https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70972
--- Comment #2 from TC <rs2740 at gmail dot com> --- Not exactly that familiar with GCC, but looking at https://gcc.gnu.org/viewcvs/gcc/trunk/gcc/cp/method.c?r1=233719&r2=233718&pathrev=233719 tree type = TREE_TYPE (parm); if (DECL_PACK_P (parm)) type = PACK_EXPANSION_PATTERN (type); exp = build_static_cast (type, exp, tf_warning_or_error); This seems to do the equivalent of `static_cast<decltype(p)>(p)` (which is a copy) rather than the desired `static_cast<decltype(p)&&>(p)`. Consistent with this hypothesis, with -fno-elide-constructors, a copy constructor call is emitted *in addition to* a move constructor call (http://coliru.stacked-crooked.com/a/5dd154da9c26472f), rather than instead of one.
