http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3744.pdf

Discussed in Chicago 2013:

Poll 4: Conservative approach. SF 3 - 2 - 5 - 0 - 0 SA

Poll 5: Aggressive approach: SF 6 - 1 - 3 - 0 - 0 SA

Poll 6: Support both, with different attributes. SF 4 - 2 - 3 - 1 - 0 SA

Vandevoorde expressed that he likes the idea of having two attributes, one for memoizing and the other for non-side-effecting. Stroustrup and Spertus expressed concern about multiple attributes being confusing. Stroustrup gave his guidance to have a two-part proposal with both the "aggressive" mode and the more conservative mode. Vandevoorde promised his assistance for writing the wording.