CWG Issue 62 (original) (raw)

This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 117a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2025-04-13

62. Unnamed members of classes used as type parameters

Section: 13.4.2 [temp.arg.type]Status: CD1Submitter: Steve AdamczykDate: 13 Oct 1998

[Moved to DR at 4/01 meeting.]

Section 13.4.2 [temp.arg.type] paragraph 2 says

A local type, a type with no linkage, an unnamed type or a type compounded from any of these types shall not be used as a _template-argument_for a template type-parameter.

It probably wasn't intended that classes with unnamed members should be included in this list, but they are arguably compounded from unnamed types.

Proposed resolution (04/01):

In 13.4.2 [temp.arg.type] paragraph 2, change

A local type, a type with no linkage, an unnamed type or a type compounded from any of these types shall not be used as a_template-argument_ for a template type-parameter.

to

The following types shall not be used as a _template-argument_for a template type-parameter:

• a type whose name has no linkage
• an unnamed class or enumeration type that has no name for linkage purposes (9.2.4 [dcl.typedef])
• a cv-qualified version of one of the types in this list
• a type created by application of declarator operators to one of the types in this list
• a function type that uses one of the types in this list