TypeScript generates invalid import for re-exported types

The issue was reported on #24941 (comment). It was initially discovered in loopbackio/loopback-next#1643.

In this case, MetadataAccessor is exported from @loopback/metadata and re-exported by @loopback/context. Please note that @loopback/repository-json-schema module imports MetadataAccessor from @loopback/context. It leads to incorrectly generated code.

TypeScript Version: 3.0.x and up

Search Terms: TypeScript import types

Code

https://github.com/strongloop/loopback-next/blob/5b27323ba420bfc500fdf9f2762e7292b96ffa0f/packages/repository-json-schema/src/keys.ts

// A *self-contained* demonstration of the problem follows...
// Test this by running `tsc` on the command-line, rather than through another build tool such as Gulp, Webpack, etc.

Expected behavior:

TypeScript generates the following code:

import { MetadataAccessor } from '@loopback/context';
import { JSONSchema6 as JSONSchema } from 'json-schema';
/**
 * Metadata key used to set or retrieve repository JSON Schema
 */
export declare const JSON_SCHEMA_KEY: MetadataAccessor<JSONSchema, import("@loopback/context").DecoratorType>;

Actual behavior:

TypeScript generates invalid code as follows:

import { MetadataAccessor } from '@loopback/context';
import { JSONSchema6 as JSONSchema } from 'json-schema';
/**
 * Metadata key used to set or retrieve repository JSON Schema
 */
export declare const JSON_SCHEMA_KEY: MetadataAccessor<JSONSchema, import("../context/node_modules/@loopback/metadata/src/types").DecoratorType>;

Playground Link:

Related Issues:
#24874

fix(rest): use direct import to work around a TS bug

Wesley Wigham (@weswigham)

Wesley Wigham (@weswigham) I created a simpler project to reproduce the problem - https://github.com/raymondfeng/ts-26985.

fix(rest): use direct import to work around a TS bug

fix(metadata): remove the default type to work around a TS bug

Is it expected behavior that the PR that was just merged for this (#27340) seems to break certain export const statements in a project with "declaration": true set in tsconfig?

For example:

error TS2742: The inferred type of 'Wrapper' cannot be named without a reference to '../../../../../../../../../../Users/mbrowne/GoogleDrive/www/artnet-styled/styled/node_modules/@types/styled-components'. This is likely not portable. A type annotation is necessary.

13 export const Wrapper = styled.div`

Yup. When that error occurs, we would otherwise have written a reference to the module specifier in the message (and you see how bad that is, right?). It's better to require an annotation when we detect a required path like that.

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TypeScript generates invalid `import` for re-exported types #26985

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TypeScript generates invalid import for re-exported types #26985

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raymondfeng commented on Sep 9, 2018

mbrowne commented on Nov 19, 2018

weswigham commented on Nov 19, 2018

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TypeScript generates invalid `import` for re-exported types #26985