[api-extractor] Unused import statements not trimmed --> causing errors when consuming rollup file

[AvatharDG]

Summary

When trimming certain members during rollup (e.g. removing interfaces/classes), related import statements at the top of the rollup file are not trimmed, when they are no longer needed.

Repro steps

I have two libraries library-a and library-b.

They have some internal members (decorated with @internal comment), which I want to remove in a public distributable version. Library-b is extending some internal members of library-a.

The public trimmed rollup of library-b however remains with some import statements to internals of library-a.

Since they are no longer exported, this results in "Module library-a has no exported member xxxx" when consuming both public versions of these libraries.

Possible solution

It would help if api-extractor would remove any unused import statements when all processing is done.

Example

library-a.d.ts (untrimmed):

/**
 * @internal
 */
export declare interface _InterfaceA {
}

library-b.d.ts (untrimmed):

import { _InterfaceA } from 'library-a';

/**
 * @internal
 */
export declare interface _InterfaceB extends _InterfaceA {
}

library-b.public.d.ts (trimmed):

import { _InterfaceA } from 'library-a'; --> this line should be removed

Standard questions

Please answer these questions to help us investigate your issue more quickly:

Question	Answer
@microsoft/api-extractor version?	7.19.2
Operating system?	Windows
API Extractor scenario?	rollups (.d.ts) -->
Would you consider contributing a PR?	Maybe
TypeScript compiler version?	4.5.3
Node.js version (node -v)?

[j-ulrich]

Note that a similar issue also exists for export of @internal APIs. See #2791.

[akania]

+1 to fix this please

[sharifrahaman]

Plese fix this issue.

[vamshich13]

please fix this