Types conversions

No-promotion conversions may imply a loss of precision, which the compiler can signal with a warning. This warning can be avoided with an explicit conversion.
For non-fundamental types, arrays and functions implicitly convert to pointers, and pointers in general allow the following conversions:

Null pointers can be converted to pointers of any type
Pointers to any type can be converted to void pointers.
Pointer upcast: pointers to a derived class can be converted to a pointer of an accessible and unambiguous base class, without modifying its const or volatile qualification.