Make the tab width used for whitespace checks configurable

A new whitespace "rule" is added that sets the tab width to use for
whitespace checks and fix-ups and replaces the hard-coded constant 8.

Since the setting is part of the rules, it can be set per file using
.gitattributes.

The new configuration is backwards compatible because older git versions
simply ignore unknown whitespace rules.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 130 insertions, 6 deletions

diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 8622eb51c7..9059bcd69e 100755
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -344,6 +344,13 @@ test_expect_success 'check spaces as indentation (indent-with-non-tab: on)' '
 
 '
 
+test_expect_success 'ditto, but tabwidth=9' '
+
+	git config core.whitespace "indent-with-non-tab,tabwidth=9" &&
+	git diff --check
+
+'
+
 test_expect_success 'check tabs and spaces as indentation (indent-with-non-tab: on)' '
 
 	git config core.whitespace "indent-with-non-tab" &&
@@ -352,6 +359,20 @@ test_expect_success 'check tabs and spaces as indentation (indent-with-non-tab:
 
 '
 
+test_expect_success 'ditto, but tabwidth=10' '
+
+	git config core.whitespace "indent-with-non-tab,tabwidth=10" &&
+	test_must_fail git diff --check
+
+'
+
+test_expect_success 'ditto, but tabwidth=20' '
+
+	git config core.whitespace "indent-with-non-tab,tabwidth=20" &&
+	git diff --check
+
+'
+
 test_expect_success 'check tabs as indentation (tab-in-indent: off)' '
 
 	git config core.whitespace "-tab-in-indent" &&
@@ -376,6 +397,13 @@ test_expect_success 'check tabs and spaces as indentation (tab-in-indent: on)' '
 
 '
 
+test_expect_success 'ditto, but tabwidth=1 (must be irrelevant)' '
+
+	git config core.whitespace "tab-in-indent,tabwidth=1" &&
+	test_must_fail git diff --check
+
+'
+
 test_expect_success 'check tab-in-indent and indent-with-non-tab conflict' '
 
 	git config core.whitespace "tab-in-indent,indent-with-non-tab" &&
diff --git a/t/t4019-diff-wserror.sh b/t/t4019-diff-wserror.sh
index f7c85ec604..6f992c88eb 100755
--- a/t/t4019-diff-wserror.sh
+++ b/t/t4019-diff-wserror.sh
@@ -51,8 +51,65 @@ test_expect_success default '
 
 '
 
+test_expect_success 'default (attribute)' '
+
+	test_might_fail git config --unset core.whitespace &&
+	echo "F whitespace" >.gitattributes &&
+	prepare_output &&
+
+	grep Eight error >/dev/null &&
+	grep HT error >/dev/null &&
+	grep With error >/dev/null &&
+	grep Return error >/dev/null &&
+	grep No normal >/dev/null
+
+'
+
+test_expect_success 'default, tabwidth=10 (attribute)' '
+
+	git config core.whitespace "tabwidth=10" &&
+	echo "F whitespace" >.gitattributes &&
+	prepare_output &&
+
+	grep Eight normal >/dev/null &&
+	grep HT error >/dev/null &&
+	grep With error >/dev/null &&
+	grep Return error >/dev/null &&
+	grep No normal >/dev/null
+
+'
+
+test_expect_success 'no check (attribute)' '
+
+	test_might_fail git config --unset core.whitespace &&
+	echo "F -whitespace" >.gitattributes &&
+	prepare_output &&
+
+	grep Eight normal >/dev/null &&
+	grep HT normal >/dev/null &&
+	grep With normal >/dev/null &&
+	grep Return normal >/dev/null &&
+	grep No normal >/dev/null
+
+'
+
+test_expect_success 'no check, tabwidth=10 (attribute), must be irrelevant' '
+
+	git config core.whitespace "tabwidth=10" &&
+	echo "F -whitespace" >.gitattributes &&
+	prepare_output &&
+
+	grep Eight normal >/dev/null &&
+	grep HT normal >/dev/null &&
+	grep With normal >/dev/null &&
+	grep Return normal >/dev/null &&
+	grep No normal >/dev/null
+
+'
+
 test_expect_success 'without -trail' '
 
+	rm -f .gitattributes &&
 	git config core.whitespace -trail &&
 	prepare_output &&
 
