* rs/diff-whole-function:
  diff: add option to show whole functions as context
  xdiff: factor out get_func_line()

* rs/diff-cleanup-records-fix:
  diff: resurrect XDF_NEED_MINIMAL with --minimal
  Revert removal of multi-match discard heuristic in 27af01

* jc/maint-diffstat-numstat-context:
  diff: teach --stat/--numstat to honor -U$num

Add the option -W/--function-context to git diff.  It is similar to
the same option of git grep and expands the context of change hunks
so that the whole surrounding function is shown.  This "natural"
context can allow changes to be understood better.

Note: GNU patch doesn't like diffs generated with the new option;
it seems to expect context lines to be the same before and after
changes.  git apply doesn't complain.

This implementation has the same shortcoming as the one in grep,
namely that there is no way to explicitly find the end of a
function.  That means that a few lines of extra context are shown,
right up to the next recognized function begins.  It's already
useful in its current form, though.

The function get_func_line() in xdiff/xemit.c is extended to work
forward as well as backward to find post-context as well as
pre-context.  It returns the position of the first found matching
line.  The func_line parameter is made optional, as we don't need
it for -W.

The enhanced function is then used in xdl_emit_diff() to extend
the context as needed.  If the added context overlaps with the
next change, it is merged into the current hunk.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Earlier, 582aa00 (git diff too slow for a file, 2010-05-02)
unconditionally dropped XDF_NEED_MINIMAL option from the internal xdiff
invocation to help performance on pathological cases, while hinting that a
follow-up patch could reintroduce it with "--minimal" option from the
command line.

Make it so.

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

"git diff -p" piped to external diffstat and "git diff --stat" may see
different patch text (both are valid and describe the same change
correctly) when counting the number of added and deleted lines, arriving
at different results to confuse the users, as --stat/--numstat codepath
always uses the hardcoded -U0 as the context length.

Make --stat/--numstat codepath to honor the context length the same way
as the textual patch codepath does to avoid this problem.

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

* jk/color-and-pager:
  want_color: automatically fallback to color.ui
  diff: don't load color config in plumbing
  config: refactor get_colorbool function
  color: delay auto-color decision until point of use
  git_config_colorbool: refactor stdout_is_tty handling
  diff: refactor COLOR_DIFF from a flag into an int
  setup_pager: set GIT_PAGER_IN_USE
  t7006: use test_config helpers
  test-lib: add helper functions for config
  t7006: modernize calls to unset

Conflicts:
	builtin/commit.c
	parse-options.c

The diff config callback is split into two functions: one
which loads "ui" config, and one which loads "basic" config.
The former chains to the latter, as the diff UI config is a
superset of the plumbing config.

The color.diff variable is only loaded in the UI config.
However, the basic config actually chains to
git_color_default_config, which loads color.ui. This doesn't
actually cause any bugs, because the plumbing diff code does
not actually look at the value of color.ui.

However, it is somewhat nonsensical, and it makes it
difficult to refactor the color code. It probably came about
because there is no git_color_config to load only color
config, but rather just git_color_default_config, which
loads color config and chains to git_default_config.

This patch splits out the color-specific portion of
git_color_default_config so that the diff UI config can call
it directly. This is perhaps better explained by the
chaining of callbacks. Before we had:

  git_diff_ui_config
    -> git_diff_basic_config
      -> git_color_default_config
        -> git_default_config

Now we have:

  git_diff_ui_config
    -> git_color_config
    -> git_diff_basic_config
      -> git_default_config

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

When we read a color value either from a config file or from
the command line, we use git_config_colorbool to convert it
from the tristate always/never/auto into a single yes/no
boolean value.

This has some timing implications with respect to starting
a pager.

If we start (or decide not to start) the pager before
checking the colorbool, everything is fine. Either isatty(1)
will give us the right information, or we will properly
check for pager_in_use().

However, if we decide to start a pager after we have checked
the colorbool, things are not so simple. If stdout is a tty,
then we will have already decided to use color. However, the
user may also have configured color.pager not to use color
with the pager. In this case, we need to actually turn off
color. Unfortunately, the pager code has no idea which color
variables were turned on (and there are many of them
throughout the code, and they may even have been manipulated
after the colorbool selection by something like "--color" on
the command line).

This bug can be seen any time a pager is started after
config and command line options are checked. This has
affected "git diff" since 89d07f7 (diff: don't run pager if
user asked for a diff style exit code, 2007-08-12). It has
also affect the log family since 1fda91b (Fix 'git log'
early pager startup error case, 2010-08-24).

This patch splits the notion of parsing a colorbool and
actually checking the configuration. The "use_color"
variables now have an additional possible value,
GIT_COLOR_AUTO. Users of the variable should use the new
"want_color()" wrapper, which will lazily determine and
cache the auto-color decision.

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

Usually this function figures out for itself whether stdout
is a tty. However, it has an extra parameter just to allow
git-config to override the auto-detection for its
--get-colorbool option.

Instead of an extra parameter, let's just use a global
variable. This makes calling easier in the common case, and
will make refactoring the colorbool code much simpler.

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