Andy Little wrote:
"Tobias Schwinger" wrote
How does the declaration of your operator- look like?
Here's operator +. (All operators fail in a similar way )
[...code]
Your operator- (in the code of your initial post) is not the problem it must be the context it's used in. I got a copy of your lib and comented the workaround and operator- and added template<typename T0,typename T1> T0 operator-(T0 const &, T1 const &); and it didn't change anything.
Does it instantiate templates that use sizeof- or conditional tricks (as BOOST_TYPEOF_TPL does)?
The pqs::meta::binary_operation result_type scheme in the operator+ definition above uses SFINAE quite heavily though. I shall try reducing it to a minimal example.
SFINAE (at least SFINAE alone) is not the problem, either. I wrote this little test which compiles fine (it would have been too easy, I guess) ;-(. namespace user_namespace { // some class template template<typename T> struct t1 { }; // traits to detect its specializations template<typename T> struct is_t1 { static bool const value = false; }; template<typename T> struct is_t1<t1<T> > { static const bool value = true; }; // another class template template<typename T> struct t2 { }; // traits to detect its specializations template<typename T> struct is_t2 { static bool const value = false; }; template<typename T> struct is_t2<t2<T> > { static const bool value = true; }; // tool to create a sfinae condition if the first argument is false template<bool, typename T> struct enable_if { typedef T type; }; template<typename T> struct enable_if<false,T> { }; // function templates template<typename T> typename enable_if<is_t1<T>::value, T >::type outer(t1<T> const & v); template<typename T> typename enable_if<is_t2<T>::value, T >::type outer(t1<T> const & v); template<typename T> t1<T> inner(t1<T> const & v); } void func() { user_namespace::t1< user_namespace::t1<int> > x; user_namespace::t1< user_namespace::t2<int> > y; // 'inner' is found by ADL outer(inner(x)); outer(inner(y)); }
Boost.Typeof use in the implementation (for operations on built-in types) is optional though I havent tried turning it off yet
BOOST_TYPEOF_TPL in particular messes up ADL for the expression passed to it (the thread I linked to). Guessing from VC8's extremely strange behaviour in that case TYPEOF_TPL might act as some sort of "bug attractant"... I'd definitely give it a try! Hope it helps, Tobias