This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 116a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-12-19

2949. Treatment of ellipsis during partial ordering

(From submission #632.)

The partial ordering rules in 13.7.7.3 [temp.func.order] paragraph 6 do not consider the possible presence of an ellipsis in the function parameter list:

• The length of a template-parameter-list is not defined.
• The term "function parameter list" is not defined.
• The length of a function parameter list is not defined: Does an ellipsis count towards the length?
• What does it mean for corresponding function parameter to be of the same type, if one of those parameters is an ellipsis?

Suggested resolution:

Change in 13.7.7.3 [temp.func.order] paragraph 6 and add bullets as follows:

If deduction against the other template succeeds for both transformed templates, constraints can be considered as follows:

• If
  • their template-parameter-lists (possibly including template-parameters invented for an abbreviated function template (9.3.4.6 [dcl.fct])) have different numbers of template-parameters or
  • function parameter lists differ in length
  • their parameter-type-lists have different numbers of parameters or
  • either, but not both, of their parameter-type-lists has an ellipsis,
  neither template is more specialized than the other.
• Otherwise: ...