Meta-issue for discussion of the proposal to allow optional and named arguments in the same argument list

[leafpetersen]

This issue is to provide a forum for community discussion and feedback related to the proposal to allow named optional parameters and positional optional parameters to appear simultaneously in a parameter list.

That is, a method declaration with both types of optional parameters can be written, perhaps like:

Future<Isolate> spawn(Uri target, [List<String> args, Object param], {bool paused});

This entry will be updated when a proposal is available.

cc @munificent @eernstg @floitschG @lrhn

[rmacnak-google]

Function objects are the biggest contributor to space in core snapshots, and tracking separately the number of optional positional and optional named arguments will further increase this cost. This also seems likely to slow down the prologue of functions with optional arguments.

@crelier @a-siva

Dart's selector space is already a horrible mess. We should be shrinking it, not growing it.

[matanlurey]

I personally think #30353 is better.

[leafpetersen]

@rmacnak-google Implementation concerns are definitely the main issue holding this back. I actually don't know much about how the VM supports optional and named arguments now, and how it would have to change to support this - could you expand?

Also, can you elaborate on Function objects are the biggest contributor to space in core snapshots? I'm presuming that you don't mean code. Instantiated closure objects? VTables? Something else?