[PATCH] Make the tab width used for whitespace checks configurable

[PATCH] Make the tab width used for whitespace checks configurable

[Johannes Sixt]

From: Johannes Sixt <j6t@kdbg.org>

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>
---
 I have a project that uses tab width 4, and which has a lot of whitespace
 errors. This is very helpful to spot them when lines are changed that
 are indented with 4 spaces.

 -- Hannes

 Documentation/config.txt        |    3 +
 Documentation/gitattributes.txt |    6 ++-
 cache.h                         |   17 +++++---
 t/t4015-diff-whitespace.sh      |   28 +++++++++++++
 t/t4019-diff-wserror.sh         |   85 +++++++++++++++++++++++++++++++++++++++
 t/t4124-apply-ws-rule.sh        |   19 +++++++--
 ws.c                            |   17 +++++---
 7 files changed, 156 insertions(+), 19 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 6a6c0b5..d88db1c 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -513,6 +513,9 @@ core.whitespace::
   part of the line terminator, i.e. with it, `trailing-space`
   does not trigger if the character before such a carriage-return
   is not a whitespace (not enabled by default).
+* `tabwidth=<n>` tells how many character positions a tab occupies; this
+  is relevant for `indent-with-non-tab` and when git fixes whitespace
+  errors. The default tab width is 8. Allowed values are 1 to 63.
 
 core.fsyncobjectfiles::
 	This boolean will enable 'fsync()' when writing object files.
diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index c80ca5d..5a7f936 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -723,6 +723,8 @@ control per path.
 Set::
 
 	Notice all types of potential whitespace errors known to git.
+	The tab width is taken from the value of the `core.whitespace`
+	configuration variable.
 
 Unset::
 
@@ -730,13 +732,13 @@ Unset::
 
 Unspecified::
 
-	Use the value of `core.whitespace` configuration variable to
+	Use the value of the `core.whitespace` configuration variable to
 	decide what to notice as error.
 
 String::
 
 	Specify a comma separate list of common whitespace problems to
-	notice in the same format as `core.whitespace` configuration
+	notice in the same format as the `core.whitespace` configuration
 	variable.
 
 
diff --git a/cache.h b/cache.h
index 33decd9..8e8c9d4 100644
--- a/cache.h
+++ b/cache.h
@@ -1087,15 +1087,17 @@ void shift_tree_by(const unsigned char *, const unsigned char *, unsigned char *
 /*
  * whitespace rules.
  * used by both diff and apply
+ * last two digits are tab width
  */
-#define WS_BLANK_AT_EOL         01
-#define WS_SPACE_BEFORE_TAB	02
-#define WS_INDENT_WITH_NON_TAB	04
-#define WS_CR_AT_EOL           010
-#define WS_BLANK_AT_EOF        020
-#define WS_TAB_IN_INDENT       040
+#define WS_BLANK_AT_EOL         0100
+#define WS_SPACE_BEFORE_TAB     0200
+#define WS_INDENT_WITH_NON_TAB  0400
+#define WS_CR_AT_EOL           01000
+#define WS_BLANK_AT_EOF        02000
+#define WS_TAB_IN_INDENT       04000
 #define WS_TRAILING_SPACE      (WS_BLANK_AT_EOL|WS_BLANK_AT_EOF)
-#define WS_DEFAULT_RULE (WS_TRAILING_SPACE|WS_SPACE_BEFORE_TAB)
+#define WS_DEFAULT_RULE (WS_TRAILING_SPACE|WS_SPACE_BEFORE_TAB|8)
+#define WS_TAB_WIDTH_MASK        077
 extern unsigned whitespace_rule_cfg;
 extern unsigned whitespace_rule(const char *);
 extern unsigned parse_whitespace_rule(const char *);
@@ -1104,6 +1106,7 @@ extern void ws_check_emit(const char *line, int len, unsigned ws_rule, FILE *str
 extern char *whitespace_error_string(unsigned ws);
 extern void ws_fix_copy(struct strbuf *, const char *, int, unsigned, int *);
 extern int ws_blank_line(const char *line, int len, unsigned ws_rule);
+#define ws_tab_width(rule)     ((rule) & WS_TAB_WIDTH_MASK)
 
