Thread-loader with non-serializable types

[RobbinBaauw]

Version

4.5.0

Reproduction link

https://github.com/RobbinBaauw/vue-cli-thread-repro

Environment info

 System:
    OS: Linux 5.7 Pop!_OS 20.04 LTS
    CPU: (8) x64 Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz
  Binaries:
    Node: 14.5.0 - /opt/node/bin/node
    Yarn: 1.22.4 - /opt/node/bin/yarn
    npm: 6.14.5 - /opt/node/bin/npm
  Browsers:
    Chrome: 83.0.4103.116
    Firefox: 78.0.2
  npmPackages:
    @vue/cli: ^4.5.0 => 4.5.0 
    @vue/cli-shared-utils:  4.5.0 
    @vue/cli-ui:  4.5.0 
    @vue/cli-ui-addon-webpack:  4.5.0 
    @vue/cli-ui-addon-widgets:  4.5.0 
    @vue/compiler-core:  3.0.0-rc.4 
    @vue/compiler-dom:  3.0.0-rc.4 
    @vue/compiler-sfc:  3.0.0-rc.4 
    @vue/compiler-ssr:  3.0.0-rc.4 
    @vue/reactivity:  3.0.0-rc.4 
    @vue/runtime-core:  3.0.0-rc.4 
    @vue/runtime-dom:  3.0.0-rc.4 
    @vue/shared:  3.0.0-rc.4 
    typescript:  3.9.7 
    vue:  3.0.0-rc.4 (2.6.11)
    vue-cli-plugin-apollo:  0.21.3 
    vue-codemod:  0.0.4 
  npmGlobalPackages:
    @vue/cli: 4.5.0

Steps to reproduce

Note that I made 2 changes w.r.t. a generated project (RobbinBaauw/vue-cli-thread-repro@7295f13):

1. Added invalid typescript in main.ts
2. Added vue.config.js and changed ts-loader with an errorFormatter. Set parallel to true.

Now build. You'll get an error:

 error  in ./src/main.ts

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

If you change parallel to false, it'll give the custom typescript error. This is expected behavior.

What is expected?

Both parallel and non-parallel give this typescript custom error

What is actually happening?

If thread-loader is used (so for compiling Typescript or by using Babel), the config is passed to the threads in buffers (strings). If you use non-serializable objects in your vue.config.js (such as functions), these objects are removed when serializing to this string, and thus you get these "undefined" errors when using thread-loader (see webpack-contrib/thread-loader#89 (comment)).

---

I ran into this "bug" when providing a custom renderer in Vue. This repro however shows that any reference type (such as functions) doesn't work. I don't know how to solve this properly, but at least providing a clear heads up in the docs (for example on https://cli.vuejs.org/guide/webpack.html) would be nice.

[haoqunjiang]

Fixed in vue-loader v16.0.0-beta.5

[RobbinBaauw]

This doesn't fix the issues for other loaders. I think a warning in the docs at the parallel option would prevent some people from having to debug this (as many will probably be unknown with the fact that thread-loader is used and that it has this downside).

[haoqunjiang]

Makes sense. PR's welcome.