This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 114a. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-04-28

2829. Redundant case in restricting user-defined conversion sequences

(From editorial issue 3871.)

Subclause 12.2.4.2.1 [over.best.ics.general] paragraph 4 specifies:

However, if the target is

• the first parameter of a constructor or
• ...

and the constructor ... is a candidate by

• 12.2.2.4 [over.match.ctor], when the argument is the temporary in the second step of a class copy-initialization,
• 12.2.2.5 [over.match.copy], 12.2.2.6 [over.match.conv], or 12.2.2.7 [over.match.ref] (in all cases), or
• ...

user-defined conversion sequences are not considered.

A temporary is no longer created in 9.4.1 [dcl.init.general] bullet 16.6.3 "for the remaining copy-initialization cases". Instead, that section directly branches to 12.2.2.5 [over.match.copy], which is covered by the fourth bullet above.

Suggested resolution:

Change in 12.2.4.2.1 [over.best.ics.general] paragraph 4 as follows:

However, if the target is

• ...

and the constructor ... is a candidate by

• 12.2.2.4 [over.match.ctor], when the argument is the temporary in the second step of a class copy-initialization,
• 12.2.2.5 [over.match.copy], 12.2.2.6 [over.match.conv], or 12.2.2.7 [over.match.ref] (in all cases), or
• ...

user-defined conversion sequences are not considered.