 /* ls-files */
 int report_path_error(const char *ps_matched, const char **pathspec, int prefix_offset);
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 8622eb5..9059bcd 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 f7c85ec..6f992c8 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 61bfc56..27f0c47 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>
@@ -129,7 +130,7 @@ 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$i" ] && continue
@@ -142,12 +143,22 @@ do
 					test_fix "$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
diff --git a/ws.c b/ws.c
index 7302f8f..0a2914c 100644
--- a/ws.c
+++ b/ws.c
@@ -56,6 +56,11 @@ unsigned parse_whitespace_rule(const char *string)
 				rule |= whitespace_rule_names[i].rule_bits;
 			break;
 		}
+		if (strncmp(string, "tabwidth=", 9) == 0) {
+			unsigned tabwidth = atoi(string + 9);
+			if (0 < tabwidth && tabwidth < 0100)
+				rule &= ~WS_TAB_WIDTH_MASK, rule |= tabwidth;
+		}
 		string = ep;
 	}
 
@@ -84,7 +89,7 @@ unsigned whitespace_rule(const char *pathname)
 		value = attr_whitespace_rule.value;
 		if (ATTR_TRUE(value)) {
 			/* true (whitespace) */
-			unsigned all_rule = 0;
+			unsigned all_rule = ws_tab_width(whitespace_rule_cfg);
 			int i;
 			for (i = 0; i < ARRAY_SIZE(whitespace_rule_names); i++)
 				if (!whitespace_rule_names[i].loosens_error &&
@@ -93,7 +98,7 @@ unsigned whitespace_rule(const char *pathname)
 			return all_rule;
 		} else if (ATTR_FALSE(value)) {
 			/* false (-whitespace) */
-			return 0;
+			return ws_tab_width(whitespace_rule_cfg);
 		} else if (ATTR_UNSET(value)) {
 			/* reset to default (!whitespace) */
 			return whitespace_rule_cfg;
@@ -206,7 +211,7 @@ static unsigned ws_check_emit_1(const char *line, int len, unsigned ws_rule,
 	}
 
 	/* Check for indent using non-tab. */
-	if ((ws_rule & WS_INDENT_WITH_NON_TAB) && i - written >= 8) {
+	if ((ws_rule & WS_INDENT_WITH_NON_TAB) && i - written >= ws_tab_width(ws_rule)) {
 		result |= WS_INDENT_WITH_NON_TAB;
 		if (stream) {
 			fputs(ws, stream);
@@ -320,7 +325,7 @@ void ws_fix_copy(struct strbuf *dst, const char *src, int len, unsigned ws_rule,
 		} else if (ch == ' ') {
 			last_space_in_indent = i;
 			if ((ws_rule & WS_INDENT_WITH_NON_TAB) &&
-			    8 <= i - last_tab_in_indent)
+			    ws_tab_width(ws_rule) <= i - last_tab_in_indent)
 				need_fix_leading_space = 1;
 		} else
 			break;
@@ -350,7 +355,7 @@ void ws_fix_copy(struct strbuf *dst, const char *src, int len, unsigned ws_rule,
 				strbuf_addch(dst, ch);
 			} else {
 				consecutive_spaces++;
-				if (consecutive_spaces == 8) {
+				if (consecutive_spaces == ws_tab_width(ws_rule)) {
 					strbuf_addch(dst, '\t');
 					consecutive_spaces = 0;
 				}
@@ -368,7 +373,7 @@ void ws_fix_copy(struct strbuf *dst, const char *src, int len, unsigned ws_rule,
 			if (src[i] == '\t')
 				do {
 					strbuf_addch(dst, ' ');
-				} while (dst->len % 8);
+				} while (dst->len % ws_tab_width(ws_rule));
 			else
 				strbuf_addch(dst, src[i]);
 		}
-- 
1.7.3.2.1463.g5fe2

Re: [PATCH] Make the tab width used for whitespace checks configurable

[Jonathan Nieder]

Johannes Sixt wrote:

> Signed-off-by: Johannes Sixt <j6t@kdbg.org>
> ---
>  I have a project that uses tab width 4, and which has a lot of whitespace
>  errors. This is very helpful to spot them when lines are changed that
>  are indented with 4 spaces.

Thanks.

For what it's worth, I like the idea and the patch looks good.
(I haven't checked for missed spots or read the test in detail,
though.)

> +                       if (0 < tabwidth && tabwidth < 0100)
> +                               rule &= ~WS_TAB_WIDTH_MASK, rule |= tabwidth;

Tab widths are recognized with atoi and out-of-range tab widths are
silently ignored.  Could we help the user spot typos somehow?

Re: [PATCH] Make the tab width used for whitespace checks configurable

[Junio C Hamano]

Johannes Sixt <j.sixt@viscovery.net> writes:

> From: Johannes Sixt <j6t@kdbg.org>
>
> 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>
> ---
>  I have a project that uses tab width 4, and which has a lot of whitespace
>  errors. This is very helpful to spot them when lines are changed that
>  are indented with 4 spaces.

