Default values in C++ initializer lists

Question

I only just learned yesterday that specifying parameters to initializer list items is optional. However, what are the rules for what happens in this case?

In the bel

Answer 1

Initialisations are covered in [dcl.init] (aka 8.5)

Point 10 says:

An object whose initializer is an empty set of parentheses, i.e., (), shall be value-initialized.

Value-initialisation is, put simply, default construction for classes and zero-initialisation for non-class types.