[v3] Add __uninitialized_default*; use __is_trivial instead of __is_pod in most places

[Paolo Carlini]

On 06/17/2010 04:14 PM, Jason Merrill wrote:
> On 06/17/2010 04:41 AM, Paolo Carlini wrote:
>> Some infrastructure for forthcoming C++0x work + finally got around to
>> use __is_trivial instead of the more restrictive __is_pod in many
>> places. About the latter in particular, I'm also adding in CC Jason -
>> implemented __is_trivial and briefly discussed with him the rather
>> straightforward plan of replacing most dispatches in the library based
>> on POD-ness to trivial-ness.
>
> Note that I've submitted an NB comment on the FCD suggesting that POD
> be changed from "trivial and standard layout" to "trivially copyable
> and standard layout" to make struct A { const int i; }; POD again.
Ok... That issue with POD, good. Thus the idea is resolving it by taking
out from POD-ness the trivial default bit... It seems to me then that,
post that kind of resolution, what we *had* before my patch would be
wrong, because we used to rely on the trivial default constructor. What
we have now, however, seems correct -  maybe could be loosened a bit,
we'll see - but it seems correct, because if I understand correctly,
trivial itself is not going to change, thus still includes the trivial
default constructor bit.

Paolo.