[Bug c++/42281] g++ instantiates function templates at the wrong place

[jezz at hkfree dot org]

------- Comment #2 from jezz at hkfree dot org  2009-12-04 21:30 -------
I have tried to simplify the code, but I have created only problem with int
(not with user structure). In real code we have also something like this:

Tested with same compilers:
template2.cc: In function ‘bool isEqual(const A&, const B&) [with A =
std::map<int, int>, B = std::map<int, double>]&#8217;:
template2.cc:16:4:   instantiated from &#8216;void isTrue(const A&, const B&)
[with A = std::map<int, int>, B = std::map<int, double>]&#8217;
template2.cc:53:17:   instantiated from here
template2.cc:6:17: error: no match for &#8216;operator==&#8217; in &#8216;aA ==
aB&#8217;


[Code]
#include <map>

template <typename A, typename B>
bool isEqual(A const &aA, B const &aB)
   {
   return aA == aB;
   }

// Forward declaration works
//template <typename Key, typename Value1, typename Value2>
//bool isEqual(std::map<Key,Value1> const &aA, std::map<Key,Value2> const &aB);

template <typename A, typename B>
inline void isTrue(A const &aA, B const &aB)
   {
   if (not isEqual(aA, aB)) throw new std::exception();
   }

template <typename A, typename B>
void isFalse(A const &aA, B const &aB)
   {
   if (isEqual(aA, aB)) throw new std::exception();
   }

template <typename Key, typename Value1, typename Value2>
bool isEqual(std::map<Key,Value1> const &aA, std::map<Key,Value2> const &aB)
   {
   if (aA.size() != aB.size()) return false;
   for (typename std::map<Key,Value1>::const_iterator it1 = aA.begin();
         it1 != aA.end(); ++it1)
      {
      typename std::map<Key,Value2>::const_iterator it2 = aB.find(it1->first);
      if (it2 == aB.end() or it1->second != it2->second) return false;
      }
   return true;
   }

int
main(int argc, char *argv[])
   {
   isTrue(1, 1);

   double da, db;
   da = 1.0;
   db = 2.0;
   isFalse(da, db);

   isTrue(da, 1);

   std::map<int, int> ma;
   std::map<int, double> mb;

   isTrue(ma, mb); // Error here

   return 0;
   }
[/Code]


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42281