handle additional append cases

Author: deelawn

gno.land/cmd/gnoland/testdata/append.txtar

@@ -8,6 +8,9 @@ stdout OK!
 gnokey maketx call -pkgpath gno.land/r/append -func Append -gas-fee 1000000ugnot -gas-wanted 2000000 -args '1' -broadcast -chainid=tendermint_test test1
 stdout OK!
 
+gnokey maketx call -pkgpath gno.land/r/append -func AppendNil -gas-fee 1000000ugnot -gas-wanted 2000000 -broadcast -chainid=tendermint_test test1
+stdout OK!
+
 # Call Append 2
 gnokey maketx call -pkgpath gno.land/r/append -func Append -gas-fee 1000000ugnot -gas-wanted 2000000 -args '2' -broadcast -chainid=tendermint_test test1
 stdout OK!
@@ -60,6 +63,10 @@ gnokey maketx call -pkgpath gno.land/r/append -func Render -gas-fee 1000000ugnot
 stdout '("2-3-42-70-100-" string)'
 stdout OK!
 
+gnokey maketx call -pkgpath gno.land/r/append -func Render -gas-fee 1000000ugnot -gas-wanted 2000000 -args 'd' -broadcast -chainid=tendermint_test test1
+stdout '("1-" string)'
+stdout OK!
+
 -- append.gno --
 package append
 
@@ -69,7 +76,7 @@ import (
 
 type T struct{ i int }
 
-var a, b []T
+var a, b, d []T
 var c = []T{{i: 100}}
 
 
@@ -104,10 +111,19 @@ func ReassignC() {
 	c[0] = T{i: 200}
 }
 
+func AppendNil() {
+	d = append(d, a...)
+}
+
 func Render(path string) string {
+	source := a
+	if path == "d" {
+		source = d
+	}
+
 	var s string
-	for i:=0;i<len(a);i++{
-		s+=ufmt.Sprintf("%d-", a[i].i)
+	for i:=0;i<len(source);i++{
+		s+=ufmt.Sprintf("%d-", source[i].i)
 	}
 	return s
 }

gnovm/pkg/gnolang/uverse.go

@@ -210,9 +210,9 @@ func UverseNode() *PackageNode {
 						// append(nil, *SliceValue) new list ---------
 						list := make([]TypedValue, argsl)
 						if 0 < argsl {
-							copy(
-								list[:argsl],
-								argsb.List[argso:argso+argsl])
+							for i := 0; i < argsl; i++ {
+								list[i] = argsb.List[argso+i].DeepCopy(m.Alloc, m.Store)
+							}
 						}
 						m.PushValue(TypedValue{
 							T: xt,
@@ -469,11 +469,12 @@ func UverseNode() *PackageNode {
 						return
 					} else {
 						// append(*SliceValue, *NativeValue) new list --------
-						list := make([]TypedValue, xvl+argsl)
+						listLen := xvl + argsl
+						list := make([]TypedValue, listLen)
 						if 0 < xvl {
-							copy(
-								list[:xvl],
-								xvb.List[xvo:xvo+xvl])
+							for i := 0; i < listLen; i++ {
+								list[i] = xvb.List[xvo+i].DeepCopy(m.Alloc, m.Store)
+							}
 						}
 						if 0 < argsl {
 							copyNativeToList(