[Bug libstdc++/48848] [C++0x] std::valarray functions missing

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48848

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-05-03 
09:03:22 UTC ---
Good point.  I think the requirement for constant complexity should have been
removed by LWG 675.  Pending clarification from the committee I think I would
implement it with the usual swap with temporary, giving linear complexity.
  valarray(std::move(v)).swap(*this);