Record fields can't be used as const?

[mdebbar]

In the following code snippet, info.age is a const value (the entire info record is const). But the analyzer isn't happy with it.

const info = (name: 'John', age: 20);

String getNameByAge(int age) {
  switch (age) {
    case info.age: return info.name;
    default: 'unkown';
  }
}

I get the following error about case info.age:

The expression of a constant pattern must be a valid constant.

Try making the expression a valid constant.

Is this working as intended or a bug?

[eernstg]

This is working as intended: The only getter which can be invoked as part of constant expression evaluation is length, and that is only allowed when the receiver is an instance of String (that's the actual value of the constant expression, not the static type).

Check out https://github.com/dart-lang/language/issues?q=is%3Aopen+is%3Aissue+label%3Aenhanced-const for issues about generalizations of the constant expression sublanguage in general, and, e.g., dart-lang/language#2219, where several new constant expression forms are proposed.