fix(gnovm): fix unary operator ^ on constants (#3876)

Apply Bigint.Not for untyped big ints.

Fixes #3864.

Author: mvertes

gnovm/pkg/gnolang/op_unary.go

@@ -113,8 +113,8 @@ func (m *Machine) doOpUxor() {
 	case Uint64Type:
 		xv.SetUint64(^xv.GetUint64())
 	case UntypedBigintType:
-		// XXX can it even be implemented?
-		panic("not yet implemented")
+		bv := xv.V.(BigintValue)
+		xv.V = BigintValue{V: new(big.Int).Not(bv.V)}
 	default:
 		panic(fmt.Sprintf("unexpected type %s in operation",
 			baseOf(xv.T)))

gnovm/tests/files/const59.gno

@@ -0,0 +1,15 @@
+package main
+
+const (
+	A = ^0
+	B = ^1
+	C = int8(^1)
+	D = ^uint8(1)
+)
+
+func main() {
+	println(A, B, C, D)
+}
+
+// Output:
+// -1 -2 -2 254

gnovm/tests/files/const60.gno

@@ -0,0 +1,12 @@
+package main
+
+const (
+	A = uint(^1)
+)
+
+func main() {
+	println(A)
+}
+
+// Error:
+// main/files/const60.gno:4:6: bigint underflows target kind

gnovm/tests/files/const61.gno

@@ -0,0 +1,12 @@
+package main
+
+const (
+	A = uint8(^0)
+)
+
+func main() {
+	println(A)
+}
+
+// Error:
+// main/files/const61.gno:4:6: bigint underflows target kind