wishful thinking

If you say that an idea, wish, or hope is wishful thinking, you mean that it has failed to come true or is unlikely to come true.

如果你说一个想法、愿望或希望是 wishful thinking 的想法，你的意思是它没有实现或不太可能实现。

A: Do you think you might be in line for promotion?

你是否认为自己会获得提升?

B: No, it's just wishful thinking.

不，那只不过是痴心妄想而已。