Closured constants as default argument values don't work on functions with modifiers in the VM

[greglittlefield-wf]

Default values for optional arguments that come from closured const variables don't work on functions with modifiers (async, async*, sync*).

This bug seems to be new in Dart 1.20, as it was working in 1.19.1.

This is not an issue for normal functions without modifiers, and not an issue for const variables that are top-level or within a class.

It also only occurs on the VM, and not dart2js.

This issue applies for both named and positional optional arguments.

Reduced test case

const topLevelConst = 'topLevelConst';

main() {
  const closureConst = 'closureConst';

  test({
    defaultFromTopLevelConst: topLevelConst,
    defaultFromClosureConst: closureConst
  }) async {
    print('Success!');
  }

  test();
}

error: line 8 pos 30: expression is not a valid compile-time constant
    defaultFromClosureConst: closureConst
                             ^

#0      Future.Future.microtask.<anonymous closure> (dart:async/future.dart:144)
#1      _microtaskLoop (dart:async/schedule_microtask.dart:41)
#2      _startMicrotaskLoop (dart:async/schedule_microtask.dart:50)
#3      _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:96)
#4      _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:149)

[crelier]

This issue is a duplicate of #27659, which was fixed on Oct 25.

[greglittlefield-wf]

@crelier Is this a duplicate? The names don't have to be the same for this issue to occur.

[crelier]

@greglittlefield-wf If I run your test case, I get "Success!". The error was due to a side effect of parsing the signature twice.

[greglittlefield-wf]

Awesome, just wanted to make sure. Thanks for double-checking!