https://github.com/ClickHouse/ClickHouse/blob/9a48cf0da8badfc5f3da08611eb44961aa28e3f6/src/Functions/FunctionsHashing.h#L669-L671

There's a call to `blake3_free_char_pointer` that passes ownership of the pointer back to Rust (which then frees the memory), then there's a call to `std::string`'s constructor that accepts that now-freed pointer.
executeForArgument(type_map.getNestedType().get(), const_map->getNestedColumnPtr().get(), vec_to, is_first);
        }
        else
        {
            if (is_first)
                executeAny<true>(type, column, vec_to);
            else
                executeAny<false>(type, column, vec_to);
        }
        is_first = false;
    }
public:
    String getName() const override
    {
        return name;
    }
    bool isVariadic() const override { return true; }
    size_t getNumberOfArguments() const override { return 0; }
    bool useDefaultImplementationForConstants() const override { return true; }
    bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & ) const override { return true; }
    DataTypePtr getReturnTypeImpl(const DataTypes & ) const override
    {
        if constexpr (std::is_same_v<ToType, UInt128>) 
        {
            return std::make_shared<DataTypeFixedString>(sizeof(UInt128));
        }
        else
            return std::make_shared<DataTypeNumber<ToType>>();
    }
    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t input_rows_count) const override