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2014/06/12

C++N3242, 2011 (22) 3.5 Program and linkage

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// 1 filename:cpp2011-3-5.cpp
// ver 0.1 June.12, 2014
//
// 2 original examples and/or notes:
// (c) ISO/IEC JTC1 SC22 WG21 N3242, April 12, 2011
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf
// 3 Basic concepts.3.5 Program and linkage
//
// 3 compile and output mechanism:
// (c) Dr. OGAWA Kiyoshi, kaizen at gifu-u.ac.jp,
//
// 4 compile errors and/or warnings:
// 4.1(c) Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
// Target: x86_64-apple-darwin13.2.0,  Thread model: posix
// Command/Options: c++ -std=c++11 -stdlib=libc++ -Wall cpp2011-3-5.cpp 
// (c) LLVM 2003-2009 University of Illinois at Urbana-Champaign.

// 4.2. g++-4.9 (GCC) 4.9.0 20131229 (experimental)
// Copyright (C) 2013 Free Software Foundation, Inc.
// This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// http://gcc.gnu.org/onlinedocs/gcc/Standards.html
// Command/Options: g++-4.9  -std=c++11  -Wall cpp2011-3-5.cpp 
// g++-4.9: error: unrecognized command line option '-stdlib=libc++'
// Configuration:brew install gcc49
//
// 4.3. Visual Studio Express 2013, 
// (c) Microsoft http://www.visualstudio.com/
// SPEC:
// Windows 7, .NET Framework
// (c) VMware, Inc.
// VMWare fusion 6
//
// 5. Hardware:  MacBook Pro, 
//(c) Intel http://ark.intel.com/products/37006/
//Core 2 Duo 2.53GHz, 8GB, 1067MHz DDR3
//
// 6. Special Thanks: Upper organizatios and 
// ITSCJ/IPSJ http://www.itscj.ipsj.or.jp/itscj_english/index.html
// Renesas Electronics Corporation.http://www.renesas.com/
// NPO SESSAME project, http://www.sessame.jp/workinggroup/WorkingGroup3/
// Toyo Corporation, http://www.toyo.co.jp/English/
// Japan Standard Association, http://bit.ly/1lzykg1
// NPO TOPPERS project, https://www.toppers.jp/asp-d-download.html
// Daido Universcity, http://www.daido-it.ac.jp/gakubugakka/computer/index.html
// WITZ Co.Ltd., http://www.witz-inc.co.jp/products/solution/solution.html
// SevenWise.co., http://www.7ws.co.jp/index.html
// TOYOTA Motor Corporation, http://toyota.jp/
// IT planning Inc., http://www.itpl.co.jp/en/index.html
// DENSO Corporation, http://www.globaldenso.com/en/
// Aisin Seiki co. Ltd., http://www.aisin.com/
// Spancion Inc., http://www.spansion.com/
// Yazaki Corporation, http://www.yazaki-group.com/global/
// Pananosic Corporation, http://www.panasonic.net/
// SWEST: Summer Workshop on Embedded System Technologies , http://swest.toppers.jp
// CEST: Consortium for Embedded System Technology, http://www.ertl.jp/CEST/
// JUSE: Union of Japanese Scientists and Engineers, http://www.juse.or.jp/e/
// OSC:Open Source Conference, http://www.ospn.jp/

#include <iostream>
//#include <string>
//#include <cassert>

using namespace std;
//
static void f();
static int i = 0; // #1
void g() {
extern void f(); // internal linkage
int i; // #2 i has no linkage
cout << "i=" << i << std::endl;
{
extern void f(); // internal linkage
extern int i; // #3 external linkage
cout << "i=" << i << std::endl;
}
}
//
namespace X {
void p() {
// q(); // error: q not yet declared
extern void q(); // q is a member of namespace X
}
void middle() {
// q(); // error: q not yet declared
}
void q() { /* ... */ } // definition of X::q
}
void q() { /* ... */ } // some other, unrelated q
//
template <class T> struct B {
void g(T) { }
void h(T);
friend void i2(B, T) { }
};
void f() {
struct A { int x; }; // no linkage
A a = { 1 };
B<A> ba; // declares B<A>::g(A) and B<A>::h(A)
ba.g(a); // OK
// cpp2011-3-5.cpp:92:6: warning: function 'B<A>::h' has internal linkage but is not defined [-Wundefined-internal]
// Undefined symbols for architecture x86_64:  "B<f()::A>::h(f()::A)", referenced from:
    //  f() in cpp2011-3-5-984872.o,  ld: symbol(s) not found for architecture x86_64
// ba.h(a); // error: B<A>::h(A) not defined in the translation unit
i2(ba, a); // OK
cout << "f.a=" << a.x << std::endl;
}

int main() {
f();
g();
cout << "i=" << i << std::endl;
cout << "3 Basic concepts.3.5 Program and linkage"<<std::endl;

return 0;
}
// output
// f.a=1
// i=0
// i=0
// i=0
// 3 Basic concepts.3.5 Program and linkage

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