Re: Pattern matching, not informative error message when the binding name is missing

2021-06-07 Thread Jan Lahoda 

Hi Remi,


Thanks. I've filled:
https://bugs.openjdk.java.net/browse/JDK-8268320


FWIW, I think compiler-dev is a better place for reports like this.


Jan


On 07. 06. 21 11:03, Remi Forax wrote:

Hi all,
with this code

   sealed interface Vehicle {}
   record Car(String owner, String color) implements Vehicle {}
   record Bus(String owner) implements Vehicle {}

   public static void example3() {
 var vehicles = List.of(
 new Car("Bob", "red"),
 new Bus("Ana")
 );
 var tax = vehicles.stream()
 .mapToInt(v -> switch(v) {
 case Car -> 100;
 case Bus -> 200;
 default -> throw new AssertionError();
 }).sum();
 System.out.println("tax " + tax);
   }

If there is no binding name in the case,
   case Car
instead of
   case Car car
the error message is not very explicit

PatternMatching101.java:40: error: cannot find symbol
  case Car -> 100;
   ^
   symbol:   variable Car
   location: class PatternMatching101

I believe that in this case, it's possible to know that this is a switch on 
types, so provide a better error message.

regards,
Rémi

Pattern matching, not informative error message when the binding name is missing

2021-06-07 Thread Remi Forax 
Hi all,
with this code

  sealed interface Vehicle {}
  record Car(String owner, String color) implements Vehicle {}
  record Bus(String owner) implements Vehicle {}

  public static void example3() {
var vehicles = List.of(
new Car("Bob", "red"),
new Bus("Ana")
);
var tax = vehicles.stream()
.mapToInt(v -> switch(v) {
case Car -> 100;
case Bus -> 200;
default -> throw new AssertionError();
}).sum();
System.out.println("tax " + tax);
  }

If there is no binding name in the case,
  case Car
instead of
  case Car car
the error message is not very explicit

PatternMatching101.java:40: error: cannot find symbol
 case Car -> 100;
  ^
  symbol:   variable Car
  location: class PatternMatching101

I believe that in this case, it's possible to know that this is a switch on 
types, so provide a better error message.

regards,
Rémi