ksh: .sh.match index array result issues, crash after unset

While researching, I became aware of some issues with .sh.match index array results: parent array having both -C and -a types, invalid script names of NULL, concealed/null array elements expressed as spaces, these null elements count towards size and subscript listing, and finally invalid size count on parent array. All of these issues have been fixed in ksh93v-.

ksh93u+m/1.1.0-alpha+1fc28dc2 2021-05-13: extra compound variable attribute, phantom array elements, and a static number of 4194303 for the size for parent array, invalid subscript names.

$ ./ksh -c 'x=1234; true ${x//~(X)([012])|([345])/ }; typeset -p .sh.match .sh.match[1] .sh.match[2]; echo ${#.sh.match[@]} ${#.sh.match[1][@]} ${#.sh.match[2][@]}; echo ${!.sh.match[2][@]};'
typeset -C -a .sh.match=((1 2 3 4) (1 2  ) (  3 4) )
typeset -a .sh.match[(null)]=(1 2  )
typeset -a .sh.match[(null)]=(  3 4)
4194303 4 4
0 1 2 3

ksh93u+ 2012-08-01: sparse interval array listing for arrays and subarrays when most are not, wrong subarray sizes, invalid subscript names, phantom array elements.

$ ./ksh-att -c 'x=1234; true ${x//~(X)([012])|([345])/ }; typeset -p .sh.match .sh.match[1] .sh.match[2]; echo ${#.sh.match[@]} ${#.sh.match[1][@]} ${#.sh.match[2][@]}; echo ${!.sh.match[2][@]};'
typeset -a .sh.match=(([0]=1 [1]=2 [2]=3 [3]=4) ([0]=1 [1]=2) ([2]=3 [3]=4) )
typeset -a .sh.match[(null)]=([0]=1 [1]=2)
typeset -a .sh.match[(null)]=([2]=3 [3]=4)
3 3 3
2 3

ksh93v- 2014-12-24: all good. even the sparse indexed match[2] array is correct. 😃

$ ./ksh93v- -c 'x=1234; true ${x//~(X)([012])|([345])/ }; typeset -p .sh.match .sh.match[1] .sh.match[2]; echo ${#.sh.match[@]} ${#.sh.match[1][@]} ${#.sh.match[2][@]}; echo ${!.sh.match[2][@]};'
typeset -a .sh.match=((1 2 3 4) (1 2) ([2]=3 [3]=4) )
typeset -a .sh.match[1]=(1 2)
typeset -a .sh.match[2]=([2]=3 [3]=4)
3 2 2
2 3

ksh93u+m/1.1.0-alpha+dev 2021-05-13 (patch provided below): same as first but provided patch fixes -C issue.

$ ./ksh-p1 -c 'x=1234; true ${x//~(X)([012])|([345])/ }; typeset -p .sh.match .sh.match[1] .sh.match[2]; echo ${#.sh.match[@]} ${#.sh.match[1][@]} ${#.sh.match[2][@]}; echo ${!.sh.match[2][@]};'
typeset -a .sh.match=((1 2 3 4) (1 2  ) (  3 4) )
typeset -a .sh.match[(null)]=(1 2  )
typeset -a .sh.match[(null)]=(  3 4)
4194303 4 4
0 1 2 3

diff --git a/src/cmd/ksh93/sh/init.c b/src/cmd/ksh93/sh/init.c
index 5b7dcdc..a4839ea 100644
--- a/src/cmd/ksh93/sh/init.c
+++ b/src/cmd/ksh93/sh/init.c
@@ -801,7 +801,10 @@ void sh_setmatch(Shell_t *shp,const char *v, int vsize, int nmatch, regoff_t mat
 		if(!nv_hasdisc(SH_MATCHNOD,mp->hdr.disc))
 			nv_disc(SH_MATCHNOD,&mp->hdr,NV_LAST);
 		if(nmatch)
+		{
+			nv_onattr(SH_MATCHNOD,NV_NOFREE|NV_ARRAY);
 			nv_putsub(SH_MATCHNOD, NIL(char*), (nmatch-1)|ARRAY_FILL|ARRAY_SETSUB);
+		}
 		ap_save->nelem = mp->nmatch = nmatch;
 		mp->v = v;
 		mp->first = match[0];
@@ -813,7 +816,6 @@ void sh_setmatch(Shell_t *shp,const char *v, int vsize, int nmatch, regoff_t mat
 		{
 			np->nvalue.cp = Empty;
 			np->nvfun = SH_MATCHNOD->nvfun;
-			nv_onattr(np,NV_NOFREE|NV_ARRAY);
 			SH_MATCHNOD->nvfun = 0;
 			for(i=0; i < mp->nmatch; i++)
 			{

RESEARCH

• https://github.com/att/ast/blob/2016-01-10-beta/src/cmd/ksh93/RELEASE: 12-08-10 Rewrote .sh.match expansions fixing several bugs and improving performance.
• https://marc.info/?l=ast-users&m=134461525925663&w=2
• https://marc.info/?l=ast-developers&m=134462636529838&w=2