diff: add diff.orderfile configuration variable

diff.orderfile acts as a default for the -O command line option.

[sb: split up aw's original patch; rework tests and docs, treat option
as pathname]

Signed-off-by: Anders Waldenborg <[email protected]>
Signed-off-by: Samuel Bronson <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: SamB

Documentation/diff-config.txt

@@ -98,6 +98,11 @@ diff.mnemonicprefix::
 diff.noprefix::
 	If set, 'git diff' does not show any source or destination prefix.
 
+diff.orderfile::
+	File indicating how to order files within a diff, using
+	one shell glob pattern per line.
+	Can be overridden by the '-O' option to linkgit:git-diff[1].
+
 diff.renameLimit::
 	The number of files to consider when performing the copy/rename
 	detection; equivalent to the 'git diff' option '-l'.

Documentation/diff-options.txt

@@ -432,6 +432,9 @@ endif::git-format-patch[]
 -O<orderfile>::
 	Output the patch in the order specified in the
 	<orderfile>, which has one shell glob pattern per line.
+	This overrides the `diff.orderfile` configuration variable
+	(see linkgit:git-config[1]).  To cancel `diff.orderfile`,
+	use `-O/dev/null`.
 
 ifndef::git-format-patch[]
 -R::

diff.c

@@ -30,6 +30,7 @@ static int diff_use_color_default = -1;
 static int diff_context_default = 3;
 static const char *diff_word_regex_cfg;
 static const char *external_diff_cmd_cfg;
+static const char *diff_order_file_cfg;
 int diff_auto_refresh_index = 1;
 static int diff_mnemonic_prefix;
 static int diff_no_prefix;
@@ -201,6 +202,8 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 		return git_config_string(&external_diff_cmd_cfg, var, value);
 	if (!strcmp(var, "diff.wordregex"))
 		return git_config_string(&diff_word_regex_cfg, var, value);
+	if (!strcmp(var, "diff.orderfile"))
+		return git_config_pathname(&diff_order_file_cfg, var, value);
 
 	if (!strcmp(var, "diff.ignoresubmodules"))
 		handle_ignore_submodules_arg(&default_diff_options, value);
@@ -3207,6 +3210,8 @@ void diff_setup(struct diff_options *options)
 	options->detect_rename = diff_detect_rename_default;
 	options->xdl_opts |= diff_algorithm;
 
+	options->orderfile = diff_order_file_cfg;
+
 	if (diff_no_prefix) {
 		options->a_prefix = options->b_prefix = "";
 	} else if (!diff_mnemonic_prefix) {

t/t4056-diff-order.sh

@@ -89,6 +89,16 @@ do
 		wait &&
 		test_cmp expect_$i actual
 	'
+
+	test_expect_success "orderfile using config ($i)" '
+		git -c diff.orderfile=order_file_$i diff --name-only HEAD^..HEAD >actual &&
+		test_cmp expect_$i actual
+	'
+
+	test_expect_success "cancelling configured orderfile ($i)" '
+		git -c diff.orderfile=order_file_$i diff -O/dev/null --name-only HEAD^..HEAD >actual &&
+		test_cmp expect_none actual
+	'
 done
 
 test_done