arithmetic: Fix the octal leading zero mess (#337)

In C/POSIX arithmetic, a leading 0 denotes an octal number, e.g.
010 == 8. But this is not a desirable feature as it can cause
problems with processing things like dates with a leading zero.
In ksh, you should use 8#10 instead ("10" with base 8).

It would be tolerable if ksh at least implemented it consistently.
But AT&T made an incredible mess of it. For anyone who is not
intimately familiar with ksh internals, it is inscrutable where
arithmetic evaluation special-cases a leading 0 and where it
doesn't. Here are just some of the surprises/inconsistencies:

1. The AT&T maintainers tried to honour a leading 0 inside of
   ((...)) and $((...)) and not for arithmetic contexts outside it,
   but even that inconsistency was never quite consistent.

2. Since 2010-12-12, $((x)) and $(($x)) are different:
      $ /bin/ksh -c 'x=010; echo $((x)) $(($x))'
      10 8
   That's a clear violation of both POSIX and the principle of
   least astonishment. $((x)) and $(($x)) should be the same in
   all cases.

3. 'let' with '-o letoctal' acts in this bizarre way:
      $ set -o letoctal; x=010; let "y1=$x" "y2=010"; echo $y1 $y2
      10 8
   That's right, 'let y=$x' is different from 'let y=010' even
   when $x contains the same string value '010'! This violates
   established shell grammar on the most basic level.

This commit introduces consistency. By default, ksh now acts like
mksh and zsh: the octal leading zero is disabled in all arithmetic
contexts equally. In POSIX mode, it is enabled equally.

The one exception is the 'let' built-in, where this can still be
controlled independently with the letoctal option as before (but,
because letoctal is synched with posix when switching that on/off,
it's consistent by default).

We're also removing the hackery that causes variable expansions for
the 'let' builtin to be quietly altered, so that 'x=010; let y=$x'
now does the same as 'let y=010' even with letoctal on.

Various files:
- Get rid of now-redundant sh.inarith (shp->inarith) flag, as we're
  no longer distinguishing between being inside or outside ((...)).

src/cmd/ksh93/sh/arith.c:
- arith(): Let disabling POSIX octal constants by skipping leading
  zeros depend on either the letoctal option being off (if we're
  running the "let" built-in") or the posix option being off.
- sh_strnum(): Preset a base of 10 for strtonll(3) depending on the
  posix or letoctal option being off, not on the sh.inarith flag.

src/cmd/ksh93/include/argnod.h,
src/cmd/ksh93/sh/args.c,
src/cmd/ksh93/sh/macro.c:
- Remove astonishing hackery that violated shell grammar for 'let'.

src/cmd/ksh93/sh/name.c (nv_getnum()),
src/cmd/ksh93/sh/nvdisc.c (nv_getn()):
- Remove loops for skipping leading zeroes that included a broken
  check for justify/zerofill attributes, thereby fixing this bug:
	$ typeset -Z x=0x15; echo $((x))
	-ksh: x15: parameter not set
  Even if this code wasn't redundant before, it is now: sh_arith()
  is called immediately after the removed code and it ignores
  leading zeroes via sh_strnum() and strtonll(3).

Resolves: https://github.com/ksh93/ksh/issues/334

NEWS

@@ -3,6 +3,19 @@ For full details, see the git log at: https://github.com/ksh93/ksh
 
 Any uppercase BUG_* names are modernish shell bug IDs.
 
+2021-11-16:
+
+- By default, arithmetic expressions in ksh no longer interpret a number
+  with a leading zero as octal in any context. Use 8#octalnumber instead.
+  Before, ksh would arbitrarily recognize the leading octal zero in some
+  contexts but not others, e.g., both of:
+	$ x=010; echo "$((x)), $(($x))"
+	$ set -o letoctal; x=010; let y=$x z=010; echo "$y, $z"
+  would output '10, 8'. These now output '10, 10' and '8, 8', respectively.
+  Arithmetic expressions now also behave identically within and outside
+  ((...)) and $((...)). Setting the --posix compliance option turns on the
+  recognition of the leading octal zero for all arithmetic contexts.
+
 2021-11-15:
 
 - In arithmetic evaluation, the --posix compliance option now disables the
@@ -42,11 +55,6 @@ Any uppercase BUG_* names are modernish shell bug IDs.
 
