## Why is this an issue?

Invoking a method designed to return a string representation of an object which is already a string is a waste of keystrokes. Similarly, explicitly invoking `ToString()` when the compiler would do it implicitly is also needless code-bloat.

This rule raises an issue when `ToString()` is invoked:

- on a `string`
- on a non-`string` operand to concatenation
- on an argument to `string.Format`

### Noncompliant code example

    var s = "foo";
    var t = "fee fie foe " + s.ToString();  // Noncompliant
    var someObject = new object();
    var u = "" + someObject.ToString(); // Noncompliant
    var v = string.Format("{0}", someObject.ToString()); // Noncompliant

### Compliant solution

    var s = "foo";
    var t = "fee fie foe " + s;
    var someObject = new object();
    var u = "" + someObject;
    var v = string.Format("{0}", someObject);

### Exceptions

The rule does not report on value types, where leaving off the `ToString()` call would result in automatic boxing.

    var v = string.Format("{0}", 1.ToString());