checker: fix autocast in complex if condtions 4 (#18744)

vlib/v/checker/infix.v

@@ -830,18 +830,17 @@ fn (mut c Checker) invalid_operator_error(op token.Kind, left_type ast.Type, rig
 }
 
 // `if node is ast.Ident && node.is_mut { ... }` -> `if node is ast.Ident && (node as ast.Ident).is_mut { ... }`
-fn (mut c Checker) autocast_in_if_conds(mut right_ ast.Expr, from_expr ast.Expr, from_type ast.Type, to_type ast.Type) {
-	mut right := right_
-	match mut right {
-		ast.Ident {
-			if right.name == from_expr.str() {
-				right_ = ast.AsCast{
-					typ: to_type
-					expr: from_expr
-					expr_type: from_type
-				}
-			}
+fn (mut c Checker) autocast_in_if_conds(mut right ast.Expr, from_expr ast.Expr, from_type ast.Type, to_type ast.Type) {
+	if '${right}' == from_expr.str() {
+		right = ast.AsCast{
+			typ: to_type
+			expr: from_expr
+			expr_type: from_type
 		}
+		return
+	}
+
+	match mut right {
 		ast.SelectorExpr {
 			if right.expr.str() == from_expr.str() {
 				right.expr = ast.ParExpr{

vlib/v/tests/autocast_in_if_conds_5_test.v

@@ -0,0 +1,45 @@
+type MySumType = S1 | S2
+
+struct Info {
+	name string
+}
+
+struct Node {
+	left MySumType
+}
+
+struct S1 {
+	is_info bool
+	info    Info
+}
+
+fn (s1 S1) is_info() bool {
+	return s1.is_info
+}
+
+struct S2 {
+	field2 string
+}
+
+fn get_name(s1 S1) string {
+	return s1.info.name
+}
+
+fn test_autocast_in_if_conds() {
+	node := Node{
+		left: MySumType(S1{
+			is_info: false
+			info: Info{'foo'}
+		})
+	}
+
+	a := 22
+
+	if a > 0 && node.left is S1 && !node.left.is_info && get_name(node.left) == 'foo'
+		&& !node.left.is_info() {
+		println('ok')
+		assert true
+	} else {
+		assert false
+	}
+}