Can not emit declaration files for TypeScript

[duduluu]

Version

3.0.0-beta.6

Reproduction link

https://github.com/HuijiFE/void-ui/tree/0.1

Steps to reproduce

git clone git@github.com:HuijiFE/void-ui.git
cd void-ui
git checkout 0.1
yarn
yarn build:void

What is expected?

Output declaration files after building.

What is actually happening?

There is not any declaration files after building.

---

I have set "declaration": true, in tsconfig.json, but it doesn't output the typescript declaration files.

And then I use tsc --emitDeclarationOnly, although it output the declaration files but without vue single file component.

[yyx990803]

This doesn't seem to be a Vue issue... At least doesn't qualify as a bug report.

[duduluu]

But I actually emit the declaration files all along, using legacy webpack template in branch master of my project.

[dhensche]

I am unable to get the build:void script to run in your example repository without modifying the package.json (it references src/void.ts but the only similarly named file I can see is src/VoidUI.ts). Modifying the script to point to this file gets the build going (not seeing typing files though). Just running yarn tsc --emitDeclarationOnly results in an error in the console. Are you running a globally installed version of tsc? if so, can you specify which version to make sure that is not causing us problems

[dhensche]

after simplifying the ts file so that typescript stopped complaining on build, I found this issue TypeStrong/ts-loader#711 . Turns out that using the happyPackMode (used when building for production and the parallel flag is set) or setting transpileOnly: true (always the case in the current typescript plugin) in the ts-loader config options will disable the output of declaration files. I'm pretty sure these settings are for build performance reasons so I don't know how the team would like to handle this

[yyx990803]

@dhensche thanks for looking into this!

[duduluu]

@dhensche
Thx, you could checkout https://github.com/HuijiFE/void-ui/tree/alpha-1.0
So... it's a issue for ts-loader.

[dhensche]

yes, ts-loader related issue. I'm wondering if we need to change the build task for projects with the typescript plugin to change the related options so that we still see the performance gains during development (serve), but build the definitions file during a full build. You could modify your webpack config in your vue.config.js to fix the issue locally by adding

config.module
  .rule('ts')
    .use('ts-loader')
      .loader('ts-loader')
        .tap(opts => {
          opts.transpileOnly = false;
          opts.happyPackMode = false;
          return opts;
        });

to disable the transpileOnly and happyPackMode options.

[elevatebart]

Declaration files are only relevant when generating a library consumable by a package manager.
The build time overhead would only happen in this case.
We could disable HappyPack in this case only.

I will cook up a quick PR.

[azampagl]

@dhensche I've tried your suggestion with vu-cli 3.0. When opts.happyPackMode = false I get the following error during build:

error in ./src/index.ts

Module build failed (from ./node_modules/thread-loader/dist/cjs.js):
Thread Loader (Worker 0)
Cannot read property 'options' of undefined

    at Object.makeServicesHost (C:\...\node_modules\ts-loader\dist\servicesHost.js:18:66)
    at successfulTypeScriptInstance (C:\...\node_modules\ts-loader\dist\instances.js:164:45)
    at Object.getTypeScriptInstance (C:\...\node_modules\ts-loader\dist\instances.js:51:12)
    at Object.loader (C:\...\node_modules\ts-loader\dist\index.js:16:41)

 @ ./node_modules/@vue/cli-service/lib/commands/build/entry-lib.js 2:0-24 3:15-18 4:0-22 4:0-22

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

(Oddly enough, if I comment out opts.happyPackMode = false; everything is fine).

[mumrich]

exacly the same issue here...

[mumrich]

after some further investigation, it seems that (at least in my case), the issue is related with the 'thread-loader' package that the 'cli-plugin-typescript' is using...
if I set parallel: false in the vue.config.js, the typings are correctly emitted, if I override the 'ts-loader'-options as @dhensche suggested!