[ Batavia (2009-05): ]

Move to Open, pending proposed wording from Alisdair and/or Doug for further review.

[ Doug adds: ]

We need something like this, but it should be a more general statement about implementations respecting the concept maps provided by the user. Use of late_check is one way in which implementations can subvert the concept maps provided by the user, but there are other ways as well ("pattern-based" overloading, tricks with "auto" concept maps and defaulted associated type arguments).

The example in 6.9p2 shows how late_check blocks inhibit concept_map lookup inside a constrained context, and so inhibit concept map adaption by users to meet template requirements.

Do we need some text in clause 17 prohibitting use of late_check in library template definitions unless otherwise documented?