PR c++/80452 - Core 1579, implicit move semantics on return/throw
* cp-tree.h (LOOKUP_PREFER_RVALUE): Now means that we've already
tentatively changed the lvalue to an rvalue.
* call.c (reference_binding): Remove LOOKUP_PREFER_RVALUE handling.
(build_over_call): If LOOKUP_PREFER_RVALUE, check that the first
parameter is an rvalue reference.
* except.c (build_throw): Do maybe-rvalue overload resolution twice.
* typeck.c (check_return_expr): Likewise.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@251035 138bc75d-0d04-0410-961f-82ee72b054a4