Pull in r291403 from upstream clang trunk (by Richard Smith):
PR30305: Implement proposed DR resolution to prevent slicing via inherited constructor. The rule we use is that a construction of a class type T from an argument of type U cannot use an inherited constructor if U is the same as T or is derived from T (or if the initialization would first convert it to such a type). This (approximately) matches the rule in use by GCC, and matches the current proposed DR resolution.
Pull in r291955 from upstream clang trunk (by Richard Smith):
PR31606: Generalize our tentative DR resolution for inheriting copy/move constructors to better match the pre-P0136R1 behavior.
Together, these fix an issue with C++ using declarations sometimes
enabling illegal implicit casts.
Direct commit to stable/11, since head already has clang 4.0.0, which
includes this change.
Reported by: kami
PR: 215969