checker: disallow expr is Type if expr is Optional

vlib/v/checker/infix.v

@@ -781,6 +781,10 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 			if typ != ast.no_type {
 				typ_sym := c.table.sym(typ)
 				op := node.op.str()
+				if left_type.has_flag(.option) && !c.inside_sql {
+					c.error('${node.left} is an Optional, it needs to be unwrapped first',
+						node.left.pos())
+				}
 				if typ_sym.kind == .placeholder {
 					c.error('${op}: type `${typ_sym.name}` does not exist', right_expr.pos())
 				}

vlib/v/checker/tests/opt_is_op_check_err.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/opt_is_op_check_err.vv:13:7: error: t.a is an Optional, it needs to be unwrapped first
+   11 |         a: s
+   12 |     }
+   13 |     if t.a is string {
+      |          ^
+   14 |         r(t.a)
+   15 |     }

vlib/v/checker/tests/opt_is_op_check_err.vv

@@ -0,0 +1,21 @@
+type Foo = int | string
+
+struct Struct {
+	a ?Foo
+}
+
+fn r(a string) {}
+
+fn t(s ?Foo) {
+	mut t := Struct{
+		a: s
+	}
+	if t.a is string {
+		r(t.a)
+	}
+}
+
+fn main() {
+	s := ?Foo('hello')
+	t(s)
+}

vlib/v/debug/tests/sumtype.vv

@@ -20,9 +20,11 @@ fn sumtype() {
 	b := ?MySum(Test{
 		a: 1
 	})
-	if b is Test {
-		dump(b)
-		$dbg;
+	if b != none {
+		if b is Test {
+    		dump(b)
+    		$dbg;
+    	}
 	}
 }
 

vlib/v/gen/c/cgen.v

@@ -4347,17 +4347,20 @@ fn (mut g Gen) debugger_stmt(node ast.DebuggerStmt) {
 				cast_sym := g.table.sym(var_typ)
 
 				mut param_var := strings.new_builder(50)
-				is_option := obj.typ.has_flag(.option)
+				is_option := obj.orig_type.has_flag(.option)
 				var_typ_is_option := var_typ.has_flag(.option)
 				if obj.smartcasts.len > 0 {
-					is_option_unwrap := is_option && var_typ == obj.typ.clear_flag(.option)
+					is_option_unwrap := is_option && !obj.typ.has_flag(.option)
+						&& obj.orig_type.has_flag(.option)
 					mut opt_cast := false
 					mut func := if cast_sym.info is ast.Aggregate {
 						''
 					} else {
 						g.get_str_fn(var_typ)
 					}
-
+					if obj.smartcasts.len > 1 && obj_sym.kind == .sum_type {
+						param_var.write_string('*(')
+					}
 					param_var.write_string('(')
 					if obj_sym.kind == .sum_type && !obj.is_auto_heap {
 						if is_option {

vlib/v/tests/options/option_sumtype_test.v

@@ -6,11 +6,13 @@ pub fn teste() ?TType {
 
 fn test_main() {
 	x := teste()
-	if x is []int {
-		dump(x)
-		y := x as []int
-		assert y == [1, 2]
-		return
+	if x != none {
+		if x is []int {
+			dump(x)
+			y := x as []int
+			assert y == [1, 2]
+			return
+		}
 	}
 	assert false
 }