From: Denis Vlasenko <vda.linux@googlemail.com>
Date: Thu, 2 Apr 2009 20:17:49 +0000 (-0000)
Subject: hush: rename ->o_quote to ->o_escape
X-Git-Tag: 1_14_0~128
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=b7aaae9052025426b669a0edeec1da5997fea8be;p=oweals%2Fbusybox.git

hush: rename ->o_quote to ->o_escape
hush_test/hush-arith/*: new tests for arithmetic evaluation
---

diff --git a/shell/hush.c b/shell/hush.c
index b46a1fd76..f0d372625 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -392,9 +392,9 @@ typedef struct o_string {
 	char *data;
 	int length; /* position where data is appended */
 	int maxlen;
-	/* Misnomer! it's not "quoting", it's "protection against globbing"!
-	 * (by prepending \ to *, ?, [ and to \ too) */
-	smallint o_quote;
+	/* Protect newly added chars against globbing
+	 * (by prepending \ to *, ?, [, \) */
+	smallint o_escape;
 	smallint o_glob;
 	smallint nonnull;
 	smallint has_empty_slot;
@@ -1440,7 +1440,7 @@ static void o_addqchr(o_string *o, int ch)
 static void o_addQchr(o_string *o, int ch)
 {
 	int sz = 1;
-	if (o->o_quote && strchr("*?[\\", ch)) {
+	if (o->o_escape && strchr("*?[\\", ch)) {
 		sz++;
 		o->data[o->length] = '\\';
 		o->length++;
@@ -1453,7 +1453,7 @@ static void o_addQchr(o_string *o, int ch)
 
 static void o_addQstr(o_string *o, const char *str, int len)
 {
-	if (!o->o_quote) {
+	if (!o->o_escape) {
 		o_addstr(o, str, len);
 		return;
 	}
@@ -1668,7 +1668,7 @@ static int expand_on_ifs(o_string *output, int n, const char *str)
 	while (1) {
 		int word_len = strcspn(str, G.ifs);
 		if (word_len) {
-			if (output->o_quote || !output->o_glob)
+			if (output->o_escape || !output->o_glob)
 				o_addQstr(output, str, word_len);
 			else /* protect backslashes against globbing up :) */
 				o_addstr_duplicate_backslash(output, str, word_len);
@@ -1751,9 +1751,9 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
 				break;
 			ored_ch |= first_ch; /* do it for "$@" _now_, when we know it's not empty */
 			if (!(first_ch & 0x80)) { /* unquoted $* or $@ */
-				smallint sv = output->o_quote;
-				/* unquoted var's contents should be globbed, so don't quote */
-				output->o_quote = 0;
+				smallint sv = output->o_escape;
+				/* unquoted var's contents should be globbed, so don't escape */
+				output->o_escape = 0;
 				while (G.global_argv[i]) {
 					n = expand_on_ifs(output, n, G.global_argv[i]);
 					debug_printf_expand("expand_vars_to_list: argv %d (last %d)\n", i, G.global_argc - 1);
@@ -1766,7 +1766,7 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
 						debug_print_list("expand_vars_to_list[3]", output, n);
 					}
 				}
-				output->o_quote = sv;
+				output->o_escape = sv;
 			} else
 			/* If or_mask is nonzero, we handle assignment 'a=....$@.....'
