Autosar Guidelines C++14, example code compile list(46)Rule A5-2-4 reinterpret_cast shall not be used.

Guidelines for the use of the C++14 language in critical and
safety-related systems Sample code compile list(46)
https://www.autosar.org/fileadmin/user_upload/standards/adaptive/17-03/AUTOSAR_RS_CPP14Guidelines.pdf
Autosar Guidelines C++14 example code compile list
https://qiita.com/kaizen_nagoya/items/8ccbf6675c3494d57a76
#目的(purpose)
AutosarのC++ GuidelineをOS, 制御のプログラムで利用するにあたって、(1)hosted, freestandingのどちらを基本にすべきか。(2)C++2014,C++2017, C++202aのどれを用いると良いか, (3)どの処理系を併用すると良いかを検討するため、-std=c++14, -std=c++17, -std=c++2aの3種類で、複数のコンパイラでコンパイルすることにより、誤(error)、警告(warning)、関数・変数連携(link)、出力(output)、にどのような影響があるかを確認する。
#成果(outcome)
複数の処理系の特徴が明確になるとともに、各標準段階, hosted, freestandingの特徴と課題を明確にする。


#A5-2-4.cpp
##算譜(source code)

```c++:A5-2-4.cpp
//Guidelines for the use of the C++14 language in critical and safety-related systems
const char* msg="Rule A5-2-4 (required, implementation, automated)reinterpret_cast shall not be used.(46)A5-2-4.cpp";
//https://www.autosar.org/fileadmin/user_upload/standards/adaptive/17-03/AUTOSAR_RS_CPP14Guidelines.pdf
// There is no description about Autosar declear hosted or freestanding.
// If the Autosar intended both depending on the cases, autosar.h can choose one.
// Compile with -DHOSTED work as  hosted environment, -DFREESTANDING work as freestanding.

#include "autosar.h"/// @line add header file https://qiita.com/kaizen_nagoya/items/4bde8f21ab059b96cf2a
#include <cstdint>


using namespace std;/// @line add using

///start AUTOSAR: From here to the "///end AUTOSAR" is from AUTOSAR without code having /// comment in line.
// $Id: A5-2-4.cpp 271696 2017-03-23 09:23:09Z piotr.tanski $
#include <cstdint>
#include <string>
void f1() noexcept
{
  std::string str = "Hello";
  std::int32_t* ptr = reinterpret_cast<std::int32_t*>(&str); // Non-compliant
  cout << "ptr"<<ptr<<endl;/// @ line for output
}
struct A
{
  std::int32_t x;
  std::int32_t y;
};
class B
{
public:
  virtual ~B() {}
  void f() {
    cout <<"x="<<x<<endl; /// @ line for output
  }
private:
  std::int32_t x;
};
class C : public B
{
};
class D : public B
{
};
void f2(A* ptr) noexcept
{
  B* b1 = reinterpret_cast<B*>(ptr); // Non-compliant
  std::int32_t num = 0;
  A* a1 = reinterpret_cast<A*>(num); // Non-compliant
  A* a2 = (A*)
          num; // Compliant with this rule, but non-compliant with Rule A5-2-2.
  B* b2 = reinterpret_cast<B*>(num); // Non-compliant
  D d;
  C* c1 = reinterpret_cast<C*>(&d); // Non-compliant - cross cast
  C* c2 = (C*)&d; // Compliant with this rule, but non-compliant with Rule
// A5-2-2. Cross-cast.
  B* b3 = &d; // Compliant - class D is a subclass of class B
  cout <<"b1="<<b1<< " a1="<<a1<<" a2="<<a2<<" b2="<<b2<<" c1="<<c1<<" c2="<<c2<<" b3="<<b3<<endl;/// @ line for output
}
///end AUTOSAR
int start() { /// @{} for start
  A a;
  A * ap=&a;
  f1();
  f2(ap);
  cout<< msg << endl;
  ShutdownOS()  EXIT_SUCCESS;
/// Autosar OS 3.1.1, 2009: 7.1.2.2 Undefined Behaviour in OSEK OS
/// OS425 If ShutdownOS is called and ShutdownHook() returns then the operating system shall disable all interrupts and enter an endless loop.
}
```

