von Zweigbergk <martinvonz@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
cherry-pick/revert: respect order of revisions to pick

When giving multiple individual revisions to cherry-pick or revert, as
in 'git cherry-pick A B' or 'git revert B A', one would expect them to
be picked/reverted in the order given on the command line. They are
instead ordered by their commit timestamp -- in chronological order
for "cherry-pick" and in reverse chronological order for
"revert". This matches the order in which one would usually give them
on the command line, making this bug somewhat hard to notice. Still,
it has been reported at least once before [1].

It seems like the chronological sorting happened by accident because
the revision walker has traditionally always sorted commits in reverse
chronological order when rev_info.no_walk was enabled. In the case of
'git revert B A' where B is newer than A, this sorting is a no-op. For
'git cherry-pick A B', the sorting would reverse the arguments, but
because the sequencer also flips the rev_info.reverse flag when
picking (as opposed to reverting), the end result is a chronological
order. The rev_info.reverse flag was probably flipped so that the
revision walker emits B before C in 'git cherry-pick A..C'; that it
happened to effectively undo the unexpected sorting done when not
walking, was probably a coincidence that allowed this bug to happen at
all.

Fix the bug by telling the revision walker not to sort the commits
when not walking. The only case we want to reverse the order is now
when cherry-picking and walking revisions (rev_info.no_walk = 0).

 [1] http://thread.gmane.org/gmane.comp.version-control.git/164794

Signed-off-by: Martin von Zweigbergk <martinvonz@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
merge_bases_many(): split out the logic to paint history

Introduce a new helper function paint_down_to_common() that takes
the same parameters as merge_bases_many(), but without the first
optimization of not painting anything when "one" is one of the
"twos" (or vice versa), and the last clean-up of removing the common
ancestor that is known to be an ancestor of another common one.

This way, the caller of the new function could tell if "one" is
reachable from any of the "twos" by simply looking at the flag bits
of "one".  If (and only if) it is painted in PARENT2, it is
reachable from one of the "twos".

Signed-off-by: Junio C Hamano <gitster@pobox.com>
in_merge_bases(): use paint_down_to_common()

With paint_down_to_common(), we can tell if "commit" is reachable
from "reference" by simply looking at its object flag, instead of
iterating over the merge bases.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
get_merge_bases_many(): walk from many tips in parallel

The get_merge_bases_many() function reduces the result returned by
the merge_bases_many() function, which is a set of possible merge
bases, by excluding commits that can be reached from other commits.
We used to do N*(N-1) traversals for this, but we can check if one
commit reaches which other (N-1) commits by a single traversal, and
repeat it for all the candidates to find the answer.

Introduce remove_redundant() helper function to do this painting; we
should be able to use it to reimplement reduce_heads() as well.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
merge-base: "--is-ancestor A B"

In many scripted Porcelain commands, we find this idiom:

    if test "$(git rev-parse --verify A)" = "$(git merge-base A B)"
    then
    	... A is an ancestor of B ...
    fi

But you do not have to compute exact merge-base only to see if A is
an ancestor of B.  Give them a more direct way to use the underlying
machinery.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
reduce_heads(): reimplement on top of remove_redundant()

This is used by "git merge" and "git merge-base --independent" but
used to use a similar N*(N-1) traversals to reject commits that are
ancestors of other commits.

Reimplement it on top of remove_redundant().  Note that the callers
of this function are allowed to pass the same commit more than once,
but remove_redundant() is designed to be fed each commit only once.
The function removes duplicates before calling remove_redundant().

Signed-off-by: Junio C Hamano <gitster@pobox.com>
i18n: mark more index-pack strings for translation

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'jk/maint-quiet-is-synonym-to-s-in-log' into next

We tried to bend backwards to allow "--quiet" to be a synonym as
"-s" when given as e.g. "git show --quiet", but did not quite
succeed.

* jk/maint-quiet-is-synonym-to-s-in-log:
  log: fix --quiet synonym for -s
Merge branch 'ph/credential-gnome-keyring' into next

Add Gnome keyring support to the credential subsystem.

* ph/credential-gnome-keyring:
  contrib: add credential helper for GnomeKeyring