16 Library introduction [library]

16.4 Library-wide requirements [requirements]

16.4.4 Requirements on types and expressions [utility.requirements]

16.4.4.2 Template argument requirements [utility.arg.requirements]

Table 29: Cpp17DefaultConstructible requirements [tab:cpp17.defaultconstructible]
Expression
Post-condition
T t;
object t is default-initialized
T u{};
object u is value-initialized or aggregate-initialized
T()
T{}
an object of type T is value-initialized or aggregate-initialized