 2021-09-13:
 
-- Fixed a bug introduced in 93u+ 2012-02-07 that caused the 'printf' builtin
-  (and its 'print -f' equivalent) to fail to recognise integer arguments with a
-  leading zero as octal numbers. For example, 'printf "%d\n" 010' now once
-  again outputs '8' instead of '10'.
-
 - Disable the POSIX arithmetic context while running a command substitution
   invoked from within an arithmetic expression. This fixes a bug that caused
   integer arguments with a leading zero to be incorrectly interpreted as octal

src/cmd/ksh93/COMPATIBILITY

@@ -151,10 +151,15 @@ For more details, see the NEWS file and for complete details, see the git log.
 	correctly negates another '!', e.g., [[ ! ! 1 -eq 1 ]] now returns
 	0/true. Note that this has always been the case for 'test'/'['.
 
-28.	In the 'printf' builtin (and the 'print -f' equivalent), numeric
+28.	By default, arithmetic expressions in ksh no longer interpret a number
-	arguments with a leading zero are now once again recognized as octal
+	with a leading zero as octal in any context. Use 8#octalnumber instead.
-	numbers as in ksh93 versions before 2012-02-07, and as POSIX requires.
+	Before, ksh would arbitrarily recognize the leading octal zero in some
-	For example, 'printf "%d\n" 010' now once again outputs '8'.
+	contexts but not others. One of several examples is:
+		x=010; echo "$((x)), $(($x))"
+	would output '10, 8'. This now outputs '10, 10'. Arithmetic
+	expressions now also behave identically within and outside ((...))
+	and $((...)). Setting the --posix compliance option turns on the
+	recognition of the leading octal zero for all arithmetic contexts.
 
 ____________________________________________________________________________
 

src/cmd/ksh93/bltins/print.c

@@ -884,9 +884,7 @@ static int extend(Sfio_t* sp, void* v, Sffmt_t* fe)
 				}
 				break;
 			default:
-				shp->inarith = 1;	/* POSIX compliance: recognize octal constants, e.g. printf '%d\n' 010 */
 				d = sh_strnum(argp,&lastchar,0);
-				shp->inarith = 0;
 				if(d<longmin)
 				{
 					errormsg(SH_DICT,ERROR_warn(0),e_overflow,argp);

src/cmd/ksh93/include/argnod.h

@@ -125,7 +125,6 @@ struct argnod
 #define ARG_ARITH	0x100	/* arithmetic expansion */
 #define ARG_OPTIMIZE	0x200	/* try to optimize */
 #define ARG_NOGLOB	0x400	/* no file name expansion */
-#define ARG_LET		0x800	/* processing let command arguments */
 #define ARG_ARRAYOK	0x1000	/* $x[sub] ==> ${x[sub]} */
 
 extern struct dolnod	*sh_argcreate(char*[]);

src/cmd/ksh93/include/defs.h

@@ -204,7 +204,6 @@ struct shared
 	char		used_pos;	/* used positional parameter */\
 	char		universe; \
 	char		winch; \
-	char		inarith; 	/* set when in POSIX arith context, i.e. leading zero = octal, e.g. in ((...)) */ \
 	short		arithrecursion;	/* current arithmetic recursion level */ \
 	char		indebug; 	/* set when in debug trap */ \
 	unsigned char	ignsig;		/* ignored signal in subshell */ \

src/cmd/ksh93/include/version.h

@@ -21,7 +21,7 @@
 
 #define SH_RELEASE_FORK	"93u+m"		/* only change if you develop a new ksh93 fork */
 #define SH_RELEASE_SVER	"1.0.0-beta.2"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2021-11-15"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2021-11-16"	/* must be in this format for $((.sh.version)) */
 #define SH_RELEASE_CPYR	"(c) 2020-2021 Contributors to ksh " SH_RELEASE_FORK
 
 /* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */

src/cmd/ksh93/sh.1

@@ -332,7 +332,7 @@ The arithmetic expression
 .I expr1
 is evaluated first
 (see
-.I "Arithmetic evaluation"
+.I "Arithmetic Evaluation"
 below).
 The arithmetic expression
 .I expr2
@@ -1029,7 +1029,7 @@ for an indexed array is denoted by
 an
 .I arithmetic expression\^
 (see
-.I "Arithmetic evaluation"
+.I "Arithmetic Evaluation"
 below)
 between a
 .B [
@@ -1693,7 +1693,7 @@ is assigned a new value.
 .B .sh.math
 Used for defining arithmetic functions
 (see
-.I "Arithmetic evaluation"
+.I "Arithmetic Evaluation"
 below)
 and stores the list of user defined arithmetic functions.
 .TP
@@ -6447,7 +6447,7 @@ is a separate
 .I "arithmetic expression"
 to be evaluated.
 .B let
-only recognizes octal constants starting with
+only recognizes octal numbers starting with
 .B 0
 when the
 .B set
@@ -6456,7 +6456,7 @@ option
 is on.
 See
 .I "Arithmetic Evaluation"
-above, for a description of arithmetic expression evaluation.
+above for a description of arithmetic expression evaluation.
 .sp .5
 The exit status is
 0 if the value of the last expression
@@ -7174,7 +7174,7 @@ Same as
 .B letoctal
 The
 .B let
-command allows octal constants starting with
+command allows octal numbers starting with
 .BR 0 .
 On by default if ksh is invoked as \fBsh\fR or \fBrsh\fR.
 .TP 8
@@ -7250,6 +7250,10 @@ disables the special floating point constants \fBInf\fR and \fBNaN\fR in
 arithmetic evaluation so that, e.g., \fB$((inf))\fR and \fB$((nan))\fR refer
 to the variables by those names;
 .IP \[bu]
+enables the recognition of a leading zero as introducing an octal number in
+all arithmetic evaluation contexts, except in the \fBlet\fR built-in while
+\fBletoctal\fR is off;
+.IP \[bu]
 changes the \fBtest\fR/\fB[\fR built-in command to make its deprecated
 \fIexpr1\fR \fB-a\fR \fIexpr2\fR and \fIexpr1\fR \fB-o\fR \fIexpr2\fR operators
 work even if \fIexpr1\fR equals "\fB!\fR" or "\fb(\fR" (which means the

src/cmd/ksh93/sh/args.c

@@ -664,8 +664,6 @@ char **sh_argbuild(Shell_t *shp,int *nargs, const struct comnod *comptr,int flag
 		*nargs = 0;
 		if(ac)
 		{
-			if(ac->comnamp == SYSLET)
-				flag |= ARG_LET;
 			argp = ac->comarg;
 			while(argp)
 			{

