Title
Potential results of a member access expression for a static data member
Status
cd5
Section
6.3 [basic.def.odr]
Submitter
Richard Smith

Created on 2017-08-18.00:00:00 last changed 20 months ago

Messages

Date: 2019-02-15.00:00:00

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 expression e1.

  • 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 expression of the form e1 .* e2, the set contains the potential results of the object expression e1.

  • ...

Date: 2018-04-15.00:00:00

Notes from the April, 2018 teleconference:

CWG agreed with the suggested direction to make the member a potential result in cases like the example.

Date: 2019-02-15.00:00:00

[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.

History
Date User Action Args
2020-12-15 00:00:00adminsetmessages: + msg6351
2020-12-15 00:00:00adminsetstatus: drafting -> cd5
2018-04-11 00:00:00adminsetmessages: + msg6188
2018-04-11 00:00:00adminsetstatus: open -> drafting
2017-08-18 00:00:00admincreate