Issue 1729: Matching declarations and definitions of variable templates

Title: Matching declarations and definitions of variable templates
Status: cd6
Section: 13.7 [temp.decls]
Submitter: Larisse Voufo

Created on 2013-08-05.00:00:00 last changed 28 months ago

Messages

msg5912 (view)

Date: 2017-05-15.00:00:00

Proposed resolution (May, 2017):

This issue is resolved by the resolution of issue 1704.

msg4541 (view)

Date: 2020-11-15.00:00:00

[Accepted at the November, 2020 meeting as part of paper P1787R6 and moved to DR at the February, 2021 meeting.]

The relationship between declarations and definitions of variable templates is not clear. For example:

  template<typename T> auto var0 = T();  // #1a.
  template<typename T> extern T var0;    // #1b.

  template<typename T> T var1;           // #2a.
  template<typename T> extern auto var1; // #2b.
  template<typename T> extern T var1;    // #2c.
  template<typename T> T var1;           // #2d.

Questions:

When is a variable template declaration a definition and when a non-defining declaration?
What declarations are valid?
Should auto declarations be allowed?
To what extent, if any, do these involve type matching?
How are types matched, especially in the presence of auto?

History
Date	User	Action	Args
2022-08-19 07:54:33	admin	set	status: drwp -> cd6
2021-02-24 00:00:00	admin	set	status: accepted -> drwp
2020-12-15 00:00:00	admin	set	status: drafting -> accepted
2018-02-27 00:00:00	admin	set	messages: + msg5912
2013-10-14 00:00:00	admin	set	status: open -> drafting
2013-08-05 00:00:00	admin	create