src/cmd/ksh93/sh/arith.c

@@ -405,11 +405,9 @@ static Sfdouble_t arith(const char **ptr, struct lval *lvalue, int type, Sfdoubl
 			const char radix = GETDECIMAL(0);
 			lvalue->eflag = 0;
 			errno = 0;
-			if(shp->bltindata.bnode==SYSLET && !sh_isoption(SH_LETOCTAL))
+			if(!sh_isoption(shp->bltindata.bnode==SYSLET ? SH_LETOCTAL : SH_POSIX))
-			{	/*
+			{
-				 * Since we're running the "let" builtin, disable octal number processing by
+				/* Skip leading zeros to avoid parsing as octal */
-				 * skipping all initial zeros, unless the 'letoctal' option is on.
-				 */
 				while(*val=='0' && isdigit(val[1]))
 					val++;
 			}
@@ -534,7 +532,7 @@ Sfdouble_t sh_strnum(register const char *str, char** ptr, int mode)
 {
 	Shell_t	*shp = sh_getinterp();
 	register Sfdouble_t d;
-	char base=(shp->inarith?0:10), *last;
+	char base = (sh_isoption(shp->bltindata.bnode==SYSLET ? SH_LETOCTAL : SH_POSIX) ? 0 : 10), *last;
 	if(*str==0)
 	{
 		d = 0.0;
@@ -544,7 +542,7 @@ Sfdouble_t sh_strnum(register const char *str, char** ptr, int mode)
 	{
 		errno = 0;
 		d = strtonll(str,&last,&base,-1);
-		if(*last && !shp->inarith && sh_isstate(SH_INIT))
+		if(*last && sh_isstate(SH_INIT))
 		{
 			/* This call is to handle "base#value" literals if we're importing untrusted env vars. */
 			errno = 0;
@@ -580,6 +578,7 @@ Sfdouble_t sh_strnum(register const char *str, char** ptr, int mode)
 
 Sfdouble_t sh_arith(Shell_t *shp,register const char *str)
 {
+	NOT_USED(shp);
 	return(sh_strnum(str, (char**)0, 1));
 }
 

