I've looked at SO/IEC 9899:201x under J.1 Unspecified behavior:
"The order in which subexpressions are evaluated and the order in which side effects
take place, except as specified for the function-call (), &&, ||, ?:, and comma
operators (6.5)."
Does this means that in
func1() + func2();
func2() may be preformed before func1(), or even during func1() ?