UnboundMap

An optional detector that highlights cases where a map field allows inserting values (e.g., via .set) but lacks functionality for removing entries (e.g., via .del).

Why is it bad?

A map without a method to remove elements can lead to storage overflow, particularly in long-term contract usage. Failing to provide a way to clear or delete entries can result in uncontrolled storage growth, which not only wastes resources but may also increase the cost of contract execution and maintenance over time.

Example

contract Test {
    map: Map<Int, String>;

    setEntry(key: Int, value: String) {
        self.map.set(key, value); // Bad
    }
}

Use instead:

contract Test {
    map: Map<Int, String>;

    setEntry(key: Int, value: String) {
        self.map.set(key, value);
    }

    delEntry(key: Int) {
        self.map.del(key); // Fixed: Added a new API method
    }
}