Allow all private declarations to be emitted in declaration output

[weswigham]

Followup to #22798 the allows any top-level declaration to be made visible if it is required to properly emit another emitted declaration.

Fixes #23127

Makes #15058 redundant.

As a side effect, because we now consider these declarations "visible", we now sometimes use their names in the type baselines.

[bluelovers]

looks like this is something i need it lol

[weswigham]

@sheetalkamat Would you like to give this a review? The GH UI won't let me add people T.T

[sheetalkamat]

where is this coming from ?

[weswigham]

declare const FilteredThing_base: {
     new (...args: any[]): {	     new (...args: any[]): {
         match(path: string): boolean;	         match(path: string): boolean;
         thing: number;	         thing: number;
     };	     };
 } & typeof Unmixed;	 } & typeof Unmixed;

doesn't exist at runtime (we just emit it so we have a thing for the extends clause) - this scopes the file so it's actually private.

[sheetalkamat]

unwanted export {} ?

[weswigham]

declare class D extends C {
}

isn't exported (but it used in C). To keep it that way, we need to emit export {} to fix the scoping of the file.

[sheetalkamat]

But there is export declare class C so export {} is not needed. https://github.com/Microsoft/TypeScript/pull/23351/files/aa71540de296549fa21676bee32349088189fa35#diff-880f6135e59878559ff8c952515ec352R43

[sheetalkamat]

In mostly all of these scenarios the error you are fixing is public -> private so you are just adding private types to file, the scoping of file shouldnt affect by any of these additions.

[weswigham]

No, it is. Our .d.ts scope rules are odd - any export statement makes it a module, but (separately from that) in a .d.ts unless there's an export assignment or export declaration, every top-level declaration is seen at exported, even without an explicit export modifier. AFAIK this was a decision made to reduce the noise in writing declaration files a long time ago.

[bluelovers]

does can fix this code too? and @ts-ignore not work here

function fn(inputRegExp: RegExp, input: string){}

namespace fn
{
	export const S = Symbol('fn');
}

// @ts-ignore
const fn2 = fn;

export = fn2;

Error:(13, 7) TS4025: Exported variable 'fn2' has or is using private name 'fn'.

[rbuckton]

What does getAccessTypeSplitNode mean? The name is quite opaque, so a doc comment would be helpful.

[rbuckton]

Why was this needed? If AccessorDeclaration is now synthetic, you could just call getParseTreeNode (which you are still doing in the version in the checker) and use the existing getAllAccessorDeclarations in utilities.ts.

[weswigham]

Computed property names have differing names and need to merge - the only way to do so is via their symbol.

[weswigham]

@rbuckton anything else?