11 Declarators [dcl.decl]

In a declaration T D where D has the form

nested-name-specifier * attribute-specifier-seq${}_{opt}$ cv-qualifier-seq${}_{opt}$ D1

and the nested-name-specifier denotes a class, and the type of the identifier in the declaration T D1 is “derived-declarator-type-list T”, then the type of the identifier of D is “derived-declarator-type-list cv-qualifier-seq pointer to member of class nested-name-specifier of type T”. The optional attribute-specifier-seq appertains to the pointer-to-member.

[ Example:

struct X {
  void f(int);
  int a;
};
struct Y;

int X::* pmi = &X::a;
void (X::* pmf)(int) = &X::f;
double X::* pmd;
char Y::* pmc;

declares pmi, pmf, pmd and pmc to be a pointer to a member of X of type int, a pointer to a member of X of type void(int), a pointer to a member of X of type double and a pointer to a member of Y of type char respectively. The declaration of pmd is well-formed even though X has no members of type double. Similarly, the declaration of pmc is well-formed even though Y is an incomplete type. pmi and pmf can be used like this:

X obj;
// ...
obj.*pmi = 7;       // assign 7 to an integer member of obj
(obj.*pmf)(7);      // call a function member of obj with the argument 7

 — end example ]

A pointer to member shall not point to a static member of a class, a member with reference type, or “cv void”.

[ Note: See also [expr.unary] and [expr.mptr.oper]. The type “pointer to member” is distinct from the type “pointer”, that is, a pointer to member is declared only by the pointer to member declarator syntax, and never by the pointer declarator syntax. There is no “reference-to-member” type in C++.  — end note ]