tsc with allowJs reports TS9005 error for nested anonymous constructor functions

[brian6932]

🔎 Search Terms

TS9005: Declaration emit for this file requires using private name '(Anonymous function)'. An explicit type annotation may unblock declaration emit.

🕗 Version & Regression Information

• Occurs on versions 3.7.5 - nightly
• Related to PR Avoid trying to emit anonymous classish/expando functions as assignments #55472

Related to #55172
When 2 separate nested this bindings are used within constructor functions, the following error's returned always at the top of the file (this was really annoying to debug 😅)

Declaration emit for this file requires using private name '(Anonymous function)'. An explicit type annotation may unblock declaration emit.

⏯ Playground Link

https://tsplay.dev/NV57Gw

💻 Code

const a = new function () {
	this.b = new function () {
		this.c = 1
	}
}

🙁 Actual behavior

Complains

🙂 Expected behavior

Shouldn't complain

Additional information about the issue

No response

[rubiesonthesky]

Last typescript version in playground that does not report error is 3.6.2 so I don't think this changed in the linked PR.

In the linked issue #55172, weswigham notes that versions 3.6.6 do not show error that the code there is creating, so this probably is not working earlier versions either.

[Andarist]

I'm not sure if this is meant to compile successfully but, if I'm reading this correctly, it shows an extra thing that is a bug. If you comment out the nested assignment to the this.c property then you might see this emit:

declare function a(): void;
declare class a {
    b: any;
}

This doesn't seem right because a is not a class - it's an instance of a class. Extra TS playground that shows the difference between anonymous and named functions here: TS playground

And an extra thing that I observed here, private name for #prop can leak in the declaration emit - this shouldn't happen (TS playground):

// input

// @target: esnext
function test() {
  return class A {
    #prop = 10;
  };
}

export const a = new (test())();

// dts
export declare const a: {
    "__#12@#prop": number;
};

[fatcerberus]

@Andarist Re: Private name leakage - #56145 -> #36548

[kopax]

Hello, any update on this ?

Using yarn4 and prisma, we get stuck as :

• yarn4 can't generate prisma client in node_modules, so it is generated in the workspace with my files
• I can't use annotation as this is often re-generated code

This makes me totally blocked and forced to downgrade yarn :(.

Any workaround exisiting ?

[Jeangowhy]

Can someone tell what is this problem?

[seahindeniz]

In my case, "composite": true, was in my tsconfig.json file. Removing it solved the issue