I get confused when I encounter this sentence (bold) from the standard - [temp.deduct]/11:
[ Note: Type deduction may fail for the following reasons:
- (11.1) Attempting to instantiate a pack expansion containing multiple packs of differing lengths.
- [..]
It's known that "instantiation" is a process of creating an instance of a class or template. So a pack expansion is not a template or class to instantiate an instance from.
My question is what does "instantiating a pack expansion" mean? Is it mean "expanding" pack expansion?
And how I can instantiate a pack expansion?