[Bug c++/31816] New: If a function foo is defined before declaring a template class A<T>, overloaded version of foo defined after the class declaration will not be available within class A<T>.

["gcc-bugzilla at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

Let us consider the following code:
-----
void qHash(double) {}

template <class T>
struct QSet
{
  void foo()
  {
    qHash(T());
  }
};

// void qHash(double) {} // ok if placed here
void qHash(int*) {}

int main()
{
  QSet<double> s;
  s.foo(); // ok

  QSet<int*> sp;
  sp.foo(); // do not compile, qHash(int*) is not considered.
}
-----

It does not compile, because the overloaded version of qHash() for
int* is not available in QSet, even if QSet is instantiated after the
declaration of qHash(int*). If no qHash function is defined before the
declaration of QSet, it works fine. Although I'm not absolutely
certain that this code is valid, my intuition tells me this behavior
is strongly suspect ..

It works fine with g++ 4.0.4, 3.3 and 2.95.

Environment:
System: Linux stageuei9 2.6.18-3-686 #1 SMP Mon Dec 4 16:41:14 UTC 2006 i686
GNU/Linux
Architecture: i686


host: i486-pc-linux-gnu
build: i486-pc-linux-gnu
target: i486-pc-linux-gnu
configured with: ../src/configure -v
--enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr
--enable-shared --with-system-zlib --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --enable-nls
--program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu
--enable-libstdcxx-debug --enable-mpfr --with-tune=i686
--enable-checking=release i486-linux-gnu

How-To-Repeat:

Compile the given code.


------- Comment #1 from nicolas dot burrus at ensta dot fr  2007-05-04 14:31 -------
Fix:

Do not overload a function before and after a template class
using it.


-- 
           Summary: If a function foo is defined before declaring a template
                    class A<T>, overloaded version of foo defined after the
                    class declaration will not be available within class
                    A<T>.
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: nicolas dot burrus at ensta dot fr
 GCC build triplet: i486-pc-linux-gnu
  GCC host triplet: i486-pc-linux-gnu
GCC target triplet: i486-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31816