si tienes estructuras o clases básicas (PODS), éstos carecen de inicializadores y, por tanto, el programa está mal formado.

Paragraph 5.3.4/15 states that

A new-expression that creates an object of type T initializes that object as follows:

[...]

* If the new-initializer is of the form (), the item is value-initialized (8.5)

where value initialized for POD means zero-initialize.

[...]

If the new-initializer is omitted:

* If T is a (possibly cv-qualified) non-POD class type (or array thereof), the object is default-initialized (8.5). If T is a const-qualified type, the underlying class type shall have a user-declared default constructor.

* Otherwise, the object created has indeterminate value. If T is a const-qualified type, or a (possibly cv-qualified) POD class type (or array thereof) containing (directly or indirectly) a member of const-qualified type, the program is ill-formed;