PATCH RFA: Build stages 2 and 3 with C++

[Joseph S. Myers]

On Mon, 1 Aug 2011, Richard Guenther wrote:

> I think it's the only viable solution (use the full enum for a non-GCC stage1
> C++ compiler).  We could help it somewhat by at least placing
> enum bitfields first/last in our bitfield groups.

Are GCC and other compilers declaring that they support the GNU C and C++ 
languages by defining __GNUC__ really the only compilers with this 
extension?  Feature tests for particular features are generally better 
than testing for whether the compiler in use is GCC.  (Using configure 
tests for things in ansidecl.h does require checking where in the gcc and 
src repositories those things are used, to make sure that the relevant 
configure tests are used everywhere necessary.)

(Actually, C++03 appears to support enum bit-fields - it's only for C that 
they are a GNU extension - so can't we just enable them unconditionally 
when building as C++?)

-- 
Joseph S. Myers
joseph@codesourcery.com