[ Issues Telecon 16-Dec-2016 ]

Resolved by adoption of P0508R0.

The requirements for associative and unordered associative containers list insert_return_type for all containers, but looking at the class description in [map.overview], [multimap.overview] etc. it's only defined for containers with unique keys. Jonathan Wakely pointed out that this depends on the resolution of LWG 2772, which might remove insert_return_type completely.

A possible resolution would be to put in [associative.reqmts]: 'insert_return_type (map and set only)' and in [unord.req]: 'insert_return_type (unordered_map and unordered_set only)'. Or maybe something like '(containers with unique keys only)'.