Re: [boost] [typeof][spirit][msvc gurus] is it possible to work around this bug??

From: Tobias Schwinger (tschwinger_at_[hidden])
Date: 2006-01-17 05:06:23

Forgot something...

Tobias Schwinger wrote:
>    template<typename T>
>    class a_rule_parser_template
>      : boost::spirit::parser< a_rule_parser_template<T> >
>    {
>      T a_placeholder;
> 
>      struct __rule
>      {
>        // hide the placeholder member variable of the outer class with a static
>        // variable of the same type
>        static T & a_placeholder;
> 
>        typedef BOOST_TYPEOF_TPL( an_expression ) type;
Line 77  ^^
Typeof acts like a black hole in this context; the "laws of C++ physics" seem not 
to apply any longer. There should be absolutely no reason for deduction to fail 
like this:

   test.cpp(77) : error C2784: 'boost::spirit::positive<S> boost::spirit::operator
   +(const boost::spirit::parser<DerivedT> &)' : could not deduce template argument
   for 'const boost::spirit::parser<DerivedT> &' from 'T'
           e:\Libs\Boost\MainCVS2\boost/spirit/core/composite/positive.hpp(93) :
   see declaration of 'boost::spirit::operator +'
   test.cpp(72) : see reference to class template instantiation
   'a_rule_parser_template<T>::__rule' being compiled
   test.cpp(89) : see reference to class template instantiation
   'a_rule_parser_template<T>' being compiled
   test.cpp(77) : error C2675: unary '+' : 'T' does not define this operator or a
   conversion to a type acceptable to the predefined operator
   test.cpp(77) : error C2784: 'boost::spirit::positive<S> boost::spirit::operator
   +(const boost::spirit::parser<DerivedT> &)' : could not deduce template argument
   for 'const boost::spirit::parser<DerivedT> &' from 'T'
   e:\Libs\Boost\MainCVS2\boost/spirit/core/composite/positive.hpp(93) : see
   declaration of 'boost::spirit::operator +'
   test.cpp(77) : error C2675: unary '+' : 'T' does not define this operator or a
   conversion to a type acceptable to the predefined operator
   test.cpp(77) : error C2784: 'boost::spirit::positive<S> boost::spirit::operator
   +(const boost::spirit::parser<DerivedT> &)' : could not deduce template argument
   for 'const boost::spirit::parser<DerivedT> &' from 'T'
   e:\Libs\Boost\MainCVS2\boost/spirit/core/composite/positive.hpp(93) : see
   declaration of 'boost::spirit::operator +'
   [...] last two messages repeat several times

--
Tobias