Fix ${x=y} and ${x:=y} for numeric types of x

These POSIX expansions first assign y to x if x is unset or empty,
respectively, and then they yield the value of x. This was not
working on any ksh93 version if x was typeset as numeric (integer
or float) but still unset, as in not assigned a value.

$ unset a; typeset -i a; printf '%q\n' "${a:=42}" "$a"
0
''

Expected output:
42
42

src/cmd/ksh93/sh/macro.c:
- Fix the test for set/unset variable. It was broken because it
  only checked for the existence of the node, which exists after
  'typeset', but did not check if a value had been assigned. This
  additional check needs to be done with the nv_isnull() macro, but
  only for expansions of the regular M_BRACE type. Special
  expansions cannot have an unset state.
- As of commit 95294419, we know that an nv_optimize() call may be
  needed before using nv_isnull() if the shell is compiled with
  SHOPT_OPTIMIZE. Move the nv_optimize() call from that commit
  forward to before the new check that calls nv_isnull(), and only
  bother with it if the type is M_BRACE.

src/cmd/ksh93/tests/variables.sh:
- Add tests for this bug. Test float and integer, and also check
  that ${a=b} and ${a:=b} correctly treat the value of 'b' as an
  arithmetic expression of which the result is assigned to 'a' if
  'a' was typeset as numeric.

src/cmd/ksh93/tests/attributes.sh,
src/cmd/ksh93/tests/comvar.sh,
src/cmd/ksh93/tests/nameref.sh,
src/cmd/ksh93/tests/types.sh:
- Fix a number of tests to report failures correctly.

Resolves: https://github.com/ksh93/ksh/issues/157

NEWS

@@ -3,6 +3,12 @@ For full details, see the git log at: https://github.com/ksh93/ksh
 
 Any uppercase BUG_* names are modernish shell bug IDs.
 
+2021-03-06:
+
+- Fixed an old expansion bug: expansions of type ${var=value} and ${var:=value}
+  did not perform an assignment and yielded the value 0 if 'var' was typeset as
+  numeric (integer or float) but had not yet been assigned a value.
+
 2021-03-05:
 
 - Unbalanced quotes and backticks now correctly produce a syntax error

src/cmd/ksh93/include/version.h

@@ -20,7 +20,7 @@
 
 #define SH_RELEASE_FORK	"93u+m"		/* only change if you develop a new ksh93 fork */
 #define SH_RELEASE_SVER	"1.0.0-alpha"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2021-03-05"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2021-03-06"	/* 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/macro.c

@@ -1314,7 +1314,7 @@ retry1:
 			 * a value; otherwise it always follows the code path for a set parameter, so is
 			 * not subject to 'set -u', and may test as set even after 'unset -v IFS'.
 			 */
-			if(!(*id=='I' && strcmp(id,"IFS")==0 && nv_getval(sh_scoped(mp->shp,IFSNOD)) == NULL))
+			if(!(*id=='I' && strcmp(id,"IFS")==0 && nv_getval(sh_scoped(mp->shp,IFSNOD)) == NIL(char*)))
 				np = nv_open(id,mp->shp->var_tree,flag|NV_NOFAIL);
 			if(!np)
 			{
@@ -1405,9 +1405,13 @@ retry1:
 		/*
 		 * Check if the parameter is set or unset.
 		 */
-		if(np && (type==M_TREE || !c || !ap))
+#if SHOPT_OPTIMIZE
+		if(np && type==M_BRACE && mp->shp->argaddr)
+			nv_optimize(np);  /* needed before calling nv_isnull() */
+#endif /* SHOPT_OPTIMIZE */
+		if(np && (type==M_BRACE ? !nv_isnull(np) : (type==M_TREE || !c || !ap)))
 		{
-			/* The parameter is set. */
+			/* Either the parameter is set, or it's a special type of expansion where 'unset' doesn't apply. */
 			char *savptr;
 			c = *((unsigned char*)stkptr(stkp,offset-1));
 			savptr = stkfreeze(stkp,0);
@@ -1443,13 +1447,7 @@ retry1:
 					if(ap)
 						v = nv_arrayisset(np,ap)?(char*)"x":0;
 					else
-					{
-#if SHOPT_OPTIMIZE
-						if(mp->shp->argaddr)
-							nv_optimize(np);  /* avoid BUG_ISSETLOOP */
-#endif /* SHOPT_OPTIMIZE */
 						v = nv_isnull(np)?0:(char*)"x";
-					}
 				}
 				else
 					v = nv_getval(np);

src/cmd/ksh93/tests/attributes.sh

@@ -204,7 +204,7 @@ else	b1=iIWTk5ZAppaZk4Q=
 fi
 z=$b1
 typeset -b x=$b1
-[[ $x == "$z" ]] || print -u2 'binary variable not expanding correctly'
+[[ $x == "$z" ]] || err_exit "binary variable not expanding correctly ($(printf %q "$x") != $(printf %q "$z"))"
 [[  $(printf "%B" x) == $t1 ]] || err_exit 'typeset -b not working'
 typeset -b -Z5 a=$b1
 [[  $(printf "%B" a) == $w1 ]] || err_exit 'typeset -b -Z5 not working'

