[api-extractor] improve the .d.ts rollup to handle augmented types #1709
Description
This issue proposes to improve API Extractor's analysis to handle augmented types, as illustrated in this repro from @manrueda:
https://github.com/manrueda/api-extractor-module-augmentation
In TypeScript, types can get "augmented" when the original declaration is extended locally in a file, via declaration merging. For example, we might have an entry point like this:
index.ts
// imports an interface declaration
import { Extras } from './core';
// adds more members to the interface, but only from the perspective of this file
import './plugin';
// exports the augmented result
export { Extras }Note: The original issue description involved global variables, but we have narrowed the scope to only consider augmentation of normal exports. Details in this comment.
Original description involving global augmentation
Is this a feature or a bug?
- Feature
- Bug
Please describe the actual behavior.
.d.ts rollup generation will remove global type extension.
If the issue is a bug, how can we reproduce it? Please provide detailed steps and include a GitHub branch if applicable. Your issue will get resolved faster if you can make it easy to investigate.
Source code:
declare global {
namespace jest {
interface Matchers<R, T> {
toHaveBeenWarned(): R
toHaveBeenWarnedLast(): R
toHaveBeenWarnedTimes(n: number): R
}
}
}
export interface User {
name: string
}Generated code:
export declare interface User {
name: string
}
export { }What is the expected behavior?
Generated code should keep global type extension.
If this is a bug, please provide the tool version, Node.js version, and OS.
- Tool: api-extractor
- Tool Version: 7.7.6
- Node Version: 13.7.0
- Is this a LTS version? No
- Have you tested on a LTS version? No
- OS: macOS Catalina 10.15.2