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

2425. Confusing wording for deduction from a type

In 12.2.2.9 [over.match.class.deduct] paragraph 3 we read:

The arguments of a template A are said to be deducible from a type T if, given a class template

  template <typename> class AA;

with a single partial specialization whose template parameter list is that of A and whose template argument list is a specialization of A with the template argument list of A (13.8.3.2 [temp.dep.type]), AA<T> matches the partial specialization.

The relationship between A, AA and its partial specialization, and the argument list of A is not clear. An example would be very helpful here. Also, using a different name than A would help, since A is used in close proximity to this wording to denote an alias template, while this wording applies to both class and alias templates. Finally, there should be a cross-reference to 13.7.6.2 [temp.spec.partial.match] for matching the partial specialization.