src/cmd/ksh93/sh/macro.c

@@ -74,8 +74,6 @@ typedef struct  _mac_
 	char		patfound;	/* set if pattern character found */
 	char		assign;		/* set for assignments */
 	char		arith;		/* set for ((...)) */
-	char		let;		/* set when expanding let arguments */
-	char		zeros;		/* strip leading zeros when set */
 	char		arrayok;	/* $x[] ok for arrays */
 	char		subcopy;	/* set when copying subscript */
 	int		dotdot;		/* set for .. in subscript */
@@ -161,7 +159,6 @@ char *sh_mactrim(Shell_t *shp, char *str, register int mode)
 	savemac = *mp;
 	stkseek(stkp,0);
 	mp->arith = (mode==3);
-	mp->let = 0;
 	shp->argaddr = 0;
 	mp->pattern = (mode==1||mode==2);
 	mp->patfound = 0;
@@ -219,7 +216,6 @@ int sh_macexpand(Shell_t* shp, register struct argnod *argp, struct argnod **arg
 	mp->arghead = arghead;
 	mp->quoted = mp->lit = mp->quote = 0;
 	mp->arith = ((flag&ARG_ARITH)!=0);
-	mp->let = ((flag&ARG_LET)!=0);
 	mp->split = !(flag&ARG_ASSIGN);
 	mp->assign = !mp->split;
 	mp->pattern = mp->split && !(flag&ARG_NOGLOB) && !sh_isoption(SH_NOGLOB);
@@ -279,7 +275,7 @@ void sh_machere(Shell_t *shp,Sfio_t *infile, Sfio_t *outfile, char *string)
 	stkseek(stkp,0);
 	shp->argaddr = 0;
 	mp->sp = outfile;
-	mp->split = mp->assign = mp->pattern = mp->patfound = mp->lit = mp->arith = mp->let = 0;
+	mp->split = mp->assign = mp->pattern = mp->patfound = mp->lit = mp->arith = 0;
 	mp->quote = 1;
 	mp->ifsp = nv_getval(sh_scoped(shp,IFSNOD));
 	mp->ifs = ' ';
@@ -1101,7 +1097,6 @@ static int varsub(Mac_t *mp)
 	int		var=1,addsub=0,oldpat=mp->pattern,idnum=0,flag=0,d;
 	Stk_t		*stkp = mp->shp->stk;
 retry1:
-	mp->zeros = 0;
 	idbuff[0] = 0;
 	idbuff[1] = 0;
 	c = fcmbget(&LEN);
@@ -1466,9 +1461,6 @@ retry1:
 				else
 					v = nv_getval(np);
 				mp->atmode = (v && mp->quoted && mode=='@');
-				/* special case --- ignore leading zeros */  
-				if((mp->let || (mp->arith&&nv_isattr(np,(NV_LJUST|NV_RJUST|NV_ZFILL)))) && !nv_isattr(np,NV_INTEGER) && (offset==0 || isspace(c) || strchr(",.+-*/=%&|^?!<>",c)))
-					mp->zeros = 1;
 			}
 			if(savptr==stakptr(0))
 				stkseek(stkp,offset);
@@ -1621,7 +1613,6 @@ retry1:
 				int split = mp->split;
 				int quoted = mp->quoted;
 				int arith = mp->arith;
-				int zeros = mp->zeros;
 				int assign = mp->assign;
 				if(newops)
 				{
@@ -1638,7 +1629,7 @@ retry1:
 					mp->split = 0;
 					mp->quoted = 0;
 					mp->assign &= ~1;
-					mp->arith = mp->zeros = 0;
+					mp->arith = 0;
 					newquote = 0;
 				}
 				else if(c=='?' || c=='=')
@@ -1650,7 +1641,6 @@ retry1:
 				mp->split = split;
 				mp->quoted = quoted;
 				mp->arith = arith;
-				mp->zeros = zeros;
 				mp->assign = assign;
 				/* add null byte */
 				sfputc(stkp,0);
@@ -2111,7 +2101,6 @@ static void comsubst(Mac_t *mp,register Shnode_t* t, int type)
 			t = sh_dolparen((Lex_t*)mp->shp->lex_context);
 		if(t && t->tre.tretyp==TARITH)
 		{
-			mp->shp->inarith = 1;
 			fcsave(&save);
 			if(t->ar.arcomp)
 				num = arith_exec(t->ar.arcomp);
@@ -2119,7 +2108,6 @@ static void comsubst(Mac_t *mp,register Shnode_t* t, int type)
 				num = sh_arith(mp->shp,t->ar.arexpr->argval);
 			else
 				num = sh_arith(mp->shp,sh_mactrim(mp->shp,t->ar.arexpr->argval,3));
-			mp->shp->inarith = 0;
 		out_offset:
 			stkset(stkp,savptr,savtop);
 			*mp = savemac;
@@ -2330,18 +2318,6 @@ static void mac_copy(register Mac_t *mp,register const char *str, register int s
 	Stk_t			*stkp=mp->shp->stk;
 	int			oldpat = mp->pattern;
 	nopat = (mp->quote||(mp->assign==1)||mp->arith);
-	if(mp->zeros)
-	{
-		/* prevent leading 0's from becoming octal constants */
-		while(size>1 && *str=='0')
-		{
-			if(str[1]=='x' || str[1]=='X')
-				break;
-			str++,size--;
-		}
-		mp->zeros = 0;
-		cp = str;
-	}
 	if(mp->sp)
 		sfwrite(mp->sp,str,size);
 	else if(mp->pattern>=2 || (mp->pattern && nopat) || mp->assign==3)

src/cmd/ksh93/sh/name.c

@@ -2954,14 +2954,7 @@ Sfdouble_t nv_getnum(register Namval_t *np)
 		}
 	}
 	else if((str=nv_getval(np)) && *str!=0)
-	{
-		if(nv_isattr(np,NV_LJUST|NV_RJUST) || (*str=='0' && !(str[1]=='x'||str[1]=='X')))
-		{
-			while(*str=='0')
-				str++;
-		}
 		r = sh_arith(shp,str);
-	}
 	return(r);
 }
 

src/cmd/ksh93/sh/nvdisc.c

@@ -105,14 +105,7 @@ Sfdouble_t nv_getn(Namval_t *np, register Namfun_t *nfp)
 		else
 			str = nv_getv(np,fp?fp:nfp);
 		if(str && *str)
-		{
-			if(nv_isattr(np,NV_LJUST|NV_RJUST) || (*str=='0' && !(str[1]=='x'||str[1]=='X')))
-			{
-				while(*str=='0')
-					str++;
-			}
 			d = sh_arith(shp,str);
-		}
 	}
 	return(d);
 }

