It's an easy mistake to add a repository inside another
repository, like:

  git clone $url
  git add .

The resulting entry is a gitlink, but there's no matching
.gitmodules entry. Trying to use "submodule init" (or clone
with --recursive) doesn't do anything useful. Prior to
v2.13, such an entry caused git-submodule to barf entirely.
In v2.13, the entry is considered "inactive" and quietly
ignored. Either way, no clone of your repository can do
anything useful with the gitlink without the user manually
adding the submodule config.

In most cases, the user probably meant to either add a real
submodule, or they forgot to put the embedded repository in
their .gitignore file.

Let's issue a warning when we see this case. There are a few
things to note:

  - the warning will go in the git-add porcelain; anybody
    wanting to do low-level manipulation of the index is
    welcome to create whatever funny states they want.

  - we detect the case by looking for a newly added gitlink;
    updates via "git add submodule" are perfectly reasonable,
    and this avoids us having to investigate .gitmodules
    entirely

  - there's a command-line option to suppress the warning.
    This is needed for git-submodule itself (which adds the
    entry before adding any submodule config), but also
    provides a mechanism for other scripts doing
    submodule-like things.

We could make this a hard error instead of a warning.
However, we do add lots of sub-repos in our test suite. It's
not _wrong_ to do so. It just creates a state where users
may be surprised. Pointing them in the right direction with
a gentle hint is probably the best option.

There is a config knob that can disable the (long) hint. But
I intentionally omitted a config knob to disable the warning
entirely. Whether the warning is sensible or not is
generally about context, not about the user's preferences.
If there's a tool or workflow that adds gitlinks without
matching .gitmodules, it should probably be taught about the
new command-line option, rather than blanket-disabling the
warning.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Since d38a30d (Be more user-friendly when refusing to do something
because of conflict., 2010-01-12), git-pull will error out with
user-friendly advices if the user is in the middle of a merge or has
unmerged files.

Re-implement this behavior. While the "has unmerged files" case can be
handled by die_resolve_conflict(), we introduce a new function
die_conclude_merge() for printing a different error message for when
there are no unmerged files but the merge has not been finished.

Signed-off-by: Paul Tan <pyokagan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Finally update the "git push" default behaviour to "simple".

Use the function attributes extension to catch mistakes in use of
our own variadic functions that use NULL sentinel at the end
(i.e. like execl(3)) and format strings (i.e. like printf(3)).

* jk/gcc-function-attributes:
  Add the LAST_ARG_MUST_BE_NULL macro
  wt-status: use "format" function attribute for status_printf
  use "sentinel" function attribute for variadic lists
  add missing "format" function attributes

For most of our functions that take printf-like formats, we
use gcc's __attribute__((format)) to get compiler warnings
when the functions are misused. Let's give a few more
functions the same protection.

In most cases, the annotations do not uncover any actual
bugs; the only code change needed is that we passed a size_t
to transfer_debug, which expected an int. Since we expect
the passed-in value to be a relatively small buffer size
(and cast a similar value to int directly below), we can
just cast away the problem.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Give a single message followed by list of paths from "git rm" to
report multiple paths that cannot be removed.

* mm/rm-coalesce-errors:
  rm: introduce advice.rmHints to shorten messages
  rm: better error message on failure for multiple files

We promised to change the behaviour of lazy "git push [there]" that
does not say what to push on the command line from "matching" to
"simple" in Git 2.0.

This finally flips that bit.

Helped-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Introduce advice.rmHints to choose whether to display advice or not
when git rm fails. Defaults to true, in order to preserve current behavior.

As an example, the message:
	error: 'foo.txt' has changes staged in the index
	(use --cached to keep the file, or -f to force removal)

would look like, with advice.rmHints=false:
	error: 'foo.txt' has changes staged in the index

Signed-off-by: Mathieu Lienard--Mayor <Mathieu.Lienard--Mayor@ensimag.imag.fr>
Signed-off-by: Jorge Juan Garcia Garcia <Jorge-Juan.Garcia-Garcia@ensimag.imag.fr>
Signed-off-by: Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

"git cmd <name>", when <name> happens to be a 40-hex string,
directly uses the 40-hex string as an object name, even if a ref
"refs/<some hierarchy>/<name>" exists.  This disambiguation order
is unlikely to change, but we should warn about the ambiguity just
like we warn when more than one refs/ hierachies share the same
name.

* nd/warn-ambiguous-object-name:
  get_sha1: warn about full or short object names that look like refs

When we get 40 hex digits, we immediately assume it's an SHA-1. This
is the right thing to do because we have no way else to specify an
object. If there is a ref with the same object name, it will be
ignored. Warn the user about this case because the ref with full
object name is likely a mistake, for example

    git checkout -b $empty_var $(git rev-parse something)

advice.object_name_warning is not documented because frankly people
should not be aware about it until they encounter this situation.

While at there, warn about ambiguation with abbreviated SHA-1 too.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>