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

2023-02-07


1726. Declarator operators and conversion function

Section: 11.4.8.3  [class.conv.fct]     Status: CD6     Submitter: James Widman     Date: 2013-08-02

[Accepted at the February, 2022 meeting.]

Presumably the following example is intended to be ill-formed:

  struct A {
    (*operator int*());
  };
  A a;
  int *x = a; // Ok?

It is not clear, however, which rule is supposed to reject such a member-declaration.

Proposed resolution (December, 2021):

Change 11.4.8.3 [class.conv.fct] paragraph 1 as follows, splitting the paragraph as indicated:

A member function of a class X with a name of the form

A declaration whose declarator-id has an unqualified-id that is a conversion-function-id declares a conversion function; its declarator shall be a function declarator (9.3.4.6 [dcl.fct]) of the form

where the ptr-declarator consists solely of an id-expression, an optional attribute-specifier-seq, and optional surrounding parentheses, and the id-expression has one of the following forms:

A conversion function shall have no parameters and shall be a non-static member function of a class or class template X; it specifies a conversion from X to the type specified by the conversion-type-id, interpreted as a type-id (9.3.2 [dcl.name]). Such functions are called conversion functions.

A decl-specifier in the decl-specifier-seq of a conversion function (if any) shall not be neither a defining-type-specifier nor static. The type of the conversion function (9.3.4.6 [dcl.fct]) is “noexceptopt function taking no parameter cv-qualifier-seqopt ref-qualifieropt returning conversion-type-id”.

A conversion function is never used to convert a (possibly cv-qualified) object to the (possibly cv-qualified) same object type (or a reference to it), to a (possibly cv-qualified) base class of that type (or a reference to it), or to cv void.102 [Example 1:...