TypeScript infer wrongly copying 'this'

[maciejsikora]

TypeScript Version: 3.7-Beta

Search Terms: copy this, spread this

Code

class A {
  method1() {
     return 'method1'
  }
  copy() {
    return { ...this };
  }
}
const a = new A();
a.copy().method1(); // runtime error

Expected behavior:
Return of a.copy() should not consider having prototype methods.

Actual behavior:
Return of a.copy() has a type this

[DanielRosenwasser]

Initially thought the bug was the runtime behavior and not the type. I thought that generally speaking, method-declared values weren't included on spreads @sandersn.

[fatcerberus]

I thought that generally speaking, method-declared values weren't included on spreads

No, they definitely are. See e.g.

• Destructuring array into an object is assignable to an array type #34780 (comment)
• Spreading array into object should not be assignable to array #28801
• Wrong type infer for spread arrays #31809

And probably some others.

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.