src/cmd/ksh93/tests/comvar.sh

@@ -482,9 +482,11 @@ typeset -C -A hello19=(
 	)
 )
 expected="typeset -C -A hello19=([19]=(one='xone 19';two='xtwo 19') [23]=(one='xone 23';two='xtwo 23'))"
-[[ $(typeset -p hello19) == "$expected" ]] || print -u2 'typeset -p hello19 incorrect'
+got=$(typeset -p hello19)
+[[ $got == "$expected" ]] || err_exit "typeset -p hello19 incorrect (expected $(printf %q "$expected"), got $(printf %q "$got"))"
 expected=$'(\n\tone=\'xone 19\'\n\ttwo=\'xtwo 19\'\n) (\n\tone=\'xone 23\'\n\ttwo=\'xtwo 23\'\n)'
-[[ ${hello19[@]} == "$expected" ]] || print -u2 '${hello19[@]} incorrect'
+got=${hello19[@]}
+[[ $got == "$expected" ]] || err_exit "\${hello19[@]} incorrect (expected $(printf %q "$expected"), got $(printf %q "$got"))"
 
 typeset -C -A foo1=( abc="alphabet" ) foo2=( abc="alphabet" )
 function add_one

src/cmd/ksh93/tests/nameref.sh

@@ -161,9 +161,10 @@ then 	err_exit 'for loop nameref optimization test2 error'
 fi
 
 unset -n x foo bar
-if	[[ $(nameref x=foo;for x in foo bar;do print ${!x};done) != $'foo\nbar' ]]
+exp=$'foo\nbar'
-then	err_exit 'for loop optimization with namerefs not working'
+got=$(nameref x=foo;for x in foo bar;do print ${!x};done)
-fi
+[[ $got == "$exp" ]] || err_exit 'for loop optimization with namerefs not working' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
 if	[[ $(
 	p=(x=(r=3) y=(r=4))
 	for i in x y
@@ -465,9 +466,9 @@ EOF
 } 2> /dev/null #|| print -u2 bad
 exitval=$?
 if	[[ $(kill -l $exitval) == SEGV ]]
-then	print -u2 'name reference to unset type instance causes segmentation violation'
+then	err_exit 'name reference to unset type instance causes segmentation violation'
 else 	if((exitval))
-	then	print -u2 'name reference to unset type instance not redirected to .deleted'
+	then	err_exit 'name reference to unset type instance not redirected to .deleted'
 	fi
 fi
 

src/cmd/ksh93/tests/types.sh

@@ -84,7 +84,7 @@ Frame_t frame
 [[ $(typeset -p frame) == 'Frame_t frame=(typeset file;typeset lineno)' ]] || err_exit 'empty fields in type not displayed'
 x=( typeset -a arr=([2]=abc [4]=(x=1 y=def));zz=abc)
 typeset -C y=x
-[[ "$x" == "$y" ]] || print -u2 'y is not equal to x'
+[[ "$x" == "$y" ]] || err_exit "y is not equal to x (y == $(printf %q "$y"); x == $(printf %q "$x"))"
 Type_t z=(y=(xa=bb xq=cc))
 typeset -A arr=([foo]=one [bar]=2)
 typeset -A brr=([foo]=one [bar]=2)

src/cmd/ksh93/tests/variables.sh

@@ -1198,5 +1198,39 @@ unset .sh.fun
 got=$(some_func() { :; }; trap some_func DEBUG; trap - DEBUG; print -r "${.sh.fun}")
 [[ -z $got ]] || err_exit "\${.sh.fun} leaks out of DEBUG trap (got $(printf %q "$got"))"
 
+# =====
+# Before 2021-03-06, ${foo=bar} and ${foo:=bar} did not work if `foo` had a numeric type
+# https://github.com/ksh93/ksh/issues/157
+
+unset a b
+typeset -i a
+b=3+39
+got=${a=b}
+[[ $got == 42 ]] || err_exit "\${a=b}: expansion not working for integer type (expected '42', got '$got')"
+[[ $a == 42 ]] || err_exit "\${a=b}: a was not assigned the correct integer value (expected '42', got '$a')"
+
+unset a b
+typeset -F a
+b=3.75+38.25
+got=${a=b}
+exp=42.0000000000
+[[ $got == "$exp" ]] || err_exit "\${a=b}: expansion not working for float type (expected '$exp', got '$got')"
+[[ $a == "$exp" ]] || err_exit "\${a=b}: a was not assigned the correct float value (expected '$exp', got '$a')"
+
+unset a b
+typeset -i a
+b=3+39
+got=${a:=b}
+[[ $got == 42 ]] || err_exit "\${a:=b}: expansion not working for integer type (expected '42', got '$got')"
+[[ $a == 42 ]] || err_exit "\${a:=b}: a was not assigned the correct integer value (expected '42', got '$a')"
+
+unset a b
+typeset -F a
+b=3.75+38.25
+got=${a:=b}
+exp=42.0000000000
+[[ $got == "$exp" ]] || err_exit "\${a:=b}: expansion not working for float type (expected '$exp', got '$got')"
+[[ $a == "$exp" ]] || err_exit "\${a:=b}: a was not assigned the correct float value (expected '$exp', got '$a')"
+
 # ======
 exit $((Errors<125?Errors:125))