### What it does
Denies the configured types in clippy.toml.

Note: Even though this lint is warn-by-default, it will only trigger if
types are defined in the clippy.toml file.

### Why is this bad?
Some types are undesirable in certain contexts.

### Example:
An example clippy.toml configuration:
```
disallowed-types = [
    # Can use a string as the path of the disallowed type.
    "std::collections::BTreeMap",
    # Can also use an inline table with a `path` key.
    { path = "std::net::TcpListener" },
    # When using an inline table, can add a `reason` for why the type
    # is disallowed.
    { path = "std::net::Ipv4Addr", reason = "no IPv4 allowed" },
]
```

```
use std::collections::BTreeMap;
// or its use
let x = std::collections::BTreeMap::new();
```
Use instead:
```
// A similar type that is allowed by the config
use std::collections::HashMap;
```