@Override on a record component compiles but does not work

[Gavin Bierman]

Hi Remi,

Just to back up Vicente’s reply.

You’ll recall that the intent of the implicit accessor declaration is that these two record declarations are, in essence, identical:

record R(@Override int x){}

and

record R(int x){
    @Override
    public int x(){
        return this.x;
    }
}

So, given that assumption, and the snippet that Vicente included from JLS 16.9.6.4.4 that explains that @Override has a special meaning for accessor methods, then you get the behaviour that you have observed.

Thanks,
Gavin

On 19 Jul 2021, at 20:54, Vicente Romero <vicente.romero at oracle.com<mailto:vicente.romero at oracle.com>> wrote:

Hi Remi,

According to JLS 16 9.6.4.4:

...
The clause about a record class is due to the special meaning of @Override in a record
declaration. Namely, it can be used to specify that a method declaration is an accessor
method for a record component. Consider the following record declaration:

    record Roo(int x) {
        @Override
            public int x() {
                return Math.abs(x);
            }
        }
    }

The use of @Override on the accessor method int x() ensures that if the record
component x is modified or removed, then the corresponding accessor method must be
modified or removed too.
...

So it is OK to annotate a record component with the @Override annotation without the need for a superinterface defining an override equivalent method to exist,

Thanks,
Vicente

On 7/19/21 12:49 PM, Remi Forax wrote:

It does not seems that @Override correctly compiles on a record but the "override" check is not done.

By example,
  interface Named {
    String name();
  }
  record Foo(@Override String name) implements Named { }

actually compiles but
  record Foo(String name, @Override String bar) implements Named { }

also compiles ??

It seems that the logic that checks if a method "overrides" another (in the general sense i.e replace another method) is not implemented if @Override is declared on a record component.

regards,
Rémi



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