This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 112e. See for the official list.


2720. Template validity rules for templated entities and alias templates

Section: 13.8.1  [temp.res.general]     Status: DR     Submitter: Richard Smith     Date: 2023-03-29

[Accepted as a DR at the June, 2023 meeting.]

Subclause 13.8.1 [temp.res.general] paragraph 6 specifies rules to determine when a template is valid, but the specification is in terms of "instantiation". However, some kinds of templates (namely alias templates) are not instantiated.

Further, the rule discusses only templates, but should apply to any templated entity.

Proposed resolution (approved by CWG 2023-05-12):

Change in 13.8.1 [temp.res.general] paragraph 6 as follows:

The validity of a template templated entity may be checked prior to any instantiation. [Note 3: Knowing which names are type names allows the syntax of every template to be checked in this way. —end note]

The program is ill-formed, no diagnostic required, if: