Emmited Type Declarations generate empty export

Bug Report

When generating type declaration files if a type that is only used inside the typescript code however it is not exported results in an empty export at the end of the file e.g. export {};

🔎 Search Terms

• declaration empty export
• declaration “export {}”

🕗 Version & Regression Information

When i started inspecting the generated typescript declarations generated. I see the same error/behaviour when either typescript@4.8 and typescript@next

This is the behavior in every version I tried, and I reviewed the FAQ for entries about emmited code and private fields and methods.

⏯ Playground Link

• When some of the types are not exported this happens playground example here
• When all of the types are exported there is no empty export playground example here

💻 Code

Empty Export Code

type TaskType = 'ONE' | 'TWO' | 'THREE';

// would not expected to have an empty export 
// in the emitted type declaration code here is this correct?
export interface Task {
  executeTask(type:TaskType):void;
}

No Empty Export

// no empty export since all types and interfaces exported
export type TaskType = 'ONE' | 'TWO' | 'THREE';
export interface Task {
  executeTask(type:TaskType):void;
}

🙁 Actual behavior

Empty export for some reason…

🙂 Expected behavior

No default empty export.

[RyanCavanaugh]

Cool, thanks for clarifying – the additional export { } indeed shouldn’t be there.

[cristobal]

The file needs at least one export or import to be a module. If there already is one, an additional empty one is not needed.

I don’t think the documentation needs to justify every behavior needed for correctness. Correctness is an assumed facet of operation.

That was my assumption that there should be not have been any empty export {} in the generated declaration file since there is already at least on export defined to make it a module.

Seems like a side effect when generating declaration fille, perhaps a bug then? After digging into some here it seems that whenever one references a type, interface or a const value that is not exported the type declaration will include an empty export {}; at the end of the file.

Not exported reference results in empty export example e.g.:

Playground link here

No reference used that is not exported no empty export:

Playground link here