etc/config/src/EXTERN_FUNCTION_TEMPLATE.cpp

// checking for extern function template extension

/***************************************************************************
 *
 * Licensed to the Apache Software  Foundation (ASF) under one or more
 * contributor  license agreements.  See  the NOTICE  file distributed
 * with  this  work  for  additional information  regarding  copyright
 * ownership.   The ASF  licenses this  file to  you under  the Apache
 * License, Version  2.0 (the  License); you may  not use  this file
 * except in  compliance with the License.   You may obtain  a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the  License is distributed on an  "AS IS" BASIS,
 * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY  KIND, either  express or
 * implied.   See  the License  for  the  specific language  governing
 * permissions and limitations under the License.
 *
 * Copyright 1999-2007 Rogue Wave Software, Inc.
 * 
 **************************************************************************/

// establish a dependency on extern_function_template_imp.{cpp,o}
#ifndef _RWSTD_NO_extern_function_template_imp

// link the object file produced by compiling this file
// with the object file below
// LDOPTS = extern_function_template_imp.o

#endif   // _RWSTD_NO_extern_function_template_imp


template <class T>
struct S
{
    T t;
};


template <class T>
S<T> foobar (S<T> s)
{
    // foobar<int>() explicitly instantiated in extern_function_template_imp.cpp
    // is defined to set s.t to 1
    s.t = -1;

    return s;
}

extern template S<int> foobar (S<int>);

int main ()
{
    // S<int>::bar () is defined to return 1 in extern_function_template_imp.o

    S<int> s;

    int res = 0;

    // verify that the call compiles and links
    res += foobar (s).t;

    // verify that the call resolves to the definition emitted
    // by the explicit instantiation in extern_function_template_imp.o
    // and not the one here
    return !(1 == res);
}