Subject: Re: [PATCH v4] diff: add config option relative

From: Laurent Arnoud <[email-masked]>
Date: Sat, 16 May 2020 21:40:33 +0200

The `diff.relative` boolean option set to `true` show only changes on
the current directory and show relative pathnames to the current
directory.

Teach --no-relative to override earlier --relative

Signed-off-by: Laurent Arnoud <[email-masked]>
---
 Documentation/config/diff.txt   |  4 ++
 Documentation/diff-options.txt  |  3 ++
 diff.c                          | 16 ++++--
 t/t9904-diff-relative-config.sh | 93 +++++++++++++++++++++++++++++++++
 4 files changed, 113 insertions(+), 3 deletions(-)
 create mode 100755 t/t9904-diff-relative-config.sh

diff --git a/Documentation/config/diff.txt b/Documentation/config/diff.txt
index ff09f1cf73..76537c3b0c 100644
--- a/Documentation/config/diff.txt
+++ b/Documentation/config/diff.txt
@@ -105,6 +105,10 @@ diff.mnemonicPrefix::
 diff.noprefix::
 	If set, 'git diff' does not show any source or destination prefix.

+diff.relative::
+	If set to "true", 'git diff' does not show changes outside of the directory
+	and show pathnames relative to the current directory.
+
 diff.orderFile::
 	File indicating how to order files within a diff.
 	See the '-O' option to linkgit:git-diff[1] for details.
diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index bb31f0c42b..1b279904eb 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -651,6 +651,9 @@ ifndef::git-format-patch[]
 	not in a subdirectory (e.g. in a bare repository), you
 	can name which subdirectory to make the output relative
 	to by giving a <path> as an argument.
+--no-relative::
+	Turn off relative pathnames and include all changes in the repository.
+	This can be used to override configuration settings `diff.relative`.
 endif::git-format-patch[]

 -a::
diff --git a/diff.c b/diff.c
index d1ad6a3c4a..af28e39785 100644
--- a/diff.c
+++ b/diff.c
@@ -48,6 +48,7 @@ static const char *diff_order_file_cfg;
 int diff_auto_refresh_index = 1;
 static int diff_mnemonic_prefix;
 static int diff_no_prefix;
+static int diff_relative;
 static int diff_stat_graph_width;
 static int diff_dirstat_permille_default = 30;
 static struct diff_options default_diff_options;
@@ -386,6 +387,10 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 		diff_no_prefix = git_config_bool(var, value);
 		return 0;
 	}
+	if (!strcmp(var, "diff.relative")) {
+		diff_relative = git_config_bool(var, value);
+		return 0;
+	}
 	if (!strcmp(var, "diff.statgraphwidth")) {
 		diff_stat_graph_width = git_config_int(var, value);
 		return 0;
@@ -4558,6 +4563,8 @@ void repo_diff_setup(struct repository *r, struct diff_options *options)
 		options->b_prefix = "b/";
 	}

+	options->flags.relative_name = diff_relative;
+
 	options->color_moved = diff_color_moved_default;
 	options->color_moved_ws_handling = diff_color_moved_ws_default;

@@ -5195,8 +5202,11 @@ static int diff_opt_relative(const struct option *opt,
 {
 	struct diff_options *options = opt->value;

-	BUG_ON_OPT_NEG(unset);
-	options->flags.relative_name = 1;
+	if (unset) {
+		options->flags.relative_name = 0;
+	} else {
+		options->flags.relative_name = 1;
+	}
 	if (arg)
 		options->prefix = arg;
 	return 0;
@@ -5492,7 +5502,7 @@ static void prep_parse_options(struct diff_options *options)
 		OPT_GROUP(N_("Other diff options")),
 		OPT_CALLBACK_F(0, "relative", options, N_("<prefix>"),
 			       N_("when run from subdir, exclude changes outside and show relative paths"),
-			       PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
+			       PARSE_OPT_OPTARG,
 			       diff_opt_relative),
 		OPT_BOOL('a', "text", &options->flags.text,
 			 N_("treat all files as text")),
diff --git a/t/t9904-diff-relative-config.sh b/t/t9904-diff-relative-config.sh
new file mode 100755
index 0000000000..23ab1af5e0
--- /dev/null
+++ b/t/t9904-diff-relative-config.sh
@@ -0,0 +1,93 @@
+#!/bin/sh
+
+test_description='config diff.relative'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	git commit --allow-empty -m empty &&
+	echo content >file1 &&
+	mkdir subdir &&
+	echo other content >subdir/file2 &&
+	git add . &&
+	git commit -m one
+'
+
+check_diff_relative () {
+	dir=$1
+	shift
+	expect=$1
+	shift
+	relative_opt=$1
+	shift
+	short_blob=$(git rev-parse --short "$(git hash-object subdir/file2)")
+	cat >expected <<-EOF
+	diff --git a/$expect b/$expect
+	new file mode 100644
+	index 0000000..$short_blob
+	--- /dev/null
+	+++ b/$expect
+	@@ -0,0 +1 @@
+	+other content
+	EOF
+	test_expect_success "config.relative $relative_opt -p $*" "
+		test_config -C $dir diff.relative $relative_opt &&
+		git -C '$dir' diff -p $* HEAD^ >actual &&
+		test_cmp expected actual
+	"
+}
+
+check_diff_no_relative () {
+	dir=$1
+	shift
+	expect=$1
+	shift
+	relative_opt=$1
+	shift
+	short_blob_file1=$(git rev-parse --short "$(git hash-object file1)")
+	short_blob_file2=$(git rev-parse --short "$(git hash-object subdir/file2)")
+	cat >expected <<-EOF
+	diff --git a/file1 b/file1
+	new file mode 100644
+	index 0000000..$short_blob_file1
+	--- /dev/null
+	+++ b/file1
+	@@ -0,0 +1 @@
+	+content
+	diff --git a/$expect b/$expect
+	new file mode 100644
+	index 0000000..$short_blob_file2
+	--- /dev/null
+	+++ b/$expect
+	@@ -0,0 +1 @@
+	+other content
+	EOF
+	cat expected
+	test_expect_success "config.relative $relative_opt -p $*" "
+		test_config -C $dir diff.relative $relative_opt &&
+		git -C '$dir' diff -p $* HEAD^ >actual &&
+		git -C '$dir' diff -p $* HEAD^ >/tmp/actual &&
+		test_cmp expected actual
+	"
+}
+
+check_diff_relative . file2 false --relative=subdir/
+check_diff_relative . file2 false --relative=subdir
+check_diff_relative . file2 true --relative=subdir/
+check_diff_relative . file2 true --relative=subdir
+check_diff_relative subdir file2 false --relative
+check_diff_relative subdir file2 true --relative
+check_diff_relative subdir file2 true
+check_diff_relative subdir file2 false --no-relative --relative
+check_diff_relative subdir file2 true --no-relative --relative
+check_diff_relative . file2 false --no-relative --relative=subdir
+check_diff_relative . file2 true --no-relative --relative=subdir
+
+check_diff_no_relative . subdir/file2 false
+check_diff_no_relative . subdir/file2 true --no-relative
+check_diff_no_relative . subdir/file2 false --no-relative
+check_diff_no_relative subdir subdir/file2 false
+check_diff_no_relative subdir subdir/file2 true --no-relative
+check_diff_no_relative subdir subdir/file2 false --no-relative
+
+test_done
--
2.26.2