fix: allow exporting TSDeclareFunction as default

[zxbodya]

Q	A
Fixed Issues?
Patch: Bug Fix?	Yes
Major: Breaking Change?
Minor: New Feature?
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?
License	MIT

Updating @babel/types to allow TSDeclareFunction in default export.
It was working earlier, but stopped somewhere in between 7.18.2 and current (7.18.8) version

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/52535/

[nicolo-ribaudo]

What is the corresponding TS syntax? All of these error in the TS playground 🤔

declare export default function f(): any; // "export" modifier must precede "declare" modifier

export declare default function f(): any; // lots of parsing errors

export default declare function f(): any; // expects a ; after declare

[zxbodya]

example with the syntax(playground):

export default function test(a: number): boolean;
export default function test(a: boolean): boolean;
export default function test(a: any): boolean {
    return false;
};

[liuxingbaoyu]

It looks like this.

playground

[zxbodya]

@liuxingbaoyu here is it in astexplorer (for babel parser it is to be ExportDefaultDeclaration with TSDeclareFunction in a declaration field)

[liuxingbaoyu]

Related to this.
I tested in @babel/parser 7.18.8 which produces the ExportDefaultDeclaration node.

[zxbodya]

from my understanding TSDeclareFunction is not expected to get there(I would assume it is to be removed somewhere earlier, and it is fine to ignore this)

[nicolo-ribaudo]

Can you add a test so that we don't accidentally break this again?