Cannot use `record` as default value for optional parameter of class constructor

[chykon]

Cannot use record as default value for optional parameter of class constructor.

Static analysis shows error non_constant_default_value. When I try to start, I get several errors:

• Error: Not a constant expression.
• Error: Constant evaluation error:

Example code (DartPad):

abstract class AnimalNames {
   static const dogName = (buddy: 'Buddy');
}

class Dog {
   Dog({this.name = AnimalNames.dogName.buddy});

   final String name;
}

void main() {}

Functionally similar working code that doesn't use record (DartPad):

abstract class AnimalNames {
   static const dogNameBuddy = 'Buddy';
}

class Dog {
   Dog({this.name = AnimalNames.dogNameBuddy});

   final String name;
}

void main() {}

---

Dart version used: DartPad stable channel (Based on Flutter 3.13.0 Dart SDK 3.1.0)

[lrhn]

This is working as intended. The expression AnimalNames.dogName.buddy is not a constant expression, because it calls a getter.

That getter happens to be the getter of a record field of a constant record. We could safely allow that, because we know the getter is definitely side-effect free and we can evaluate it at compile-time. But we currently do not allow it.

There is already a language request for that: dart-lang/language#3004
so closing this and deferring to the language repo issue.