This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115f. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-12-06


264. Unusable template constructors and conversion functions

Section: 13.10.2  [temp.arg.explicit]     Status: open     Submitter: John Spicer     Date: 17 Nov 2000

The note in paragraph 5 of 13.10.2 [temp.arg.explicit] makes clear that explicit template arguments cannot be supplied in invocations of constructors and conversion functions because they are called without using a name. However, there is nothing in the current wording of the Standard that makes declaring a constructor or conversion operator that is unusable because of nondeduced parameters (i.e., that would need to be specified explicitly) ill-formed. It would be a service to the programmer to diagnose this useless construct as early as possible.