src/cmd/ksh93/sh/subshell.c

@@ -470,7 +470,6 @@ Sfio_t *sh_subshell(Shell_t *shp,Shnode_t *t, volatile int flags, int comsub)
 	struct rand *rp;		/* current $RANDOM discipline function data */
 	unsigned int save_rand_seed;	/* parent shell $RANDOM seed */
 	int save_rand_last;		/* last random number from $RANDOM in parent shell */
-	char save_inarith;		/* flag indicating POSIX arithmetic context */
 	memset((char*)sp, 0, sizeof(*sp));
 	sfsync(shp->outpool);
 	sh_sigcheck(shp);
@@ -592,9 +591,6 @@ Sfio_t *sh_subshell(Shell_t *shp,Shnode_t *t, volatile int flags, int comsub)
 	{
 		if(comsub)
 		{
-			/* a comsub within an arithmetic expression must not itself be in an arithmetic context */
-			save_inarith = shp->inarith;
-			shp->inarith = 0;
 			/* disable job control */
 			shp->spid = 0;
 			sp->jobcontrol = job.jobcontrol;
@@ -738,8 +734,6 @@ Sfio_t *sh_subshell(Shell_t *shp,Shnode_t *t, volatile int flags, int comsub)
 			sh_close(sp->tmpfd);
 		}
 		shp->fdstatus[1] = sp->fdstatus;
-		/* restore POSIX arithmetic context flag */
-		shp->inarith = save_inarith;
 	}
 	if(!shp->subshare)
 	{

src/cmd/ksh93/tests/arith.sh

@@ -21,6 +21,9 @@
 
 . "${SHTESTS_COMMON:-${0%/*}/_common}"
 
+integer hasposix=0
+(set -o posix) 2>/dev/null && ((hasposix++))	# not using [[ -o ?posix ]] as it's broken on 93v-
+
 trap '' FPE # NOTE: osf.alpha requires this (no ieee math)
 
 integer x=1 y=2 z=3
@@ -346,8 +349,14 @@ do	(( ipx = ip % 256 ))
 done
 unset x
 x=010
-(( x == 10 )) || err_exit 'leading zeros in x treated as octal arithmetic with $((x))'
+(( x == 10 )) || err_exit 'leading zeros in x treated as octal arithmetic with ((x))'
-(( $x == 8 )) || err_exit 'leading zeros not treated as octal arithmetic with $x'
+(( $x == 10 )) || err_exit 'leading zeros in x treated as octal arithmetic with (($x))'
+if	((hasposix))
+then	set --posix
+	((x == 8)) || err_exit 'posix: leading zeros in x not treated as octal arithmetic with ((x))'
+	(($x == 8)) || err_exit 'posix: leading zeros in x not treated as octal arithmetic with (($x))'
+	set --noposix
+fi
 unset x
 typeset -Z x=010
 (( x == 10 )) || err_exit 'leading zeros not ignored for arithmetic'
@@ -728,15 +737,26 @@ unset A
 unset r x
 integer x
 r=020
-(($r == 16)) || err_exit 'leading 0 not treated as octal inside ((...))'
+(($r == 20)) || err_exit 'leading 0 treated as octal inside ((...))'
 x=$(($r))
-(( x == 16 )) || err_exit 'leading 0 not treated as octal inside $((...))'
+((x == 20)) || err_exit 'leading 0 treated as octal inside $((...))'
 x=$r
-((x == 20 )) || err_exit 'leading 0 should not be treated as octal outside ((...))'
+((x == 20)) || err_exit 'leading 0 treated as octal outside ((...))'
 print -- -020 | read x
-((x == -20)) || err_exit 'numbers with leading -0 should not be treated as octal outside ((...))'
+((x == -20)) || err_exit 'numbers with leading -0 treated as octal outside ((...))'
 print -- -8#20 | read x
 ((x == -16)) || err_exit 'numbers with leading -8# should be treated as octal'
+if	((hasposix))
+then	set --posix
+	(($r == 16)) || err_exit 'posix: leading 0 not treated as octal inside ((...))'
+	x=$(($r))
+	(( x == 16 )) || err_exit 'posix: leading 0 not treated as octal inside $((...))'
+	x=$r
+	((x == 16)) || err_exit 'posix: leading 0 not as octal outside ((...))'
+	print -- -020 | read x
+	((x == -16)) || err_exit 'posix: numbers with leading -0 should be treated as octal outside ((...))'
+	set --noposix
+fi
 