 			 * and in this case should treat it like '$*' - see 'else...' below */
@@ -1945,17 +1945,17 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
  store_val:
 #endif
 			if (!(first_ch & 0x80)) { /* unquoted $VAR */
-				debug_printf_expand("unquoted '%s', output->o_quote:%d\n", val, output->o_quote);
+				debug_printf_expand("unquoted '%s', output->o_escape:%d\n", val, output->o_escape);
 				if (val) {
-					/* unquoted var's contents should be globbed, so don't quote */
-					smallint sv = output->o_quote;
-					output->o_quote = 0;
+					/* unquoted var's contents should be globbed, so don't escape */
+					smallint sv = output->o_escape;
+					output->o_escape = 0;
 					n = expand_on_ifs(output, n, val);
 					val = NULL;
-					output->o_quote = sv;
+					output->o_escape = sv;
 				}
 			} else { /* quoted $VAR, val will be appended below */
-				debug_printf_expand("quoted '%s', output->o_quote:%d\n", val, output->o_quote);
+				debug_printf_expand("quoted '%s', output->o_escape:%d\n", val, output->o_escape);
 			}
 		} /* default: */
 		} /* switch (char after <SPECIAL_VAR_SYMBOL>) */
@@ -1999,7 +1999,7 @@ static char **expand_variables(char **argv, int or_mask)
 	o_string output = NULL_O_STRING;
 
 	if (or_mask & 0x100) {
-		output.o_quote = 1; /* protect against globbing for "$var" */
+		output.o_escape = 1; /* protect against globbing for "$var" */
 		/* (unquoted $var will temporarily switch it off) */
 		output.o_glob = 1;
 	}
@@ -3979,7 +3979,7 @@ static int handle_dollar(o_string *dest, struct in_str *input)
 {
 	int expansion;
 	int ch = i_peek(input);  /* first character after the $ */
-	unsigned char quote_mask = dest->o_quote ? 0x80 : 0;
+	unsigned char quote_mask = dest->o_escape ? 0x80 : 0;
 
 	debug_printf_parse("handle_dollar entered: ch='%c'\n", ch);
 	if (isalpha(ch)) {
@@ -4143,7 +4143,7 @@ static int parse_stream_dquoted(o_string *dest, struct in_str *input, int dquote
 	if (ch == dquote_end) { /* may be only '"' or EOF */
 		dest->nonnull = 1;
 		if (dest->o_assignment == NOT_ASSIGNMENT)
-			dest->o_quote ^= 1;
+			dest->o_escape ^= 1;
 		debug_printf_parse("parse_stream_dquoted return 0\n");
 		return 0;
 	}
@@ -4157,8 +4157,8 @@ static int parse_stream_dquoted(o_string *dest, struct in_str *input, int dquote
 	if (ch != '\n') {
 		next = i_peek(input);
 	}
-	debug_printf_parse(": ch=%c (%d) m=%d quote=%d\n",
-					ch, ch, m, dest->o_quote);
+	debug_printf_parse(": ch=%c (%d) m=%d escape=%d\n",
+					ch, ch, m, dest->o_escape);
 	/* Basically, checking every CHAR_SPECIAL char except '"' */
 	if (ch == '\\') {
 		if (next == EOF) {
@@ -4225,13 +4225,13 @@ static int parse_stream(o_string *dest, struct parse_context *ctx,
 	int is_in_dquote;
 	int next;
 
-	/* Only double-quote state is handled in the state variable dest->o_quote.
+	/* Double-quote state is handled in the state variable is_in_dquote.
