fn copysignl(x: c_longdouble, y: c_longdouble) callconv(.c) c_longdouble
fn copysignl(x: c_longdouble, y: c_longdouble) callconv(.c) c_longdouble { return switch (@typeInfo(c_longdouble).float.bits) { 64 => std.c.copysign(x, y), else => math.copysign(x, y), }; }