fix lazy evaluation with side effects; spotted by ormaaj via IRC

Makefile

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/Makefile,v 1.152 2016/08/25 16:21:30 tg Exp $
+# $MirOS: src/bin/mksh/Makefile,v 1.153 2016/11/07 16:58:45 tg Exp $
 #-
 # Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
 #		2011, 2012, 2013, 2014, 2015, 2016
@@ -57,7 +57,7 @@ CPPFLAGS+=	-DMKSH_ASSUME_UTF8 -DMKSH_DISABLE_DEPRECATED \
 		-DHAVE_SETGROUPS=1 -DHAVE_STRERROR=0 -DHAVE_STRSIGNAL=0 \
 		-DHAVE_STRLCPY=1 -DHAVE_FLOCK_DECL=1 -DHAVE_REVOKE_DECL=1 \
 		-DHAVE_SYS_ERRLIST_DECL=1 -DHAVE_SYS_SIGLIST_DECL=1 \
-		-DHAVE_PERSISTENT_HISTORY=1 -DMKSH_BUILD_R=531
+		-DHAVE_PERSISTENT_HISTORY=1 -DMKSH_BUILD_R=539
 CPPFLAGS+=	-D${${PROG:L}_tf:C/(Mir${MAN:E}{0,1}){2}/4/:S/x/mksh_BUILD/:U}
 CPPFLAGS+=	-I.
 COPTS+=		-std=c89 -Wall

check.t

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.754 2016/10/02 22:21:43 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.755 2016/11/07 16:58:45 tg Exp $
 # -*- mode: sh -*-
 #-
 # Copyright © 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
@@ -30,7 +30,7 @@
 # (2013/12/02 20:39:44) http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/regress/bin/ksh/?sortby=date
 
 expected-stdout:
-	@(#)MIRBSD KSH R53 2016/10/02
+	@(#)MIRBSD KSH R53 2016/11/07
 description:
 	Check version of shell.
 stdin:
@@ -39,7 +39,7 @@ name: KSH_VERSION
 category: shell:legacy-no
 ---
 expected-stdout:
-	@(#)LEGACY KSH R53 2016/10/02
+	@(#)LEGACY KSH R53 2016/11/07
 description:
 	Check version of legacy shell.
 stdin:
@@ -340,6 +340,62 @@ expected-stdout:
 	2
 	0
 ---
+name: arith-lazy-5-arr-n
+description: Check lazy evaluation with side effects
+stdin:
+	a=0; echo "$((0&&b[a++],a))"
+expected-stdout:
+	0
+---
+name: arith-lazy-5-arr-p
+description: Check lazy evaluation with side effects
+stdin:
+	a=0; echo "$((0&&(b[a++]),a))"
+expected-stdout:
+	0
+---
+name: arith-lazy-5-str-n
+description: Check lazy evaluation with side effects
+stdin:
+	a=0 b=a++; ((0&&b)); echo $a
+expected-stdout:
+	0
+---
+name: arith-lazy-5-str-p
+description: Check lazy evaluation with side effects
+stdin:
+	a=0 b=a++; ((0&&(b))); echo $a
+expected-stdout:
+	0
+---
+name: arith-lazy-5-tern-l-n
+description: Check lazy evaluation with side effects
+stdin:
+	a=0; echo "$((0?b[a++]:999,a))"
+expected-stdout:
+	0
+---
+name: arith-lazy-5-tern-l-p
+description: Check lazy evaluation with side effects
+stdin:
+	a=0; echo "$((0?(b[a++]):999,a))"
+expected-stdout:
+	0
+---
+name: arith-lazy-5-tern-r-n
+description: Check lazy evaluation with side effects
+stdin:
+	a=0; echo "$((1?999:b[a++],a))"
+expected-stdout:
+	0
+---
+name: arith-lazy-5-tern-r-p
+description: Check lazy evaluation with side effects
+stdin:
+	a=0; echo "$((1?999:(b[a++]),a))"
+expected-stdout:
+	0
+---
 name: arith-ternary-prec-1
 description:
 	Check precedence of ternary operator vs assignment

expr.c

@@ -23,7 +23,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/expr.c,v 1.89 2016/09/01 12:55:21 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/expr.c,v 1.90 2016/11/07 16:58:48 tg Exp $");
 
 #define EXPRTOK_DEFNS
 #include "exprtok.h"
@@ -326,7 +326,15 @@ evalexpr(Expr_state *es, unsigned int prec)
 	vl = evalexpr(es, prec - 1);
 	while ((int)(op = es->tok) >= (int)O_EQ && (int)op <= (int)O_COMMA &&
 	    opprec[(int)op] == prec) {
+		switch ((int)op) {
+		case O_TERN:
+		case O_LAND:
+		case O_LOR:
+			break;
+		default:
 			exprtoken(es);
+		}
+
 		vasn = vl;
 		if (op != O_ASN)
 			/* vl may not have a value yet */
@@ -340,14 +348,15 @@ evalexpr(Expr_state *es, unsigned int prec)
 
 			if (!ev)
 				es->noassign++;
+			exprtoken(es);
 			vl = evalexpr(es, MAX_PREC);
 			if (!ev)
 				es->noassign--;
 			if (es->tok != CTERN)
 				evalerr(es, ET_STR, "missing :");
-			exprtoken(es);
 			if (ev)
 				es->noassign++;
+			exprtoken(es);
 			vr = evalexpr(es, P_TERN);
 			if (ev)
 				es->noassign--;
@@ -502,6 +511,7 @@ evalexpr(Expr_state *es, unsigned int prec)
 		case O_LAND:
 			if (!t1)
 				es->noassign++;
+			exprtoken(es);
 			vr = intvar(es, evalexpr(es, prec - 1));
 			res = t1 && vr->val.u;
 			if (!t1)
@@ -510,6 +520,7 @@ evalexpr(Expr_state *es, unsigned int prec)
 		case O_LOR:
 			if (t1)
 				es->noassign++;
+			exprtoken(es);
 			vr = intvar(es, evalexpr(es, prec - 1));
 			res = t1 || vr->val.u;
 			if (t1)

sh.h

@@ -175,9 +175,9 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.789 2016/10/02 22:21:47 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.790 2016/11/07 16:58:48 tg Exp $");
 #endif
-#define MKSH_VERSION "R53 2016/10/02"
+#define MKSH_VERSION "R53 2016/11/07"
 
 /* arithmetic types: C implementation */
 #if !HAVE_CAN_INTTYPES
@@ -578,7 +578,7 @@ char *ucstrstr(char *, const char *);
 #define mkssert(e)	do { } while (/* CONSTCOND */ 0)
 #endif
 
-#if (!defined(MKSH_BUILDMAKEFILE4BSD) && !defined(MKSH_BUILDSH)) || (MKSH_BUILD_R != 531)
+#if (!defined(MKSH_BUILDMAKEFILE4BSD) && !defined(MKSH_BUILDSH)) || (MKSH_BUILD_R != 539)
 #error Must run Build.sh to compile this.
 extern void thiswillneverbedefinedIhope(void);
 int