Merge branch 'jc/ws-error-highlight'

"git diff/log --ws-error-highlight=<kind>" lacked the corresponding
configuration variable to set it by default.

* jc/ws-error-highlight:
  diff: introduce diff.wsErrorHighlight option
  diff.c: move ws-error-highlight parsing helpers up
  diff.c: refactor parse_ws_error_highlight()
  t4015: split out the "setup" part of ws-error-highlight test

4 files changed, 119 insertions, 52 deletions

diff --git a/Documentation/diff-config.txt b/Documentation/diff-config.txt
index b27a38f89..58f4bd6af 100644
--- a/Documentation/diff-config.txt
+++ b/Documentation/diff-config.txt
@@ -193,3 +193,9 @@ diff.algorithm::
 	low-occurrence common elements".
 --
 +
+
+diff.wsErrorHighlight::
+	A comma separated list of `old`, `new`, `context`, that
+	specifies how whitespace errors on lines are highlighted
+	with `color.diff.whitespace`.  Can be overridden by the
+	command line option `--ws-error-highlight=<kind>`
diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index 2d77a1962..29630c238 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -308,6 +308,8 @@ ifndef::git-format-patch[]
 	lines are highlighted.  E.g. `--ws-error-highlight=new,old`
 	highlights whitespace errors on both deleted and added lines.
 	`all` can be used as a short-hand for `old,new,context`.
+	The `diff.wsErrorHighlight` configuration variable can be
+	used to specify the default behaviour.
 
 endif::git-format-patch[]
 
diff --git a/diff.c b/diff.c
index f5d6d7e4f..569f615d3 100644
--- a/diff.c
+++ b/diff.c
@@ -43,6 +43,7 @@ static int diff_stat_graph_width;
 static int diff_dirstat_permille_default = 30;
 static struct diff_options default_diff_options;
 static long diff_algorithm;
+static unsigned ws_error_highlight_default = WSEH_NEW;
 
 static char diff_colors[][COLOR_MAXLEN] = {
 	GIT_COLOR_RESET,
@@ -172,6 +173,43 @@ long parse_algorithm_value(const char *value)
 	return -1;
 }
 
+static int parse_one_token(const char **arg, const char *token)
+{
+	const char *rest;
+	if (skip_prefix(*arg, token, &rest) && (!*rest || *rest == ',')) {
+		*arg = rest;
+		return 1;
+	}
+	return 0;
+}
+
+static int parse_ws_error_highlight(const char *arg)
+{
+	const char *orig_arg = arg;
+	unsigned val = 0;
+
+	while (*arg) {
+		if (parse_one_token(&arg, "none"))
+			val = 0;
+		else if (parse_one_token(&arg, "default"))
+			val = WSEH_NEW;
+		else if (parse_one_token(&arg, "all"))
+			val = WSEH_NEW | WSEH_OLD | WSEH_CONTEXT;
+		else if (parse_one_token(&arg, "new"))
+			val |= WSEH_NEW;
+		else if (parse_one_token(&arg, "old"))
+			val |= WSEH_OLD;
+		else if (parse_one_token(&arg, "context"))
+			val |= WSEH_CONTEXT;
+		else {
+			return -1 - (int)(arg - orig_arg);
+		}
+		if (*arg)
+			arg++;
+	}
+	return val;
+}
+
 /*
  * These are to give UI layer defaults.
  * The core-level commands such as git-diff-files should
@@ -256,6 +294,15 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 
 	if (git_diff_heuristic_config(var, value, cb) < 0)
 		return -1;
+
+	if (!strcmp(var, "diff.wserrorhighlight")) {
+		int val = parse_ws_error_highlight(value);
+		if (val < 0)
+			return -1;
+		ws_error_highlight_default = val;
+		return 0;
+	}
+
 	if (git_color_config(var, value, cb) < 0)
 		return -1;
 
@@ -3307,7 +3354,7 @@ void diff_setup(struct diff_options *options)
 	options->rename_limit = -1;
 	options->dirstat_permille = diff_dirstat_permille_default;
 	options->context = diff_context_default;
-	options->ws_error_highlight = WSEH_NEW;
+	options->ws_error_highlight = ws_error_highlight_default;
 	DIFF_OPT_SET(options, RENAME_EMPTY);
 
 	/* pathchange left =NULL by default */
@@ -3698,40 +3745,14 @@ static void enable_patch_output(int *fmt) {
 	*fmt |= DIFF_FORMAT_PATCH;
 }
 
-static int parse_one_token(const char **arg, const char *token)
+static int parse_ws_error_highlight_opt(struct diff_options *opt, const char *arg)
 {
-	const char *rest;
-	if (skip_prefix(*arg, token, &rest) && (!*rest || *rest == ',')) {
-		*arg = rest;
-		return 1;
-	}
-	return 0;
-}
+	int val = parse_ws_error_highlight(arg);
 
