When the user types "git diff" outside a working tree, thinking he
is inside one, the current error message that is a single-liner
"usage: git diff --no-index <path> <path>" may not be sufficient to
make him realize the mistake. Add "Not a git repository" to the
error message when we fell into the "--no-index" mode without an
explicit command line option to instruct us to do so.

* dw/diff-no-index-doc:
  diff --no-index: describe in a separate paragraph
  diff --no-index: clarify operation when not inside a repository

Teach "git diff --diff-filter" to express "I do not want to see
these classes of changes" more directly by listing only the
unwanted ones in lowercase (e.g. "--diff-filter=d" will show
everything but deletion) and deprecate "diff-files -q" which did
the same thing as "--diff-filter=d".

* jc/diff-filter-negation:
  diff: deprecate -q option to diff-files
  diff: allow lowercase letter to specify what change class to exclude
  diff: reject unknown change class given to --diff-filter
  diff: preparse --diff-filter string argument
  diff: factor out match_filter()
  diff: pass the whole diff_options to diffcore_apply_filter()

Clarify documentation for "diff --no-index".  State that when not
inside a repository, --no-index is implied and two arguments are
mandatory.

Clarify error message from diff-no-index to inform user that CWD is
not inside a repository and thus two arguments are mandatory.

Signed-off-by: Dale Worley <worley@ariadne.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

This reimplements the ancient "-q" option to "git diff-files" that
was inherited from "show-diff -q" in terms of "--diff-filter=d".  We
will be deprecating the "-q" option, so let's issue a warning when
we do so.

Incidentally this also tentatively fixes "git diff --no-index" to
honor "-q" and hide deletions; the use will get the same warning.

We should remove the support for "-q" in a future version but it is
not that urgent.

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

Throughout git, it is assumed that the WIN32 preprocessor symbol is
defined on native Windows setups (mingw and msvc) and not on Cygwin.
On Cygwin, most of the time git can pretend this is just another Unix
machine, and Windows-specific magic is generally counterproductive.

Unfortunately Cygwin *does* define the WIN32 symbol in some headers.
Best to rely on a new git-specific symbol GIT_WINDOWS_NATIVE instead,
defined as follows:

	#if defined(WIN32) && !defined(__CYGWIN__)
	# define GIT_WINDOWS_NATIVE
	#endif

After this change, it should be possible to drop the
CYGWIN_V15_WIN32API setting without any negative effect.

[rj: %s/WINDOWS_NATIVE/GIT_WINDOWS_NATIVE/g ]

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

We do not want a link to 0{40} object stored anywhere in our objects.

* jk/maint-null-in-trees:
  fsck: detect null sha1 in tree entries
  do not write null sha1s to on-disk index
  diff: do not use null sha1 as a sentinel value

Remove unnecessary code.

* tr/void-diff-setup-done:
  diff_setup_done(): return void

diff_setup_done() has historically returned an error code, but lost
the last nonzero return in 943d5b7 (allow diff.renamelimit to be set
regardless of -M/-C, 2006-08-09).  The callers were in a pretty
confused state: some actually checked for the return code, and some
did not.

Let it return void, and patch all callers to take this into account.
This conveniently also gets rid of a handful of different(!) error
messages that could never be triggered anyway.

Note that the function can still die().

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The diff code represents paths using the diff_filespec
struct. This struct has a sha1 to represent the sha1 of the
content at that path, as well as a sha1_valid member which
indicates whether its sha1 field is actually useful. If
sha1_valid is not true, then the filespec represents a
working tree file (e.g., for the no-index case, or for when
the index is not up-to-date).

The diff_filespec is only used internally, though. At the
interfaces to the diff subsystem, callers feed the sha1
directly, and we create a diff_filespec from it. It's at
that point that we look at the sha1 and decide whether it is
valid or not; callers may pass the null sha1 as a sentinel
value to indicate that it is not.

We should not typically see the null sha1 coming from any
other source (e.g., in the index itself, or from a tree).
However, a corrupt tree might have a null sha1, which would
cause "diff --patch" to accidentally diff the working tree
version of a file instead of treating it as a blob.

This patch extends the edges of the diff interface to accept
a "sha1_valid" flag whenever we accept a sha1, and to use
that flag when creating a filespec. In some cases, this
means passing the flag through several layers, making the
code change larger than would be desirable.

One alternative would be to simply die() upon seeing
corrupted trees with null sha1s. However, this fix more
directly addresses the problem (while bogus sha1s in a tree
are probably a bad thing, it is really the sentinel
confusion sending us down the wrong code path that is what
makes it devastating). And it means that git is more capable
of examining and debugging these corrupted trees. For
example, you can still "diff --raw" such a tree to find out
when the bogus entry was introduced; you just cannot do a
"--patch" diff (just as you could not with any other
corrupted tree, as we do not have any content to diff).

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

Due to the way "git diff --no-index" is bolted onto by touching the
low level code that is shared with the rest of the "git diff" code,
even though it has to work in a very different way, any comparison
that involves a file "-" at the root level incorrectly tried to read
from the standard input.  This cleans up the no-index codepath
further to remove code that reads from the standard input from the
core side, which is never necessary when git is running its usual
diff operation.

* jc/refactor-diff-stdin:
  diff-index.c: "git diff" has no need to read blob from the standard input
  diff-index.c: unify handling of command line paths
  diff-index.c: do not pretend paths are pathspecs