Error: Constant evaluation error: The property 'call' can't be accessed on '...' in a constant expression.

[iapicca]

Given these issues
dart-lang/language#819
dart-lang/language#823
I'm admit I'm not sure if this is a bug or an expected behavior,
if the latter some warning would be great

to reproduce just run this code

class Foo {
  const Foo();
  int call() => 42;
}

const fourtyTwo = Foo();

class Bar {
  final int Function() secretOfLife;
  const Bar([this.secretOfLife = fourtyTwo]);
}

void main() => print('${Bar().secretOfLife}');

francesco@francesco-yoga720:~/projects/issue$ dart run lib/main.dart
lib/main.dart: Warning: Interpreting this as package URI, 'package:issue/main.dart'.
lib/main.dart:10:34: Error: Constant evaluation error:
  const Bar([this.secretOfLife = fourtyTwo]);
                                 ^
lib/main.dart:10:34: Context: The property 'call' can't be accessed on 'Foo {}' in a constant expression.
 - 'Foo' is from 'package:issue/main.dart' ('lib/main.dart').
  const Bar([this.secretOfLife = fourtyTwo]);
                                 ^
lib/main.dart:10:19: Context: While analyzing:
  const Bar([this.secretOfLife = fourtyTwo]);

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! Doctor found issues in 1 category.

[eernstg]

This is working as intended. The only member access you can have in a constant expression is s.length where s is a constant expression evaluating to a String. The point is that constant expression evaluation should not run arbitrary code.

(This particular design choice has been debated heavily for many years, and there are ongoing discussions about it right now, but the current rules specify that e.call is never a constant expression, no matter what e is).

[iapicca]

@eernstg
it would be great to have some warning for this situation

[eernstg]

I'm not quite sure what that warning should say, though...

[eernstg]

Note that the following proposal in the language repo is slightly related: dart-lang/language#1048.