 	 * A single-quote triggers a bypass of the main loop until its mate is
-	 * found.  When recursing, quote state is passed in via dest->o_quote. */
+	 * found.  When recursing, quote state is passed in via dest->o_escape. */
 
 	debug_printf_parse("parse_stream entered, end_trigger='%s' dest->o_assignment:%d\n", end_trigger, dest->o_assignment);
 
-	is_in_dquote = dest->o_quote;
+	is_in_dquote = dest->o_escape;
 	while (1) {
 		if (is_in_dquote) {
 			if (parse_stream_dquoted(dest, input, '"'))
@@ -4248,8 +4248,8 @@ static int parse_stream(o_string *dest, struct parse_context *ctx,
 				next = i_peek(input);
 			}
 		}
-		debug_printf_parse(": ch=%c (%d) m=%d quote=%d\n",
-						ch, ch, m, dest->o_quote);
+		debug_printf_parse(": ch=%c (%d) m=%d escape=%d\n",
+						ch, ch, m, dest->o_escape);
 		if (m == CHAR_ORDINARY) {
 			o_addQchr(dest, ch);
 			if ((dest->o_assignment == MAYBE_ASSIGNMENT
@@ -4365,7 +4365,7 @@ static int parse_stream(o_string *dest, struct parse_context *ctx,
 			dest->nonnull = 1;
 			is_in_dquote ^= 1; /* invert */
 			if (dest->o_assignment == NOT_ASSIGNMENT)
-				dest->o_quote ^= 1;
+				dest->o_escape ^= 1;
 			break;
 #if ENABLE_HUSH_TICK
 		case '`': {
@@ -4594,7 +4594,7 @@ static int parse_and_run_stream(struct in_str *inp, int parse_flag)
 			}
 #endif
 			/*temp.nonnull = 0; - o_free does it below */
-			/*temp.o_quote = 0; - o_free does it below */
+			/*temp.o_escape = 0; - o_free does it below */
 			free_pipe_list(ctx.list_head, /* indent: */ 0);
 			/* Discard all unprocessed line input, force prompt on */
 			inp->p = NULL;
diff --git a/shell/hush_test/hush-arith/arith.right b/shell/hush_test/hush-arith/arith.right
new file mode 100644
index 000000000..a35fe893f
--- /dev/null
+++ b/shell/hush_test/hush-arith/arith.right
@@ -0,0 +1,138 @@
+Format: 'expected actual'
+163 163
+4 4
+16 16
+8 8
+2 2
+4 4
+2 2
+2 2
+1 1
+0 0
+0 0
+0 0
+1 1
+1 1
+2 2
+-3 -3
+-2 -2
+1 1
+0 0
+2 2
+131072 131072
+29 29
+33 33
+49 49
+1 1
+1 1
+0 0
+0 0
+1 1
+1 1
+1 1
+2 2
+3 3
+1 1
+58 58
+2 2
+60 60
+1 1
+256 256
+16 16
+62 62
+4 4
+29 29
+5 5
+-4 -4
+4 4
+1 1
+32 32
+32 32
+1 1
+1 1
+32 32
+20 20
+30 30
+20 20
+30 30
+hush: arith: syntax error
+6 6
+6,5,3 6,5,3
+263 263
+255 255
+40 40
+hush: arith: syntax error
+hush: arith: divide by zero
+hush: can't exec 'let': No such file or directory
+hush: arith: syntax error
+hush: can't exec 'let': No such file or directory
+abc
+def
+ghi
+hush: arith: syntax error
+16 16
+hush: arith: syntax error
+hush: arith: syntax error
+hush: arith: syntax error
+9 9
+hush: arith: syntax error
+hush: arith: syntax error
+9 9
+9 9
+9 9
+7 7
+7
+4 4
+32767 32767
+32768 32768
+131072 131072
+2147483647 2147483647
+1 1
+4 4
+4 4
+5 5
+5 5
+4 4
+3 3
+3 3
+4 4
+4 4
+hush: arith: syntax error
+hush: arith: syntax error
+hush: arith: syntax error
+hush: arith: syntax error
+hush: arith: syntax error
+4 4
+7 7
+-7 -7
