user31105: There are many programming questions in Arduino (there is even a tag for it).
However, some are not related to Arduino, like 
What happens if I pass a temporary reference and store it as a class member?
There is a flag/close/offtopic because/This question belongs on another site in the Stack Exchange network option, but StackOverflow is not mentioned as possible candidate.
So far I flag the question and ask a moderator to move, but what is the preferred solution? 
Just closing down the question, seems also not useful, especially if it can be answered while it is in Arduino StackExchange (even though it will be moved preferably).

user37523: 
There is a flag/close/offtopic because/This question belongs on another site in the Stack Exchange network option, but StackOverflow is not mentioned as possible candidate.

If you are referring to the "Flagging > Closing > Off-Topic > Migration" window, I believe users with the required reputation can "see" this option but can't select a site to "migrate to". If the user can't select an option, then this option should not be displayed. Let's give the other moderators some time to see this question and hear what they know/have to say about this issue.

So far I flag the question and ask a moderator to move, but what is the preferred solution?

Flagging the question and asking a moderator to move it is the preferred solution. Arduino SE moderators may discuss questions with the other SE network moderators before we migrate a question to them.

31105: <p>There are many programming questions in Arduino (there is even a tag for it).
However, some are not related to Arduino, like </p>

<p><a href="https://arduino.stackexchange.com/questions/68861/what-happens-if-i-pass-a-temporary-reference-and-store-it-as-a-class-member">What happens if I pass a temporary reference and store it as a class member?</a></p>

<p>There is a flag/close/offtopic because/This question belongs on another site in the Stack Exchange network option, but StackOverflow is not mentioned as possible candidate.</p>

<p>So far I flag the question and ask a moderator to move, but what is the preferred solution? </p>

<p>Just closing down the question, seems also not useful, especially if it can be answered while it is in Arduino StackExchange (even though it will be moved preferably).</p>
 37523: <blockquote>
  <p>There is a flag/close/offtopic because/This question belongs on another site in the Stack Exchange network option, but StackOverflow is not mentioned as possible candidate.</p>
</blockquote>

<p>If you are referring to the "Flagging > Closing > Off-Topic > Migration" window, I believe users with the required reputation can "see" this option but can't select a site to "migrate to". If the user can't select an option, then this option should not be displayed. Let's give the other moderators some time to see this question and hear what they know/have to say about this issue.</p>

<blockquote>
  <p>So far I flag the question and ask a moderator to move, but what is the preferred solution?</p>
</blockquote>

<p>Flagging the question and asking a moderator to move it is the preferred solution. Arduino SE moderators may discuss questions with the other SE network moderators before we migrate a question to them.</p>
