Arno Schödl skrev:
Hello,
the attached patch makes boost::range_const/mutable_iterator<C>::type non-existent if C does not have the right typedef C::(const_)iterator. For me, this fixed a compilation error in the following situation:
template<class Rng, class Val, class BinPred> typename boost::range_const_iterator<Rng>::type lower_bound(Rng const& rng,Val const& x,BinPred pred); // not taken
template<class It, class Val, class BinPred> It lower_bound(It itBegin,It itEnd,Val const& x) { // taken return itBegin; // dummy }
main() { std::vector<int> vecn; int n=6; lower_bound( vecn.begin(), vecn.end(), n ); }
The return type of the overload that is not taken is range_const_iterator< std::vector<int>::iterator >::type. With the old range_const_iterator, this typedef exists, which makes the overload compile, but evaluates to std::vector<int>::iterator::const_iterator, which does not exist and causes a compiler error. With the patch, range_const_iterator< std::vector<int>::iterator >::type already does not exist, and the compiler aborts checking this overload. I don't see a way to fix this without changing or largely reimplementing range_const_iterator, because the mere presence of the "type" typedef in the default case of range_const_iterator causes the problem.
Any chance to get this adopted?
It seems like a reasonable problem to solve. Neil, what other solutions did you think about? Another question: is your fix widely portable? -Thorsten