This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115f. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
2024-12-06
[Accepted as a DR at the February, 2019 meeting.]
According to 6.3 [basic.def.odr] bullet 2.3, the potential results of a member access expression are simply the object expression. This rule incorrectly handles an example like:
struct X { static const int n = 0; }; X x = {}; int b = x.n;
Because X::n is not one of the potential results, the expression x.n odr-uses X::n, requiring it to be defined.
Notes from the April, 2018 teleconference:
CWG agreed with the suggested direction to make the member a potential result in cases like the example.
Proposed resolution (February, 2019):
Change 6.3 [basic.def.odr] paragraph 2 as follows:
An expression is potentially evaluated unless it is an unevaluated operand (7.2 [expr.prop]) or a subexpression thereof. The set of potential results of an expression e is defined as follows:
...
If e is a class member access expression (7.6.1.5 [expr.ref]) of the form e1 . templateopt e2 naming a non-static data member, the set contains the potential results of
the object expressione1.if e is a class member access expression naming a static data member, the set contains the id-expression designating the data member.
If e is a pointer-to-member expression (7.6.4 [expr.mptr.oper])
whose second operand is a constant expressionof the form e1 .* e2, the set contains the potential results ofthe object expressione1....