Default constructors
cppreference Default constructors
A default constructor is a constructor which can be called with no arguments (either defined with an empty parameter list, or with default arguments provided for every parameter). A type with a public default constructor is DefaultConstructible.
NOTE: 在维基百科C++11#Modification to the definition of plain old data 中提及了**statically initialized**,这让我想起了这样的问题:
DefaultConstructible能够被 statically initialized?