Hi Sebastian,
I've implemented the POD property of classes, and (in order to test it)
a basic infrastructure for GCC's type traits extensions, plus a concrete
implementation of the __is_pod trait.
Cool.
However, I'm not quite sure about all aspects of the patch, so I'm
posting it for review first. In particular, I have an enum called
UnaryTypeTrait that represents the various type trait keywords. Since it
is needed in the parser, the sema and the AST, I saw no other choice but
to make it part of Basic. Is this the right thing to do?
Yes, I think so. AccessSpecifier, which currently lives in Parse, should also be moved back to Basic (but that's my problem, not yours).
+/// UnaryTypeTraitExpr - A GCC or MS unary type trait, as used in the
+/// implementation of TR1/C++0x type trait templates.
Please add an example to the documentation for this class.
+ // FIXME: Some of the type traits have requirements. Interestingly, only the
+ // __is_base_of requirement is explicitly stated to be diagnosed. Indeed,
+ // G++ accepts __is_pod(Incomplete) without complaints, and claims that the
+ // type is indeed a POD.
Interesting. The documentation for __is_pod says:
Requires: type shall be a complete type, an array type of unknown bound, or is a void type.
So GCC should be diagnosing this kind of error. We should report the problem to them. However, we can address this FIXME later. The point of the patch is PODs, right? 
In Type::isPODType, could you add a FIXME for pointer-to-member types? (I almost want to just add basic pointer-to-member support now, since we seem to have lots of FIXMEs for them).
Regarding the FIXME at the end of CXXRecordDecl::hasConstCopyAssignment, I think we should assert that the CXXRecordDecl itself is marked "invalid". We shouldn't get here in any well-formed program.
This patch looks really good to me. Thanks!
- Doug
