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.
}
        
        while (pos < end && !(*pos == '/' || *pos == '?' || *pos == '#'))
            ++pos;
        if (pos != end)
            ++pos;
        if (0 == level)
            return pos - begin;
        UInt64 current_level = 0;
        while (current_level != level && pos < end)
        {
            
            while (pos < end && (*pos == '/' || *pos == '?' || *pos == '#'))
                ++pos;
            if (pos == end)
                break;
            while (pos < end && !(*pos == '/' || *pos == '?' || *pos == '#'))
                ++pos;
            if (pos != end)
                ++pos;
            ++current_level;
        }
        return current_level == level ? pos - begin : 0;
    }
    static UInt64 apply(const UInt64 level, const char * data, const size_t size)
    {
        return URLHashImpl::apply(data, findLevelLength(level, data, data + size));
    }
};
class FunctionURLHash : public IFunction