[Bug libstdc++/57666] valarray<T>::operator= in c++11 mode does not adapt to size

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57666

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to thunderliu from comment #0)
> Non-member operators for valarray<> returns instance of _Expr<> (lazy
> evaluation?), instead of another valarray<>. This is non-conforming but
> probably not a bug.

26.6.1 [valarray.syn]/3 "Any function returning a valarray<T> is permitted to
return an object of another type, provided all the const member functions of
valarray<T> are also applicable to this type."