cgen: fix error for print smartcast variable (#13634)

vlib/v/gen/c/fn.v

@@ -910,15 +910,16 @@ fn (mut g Gen) method_call(node ast.CallExpr) {
 					g.gen_expr_to_string(node.left, rec_type)
 					return
 				} else if node.left.obj.smartcasts.len > 0 {
-					cast_sym := g.table.sym(node.left.obj.smartcasts.last())
+					rec_type = node.left.obj.smartcasts.last()
+					cast_sym := g.table.sym(rec_type)
 					if cast_sym.info is ast.Aggregate {
 						rec_type = cast_sym.info.types[g.aggregate_type_idx]
+					}
 					g.gen_expr_to_string(node.left, rec_type)
 					return
 				}
 			}
 		}
-		}
 		g.get_str_fn(rec_type)
 	} else if node.name == 'free' {
 		mut rec_type := node.receiver_type
@@ -1297,7 +1298,8 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 					if expr.obj is ast.Var {
 						typ = expr.obj.typ
 						if expr.obj.smartcasts.len > 0 {
-							cast_sym := g.table.sym(expr.obj.smartcasts.last())
+							typ = expr.obj.smartcasts.last()
+							cast_sym := g.table.sym(typ)
 							if cast_sym.info is ast.Aggregate {
 								typ = cast_sym.info.types[g.aggregate_type_idx]
 							}

vlib/v/gen/c/str_intp.v

@@ -156,7 +156,8 @@ fn (mut g Gen) str_val(node ast.StringInterLiteral, i int) {
 				if g.comptime_var_type_map.len > 0 || g.comptime_for_method.len > 0 {
 					exp_typ = expr.obj.typ
 				} else if expr.obj.smartcasts.len > 0 {
-					cast_sym := g.table.sym(expr.obj.smartcasts.last())
+					exp_typ = expr.obj.smartcasts.last()
+					cast_sym := g.table.sym(exp_typ)
 					if cast_sym.info is ast.Aggregate {
 						exp_typ = cast_sym.info.types[g.aggregate_type_idx]
 					}

vlib/v/tests/print_smartcast_variable_test.v

@@ -0,0 +1,33 @@
+struct Point {
+	x int
+	y int
+}
+
+struct Line {
+	p1 Point
+	p2 Point
+}
+
+// Sum type
+type ObjSumType = Line | Point
+
+fn test_print_smartcast_variable() {
+	// Type checking and casts
+	mut point := ObjSumType(Point{2, 5})
+
+	if point is Point {
+		println('Point')
+	}
+
+	if point !is Point {
+		println('Not Point')
+	}
+
+	if mut point is Point {
+		println(point)
+		assert point.str().contains('x: 2')
+		assert point.str().contains('y: 5')
+		assert '$point'.contains('x: 2')
+		assert '$point'.contains('y: 5')
+	}
+}