'extends' is not compiling when used inside declaration file and importHelpers option is switched on

[Nipheris]

TypeScript Version: 2.1.4 / 2.2.0-dev.20161207

Code

interface Animal {
	type: string;
}

export declare class Pet implements Animal {
	public type: string;
	public name: string;
	constructor();
}

export declare class Dog extends Pet {
	public breed: string;
	constructor();
}

Expected behavior:
Compiles successfully.

Actual behavior:
Compilation fails with the following error:

error TS2354: This syntax requires an imported helper but module 'tslib' cannot be found.

The same source code compiles fine on TypeScript 2.1.1. Installed tslib package has version 1.2.0.

[mhegazy]

are you using --importHelpers?

[mhegazy]

never mind, saw the title :)

[mhegazy]

The error should not be shown in the .d.ts file, this a bug.

but if you have tslib installed you should not see the error anyways, is this correct?

[timocov]

@mhegazy yeah, this is correct

[PavelPZ]

I cannot run importHelpers with installed tslib.

TypeScript Version: 2.1.4 vith VS.NET

Code
export const o = { a: 1, name: "o" };
export const copy = { ...o };

tsconfig.json

{
  "compilerOptions": {
    "target": "es5",
    "module": "system",
    "importHelpers": true,
    "lib": [
      "dom",
      "es6"
    ],
  }
}

installation
I use both JSPM and NPM

jspm install tslib
npm install tslib --save

package.json

{
  "jspm": {
    "dependencies": {
      "tslib": "npm:tslib@^1.2.0",
    }
  "dependencies": {
    "tslib": "^1.2.0"
  }
}

[mhegazy]

@PavelPZ, the compiler uses the same module resolution strategy to resolve tslib as it does with any other module. so you will need to either 1. add "moduleResolution": "node", or 2. add a path mapping for it: "paths": { "tslib" : ["./node_modules/tslib/tslib.d.ts"] }

[PavelPZ]

@mhegazy, thanks.

I am using JSPM, so I modified my tsconfig.json:

{
  "compilerOptions": {"baseUrl": ".",
     "paths": {
        "tslib": [ "jspm_packages/npm/tslib@1.2.0/tslib.d.ts" ]
     }, 

and compiler is now OK.

But there is a problem with runtime (Uncaught (in promise) Error: (SystemJS) tslib.__assign is not a function in Chrome).
tslib.js is correctly loaded, but its factory is never called.

jspm.config.js

SystemJS.config({
  paths: {
    "tslib": "jspm_packages/npm/tslib/tslib",

[mhegazy]

Fix for the original issue should be in tonight typescript@next.

[mhegazy]

@PavelPZ i have not had time to look into the jspm issue yet. have you made progress past this issue, or are you still blocked on it?

[PavelPZ]

@mhegazy, no progress so far. I have no idea how to solve my observation tslib.js is correctly loaded, but its factory is never called. So e.g. tslib.__assign is undefined.

[mhegazy]

Filed #12887 to track it.

[prencher]

We are seeing this with 2.1.4 using Webpack 2 with awesome-typescript-loader. It only happens when using importHelpers: true. The above workaround using paths does not work:

ERROR in [at-loader] node_modules\@types\react\index.d.ts:186:31
    This syntax requires an imported helper but module 'tslib' cannot be found.

[mhegazy]

This should be fixed in latest, can you give typescript@next a try?

[prencher]

@mhegazy Just saw that in a related ticket. Just confirmed that It is indeed fixed in next, so we've just reverted the change for now. Thanks!

[schmuli]

@mhegazy I just tested this issue, using the latest version 2.2.0-dev.20161227, and I'm still seeing this error.

package.json:

{
  "name": "tslib-test",
  "version": "1.0.0",
  "dependencies": {
    "@angular/core": "^2.4.1",
    "tslib": "^1.4.0",
    "typescript": "2.2.0-dev.20161217",
    "rxjs": "^5.0.2",
    "zone.js": "0.7.4"
  }
}

tsconfig.json:

{
    "compilerOptions": {
        "target": "es5",
        "module": "es6",
        "moduleResolution": "node",
        "noEmitHelpers": true,
        "importHelpers": true,
        "emitDecoratorMetadata": true,
        "experimentalDecorators": true,
        "lib": ["es6", "dom"]
    }
}

main.ts:

import { NgModule } from '@angular/core';

@NgModule({

})
export class MyModule {

}

Error in Console:

$ node_modules/typescript/bin/tsc -p .
node_modules/@angular/core/src/metadata/di.d.ts(178,48): error TS2354: This syntax requires an imported helper but module 'tslib' cannot be found.

[mhegazy]

thanks @schmuli for the repro, fix up in https://github.com/Microsoft/TypeScript/pull/13189/files

[Delagen]

When it will be published? in 2.2.1 is the same

[mhegazy]

@Delagen we believe the issue should be fixed in TS 2.2.1, if you are still seeing it please file a new issue and give us some information to reproduce the issue locally.

[ckotzbauer]

Created new issue for 2.2.1: #14468