Is there any way to, given a CallExpression with inferred type arguments, find what those type arguments are?

Example code:

class SomeClass {
    public someMethod(arg: T): void { }
}

// What is the inferred type of T in this call?
someClass.someMethod(7);

It's easy enough to find type arguments that were explicitly assigned in the code, but I can't figure out how to find what was inferred.

function inferTypeArguments(node: ts.CallExpression, typeChecker: ts.TypeChecker) {
    node.typeArguments; // is empty
    const signature = typeChecker.getResolvedSignature(node);
    signature['typeArguments']; // is also empty

    // This returns "(arg: number): void"
    // so I know that the typeChecker has the right information,
    // but I would really like a ts.Type[]
    typeChecker.signatureToString(signature, node, ts.TypeFormatFlags.WriteTypeArgumentsOfSignature)
}