This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 110b. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2023-01-15


731. Omitted reference qualification of member function type

Section: 7.6.1.5  [expr.ref]     Status: CD2     Submitter: Daniel Krügler     Date: 6 October, 2008

N2800 comment DE 5
N2800 comment DE 10
N2800 comment DE 12

[Voted into WP at October, 2009 meeting.]

There are several places in the Standard that were overlooked when reference qualification of member functions was added. For example, 7.6.1.5 [expr.ref] paragraph 4, bullet 3, sub-bullet 2 says,

...if E1.E2 refers to a non-static member function, and the type of E2 is “function of parameter-type-list cv returning T”, then...

This wording incorrectly excludes member functions declared with a ref-qualifier.

Another place that should consider reference qualification is 7.6.4 [expr.mptr.oper]; it should not be possible to invoke an &-qualified member function with an rvalue object expression.

A third place is 9.9 [namespace.udecl] paragraph 15, which does not mention reference qualification in connection with the hiding/overriding of member functions brought in from a base class via a using-declaration.

Proposed resolution (September, 2009):

  1. Change 7.6.1.5 [expr.ref] paragraph 4, bullet 3, sub-bullet 2 as follows:

  2. Change 7.6.4 [expr.mptr.oper] paragraph 6 as follows:

  3. ...—end example] In a .* expression whose object expression is an rvalue, if the second operand is a pointer to member function with ref-qualifier &, the program is ill-formed. In a ->* expression, or in a .* expression whose object expression is an lvalue, if the second operand is a pointer to member function with ref-qualifier &&, the program is ill-formed. The result of a .* expression is an lvalue only if its first operand is an lvalue and...
  4. Change 9.9 [namespace.udecl] paragraph 15 as follows:

  5. When a using-declaration brings names from a base class into a derived class scope, member functions and member function templates in the derived class override and/or hide member functions and member function templates with the same name, parameter-type-list (9.3.4.6 [dcl.fct]), and cv-qualification, and ref-qualifier (if any) in a base class (rather than conflicting). [Note:...