7 Expressions [expr]

7.2 Properties of expressions [expr.prop]

7.2.2 Type [expr.type]

1
#
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.
[Note 1: 
Before the lifetime of the reference has started or after it has ended, the behavior is undefined (see [basic.life]).
— end note]
2
#
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.
3
#
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 ([dcl.init.ref]), the qualification-combined type ([conv.qual]) of T1 and T2 or the qualification-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 ([dcl.init.ref]), 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 ([dcl.init.ref]), the qualification-combined type of T2 and T1 or the qualification-combined type of T1 and T2, respectively;
  • (3.8)
    if T1 and T2 are similar types ([conv.qual]), the qualification-combined type of T1 and T2;
  • (3.9)
    otherwise, a program that necessitates the determination of a composite pointer type is ill-formed.
[Example 1: typedef void *p; typedef const int *q; typedef int **pi; typedef const int **pci;
The composite pointer type of p and q is “pointer to const void”; the composite pointer type of pi and pci is “pointer to const pointer to const int”.
— end example]