Heh, I like it.  This will be the second killer feature to upgrade to the
upcoming release.  We really should start calming things down.

I am sort of surprised how the patch does not have to touch neither diff.c
nor apply.c at all---it demonstrates how solidly and cleanly the ws.c
infrastructure was done in the first place, I guess ;-).

Thanks.

[PATCH 1/2 maint] apply --whitespace=fix: fix tab-in-indent

[Johannes Sixt]

From: Johannes Sixt <j6t@kdbg.org>

When the whitespace rule tab-in-indent is enabled, apply --whitespace=fix
replaces tabs by the appropriate amount of blanks. The code used
"dst->len % 8" as the criterion to stop adding blanks. But it forgot that
dst holds more than just the current line. Consequently, the modulus was
computed correctly only for the first added line, but not for the second
and subsequent lines. Fix it.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
 This can go on top of a347b17f or its ancestor.

 t/t4124-apply-ws-rule.sh |   28 ++++++++++++++++++++++++++++
 ws.c                     |    3 ++-
 2 files changed, 30 insertions(+), 1 deletions(-)

diff --git a/t/t4124-apply-ws-rule.sh b/t/t4124-apply-ws-rule.sh
index 61bfc56..40e5842 100755
--- a/t/t4124-apply-ws-rule.sh
+++ b/t/t4124-apply-ws-rule.sh
@@ -121,6 +121,34 @@ test_expect_success 'whitespace=error-all, no rule (attribute)' '
 
 '
 
+test_expect_success 'spaces inserted by tab-in-indent' '
+
+	git config core.whitespace -trailing,-space,-indent,tab &&
+	rm -f .gitattributes &&
+	test_fix % &&
+	sed -e "s/_/ /g" -e "s/>/	/" <<-\EOF >expect &&
+		An_SP in an ordinary line>and a HT.
+		________A HT (%).
+		________A SP and a HT (@%).
+		_________A SP, a HT and a SP (@%).
+		_______Seven SP.
+		________Eight SP (#).
+		________Seven SP and a HT (@%).
+		________________Eight SP and a HT (@#%).
+		_________Seven SP, a HT and a SP (@%).
+		_________________Eight SP, a HT and a SP (@#%).
+		_______________Fifteen SP (#).
+		________________Fifteen 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>
+	EOF
+	test_cmp expect target
+
+'
+
 for t in - ''
 do
 	case "$t" in '') tt='!' ;; *) tt= ;; esac
diff --git a/ws.c b/ws.c
index 7302f8f..e350436 100644
--- a/ws.c
+++ b/ws.c
@@ -363,12 +363,13 @@ void ws_fix_copy(struct strbuf *dst, const char *src, int len, unsigned ws_rule,
 		fixed = 1;
 	} else if ((ws_rule & WS_TAB_IN_INDENT) && last_tab_in_indent >= 0) {
 		/* Expand tabs into spaces */
+		int start = dst->len;
 		int last = last_tab_in_indent + 1;
 		for (i = 0; i < last; i++) {
 			if (src[i] == '\t')
 				do {
 					strbuf_addch(dst, ' ');
-				} while (dst->len % 8);
+				} while ((dst->len - start) % 8);
 			else
 				strbuf_addch(dst, src[i]);
 		}
-- 
1.7.3.67.gcc234

[PATCH 2/2 v2] Make the tab width used for whitespace checks configurable

[Johannes Sixt]

From: Johannes Sixt <j6t@kdbg.org>

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>
---
 Compared to the first submission, I added a warning() when tabwidth=foo
 is junk or out of range and tweaked the documentation. The interdiff is:

	diff --git a/Documentation/config.txt b/Documentation/config.txt
	index d88db1c..7aff5ce 100644
	--- a/Documentation/config.txt
	+++ b/Documentation/config.txt
	@@ -514,7 +514,7 @@ core.whitespace::
	   does not trigger if the character before such a carriage-return
	   is not a whitespace (not enabled by default).
	 * `tabwidth=<n>` tells how many character positions a tab occupies; this
	-  is relevant for `indent-with-non-tab` and when git fixes whitespace
	+  is relevant for `indent-with-non-tab` and when git fixes `tab-in-indent`
	   errors. The default tab width is 8. Allowed values are 1 to 63.
	 
