7 Expressions [expr]

If an expression initially has the type “reference to T” ([dcl.ref], [dcl.init.ref]), the type is adjusted to T prior to any further analysis.

The expression designates the object or function denoted by the reference, and the expression is an lvalue or an xvalue, depending on the expression.

If a prvalue initially has the type “cv T”, where T is a cv-unqualified non-class, non-array type, the type of the expression is adjusted to T prior to any further analysis.

The composite pointer type of two operands p1 and p2 having types T1 and T2, respectively, where at least one is a pointer or pointer-to-member type or std​::​nullptr_­t, is:

• (3.1)
  if both p1 and p2 are null pointer constants, std​::​nullptr_­t;
• (3.2)
  if either p1 or p2 is a null pointer constant, T2 or T1, respectively;
• (3.3)
  if T1 or T2 is “pointer to cv1 void” and the other type is “pointer to cv2 T”, where T is an object type or void, “pointer to cv12 void”, where cv12 is the union of cv1 and cv2;
• (3.4)
  if T1 or T2 is “pointer to noexcept function” and the other type is “pointer to function”, where the function types are otherwise the same, “pointer to function”;
• (3.5)
  if T1 is “pointer to cv1 C1” and T2 is “pointer to cv2 C2”, where C1 is reference-related to C2 or C2 is reference-related to C1, the cv-combined type of T1 and T2 or the cv-combined type of T2 and T1, respectively;
• (3.6)
  if T1 or T2 is “pointer to member of C1 of type function”, the other type is “pointer to member of C2 of type noexcept function”, and C1 is reference-related to C2 or C2 is reference-related to C1, where the function types are otherwise the same, “pointer to member of C2 of type function” or “pointer to member of C1 of type function”, respectively;
• (3.7)
  if T1 is “pointer to member of C1 of type cv1 U” and T2 is “pointer to member of C2 of type cv2 U”, for some non-function type U, where C1 is reference-related to C2 or C2 is reference-related to C1, the cv-combined type of T2 and T1 or the cv-combined type of T1 and T2, respectively;
• (3.8)
  if T1 and T2 are similar types, the cv-combined type of T1 and T2;
• (3.9)
  otherwise, a program that necessitates the determination of a composite pointer type is ill-formed.

typedef void *p;
typedef const int *q;
typedef int **pi;
typedef const int **pci;