# mixin_of_non_class

> Details about the mixin_of_non_class diagnostic produced by the Dart analyzer.



_Classes can only mix in mixins and classes._

## Description

The analyzer produces this diagnostic when a name in a `with` clause is
defined to be something other than a mixin or a class.

## Example

The following code produces this diagnostic because `F` is defined to be a
function type:

```dart
typedef F = int Function(String);

class C with [!F!] {}
```

## Common fixes

Remove the invalid name from the list, possibly replacing it with the name
of the intended mixin or class:

```dart
typedef F = int Function(String);

class C {}
```

