C++ Evolution Working Group(EWG)に「論理XOR演算子^^」なるものが提案（？）されているが…
2023-07-23追記：同提案は2013年会合にて却下(NAD)*1されている。
C++ Standard Evolution Active Issues List, #37. Logical xor operatorより一部引用。
(snip) This has traditionally been dismissed as un-necessary, as it is equivalent to boolean operator!=, and there is no short-circuiting benefit to justify adding it. However, contextual conversions to 'bool' are handled specially for logical operators, and in that context it would be completing a hole in the language. (snip)
function<void()> a; function<void()> b; assert(a != b); // does not compile assert(a ^^ b); // would compile, and assert!
どうでもよすぎるメモ：「(a ^^ b);」が煽り系顔文字に見えて仕方ない。
2015-03-05追記：C言語での同話題に対するDennis Ritchie氏の回答 http://c-faq.com/misc/xor.dmr.html
*1:Not A Defect
