checker: fix autocast in complex if condtions (#18699)

vlib/v/checker/infix.v

@@ -824,6 +824,20 @@ fn (mut c Checker) autocast_in_if_conds(mut right ast.Expr, from_expr ast.Expr,
 						expr_type: from_type
 					}
 				}
+			} else {
+				c.autocast_in_if_conds(mut right.expr, from_expr, from_type, to_type)
+			}
+		}
+		ast.ParExpr {
+			c.autocast_in_if_conds(mut right.expr, from_expr, from_type, to_type)
+		}
+		ast.PrefixExpr {
+			c.autocast_in_if_conds(mut right.right, from_expr, from_type, to_type)
+		}
+		ast.CallExpr {
+			c.autocast_in_if_conds(mut right.left, from_expr, from_type, to_type)
+			for mut arg in right.args {
+				c.autocast_in_if_conds(mut arg.expr, from_expr, from_type, to_type)
 			}
 		}
 		ast.InfixExpr {

vlib/v/tests/autocast_in_if_conds_2_test.v

@@ -0,0 +1,32 @@
+type MySumType = S1 | S2
+
+struct Info {
+	name string
+}
+
+struct S1 {
+	is_info bool
+	info    Info
+}
+
+struct S2 {
+	field2 string
+}
+
+fn get_name(name string) string {
+	return name
+}
+
+fn test_autocast_in_if_conds() {
+	s := MySumType(S1{
+		is_info: false
+		info: Info{'foo'}
+	})
+
+	if s is S1 && !s.is_info && get_name(s.info.name) == 'foo' {
+		println('ok')
+		assert true
+	} else {
+		assert false
+	}
+}