Version

2.6.14

Reproduction link

github.com

Steps to reproduce

create a Vue app using vue create
either 2.x or 3.x doesnt matter, as long as it is with TypeScript and object style component syntax
go to HelloWorld.vue and right below the props definition paste this:

  data (): { hellStringType: string, hellNumberType: number, hellInvalid: string} {
    debugger;
    return {
      hellStringType: this.getNumber(),
      // should fail due to field type and return type not matching
      hellNumberType: this.getNumber(),
      // should fail due to there being no such function
      hellInvalid: this.buildSomethingElse(),
    }
  },
  methods: {
    getNumber (): number {
      return 42
    }
  }

What is expected?

type inference for the method calls should work, and thus the compilation should fail

What is actually happening?

type inference doesnt work, the invalid code compiles fine. Type inference works only for props.

running the code in a browser with debug statement, the methods called are accessible