Re: Sealed local interfaces

[Vicente Romero]

Hi Remi,

On 8/17/20 10:07 AM, Remi Forax wrote:
I've found a discrepancies in the current spec of sealed,
the current spec allows local sealed interface but you have no way to provide a 
sub-types apart a sealed sub interfaces.
A record or an interface is allowed to be declared inside a method,
by example, this is a valid code
   static void foo() {
     interface I {}

     record Foo() implements I {}
   }

the interface can also be sealed
   static void foo() {
     sealed interface I {}

     record Foo implements I {}
   }

but this code does not compile because Foo is a local class and a local class 
can not implement a sealed interface.

This rule was intended to not allow this kind of code
   sealed interface I {}
   
   static void foo() {
     record Foo implements I {}
   }
because the interface I is visible while Foo is not.

But we have forgotten to discuss about the case where both Foo and I are in the 
same scope.

I see two possible fixes
- disallow sealed local interfaces
+1 having a local sealed class seems like unnecessary, this option makes 
more sense to me
- allow local class/record to implement a sealed interface if they are in the 
same scope.

Rémi
Vicente