'... is declared but its value is never read' in vue-tsc 0.40.0 and onwards

[samardzicneo]

Hello

Since updating to 0.40.0 (and later 0.40.1), we are unable to use vue-tsc on our project. On that version, we get errors like these on pretty much all of our Vue SFCs:

...
src/[...].vue - error TS6133: '...' is declared but its value is never read.
...

We are using Vue 3 and SFCs with setup scripts all throughout our application.

Reading other issues that reported similar issues, it looks like they were either using Vue 2 or had their issue fixed by editing their tsconfig.json. However, we use Vue 3 and our tsconfig.json includes these lines:

{
  "compilerOptions": {
    ...
    "jsx": "preserve",
    ...
  },
  "vueCompilerOptions": {
    "experimentalDisableTemplateSupport": true
  }
}

Our project was ported from using vue-cli and we didn't consider type-checking in templates at the time, which is why we need experimentalDisableTemplateSupport enabled. Disabling it gets rid of these errors, but introduces hundreds of other ones. Also, the IDE (WebStorm) some of us use didn't support Typescript syntax inside templates at the time.

[johnsoncodehk]

Duplicate of #1729

[sschneider-ihre-pvs]

Doesn't seem to fix it for me. I have that problem for components and variables from setup that are used in the template.

[johnsoncodehk]

@sschneider-ihre-pvs Please open a new issue and provide minimal reproduction if you have the problem in the latest version.