-static int parse_ws_error_highlight(struct diff_options *opt, const char *arg)
-{
-	const char *orig_arg = arg;
-	unsigned val = 0;
-	while (*arg) {
-		if (parse_one_token(&arg, "none"))
-			val = 0;
-		else if (parse_one_token(&arg, "default"))
-			val = WSEH_NEW;
-		else if (parse_one_token(&arg, "all"))
-			val = WSEH_NEW | WSEH_OLD | WSEH_CONTEXT;
-		else if (parse_one_token(&arg, "new"))
-			val |= WSEH_NEW;
-		else if (parse_one_token(&arg, "old"))
-			val |= WSEH_OLD;
-		else if (parse_one_token(&arg, "context"))
-			val |= WSEH_CONTEXT;
-		else {
-			error("unknown value after ws-error-highlight=%.*s",
-			      (int)(arg - orig_arg), orig_arg);
-			return 0;
-		}
-		if (*arg)
-			arg++;
+	if (val < 0) {
+		error("unknown value after ws-error-highlight=%.*s",
+		      -1 - val, arg);
+		return 0;
 	}
 	opt->ws_error_highlight = val;
 	return 1;
@@ -3950,7 +3971,7 @@ int diff_opt_parse(struct diff_options *options,
 	else if (skip_prefix(arg, "--submodule=", &arg))
 		return parse_submodule_opt(options, arg);
 	else if (skip_prefix(arg, "--ws-error-highlight=", &arg))
-		return parse_ws_error_highlight(options, arg);
+		return parse_ws_error_highlight_opt(options, arg);
 
 	/* misc options */
 	else if (!strcmp(arg, "-z"))
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 2434157aa..289806d0c 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -869,7 +869,8 @@ test_expect_success 'diff that introduces and removes ws breakages' '
 	test_cmp expected current
 '
 
-test_expect_success 'the same with --ws-error-highlight' '
+test_expect_success 'ws-error-highlight test setup' '
+
 	git reset --hard &&
 	{
 		echo "0. blank-at-eol " &&
@@ -882,10 +883,7 @@ test_expect_success 'the same with --ws-error-highlight' '
 		echo "2. and a new line "
 	} >x &&
 
-	git -c color.diff=always diff --ws-error-highlight=default,old |
-	test_decode_color >current &&
-
-	cat >expected <<-\EOF &&
+	cat >expect.default-old <<-\EOF &&
 	<BOLD>diff --git a/x b/x<RESET>
 	<BOLD>index d0233a2..700886e 100644<RESET>
 	<BOLD>--- a/x<RESET>
@@ -897,12 +895,7 @@ test_expect_success 'the same with --ws-error-highlight' '
 	<GREEN>+<RESET><GREEN>2. and a new line<RESET><BLUE> <RESET>
 	EOF
 
-	test_cmp expected current &&
-
-	git -c color.diff=always diff --ws-error-highlight=all |
-	test_decode_color >current &&
-
-	cat >expected <<-\EOF &&
+	cat >expect.all <<-\EOF &&
 	<BOLD>diff --git a/x b/x<RESET>
 	<BOLD>index d0233a2..700886e 100644<RESET>
 	<BOLD>--- a/x<RESET>
@@ -914,12 +907,7 @@ test_expect_success 'the same with --ws-error-highlight' '
 	<GREEN>+<RESET><GREEN>2. and a new line<RESET><BLUE> <RESET>
 	EOF
 
-	test_cmp expected current &&
-
-	git -c color.diff=always diff --ws-error-highlight=none |
-	test_decode_color >current &&
-
-	cat >expected <<-\EOF &&
+	cat >expect.none <<-\EOF
 	<BOLD>diff --git a/x b/x<RESET>
 	<BOLD>index d0233a2..700886e 100644<RESET>
 	<BOLD>--- a/x<RESET>
@@ -931,7 +919,57 @@ test_expect_success 'the same with --ws-error-highlight' '
 	<GREEN>+2. and a new line <RESET>
 	EOF
 
-	test_cmp expected current
+'
+
+test_expect_success 'test --ws-error-highlight option' '
+
+	git -c color.diff=always diff --ws-error-highlight=default,old |
+	test_decode_color >current &&
+	test_cmp expect.default-old current &&
+
+	git -c color.diff=always diff --ws-error-highlight=all |
+	test_decode_color >current &&
+	test_cmp expect.all current &&
+
+	git -c color.diff=always diff --ws-error-highlight=none |
+	test_decode_color >current &&
+	test_cmp expect.none current
+
+'
+
+test_expect_success 'test diff.wsErrorHighlight config' '
+
+	git -c color.diff=always -c diff.wsErrorHighlight=default,old diff |
+	test_decode_color >current &&
+	test_cmp expect.default-old current &&
+
+	git -c color.diff=always -c diff.wsErrorHighlight=all diff |
+	test_decode_color >current &&
+	test_cmp expect.all current &&
+
+	git -c color.diff=always -c diff.wsErrorHighlight=none diff |
+	test_decode_color >current &&
+	test_cmp expect.none current
+
+'
+
+test_expect_success 'option overrides diff.wsErrorHighlight' '
+
+	git -c color.diff=always -c diff.wsErrorHighlight=none \
+		diff --ws-error-highlight=default,old |
+	test_decode_color >current &&
+	test_cmp expect.default-old current &&
+
+	git -c color.diff=always -c diff.wsErrorHighlight=default \
+		diff --ws-error-highlight=all |
+	test_decode_color >current &&
+	test_cmp expect.all current &&
+
+	git -c color.diff=always -c diff.wsErrorHighlight=all \
+		diff --ws-error-highlight=none |
+	test_decode_color >current &&
+	test_cmp expect.none current
+
 '
 
 test_done