	 core.fsyncobjectfiles::
	diff --git a/ws.c b/ws.c
	index 0a2914c..e80e156 100644
	--- a/ws.c
	+++ b/ws.c
	@@ -60,6 +60,9 @@ unsigned parse_whitespace_rule(const char *string)
				unsigned tabwidth = atoi(string + 9);
				if (0 < tabwidth && tabwidth < 0100)
					rule &= ~WS_TAB_WIDTH_MASK, rule |= tabwidth;
	+			else
	+				warning("tabwidth %.*s out of range",
	+					len - 9, string + 9);
			}
			string = ep;
		}
	@@ -368,12 +371,13 @@ void ws_fix_copy(struct strbuf *dst, 
			fixed = 1;
		} else if ((ws_rule & WS_TAB_IN_INDENT) && last_tab_in_indent >= 0) {
			/* Expand tabs into spaces */
	+		int start = dst->len;
			int last = last_tab_in_indent + 1;
			for (i = 0; i < last; i++) {
				if (src[i] == '\t')
					do {
						strbuf_addch(dst, ' ');
	-				} while (dst->len % ws_tab_width(ws_rule));
	+				} while ((dst->len - start) % ws_tab_width(ws_rule));
				else
					strbuf_addch(dst, src[i]);
			}

 Documentation/config.txt        |    3 +
 Documentation/gitattributes.txt |    6 ++-
 cache.h                         |   17 +++++---
 t/t4015-diff-whitespace.sh      |   28 +++++++++++++
 t/t4019-diff-wserror.sh         |   85 +++++++++++++++++++++++++++++++++++++++
 t/t4124-apply-ws-rule.sh        |   23 ++++++++---
 ws.c                            |   20 ++++++---
 7 files changed, 161 insertions(+), 21 deletions(-)

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 6a6c0b5..7aff5ce 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -513,6 +513,9 @@ core.whitespace::
   part of the line terminator, i.e. with it, `trailing-space`
   does not trigger if the character before such a carriage-return
   is not a whitespace (not enabled by default).
+* `tabwidth=<n>` tells how many character positions a tab occupies; this
+  is relevant for `indent-with-non-tab` and when git fixes `tab-in-indent`
+  errors. The default tab width is 8. Allowed values are 1 to 63.
 
 core.fsyncobjectfiles::
 	This boolean will enable 'fsync()' when writing object files.
diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index f7e4523..a79a06b 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -722,6 +722,8 @@ control per path.
 Set::
 
 	Notice all types of potential whitespace errors known to git.
+	The tab width is taken from the value of the `core.whitespace`
+	configuration variable.
 
 Unset::
 
@@ -729,13 +731,13 @@ Unset::
 
 Unspecified::
 
-	Use the value of `core.whitespace` configuration variable to
+	Use the value of the `core.whitespace` configuration variable to
 	decide what to notice as error.
 
 String::
 
 	Specify a comma separate list of common whitespace problems to
-	notice in the same format as `core.whitespace` configuration
+	notice in the same format as the `core.whitespace` configuration
 	variable.
 
 
diff --git a/cache.h b/cache.h
index 33decd9..8e8c9d4 100644
--- a/cache.h
+++ b/cache.h
@@ -1087,15 +1087,17 @@ void shift_tree_by(const unsigned char *, const unsigned char *, unsigned char *
 /*
  * whitespace rules.
  * used by both diff and apply
+ * last two digits are tab width
  */
-#define WS_BLANK_AT_EOL         01
-#define WS_SPACE_BEFORE_TAB	02
-#define WS_INDENT_WITH_NON_TAB	04
-#define WS_CR_AT_EOL           010
-#define WS_BLANK_AT_EOF        020
-#define WS_TAB_IN_INDENT       040
+#define WS_BLANK_AT_EOL         0100
+#define WS_SPACE_BEFORE_TAB     0200
+#define WS_INDENT_WITH_NON_TAB  0400
+#define WS_CR_AT_EOL           01000
+#define WS_BLANK_AT_EOF        02000
+#define WS_TAB_IN_INDENT       04000
 #define WS_TRAILING_SPACE      (WS_BLANK_AT_EOL|WS_BLANK_AT_EOF)
-#define WS_DEFAULT_RULE (WS_TRAILING_SPACE|WS_SPACE_BEFORE_TAB)
+#define WS_DEFAULT_RULE (WS_TRAILING_SPACE|WS_SPACE_BEFORE_TAB|8)
+#define WS_TAB_WIDTH_MASK        077
 extern unsigned whitespace_rule_cfg;
 extern unsigned whitespace_rule(const char *);
 extern unsigned parse_whitespace_rule(const char *);
@@ -1104,6 +1106,7 @@ extern void ws_check_emit(const char *line, int len, unsigned ws_rule, FILE *str
 extern char *whitespace_error_string(unsigned ws);
 extern void ws_fix_copy(struct strbuf *, const char *, int, unsigned, int *);
 extern int ws_blank_line(const char *line, int len, unsigned ws_rule);
+#define ws_tab_width(rule)     ((rule) & WS_TAB_WIDTH_MASK)
 
