VM doesn't recognize top-level function as const in all cases.

[lrhn]

Example:

void main() {
  print(const Echo().echo("test"));
}


[12:08:17]lrn@lrn:~/dart/co/sdk/dev (reapply-fix-remove-resource)
typedef String EchoType(String arg);

const EchoType cecho = simpleEcho;

class Echo {
  final EchoType echo;
  const Echo() : echo = simpleEcho;
  const Echo.verbose() : echo = verboseEcho;
}

String simpleEcho(String arg) => arg;

String verboseEcho(String arg) => "arg: $arg";

void main() {
//  print(cecho("c"));
  print(const Echo().echo("test"));
}

This program fails with the error:

'file:///.../echo.dart': error: line 21 pos 21: Invalid const object field: Closure: (String) => String from Function 'simpleEcho': static.

  print(const Echo().echo("test"));
                    ^

It fails to recognize that simpleEcho is a compile-time constant in initializer list of Echo().

However, if the commented out line is enabled, the simpleEcho function is recognized as constant, even in the following line.

The simpleEcho function is a compile-time function in all cases.

[mhausner]

Fixed in c15bac4

[mhausner]

FWIW, this was another manifestation of the imperfect implementation of "potentially const values", issue #392. This fix makes it a bit less imperfect :)