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.
if constexpr (first)
                    vec_to[i] = h;
                else
                    vec_to[i] = Impl::combineHashes(vec_to[i], h);
            }
        }
        else if (const ColumnConst * col_from_const = checkAndGetColumnConstStringOrFixedString(column))
        {
            String value = col_from_const->getValue<String>();
            const ToType hash = Impl::apply(value.data(), value.size());
            const size_t size = vec_to.size();
            if constexpr (first)
            {
                vec_to.assign(size, hash);
            }
            else
            {
                for (size_t i = 0; i < size; ++i)
                {
                    vec_to[i] = Impl::combineHashes(vec_to[i], hash);
                }
            }
        }
        else
            throw Exception("Illegal column " + column->getName()
                    + " of first argument of function " + getName(),
                ErrorCodes::ILLEGAL_COLUMN);
    }
    template <bool first>
    void executeArray(const IDataType * type, const IColumn * column, typename ColumnVector<ToType>::Container & vec_to) const