 /* ls-files */
 int report_path_error(const char *ps_matched, const char **pathspec, int prefix_offset);
diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index 8622eb5..9059bcd 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 f7c85ec..6f992c8 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 40e5842..6f6ee88 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
diff --git a/ws.c b/ws.c
index e350436..e80e156 100644
--- a/ws.c
+++ b/ws.c
@@ -56,6 +56,14 @@ unsigned parse_whitespace_rule(const char *string)
 				rule |= whitespace_rule_names[i].rule_bits;
 			break;
 		}
+		if (strncmp(string, "tabwidth=", 9) == 0) {
+			unsigned tabwidth = atoi(string + 9);
+			if (0 < tabwidth && tabwidth < 0100)
+				rule &= ~WS_TAB_WIDTH_MASK, rule |= tabwidth;
+			else
+				warning("tabwidth %.*s out of range",
+					len - 9, string + 9);
+		}
 		string = ep;
 	}
 
@@ -84,7 +92,7 @@ unsigned whitespace_rule(const char *pathname)
 		value = attr_whitespace_rule.value;
 		if (ATTR_TRUE(value)) {
 			/* true (whitespace) */
-			unsigned all_rule = 0;
+			unsigned all_rule = ws_tab_width(whitespace_rule_cfg);
 			int i;
 			for (i = 0; i < ARRAY_SIZE(whitespace_rule_names); i++)
 				if (!whitespace_rule_names[i].loosens_error &&
@@ -93,7 +101,7 @@ unsigned whitespace_rule(const char *pathname)
 			return all_rule;
 		} else if (ATTR_FALSE(value)) {
 			/* false (-whitespace) */
-			return 0;
+			return ws_tab_width(whitespace_rule_cfg);
 		} else if (ATTR_UNSET(value)) {
 			/* reset to default (!whitespace) */
 			return whitespace_rule_cfg;
@@ -206,7 +214,7 @@ static unsigned ws_check_emit_1(const char *line, int len, unsigned ws_rule,
 	}
 
 	/* Check for indent using non-tab. */
-	if ((ws_rule & WS_INDENT_WITH_NON_TAB) && i - written >= 8) {
+	if ((ws_rule & WS_INDENT_WITH_NON_TAB) && i - written >= ws_tab_width(ws_rule)) {
 		result |= WS_INDENT_WITH_NON_TAB;
 		if (stream) {
 			fputs(ws, stream);
@@ -320,7 +328,7 @@ void ws_fix_copy(struct strbuf *dst, const char *src, int len, unsigned ws_rule,
 		} else if (ch == ' ') {
 			last_space_in_indent = i;
 			if ((ws_rule & WS_INDENT_WITH_NON_TAB) &&
-			    8 <= i - last_tab_in_indent)
+			    ws_tab_width(ws_rule) <= i - last_tab_in_indent)
 				need_fix_leading_space = 1;
 		} else
 			break;
@@ -350,7 +358,7 @@ void ws_fix_copy(struct strbuf *dst, const char *src, int len, unsigned ws_rule,
 				strbuf_addch(dst, ch);
 			} else {
 				consecutive_spaces++;
-				if (consecutive_spaces == 8) {
+				if (consecutive_spaces == ws_tab_width(ws_rule)) {
 					strbuf_addch(dst, '\t');
 					consecutive_spaces = 0;
 				}
@@ -369,7 +377,7 @@ void ws_fix_copy(struct strbuf *dst, const char *src, int len, unsigned ws_rule,
 			if (src[i] == '\t')
 				do {
 					strbuf_addch(dst, ' ');
-				} while ((dst->len - start) % 8);
+				} while ((dst->len - start) % ws_tab_width(ws_rule));
 			else
 				strbuf_addch(dst, src[i]);
 		}
-- 
1.7.3.67.gcc234

Re: [PATCH 1/2 maint] apply --whitespace=fix: fix tab-in-indent

[Chris Webb]

Johannes Sixt <j.sixt@viscovery.net> writes:

> When the whitespace rule tab-in-indent is enabled, apply --whitespace=fix
> replaces tabs by the appropriate amount of blanks. The code used
> "dst->len % 8" as the criterion to stop adding blanks. But it forgot that
> dst holds more than just the current line. Consequently, the modulus was
> computed correctly only for the first added line, but not for the second
> and subsequent lines. Fix it.

You're quite right! My mistake, so if you like, please feel free to add

Acked-by: Chris Webb <chris@arachsys.com>

Cheers,

Chris.