Using Typescript spread operator results in compile error

Question

Using VS17RC with TS 2.1

function foo(x:number, y:number, z:number) { console.log(x + y + z)}
var args = [0, 1, 2];
foo(...args);

gives the compile time error "Supplied parameters do not match any signature of call target."

This is the compiled js:

function foo(x, y, z) { console.log(x + y + z); }
var args = [0, 1, 2];
foo.apply(void 0, args);

which does in fact work.

Is there something I am doing wrong here?

The example comes from here: Typescript Deep Dive

Answer 1

There's an open issue on the exact same example:
Compiler incorrectly reports parameter/call target signature mismatch when using the spread operator

The issue is marked as bug, but it's there from Aug 3, 2015, and has no set milestone.

Answer 2

This is my workaround for it:

/**
 * Function definition
 */
class SockService {
  connect(...args:Array<string>) {
    if (args.length > 1) {
      [this.host, this.path] = args;
    }
  }
}

/**
 * Function usage
 */
var endpoint = {
  'local_test': [] as Array<string>,
  'local': ['0.0.0.0:8080', '/foo/websocket'],
  'production': ['192.0.2.1:8080', '/foo/websocket']
};

this.sock.connect(...endpoint.local_test);

I don't like using rest parameters like this, as it makes the function definition much less descriptive. But it's the only way I've gotten spread to work with function arguments in TypeScript.