[cfe-commits] r61746 - in /cfe/trunk: include/clang/AST/ include/clang/Basic/ include/clang/Parse/ lib/AST/ lib/Parse/ lib/Sema/ test/SemaCXX/

[Chris Lattner]

On Jan 5, 2009, at 10:26 PM, Douglas Gregor wrote:
>>> Most declarations of a class type will need to perform the check  
>>> for a POD type, which is recursive (it's only a POD if all of its  
>>> non-static data members are PODs, and so on), so it might be  
>>> expensive to compute this property on the fly. Personally, I  
>>> prefer the way Sebastian's doing it: there will be quite a few  
>>> other class properties like this, too.
>>
>> What if the query is lazy but cached?  Many types are defined in  
>> headers that are never used, I can't believe that we'd end up  
>> querying isPod for all of them...
>
> We could certainly make the query lazy but cached, but why? The most  
> expensive check needed to maintain this flag is "if (!T- 
> >isPODType())".

I'm not "afraid" of the cost to compute pod-ness eagerly or the bit to  
store it in.  I'm most interested in getting the "compute whether this  
type is pod" code together in one place.  However, I can't stomach the  
cost of doing a post-pass over the type (instead of doing it on the  
fly like Sebastian is doing), so it is probably fine to stay the way  
it is now.

-Chris