TypeScript library build using entry show warnings

[Gnuk]

Version

3.0.0-rc.3

Reproduction link

https://github.com/Gnuk/vue-typescript-build

Steps to reproduce

Generate a Vue.js application using @vue/cli 3.0.0-rc.3

Use the following plugins:

• Babel
• TypeScript
• Mocha + Chai
• Lint

Add follogind lines inside package.json :

  "main": "dist/example.common.js",
  "typings": "src/index.ts",
  "scripts": {

    "build:lib": "vue-cli-service build --target lib --name example 'src/index.ts'",

Inside the src/index.ts file add :

export * from './components';

Inside the src/components/index.ts file add :

// @ts-ignore
import HelloWorld from './HelloWorld.vue';
export {HelloWorld};

The ts-ignore is used because TypeScript don't recognize vue file as a module

Launch npm run build:lib

What is expected?

No Warning

What is actually happening?

Warnings :

  Building for production as library (commonjs + umd)...

 WARNING  Compiled with 1 warnings                                                                                                                                                                                          19:20:47

 warning  in ./node_modules/@vue/cli-service/lib/commands/build/entry-lib.js

"export 'default' (imported as 'mod') was not found in '~entry'



 WARNING  Compiled with 1 warnings                                                                                                                                                                                          19:20:47

 warning  in ./node_modules/@vue/cli-service/lib/commands/build/entry-lib.js

"export 'default' (imported as 'mod') was not found in '~entry'



 WARNING  Compiled with 1 warnings                                                                                                                                                                                          19:20:47

 warning  in ./node_modules/@vue/cli-service/lib/commands/build/entry-lib.js

"export 'default' (imported as 'mod') was not found in '~entry'

---

I've no problems when importing my component (or more than one component) inside another Vue.js application as a module.

[LinusBorg]

Can you share the exact warnings you are getting?

[Gnuk]

Yes, it's those warnings :

  Building for production as library (commonjs + umd)...

 WARNING  Compiled with 1 warnings                                                                                                                                                                                          19:20:47

 warning  in ./node_modules/@vue/cli-service/lib/commands/build/entry-lib.js

"export 'default' (imported as 'mod') was not found in '~entry'



 WARNING  Compiled with 1 warnings                                                                                                                                                                                          19:20:47

 warning  in ./node_modules/@vue/cli-service/lib/commands/build/entry-lib.js

"export 'default' (imported as 'mod') was not found in '~entry'



 WARNING  Compiled with 1 warnings                                                                                                                                                                                          19:20:47

 warning  in ./node_modules/@vue/cli-service/lib/commands/build/entry-lib.js

"export 'default' (imported as 'mod') was not found in '~entry'

(I've updated my post)

[ktsn]

Looks like the mod is come from the code that vue-loader generates.
https://github.com/vuejs/vue-loader/blob/c4a2719ffd65328dffe7170eae6d80ee5ce88994/lib/loaders/pitcher.js#L103

And this warning is not only occurred with typescript plugin. I confirmed it's printed when I rewrite all .ts with .js and remove @vue/cli-service-typescript in the original reproduction.

I'm not sure how we can avoid this warning though 😞

[LinusBorg]

/cc @yyx990803 you will have to take a look at this, I think.

[octref]

// This doesn't give you default export, thus the warning
export * from './components';

// This is dirty code but works. I recommend AGAINST it
// Also the entry would be `HelloWorld`, not `{ Helloworld }`
export { HelloWorld as default } from './components';

// Use this instead

import * as components from './components';
export default components;

// Alternatively, depending on what you want your lib to export

import * as components from './components';
export default components.HelloWorld;

[Gnuk]

@octref: Your workaraound don't show warning, I use the 3rd case to export more than one Vue component in a component library.

It's not perfect but it works.