Can't pass an inflight closure to a super ctor call

[eladb]

I tried this:

class Base {
  new(handler: inflight (): void) { }
}

class Derived extends Base {
  new() {
    super(inflight () => { });
  }
}

new Derived();

This happened:

➜  winglibs git:(main) wing compile ~/Documents/test.main.w 
ERROR: There is already a Construct with name 'Derived' in $Root [Default]

hint: Every preflight object needs a unique identifier within its scope. You can assign one as shown:

> new cloud.Bucket() as "MyBucket";

For more information, see https://www.winglang.io/docs/concepts/application-tree

../../Documents/target/test.main.wsim.543615.tmp/.wing/preflight.js:11
       class Base extends $stdlib.std.Resource {
         constructor($scope, $id, handler) {
>>         super($scope, $id);
         }
         static _toInflightType(context) {

I expected this:

To work

Is there a workaround?

No response

Component

Compiler

Wing Version

No response

Node.js Version

No response

Platform(s)

No response

Anything else?

No response

Community Notes

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[github-actions]

Hi,

This issue hasn't seen activity in 60 days. Therefore, we are marking this issue as stale for now. It will be closed after 7 days.
Feel free to re-open this issue when there's an update or relevant information to be added.
Thanks!

[staycoolcall911]

Another simpler case of this (by EladB):

class Foo {
  pub bar() {
    inflight () => {};
  }
}

let f = new Foo();
f.bar();
f.bar();

Update: this issue is a different issue and is a dup of #2853. See details for specific issue below.

[yoav-steinberg]

Detailed problem description

Passing an inflight closure to a super ctor call doesn't currently work for the following reasons:

1. We currently auto add a super call when we jsify the ctor if the first statement isn't already a super call. This fails in our case because the first statement is actually the transformed inflight closure into a class definition. So we don't detect the existing call to super (in the example above) and end up with two super calls.
2. The inflight closure transformer adds code that references this. But because we reference this before calling super we end up with invalid JS code (super must be called before using this in ctors). These are the reasons we reference this in transformed inflight closures:
   • 2.1. For setting up the parent_this used to replace this references inside the closure.
   • 2.2. When instantiating the instance of the closure class we need to pass in a scope argument and pass in this as the scope.

Thoughts about fixing this

One alternative is getting rid of inflight closure transformation altogether (see #5033). But if we want to avoid that at this point here are some other thoughts:

• Re 1. above: we can detect the transformed inflight (and perhaps all type definitions) before the super call and not blindly look at the first statement when searching for a super call.
• Re 2.2 above: we can pass a non this scope into the generated closure class. It can probably be any scope.
• Re 2.1 above: the closure transformer can check if there are any references to this in the closure code. If there aren't we don't need parent_this anyway. If there are we can fail compilation in case this closure is used inside a ctor before the super call statement.

[Chriscbr]

Related: #6387

[monadabot]

Congrats! 🚀 This was released in Wing 0.74.30.