+hush: arith: syntax error
+hush: arith: syntax error
+hush: arith: syntax error
+hush: arith: syntax error
+6 6
+3 3
+7 7
+4 4
+0 0
+3 3
+7 7
+2 2
+-2 -2
+1 1
+hush: arith: syntax error
+hush: arith: syntax error
+hush: arith: syntax error
+hush: arith: syntax error
+hush: arith: syntax error
+5 5
+1 1
+4 4
+0 0
+hush: arith: syntax error
+hush: arith: syntax error
+8 12
+hush: arith: syntax error
+42
+42
+42
+hush: can't exec 'a[b[c]d]=e': No such file or directory
diff --git a/shell/hush_test/hush-arith/arith.tests b/shell/hush_test/hush-arith/arith.tests
new file mode 100755
index 000000000..57e66e888
--- /dev/null
+++ b/shell/hush_test/hush-arith/arith.tests
@@ -0,0 +1,302 @@
+#ash# set +o posix
+#ash# declare -i iv jv
+
+echo "Format: 'expected actual'"
+
+iv=$(( 3 + 5 * 32 ))
+echo 163 $iv
+#ash# iv=iv+3
+#ash# echo 166 $iv
+iv=2
+jv=iv
+
+: $((jv *= 2)) ##hush## let "jv *= 2"
+echo 4 $jv
+jv=$(( $jv << 2 ))
+echo 16 $jv
+
+: $((jv=$jv / 2)) ##hush## let jv="$jv / 2"
+echo 8 $jv
+#ash# jv="jv >> 2"
+: $((jv=jv >> 2)) ##hush## let jv="jv >> 2"
+echo 2 $jv
+
+iv=$((iv+ $jv))
+echo 4 $iv
+echo 2 $((iv -= jv))
+echo 2 $iv
+echo 1 $(( iv == jv ))
+echo 0 $(( iv != $jv ))
+echo 0 $(( iv < jv ))
+echo 0 $(( $iv > $jv ))
+echo 1 $(( iv <= $jv ))
+echo 1 $(( $iv >= jv ))
+
+echo 2 $jv
+echo -3 $(( ~$jv ))
+echo -2 $(( ~1 ))
+echo 1 $(( ! 0 ))
+
+echo 0 $(( jv % 2 ))
+echo 2 $(( $iv % 4 ))
+
+echo 131072 $(( iv <<= 16 ))
+echo 29 $(( iv %= 33 ))
+
+echo 33 $(( 33 & 55 ))
+echo 49 $(( 33 | 17 ))
+
+echo 1 $(( iv && $jv ))
+echo 1 $(( $iv || jv ))
+
+echo 0 $(( iv && 0 ))
+echo 0 $(( iv & 0 ))
+echo 1 $(( iv && 1 ))
+echo 1 $(( iv & 1 ))
+
+echo 1 $(( $jv || 0 ))
+echo 2 $(( jv | 0 ))
+echo 3 $(( jv | 1 ))
+echo 1 $(( $jv || 1 ))
+
+: $((iv *= jv)) ##hush## let 'iv *= jv'
+echo 58 $iv
+echo 2 $jv
+: $((jv += $iv)) ##hush## let "jv += $iv"
+echo 60 $jv
+
+echo 1 $(( jv /= iv ))
+echo 256 $(( jv <<= 8 ))
+echo 16 $(( jv >>= 4 ))
+
+echo 62 $(( iv |= 4 ))
+echo 4 $(( iv &= 4 ))
+
+echo 29 $(( iv += (jv + 9)))
+echo 5 $(( (iv + 4) % 7 ))
+
+# unary plus, minus
+echo -4 $(( +4 - 8 ))
+echo 4 $(( -4 + 8 ))
+
+# conditional expressions
+echo 1 $(( 4<5 ? 1 : 32))
+echo 32 $(( 4>5 ? 1 : 32))
+echo 32 $(( 4>(2+3) ? 1 : 32))
+echo 1 $(( 4<(2+3) ? 1 : 32))
+echo 1 $(( (2+2)<(2+3) ? 1 : 32))
+echo 32 $(( (2+2)>(2+3) ? 1 : 32))
+
+# check that the unevaluated part of the ternary operator does not do
+# evaluation or assignment
+x=i+=2
+y=j+=2
+#ash# declare -i i=1 j=1
+      i=1
+      j=1
+echo 20 $((1 ? 20 : (x+=2)))
+#ash# echo $i,$x             # ash mishandles this
+echo 30 $((0 ? (y+=2) : 30))
+#ash# echo $j,$y             # ash mishandles this
+
+x=i+=2
+y=j+=2
+#ash# declare -i i=1 j=1
+      i=1
+      j=1
+echo 20 $((1 ? 20 : (x+=2)))
+#ash# echo $i,$x             # ash mishandles this
+echo 30 $((0 ? (y+=2) : 30))
+#ash# echo $i,$y             # ash mishandles this
+
