US120 14.04.1.2 p2 "the same template parameter" in parameter mappings

[wg21bot]

There is no specification for which template parameters in (the template arguments in) one parameter mapping are "the same template parameter" (from [temp.over.link]/5) as those in another parameter mapping.

Proposed change:
Use the mappings obtained by the partial-ordering deduction (which is required to have succeeded), augmented by matching by position for template parameters of the same kind that were not deduced per [temp.deduct.partial]/12 (to support constrained function templates like std::make_unique).

[jensmaurer]

See CA112 #111.

CWG in Belfast: Accepted with modification.

[jensmaurer]

CWG in Prague: Accepted with modification. See paper P2113R0.