Re: [boost] [1.33.0] VC 7.1 vs. SFINAE/type traits

From: Peter Dimov (pdimov_at_[hidden])
Date: 2005-08-17 05:16:07

Mat Marcus wrote:

> Here is a simplified version of the context in which the problem seems
> to crop up.
>
> //---- operator.hpp
>
> template <class T>
> struct is_foo {/*...*/}; // some appropriate compile time test
>
> template <class T>
> typename boost::enable_if<boost::is_foo<T>, T>::type
> operator| (T a, T b);
>
>
> //---- client.cpp
>
> #include "operator.hpp"
>
> So far things are ok. But now suppose that I am using gcc 4.0 the
> client later includes a new header system_header.hpp.
>
> //---system_header.hpp
>
> enum { kCaseInsenstiveMask = 1L << 1,
>       kReverseOrderMask = 1L << 2,
>       kOverrideMask = 1L << 3};
>
> enum { kTheWorks = kCaseInsenstiveMask | kReverseOrderMask |
> kOverrideMask };

This is very disturbing; it basically breaks all SFINAE'd operators. If this 
is what the language currently mandates, it needs to be fixed.