generated JS uses type as value

I opened https://github.com/vuejs/vue-cli/issues/1498 on vue-cli, but was redirected here.

Reproduction repo: https://github.com/doppelreim/vue-test-app/tree/test-import-route

Steps to reproduce: Run ./node_modules/.bin/vue-cli-service serve

Expected: The app should compile without warnings.

Actual: There are warnings:

 WARNING  Compiled with 4 warnings                                                                                                            09:41:30

 warning  in ./src/components/HelloWorld.vue?vue&type=script&lang=ts

"export 'Route' was not found in 'vue-router'

 warning  in ./src/components/HelloWorld.vue?vue&type=script&lang=ts

"export 'Route' was not found in 'vue-router'

 warning  in ./src/components/HelloWorld.vue?vue&type=script&lang=ts

"export 'Route' was not found in 'vue-router'

 warning  in ./src/components/HelloWorld.vue?vue&type=script&lang=ts

"export 'Route' was not found in 'vue-router'

The change that introduces the warnigns can be seen here: https://github.com/doppelreim/vue-test-app/commit/af036724ecbe53853ce10707796c82213ae07a43

I want to add a Watcher on $route. The parameters of the function (newRoute and oldRoute) should be typed. I assume Route is the correct type.

I checked out /node_modules/vue-router/types/index.d.ts and there Route does get exported, as far as I can tell.

If I use Route inside of the function-body, like this:

const r: Route = {
  path: '',
  hash: '',
  query: {},
  params: {},
  fullPath: '',
  matched: [],
};

then it does not throw errors. And if I leave out some of the required attributes, then the compiler rightfully complains. So I assume the export/import does work here.

@yyx990803 provided a technical explanation in https://github.com/vuejs/vue-cli/issues/1498#issuecomment-395461425 - but there is nothing vue-cli can do about it.

Not sure, where to address this. Maybe here?

[doppelreim]

Looks like it, see https://github.com/vuejs/vue-cli/blob/05391b6e9e51917437d79c46721548dc7038993a/packages/%40vue/cli-plugin-typescript/generator/template/tsconfig.json#L9

I will open an issue with vue-cli to remove the line from the template.

[doppelreim]

Disabling emitDecoratorMetadata works. Nice!

It was initially enabled when I created the app with vue-cli. Do you know whether they do it only because of vue-property-decorator?