[expr.type] (original) (raw)

7 Expressions [expr]

7.2 Properties of expressions [expr.prop]

7.2.2 Type [expr.type]

If an expression initially has the type “reference toT” ([dcl.ref], [dcl.init.ref]), the type is adjusted toT 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_]

If a prvalue initially has the type “cv T”, whereT 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 andp2 having types T1 and T2, respectively, where at least one is a pointer or pointer-to-member type orstd​::​nullptr_­t, is:

• if both p1 and p2 are null pointer constants,std​::​nullptr_­t;
• if either p1 or p2 is a null pointer constant, T2 or T1, respectively;
• 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;
• 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”;
• 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 typeof T1 and T2 or the cv-combined type of T2 and T1, respectively;
• 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”, andC1 is reference-related to C2 orC2 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;
• if T1 is “pointer to member of C1 of type cv1 U” andT2 is “pointer to member of C2 of type cv2 U”, for some non-function type U, where C1 isreference-related to C2 or C2 is reference-related toC1, the cv-combined type of T2 and T1 or the cv-combined type of T1 and T2, respectively;
• if T1 and T2 are similar types, the cv-combined type of T1 andT2;
• 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 toconst int”.

— _end example_]