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

[bluetech]

I see that the code has some references to tslib and importHelpers so I assume this should work transparently. If not, I'll be happy to know what is missing.

Here is how to reproduce:

Installed packages:

$ npm ls --depth=0
├── resolve@1.3.2
├── rollup@0.41.6
├── rollup-plugin-typescript2@0.4.0
├── tslib@1.6.0
└── typescript@2.2.2

tsconfig.json:

{
    "compilerOptions": {
        "target": "es5"
    }
}

rollup.config.js:

import typescript from 'rollup-plugin-typescript2';

export default {
	entry: './main.ts',

	plugins: [
		typescript()
	]
}

main.ts:

import {Foo} from './module';

console.log("HERE" + Foo);

And module.ts:

export class Foo {}

export class Bar extends Foo {}

When running rollup as follows:

./node_modules/.bin/rollup -c rollup.config.js

I get this error:

🚨   rpt2: module.ts (3,18): semantic error TS2354 This syntax requires an imported helper but module 'tslib' cannot be found.
module.ts

I think this is because the extends syntax requires an __extends helper from tslib, but typescript can't find tslib.

Expected result is that the required helpers become part of the bundle.

Thanks.

[ezolenko]

This is definitely supposed to work transparently (and works for me in my own projects). I'll try your exact setup, thanks.

[ezolenko]

Looks like you need "moduleResolution": "node" in tsconfig, otherwise typescript can't find tslib in node_modules.

Not sure if that could pose problems on non-node setups, but I haven't heard anything to that effect yet.

[bluetech]

Indeed, with "moduleResolution": "node", it works as expected. Reading https://www.typescriptlang.org/docs/handbook/module-resolution.html, I think "node" is a better fit for me, so I'll just use it. May I suggest mentioning/recommending it in the README?

I see that you opened #14 for the "classic" case, so I'll close this. Thanks!

[hueitan]

Not sure anyone else facing the same problem as mine.

I was having this problem rollup/rollup-plugin-typescript#109, therefore I switch to this repo, but then I'm getting this tslib error.

as the tsconfig is already "moduleResolution": "node"

[ezolenko]

If you post your tsconfig, rollup config and package.json, somebody might spot something amiss.

[giniedp]

@hueitan i faced the same issue while already having "moduleResolution": "node". Fixed it by adding "tslib": "^1.10.0" to my devDependencies.

[hueitan]

adding tslib as the dependencies work to me as well. although not the pretty solution

[ezolenko]

tslib is already a dependency of rollup-plugin-typescript2, how does it end up missing on your system?

Do you use npm install or something else?

[giniedp]

in my case i am using yarn. Deleting the yarn.lock and reinstalling fresh, i do not need an explicit mention of tslib in the package.json

I can reproduce it in the following repo:

https://github.com/giniedp/tweak-ui

git clone git@github.com:giniedp/tweak-ui.git
cd tweak-ui
git checkout v0.1.0

now edit the package.json and remove tslib. Then do

yarn install
yarn run build

you should run into

This syntax requires an imported helper named '__spreadArrays', but module 'tslib' has no exported member '__spreadArrays'

now delete the yarn.lock and then

yarn install
yarn run build

runs fine.

[imnickvaughn]

This was fixed with this

@hueitan i faced the same issue while already having "moduleResolution": "node". Fixed it by adding "tslib": "^1.10.0" to my devDependencies.

Fixed! Mine was in regular dependencies.

[vishnu-85]

Fixed it by adding "tslib": "^1.10.0" to my dependencies.