+# check precedence of assignment vs. conditional operator
+# should be an error
+#ash# declare -i x=2
+      x=2
+#ashnote# bash reports error but continues, ash aborts - using subshell to 'emulate' bash:
+(  y=$((1 ? 20 : x+=2))  )
+
+# check precedence of assignment vs. conditional operator
+#ash# declare -i x=2
+      x=2
+# ash says "line NNN: syntax error: 0 ? x+=2 : 20"
+#ash# echo 20 $((0 ? x+=2 : 20))
+
+# associativity of assignment-operator operator
+#ash# declare -i i=1 j=2 k=3
+i=1
+j=2
+k=3
+echo 6 $((i += j += k))
+echo 6,5,3 $i,$j,$k
+
+# octal, hex
+echo 263 $(( 0x100 | 007 ))
+echo 255 $(( 0xff ))
+#ash# echo 255 $(( 16#ff ))
+#ash# echo 127 $(( 16#FF/2 ))
+#ash# echo 36 $(( 8#44 ))
+
+echo 40 $(( 8 ^ 32 ))
+
+#ash# # other bases
+#ash# echo 10 $(( 16#a ))
+#ash# echo 10 $(( 32#a ))
+#ash# echo 10 $(( 56#a ))
+#ash# echo 10 $(( 64#a ))
+#ash#
+#ash# echo 10 $(( 16#A ))
+#ash# echo 10 $(( 32#A ))
+#ash# echo 36 $(( 56#A ))
+#ash# echo 36 $(( 64#A ))
+#ash#
+#ash# echo 62 $(( 64#@ ))
+#ash# echo 63 $(( 64#_ ))
+
+#ash# # weird bases (error)
+#ash# echo $(( 3425#56 ))
+
+#ash# # missing number after base
+#ash# echo 0 $(( 2# ))
+
+# these should generate errors
+(  echo $(( 7 = 43 ))      )
+#ash# echo $(( 2#44 ))
+(  echo $(( 44 / 0 ))      )
+(  let 'jv += $iv'         )
+(  echo $(( jv += \$iv ))  )
+(  let 'rv = 7 + (43 * 6'  )
+
+#ash# # more errors
+#ash# declare -i i
+#ash# i=0#4
+#ash# i=2#110#11
+
+((echo abc; echo def;); echo ghi)
+
+#ash# if (((4+4) + (4 + 7))); then
+#ash# 	echo ok
+#ash# fi
+
+#ash# (())	# make sure the null expression works OK
+
+#ash# a=(0 2 4 6)
+#ash# echo 6 $(( a[1] + a[2] ))
+#ash# echo 1 $(( (a[1] + a[2]) == a[3] ))
+#ash# (( (a[1] + a[2]) == a[3] )) ; echo 0 $?
+
+# test pushing and popping the expression stack
+unset A
+A="4 + "
+(  echo A $(( ( 4 + A ) + 4 ))  )
+A="3 + 5"
+echo 16 $(( ( 4 + A ) + 4 ))
+
+# badly-formed conditional expressions
+(  echo $(( 4 ? : $A ))  )
+(  echo $(( 1 ? 20 ))    )
+(  echo $(( 4 ? 20 : ))  )
+
+# precedence and short-circuit evaluation
+B=9
+echo 9 $B
+
+# error
+(  echo $(( 0 && B=42 )); echo 9 $B  )
+
+# error
+(  echo $(( 1 || B=88 )); echo 9 $B  )
+
+# ash mistakenly evaluates B=... below
+#ash# echo 0 $(( 0 && (B=42) ))
+echo 9 $B
+#ash# echo 0 $(( (${$} - $$) && (B=42) ))
+echo 9 $B
+#ash# echo 1 $(( 1 || (B=88) ))
+echo 9 $B
+
+
+# until command with (( )) command
+x=7
+
+echo 7 $x
+#ash# until (( x == 4 ))
+      until test "$x" = 4
+do
+	echo $x
+	x=4
+done
+
+echo 4 $x
+
+# exponentiation
+echo 32767 $(( 2**15 - 1))
+echo 32768 $(( 2**(16-1)))
+echo 131072 $(( 2**16*2 ))
+echo 2147483647 $(( 2**31-1))
+echo 1 $(( 2**0 ))
+
+# {pre,post}-{inc,dec}rement and associated errors
+
+x=4
+
+echo 4 $x
+echo 4 $(( x++ ))
+echo 5 $x
+echo 5 $(( x-- ))
+echo 4 $x
+
+echo 3 $(( --x ))
+echo 3 $x
+
+echo 4 $(( ++x ))
+echo 4 $x
+
+# bash 3.2 apparently thinks that ++7 is 7
