This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115d. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-10-26

1369. Function invocation substitution of this

[Voted into the WP at the February, 2012 meeting; moved to DR at the October, 2012 meeting.]

Function invocation substitution (9.2.6 [dcl.constexpr] paragraph 5) seems underspecified with respect to this.

Proposed resolution (August, 2011):

1. Change the indicated bullet of 7.7 [expr.const] paragraph 2 as follows:

• this (7.5 [expr.prim] _N4567_.5.1.1 [expr.prim.general]) unless it appears as the postfix-expression in a class member access expression, including the result of the implicit transformation in the body of a non-static member function (11.4.3 [class.mfct.non.static]) [Note: when evaluating a constant expression, function invocation substitution (9.2.6 [dcl.constexpr]) replaces each occurrence of this in a constexpr member function with a pointer to the class object. —end note];

2. Change 9.2.6 [dcl.constexpr] paragraph 5 as follows (converting the running text into a bulleted list):

Function invocation substitution for a call of a constexpr function or of a constexpr constructor means:

• implicitly converting each argument to the corresponding parameter type as if by copy-initialization,⁹¹

• substituting that converted expression for each use of the corresponding parameter in the function-body,

• in a member function, substituting for each use of this (_N4868_.11.4.3.2 [class.this]) a prvalue pointer whose value is the address of the object for which the member function is called, and

• for in a constexpr functions, implicitly converting the resulting returned expression or braced-init-list to the return type of the function as if by copy-initialization.

Such substitution...

This resolution also resolves issues 1264 and 1367.