##編纂・実行結果(compile and go)

```shell-session:cpa.sh
$ ../cpa.sh a5-2-4
$ clang++ a5-2-4.cpp -I./ -std=c++14 -Wall
a5-2-4.cpp:48:10: warning: cast to 'A *' from smaller integer type 'std::int32_t' (aka 'int') [-Wint-to-pointer-cast]
 A* a2 = (A*)
         ^
1 warning generated.
ptr0x7ffee58056a0
b1=0x7ffee5805730 a1=0x0 a2=0x0 b2=0x0 c1=0x7ffee58056c0 c2=0x7ffee58056c0 b3=0x7ffee58056c0
Rule A5-2-4 (required, implementation, automated)reinterpret_cast shall not be used.(46)A5-2-4.cpp
$ clang++ a5-2-4.cpp  -I./ -std=c++17 -Wall
a5-2-4.cpp:48:10: warning: cast to 'A *' from smaller integer type 'std::int32_t' (aka 'int') [-Wint-to-pointer-cast]
 A* a2 = (A*)
         ^
1 warning generated.
ptr0x7ffeecd136a0
b1=0x7ffeecd13730 a1=0x0 a2=0x0 b2=0x0 c1=0x7ffeecd136c0 c2=0x7ffeecd136c0 b3=0x7ffeecd136c0
Rule A5-2-4 (required, implementation, automated)reinterpret_cast shall not be used.(46)A5-2-4.cpp
$ clang++ a5-2-4.cpp  -I./ -std=c++2a -Wall
a5-2-4.cpp:48:10: warning: cast to 'A *' from smaller integer type 'std::int32_t' (aka 'int') [-Wint-to-pointer-cast]
 A* a2 = (A*)
         ^
1 warning generated.
ptr0x7ffee6c136a0
b1=0x7ffee6c13730 a1=0x0 a2=0x0 b2=0x0 c1=0x7ffee6c136c0 c2=0x7ffee6c136c0 b3=0x7ffee6c136c0
Rule A5-2-4 (required, implementation, automated)reinterpret_cast shall not be used.(46)A5-2-4.cpp

$ g++-8 a5-2-4.cpp  -I./ -std=c++14  -Wall
a5-2-4.cpp: In function 'void f2(A*)':
a5-2-4.cpp:49:2: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
  num; // Compliant with this rule, but non-compliant with Rule A5-2-2.
  ^~~
ptr0x7ffeef939700
b1=0x7ffeef939740 a1=0 a2=0 b2=0 c1=0x7ffeef9396e0 c2=0x7ffeef9396e0 b3=0x7ffeef9396e0
Rule A5-2-4 (required, implementation, automated)reinterpret_cast shall not be used.(46)A5-2-4.cpp
$ g++-8 a5-2-4.cpp  -I./ -std=c++17  -Wall
a5-2-4.cpp: In function 'void f2(A*)':
a5-2-4.cpp:49:2: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
  num; // Compliant with this rule, but non-compliant with Rule A5-2-2.
  ^~~
ptr0x7ffee5b23700
b1=0x7ffee5b23740 a1=0 a2=0 b2=0 c1=0x7ffee5b236e0 c2=0x7ffee5b236e0 b3=0x7ffee5b236e0
Rule A5-2-4 (required, implementation, automated)reinterpret_cast shall not be used.(46)A5-2-4.cpp
$ g++-8 a5-2-4.cpp  -I./ -std=c++2a  -Wall
a5-2-4.cpp: In function 'void f2(A*)':
a5-2-4.cpp:49:2: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
  num; // Compliant with this rule, but non-compliant with Rule A5-2-2.
  ^~~
ptr0x7ffee2d2d700
b1=0x7ffee2d2d740 a1=0 a2=0 b2=0 c1=0x7ffee2d2d6e0 c2=0x7ffee2d2d6e0 b3=0x7ffee2d2d6e0
Rule A5-2-4 (required, implementation, automated)reinterpret_cast shall not be used.(46)A5-2-4.cpp

```

#検討事項(agenda)
###1. 自律(freestanding)環境. 接待(hosted)環境

C++N4606 1.4 Implementation compliance p.4

###2. 対応OSの水準、対応通信規約、応用機能による分類
freestanding用の関数、ライブラリ等
###3. C++2014, C++2017, C++202aの比較項目
本件なし
###4. clang++, g++の比較検討項目
本件なし

###5 役立つまたは意味のある出力

#参考文献(reference)

###プログラミング言語教育のXYZ
https://qiita.com/kaizen_nagoya/items/1950c5810fb5c0b07be4
プログラミング言語教育のXYZ(youtube)
https://www.youtube.com/watch?v=He1_tg4px-w&t=486s

###C++N4741 2018
Working Draft, Standard for Programming Language C++
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/n4741.pdf

C++N4741, 2018 Standard Working Draft on ISO/IEC 14882 sample code compile list
https://qiita.com/kaizen_nagoya/items/3294c014044550896010

###C++N4606 2016
Working Draft, Standard for Programming Language C++
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4606.pdf

C++N4606, 2016符号断片編纂一覧(example code compile list)
 Working Draft 2016, ISO/IEC 14882(1)
https://qiita.com/kaizen_nagoya/items/df5d62c35bd6ed1c3d43/

###　CEDD(Compile Error Driven Design) 
初めての　CEDD(Compile Error Driven Design) ８回直してコンパイル。
https://qiita.com/kaizen_nagoya/items/9494236aa1753f3fd1e1

コンパイルエラーを記録するとよい理由7つ
https://qiita.com/kaizen_nagoya/items/85c0e92b206883140e89

C Puzzle Bookの有り難み5つ、C言語規格及びCコンパイラの特性を認識
https://qiita.com/kaizen_nagoya/items/d89a48c1536a02ecdec9

C言語（C++)に対する誤解、曲解、無理解、爽快。
https://qiita.com/kaizen_nagoya/items/3f3992c9722c1cee2e3a

Qiitaに投稿するCのStyle例(暫定)
https://qiita.com/kaizen_nagoya/items/946df1528a6a1ef2bc0d

C++N4606 Working Draft 2016, ISO/IEC 14882, C++ standardのコード断片をコンパイルするためにしていること
https://qiita.com/kaizen_nagoya/items/a8d7ee2f2e29e76c19c1

コンパイル用shell script C版(clangとgcc)とC++版(clang++とg++)
https://qiita.com/kaizen_nagoya/items/74220c0577a512c2d7da

[C][C++]の国際規格案の例題をコンパイルするときの課題７つ。
https://qiita.com/kaizen_nagoya/items/5f4b155030259497c4de


docker gnu(gcc/g++) and llvm(clang/clang++)
https://qiita.com/drafts/059874ea39c4de64c0f7

#文書履歴(document history)
ver 0.10 初稿 20180610
ver 0.11 一覧追記  参考文献欄追記 20180616
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