dart2js: implementing Function without defining call should be a warning

[rmacnak-google]

dart2js currently gives an error when attempting to implement Function. The spec (15.5) says this is a static warning.

import 'dart:mirrors';

class _InvocationTrampoline implements Function {
  ObjectMirror _receiver;
  Symbol _selector;
  _InvocationTrampoline(this._receiver, this._selector);
  noSuchMethod(Invocation msg) {
    if (msg.memberName != #call) return super.noSuchMethod(msg);
    return _receiver.invoke(_selector, msg.positionalArguments, msg.namedArguments);
  }
}

main(){
  print(new _InvocationTrampoline(reflect(0), #toString) is Function);
}

[rmacnak-google]

Marked this as blocking #6490.

[peter-ahe-google]

How is this related to issue #6490?

[kasperl]

This looks unrelated to mirrors to me too.

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Set owner to @karlklose.
Added this to the M8 milestone.
Removed Priority-Unassigned label.
Added Priority-Medium, Triaged labels.

[karlklose]

Set owner to @johnniwinther.

[rmacnak-google]

I wanted to implement ObjectMirror's subscript operator in terms of a fake function that supported the various arities by using noSuchMethod. I forgot that on dart2js the presence of noSuchMethod is expensive and we shouldn't use in core libs.

[rmacnak-google]

Unmarked this as blocking #6490.

[johnniwinther]

Added Started label.

[johnniwinther]

Implementing Function is now allowed. Warnings will be added later.

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Removed this from the M8 milestone.
Added this to the Later milestone.

[johnniwinther]

Fixed by https://codereview.chromium.org/26995002/

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Added Fixed label.