## `setArbitraryStorage`

### Signature

```solidity
function setArbitraryStorage(address target) external;
```

### Description

Makes the storage of the given address fully symbolic. Any subsequent `SLOAD` to target storage reads an arbitrary value which is memorized and returned if the same slot is loaded again.

If the storage slot is explicitly written (before or after first load), then the written value is returned instead.

### Parameters

| Parameter | Type      | Description                           |
|-----------|-----------|---------------------------------------|
| `target`  | `address` | The address to set arbitrary storage on |

### Examples

:::code-group
```solidity [test/ArbitraryStorage.t.sol]
contract ArbitraryStorageTest is Test {
    function testArbitraryStorage() public {
        Counter counter = new Counter();
        vm.setArbitraryStorage(address(counter));
        
        // This would fail with "array out of bounds" without arbitrary storage
        address owner = counter.getOwner(55);
        
        // Subsequent calls to same slot return same value
        assertEq(counter.getOwner(55), owner);
        
        // Explicitly written values take precedence
        counter.setOwner(55, address(111));
        assertEq(counter.getOwner(55), address(111));
    }
}
```

```solidity [src/Counter.sol]
contract Counter {
    address[] public owners;

    function getOwner(uint256 pos) public view returns (address) {
        return owners[pos];
    }

    function setOwner(uint256 pos, address owner) public {
        owners[pos] = owner;
    }
}
```
:::

### Gotchas

:::warning
Contracts with arbitrary storage cannot be targets of [`copyStorage`](/reference/cheatcodes/copy-storage).
:::

### Related Cheatcodes

* [`copyStorage`](/reference/cheatcodes/copy-storage) - Copies storage between addresses
* [`load`](/reference/cheatcodes/load) - Loads a single storage slot
* [`store`](/reference/cheatcodes/store) - Stores a value to a single storage slot