 unset x
 x=0x1
@@ -750,8 +770,13 @@ let "$x==10" || err_exit 'arithmetic with $x where $x is 010 should be decimal i
 (( 9.$x == 9.01 )) || err_exit 'arithmetic with 9.$x where x=010 should be 9.01' 
 (( 9$x == 9010 )) || err_exit 'arithmetic with 9$x where x=010 should be 9010' 
 x010=99
-((x$x == 99 )) || err_exit 'arithtmetic with x$x where x=010 should be $x010'
+((x$x == 99 )) || err_exit 'arithmetic with x$x where x=010 should be $x010'
-(( 3+$x == 11 )) || err_exit '3+$x where x=010 should be 11 in ((...))'
+(( 3+$x == 13 )) || err_exit '3+$x where x=010 should be 13 in ((...))'
+if	((hasposix))
+then	set --posix
+	(( 3+$x == 11 )) || err_exit 'posix: 3+$x where x=010 should be 11 in ((...))'
+	set --noposix
+fi
 let "(3+$x)==13" || err_exit 'let should not recognize leading 0 as octal'
 unset x
 typeset -RZ3 x=10 
@@ -878,8 +903,9 @@ unset got
 
 # ======
 # https://github.com/ksh93/ksh/issues/326
-for m in u d i o x X
+((hasposix)) && for m in u d i o x X
 do
+	set --posix
 	case $m in
 	o)	exp="10;21;32;" ;;
 	x)	exp="8;11;1a;" ;;
@@ -887,22 +913,16 @@ do
 	*)	exp="8;17;26;" ;;
 	esac
 	got=${ printf "%$m;" 010 021 032; }
-	[[ $got == "$exp" ]] || err_exit "printf %$m does not recognize octal arguments" \
+	[[ $got == "$exp" ]] || err_exit "posix: printf %$m does not recognize octal arguments" \
 		"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+	set --noposix
 done
 
-# https://github.com/ksh93/ksh/issues/326#issuecomment-917707463
-exp=18
-got=$(( $(integer x; x=010; echo $x) + 010 ))
-#		       ^^^ decimal     ^^^ octal
-[[ $got == "$exp" ]] || err_exit 'Integer with leading zero incorrectly interpreted as octal in non-POSIX arith context' \
-	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
-
 # ======
 # BUG_ARITHNAN: In ksh <= 93u+m 2021-11-15 and zsh 5.6 - 5.8, the case-insensitive
 # floating point constants Inf and NaN are recognised in arithmetic evaluation,
 # overriding any variables with the names Inf, NaN, INF, nan, etc.
-if	(set --posix) 2>/dev/null
+if	((hasposix))
 then	set --posix
 	Inf=42 NaN=13
 	inf=421 nan=137
@@ -920,5 +940,12 @@ then	set --posix
 	set --noposix
 fi
 
+# ======
+# https://github.com/ksh93/ksh/issues/334#issuecomment-968603087
+exp=21
+got=$(typeset -Z x=0x15; { echo $((x)); } 2>&1)
+[[ $got == "$exp" ]] || err_exit "typeset -Z corrupts hexadecimal number in arithmetic context" \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
 # ======
 exit $((Errors<125?Errors:125))