This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 112e. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.
According to 13.9.2 [temp.inst] paragraph 6,
If the function selected by overload resolution (12.2 [over.match]) can be determined without instantiating a class template definition, it is unspecified whether that instantiation actually takes place.
There are other contexts in which a smart implementation could presumably avoid instantiations, such as when doing argument-dependent lookup involving a class template specialization when the template definition contains no friend declarations or checking base/derived relationships involving incomplete class template definitions. It would be helpful to enumerate such contexts.