@@ -134,6 +191,34 @@ test_expect_success 'with indent-non-tab only (attribute)' '
 
 '
 
+test_expect_success 'with indent-non-tab only, tabwidth=10' '
+
+	rm -f .gitattributes &&
+	git config core.whitespace indent,tabwidth=10,-trailing,-space &&
+	prepare_output &&
+
+	grep Eight normal >/dev/null &&
+	grep HT normal >/dev/null &&
+	grep With normal >/dev/null &&
+	grep Return normal >/dev/null &&
+	grep No normal >/dev/null
+
+'
+
+test_expect_success 'with indent-non-tab only, tabwidth=10 (attribute)' '
+
+	test_might_fail git config --unset core.whitespace &&
+	echo "F whitespace=indent,-trailing,-space,tabwidth=10" >.gitattributes &&
+	prepare_output &&
+
+	grep Eight normal >/dev/null &&
+	grep HT normal >/dev/null &&
+	grep With normal >/dev/null &&
+	grep Return normal >/dev/null &&
+	grep No normal >/dev/null
+
+'
+
 test_expect_success 'with cr-at-eol' '
 
 	rm -f .gitattributes &&
diff --git a/t/t4124-apply-ws-rule.sh b/t/t4124-apply-ws-rule.sh
index 40e5842997..6f6ee88b28 100755
--- a/t/t4124-apply-ws-rule.sh
+++ b/t/t4124-apply-ws-rule.sh
@@ -10,7 +10,8 @@ prepare_test_file () {
 	#       X  RULE
 	#   	!  trailing-space
 	#   	@  space-before-tab
-	#   	#  indent-with-non-tab
+	#   	#  indent-with-non-tab (default tab width 8)
+	#	=  indent-with-non-tab,tabwidth=16
 	#   	%  tab-in-indent
 	sed -e "s/_/ /g" -e "s/>/	/" <<-\EOF
 		An_SP in an ordinary line>and a HT.
@@ -25,8 +26,8 @@ prepare_test_file () {
 		________>_Eight SP, a HT and a SP (@#%).
 		_______________Fifteen SP (#).
 		_______________>Fifteen SP and a HT (@#%).
-		________________Sixteen SP (#).
-		________________>Sixteen SP and a HT (@#%).
+		________________Sixteen SP (#=).
+		________________>Sixteen SP and a HT (@#%=).
 		_____a__Five SP, a non WS, two SP.
 		A line with a (!) trailing SP_
 		A line with a (!) trailing HT>
@@ -139,8 +140,8 @@ test_expect_success 'spaces inserted by tab-in-indent' '
 		_________________Eight SP, a HT and a SP (@#%).
 		_______________Fifteen SP (#).
 		________________Fifteen SP and a HT (@#%).
-		________________Sixteen SP (#).
-		________________________Sixteen SP and a HT (@#%).
+		________________Sixteen SP (#=).
+		________________________Sixteen SP and a HT (@#%=).
 		_____a__Five SP, a non WS, two SP.
 		A line with a (!) trailing SP_
 		A line with a (!) trailing HT>
@@ -157,7 +158,7 @@ do
 		case "$s" in '') ts='@' ;; *) ts= ;; esac
 		for i in - ''
 		do
-			case "$i" in '') ti='#' ;; *) ti= ;; esac
+			case "$i" in '') ti='#' ti16='=';; *) ti= ti16= ;; esac
 			for h in - ''
 			do
 				[ -z "$h$i" ] && continue
@@ -170,12 +171,22 @@ do
 					test_fix "$tt$ts$ti$th"
 				'
 
+				test_expect_success "rule=$rule,tabwidth=16" '
+					git config core.whitespace "$rule,tabwidth=16" &&
+					test_fix "$tt$ts$ti16$th"
+				'
+
 				test_expect_success "rule=$rule (attributes)" '
 					git config --unset core.whitespace &&
 					echo "target whitespace=$rule" >.gitattributes &&
 					test_fix "$tt$ts$ti$th"
 				'
 
+				test_expect_success "rule=$rule,tabwidth=16 (attributes)" '
+					echo "target whitespace=$rule,tabwidth=16" >.gitattributes &&
+					test_fix "$tt$ts$ti16$th"
+				'
+
 			done
 		done
 	done