+#ash# echo 7 $(( ++7 ))
+(  echo $(( 7-- ))    )
+
+(  echo $(( --x=7 ))  )
+(  echo $(( ++x=7 ))  )
+
+(  echo $(( x++=7 ))  )
+(  echo $(( x--=7 ))  )
+
+echo 4 $x
+
+echo 7 $(( +7 ))
+echo -7 $(( -7 ))
+
+# bash 3.2 apparently thinks that ++7 is 7
+#ash# echo $(( ++7 ))
+#ash# echo $(( --7 ))
+
+${THIS_SH} ./arith1.sub
+${THIS_SH} ./arith2.sub
+
+x=4
+y=7
+
+#ash# (( x=8 , y=12 ))
+      x=8
+      y=12
+echo $x $y
+
+#ash# # should be an error
+#ash# (( x=9 y=41 ))
+
+# These are errors
+unset b
+(  echo $((a b))  )
+#ash# ((a b))
+
+n=42
+printf "%d\n" $n
+printf "%i\n" $n
+#ash# echo $(( 8#$(printf "%o\n" $n) ))
+printf "%u\n" $n
+#ash# echo $(( 16#$(printf "%x\n" $n) ))
+#ash# echo $(( 16#$(printf "%X\n" $n) ))
+
+# causes longjmp botches through bash-2.05b
+a[b[c]d]=e
diff --git a/shell/hush_test/hush-arith/arith1.sub b/shell/hush_test/hush-arith/arith1.sub
new file mode 100755
index 000000000..80aa99922
--- /dev/null
+++ b/shell/hush_test/hush-arith/arith1.sub
@@ -0,0 +1,40 @@
+# test of redone post-increment and post-decrement code
+(  echo $(( 4-- ))   )
+(  echo $(( 4++ ))   )
+(  echo $(( 4 -- ))  )
+(  echo $(( 4 ++ ))  )
+
+#ash# (( array[0]++ ))
+#ash# echo ${array}
+
+#ash# (( array[0] ++ ))
+#ash# echo ${array}
+
+#ash# (( a++ ))
+#ash# echo $a
+#ash# (( a ++ ))
+#ash# echo $a
+      a=2
+
+echo 6 $(( a ++ + 4 ))
+echo 3 $a
+
+echo 7 $(( a+++4 ))
+echo 4 $a
+
+echo 0 $(( a---4 ))
+echo 3 $a
+
+echo 7 $(( a -- + 4 ))
+echo 2 $a
+
+echo -2 $(( a -- - 4 ))
+echo 1 $a
+
+#ash# (( ++ + 7 ))
+
+#ash# (( ++ ))
+(  echo $(( +++7 ))  )
+# bash 3.2 apparently thinks that ++ +7 is 7
+#ash# echo $(( ++ + 7 ))
+#ash# (( -- ))
diff --git a/shell/hush_test/hush-arith/arith2.sub b/shell/hush_test/hush-arith/arith2.sub
new file mode 100755
index 000000000..f7e3c9235
--- /dev/null
+++ b/shell/hush_test/hush-arith/arith2.sub
@@ -0,0 +1,57 @@
+# bash 3.2 apparently thinks that ++7 is 7 etc
+(  echo $(( --7 ))   )
+(  echo $(( ++7 ))   )
+(  echo $(( -- 7 ))  )
+(  echo $(( ++ 7 ))  )
+
+#ash# ((++array[0] ))
+#ash# echo 1 $array
+#ash# (( ++ array[0] ))
+#ash# echo 2 $array
+
+#ash# (( ++a ))
+#ash# echo 1 $a
+#ash# (( ++ a ))
+#ash# echo 2 $a
+
+#ash# (( --a ))
+#ash# echo 1 $a
+#ash# (( -- a ))
+#ash# echo 0 $a
+      a=0
+
+echo 5 $(( 4 + ++a ))
+echo 1 $a
+
+# ash doesn't handle it right...
+#ash# echo 6 $(( 4+++a ))
+#ash# echo 2 $a
+      a=2
+
+# ash doesn't handle it right...
+#ash# echo 3 $(( 4---a ))
+#ash# echo 1 $a
+      a=1
+
+echo 4 $(( 4 - -- a ))
+echo 0 $a
+
+#ash# (( -- ))
+# bash 3.2 apparently thinks that ---7 is -7
+#ash# echo $(( ---7 ))
+(  echo $(( -- - 7 ))  )
+
+#ash# (( ++ ))
+# bash 3.2: 7
+#ash# echo 7 $(( ++7 ))
+(  echo $(( ++ + 7 ))  )
+
+# bash 3.2: -7
+#ash# echo -7 $(( ++-7 ))
+# bash 3.2: -7
+#ash# echo -7 $(( ++ - 7 ))
+
+# bash 3.2: 7
+#ash# echo 7 $(( +--7 ))
+# bash 3.2: 7
+#ash# echo 7 $(( -- + 7 ))