Allow type assertion for "super" keyword in method. #41034

Search Terms

super type assertion

Suggestion

Currently there is no way to provide a type assertion for "super" keyword, because the "super" keyword cannot be wrapped by parentheses, so either (<T>super).x or (super as T).x will result in an error: "'super' must be followed by an argument list or member access.ts(1034)".

The parentheses wrapping "super" which only for type assertion use should be allowed.

Use Cases

class A {
  // a decorator will add a instance method "foo" here.
}

class B extends A {
  bar() {
    (<A & {foo: () => void}>super).foo(); // doesn't work.
  }
}

class C extends A {
  bar() {
    (<A & {foo: () => void}>A.prototype).foo(); // this works.
  }
}

Checklist

My suggestion meets these guidelines:

• [●] This wouldn't be a breaking change in existing TypeScript/JavaScript code
• [●] This wouldn't change the runtime behavior of existing JavaScript code
• [●] This could be implemented without emitting different JS based on the types of the expressions
• [●] This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• [●] This feature would agree with the rest of TypeScript's Design Goals.