初始化程序中的多个突变是否列出未定义的行为？

I am curious about initializer lists and sequence points. I read a while ago that the order of evaluation in initializer lists is left to right. If that is so, then there must be some kind of sequence point between the points of evaluation, am I wrong? So with that said is the following valid code? Is there anything that causes undefined behavior in it?I am curious about initializer lists and sequen