CA096 12.02 [over.dcl] p1 Declaration matching for non-dependent requires-clauses

[wg21bot]

Declaration matching ([over.dcl]) is based upon whether trailing requires-clauses are equivalent; however, equivalent, with respect to expressions ([temp.over.link]), is defined only for expressions involving template parameters.

Proposed change:
Extend the definitions of equivalent and functionally equivalent to cover expressions subject to normalization in general (not just those involving template parameters).
Further, make the determination of expression equivalence treat concept definitions as opaque by adding a condition that an expression that may be subject to constraint normalization is functionally equivalent only if each qualified-concept-name that may be expanded by normalization would be considered to name the same type if, instead of a concept, a class template was named.

[jfbastien]

See voting for #374

[jensmaurer]

CWG in Belfast: Tentatively accepted; drafting assigned.

[jensmaurer]

CWG in Belfast: Accepted with modification. See paper P1980R0.