§ States "The effect of calling any member function other than the destructor, the move-assignment operator, or valid on a future object for which valid() == false is undefined. [ Note: Implementations are encouraged to detect this case and throw an object of type future_error with an error condition of future_errc::no_state. —end note ]"

I would like to add something akin to the following paragraph in the appropriate member functions' pages (share, get, wait, wait_for, and wait_until):

A precondition of this function is that valid()== true. If this is not met, Standard Library implementations are encouraged to throw a future_error with an error condition of future_errc::no_state.

However, I'm not sure if mentioning the contents of the Note are appropriate, and if so, should that be added to an "Exceptions" section?

Fraser 18:15, 13 January 2013 (PST)

I think that would be a good addition, but perhaps it would most naturally fit under a "Notes" section on each page (see e.g. --Nate 15:03, 14 January 2013 (PST)
Thanks for the tip. Added under "Notes" now. Fraser 16:42, 14 January 2013 (PST)