v2git-config support for diff.relative setting

>
> Signed-off-by: Brandon Phillips <kelson@shysecurity.com>
> ---
>  Documentation/diff-config.txt |  6 ++++++
>  diff.c                        |  8 ++++++++
>  t/t4045-diff-relative.sh      | 21 +++++++++++++++++++++
>  3 files changed, 35 insertions(+)
>
> diff --git a/Documentation/diff-config.txt 
> b/Documentation/diff-config.txt
> index b001779..10f183f 100644
> --- a/Documentation/diff-config.txt
> +++ b/Documentation/diff-config.txt
> @@ -182,3 +182,9 @@ diff.algorithm::
>  low-occurrence common elements".
>  --
>  +
> +
> +diff.relative::
> + By default, linkgit:git-diff[1] shows changes and pathnames
> + relative to the repository root. Setting this variable to
> + `true` shows pathnames relative to the current directory and
> + excludes changes outside this directory.

> diff --git a/diff.c b/diff.c
> index d1bd534..03697a9 100644
> --- a/diff.c
> +++ b/diff.c
> @@ -223,6 +223,14 @@ int git_diff_ui_config(const char *var, const 
> char
> *value, void *cb)
>  return 0;
>  }
>
> + if (!strcmp(var, "diff.relative")) {
> + if (git_config_bool(var, value))
> + DIFF_OPT_SET(&default_diff_options, RELATIVE_NAME);
> + else
> + DIFF_OPT_CLR(&default_diff_options, RELATIVE_NAME);
> + return 0;
> + }
> +
>  if (git_color_config(var, value, cb) < 0)
>  return -1;
>
> diff --git a/t/t4045-diff-relative.sh b/t/t4045-diff-relative.sh
> index 3950f50..8c8fe0b 100755
> --- a/t/t4045-diff-relative.sh
> +++ b/t/t4045-diff-relative.sh
> @@ -29,6 +29,23 @@ test_expect_success "-p $*" "
>  "
>  }
>
> +check_config() {
> +expect=$1; shift
> +cat >expected <<EOF
> +diff --git a/$expect b/$expect
> +new file mode 100644
> +index 0000000..25c05ef
> +--- /dev/null
> ++++ b/$expect
> +@@ -0,0 +1 @@
> ++other content
> +EOF
> +test_expect_success "git-config diff.relative=true in $1" "
> + (cd $1; git -c diff.relative=true diff -p HEAD^ >../actual) &&
> + test_cmp expected actual
> +"
> +}
> +
>  check_numstat() {
>  expect=$1; shift
>  cat >expected <<EOF
> @@ -69,5 +86,9 @@ for type in diff numstat stat raw; do
>  check_$type file2 --relative=subdir
>  check_$type dir/file2 --relative=sub
>  done
> +for type in config; do
> + check_$type file2 subdir/
> + check_$type file2 subdir
> +done
>
>  test_done
> -- 

> From: <kelson@shysecurity.com>
>> By default, git-diff shows changes and pathnames relative to the
>> repository root. Setting the diff.relative config option to "true"
>> shows pathnames relative to the current directory and excludes
>> changes outside this directory (identical to "git diff --relative").
> Shouldn't this `(identical to "git diff --relative")` also be included
> in the documentation change? It would truly clarify the intenbt for
> the reader.

> From: <kelson@shysecurity.com>
>> By default, git-diff shows changes and pathnames relative to the
>> repository root. Setting the diff.relative config option to "true"
>> shows pathnames relative to the current directory and excludes
>> changes outside this directory (identical to "git diff --relative").
> Shouldn't this `(identical to "git diff --relative")` also be included
> in the documentation change? It would truly clarify the intenbt for
> the reader.

>> "Philip Oakley" <philipoakley@iee.org> wrote:
>> Shouldn't this `(identical to "git diff --relative")` also be
>>included in the documentation change? It would truly clarify the
>> intenbt for the reader.
>
> Updated as follows:
> +diff.relative::
> +	Show pathnames relative to the current directory and exclude
> +	changes outside this directory; equivalent to the 'git diff'
> +	option '--relative'.
>
>> "Junio C Hamano" <gitster@pobox.com> wrote:
>> There should be a way to run non-relative diff in a repository that
>> has the configuration set, perhaps by overriding with some command
>> line option (e.g. "--no-relative").
>
> Good idea; I'll put together a second patch for a "--no-relative"
> option to disable diff.relative.