Autosar Guidelines C++14, example code compile list(64)Rule A7-2-1 An expression with enum underlying type 

Guidelines for the use of the C++14 language in critical and
safety-related systems Sample code compile list(64)
https://www.autosar.org/fileadmin/user_upload/standards/adaptive/17-03/AUTOSAR_RS_CPP14Guidelines.pdf
Autosar Guidelines C++14, example code compile list(
#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。


#A7-2-1.cpp
##算譜(source code)

```c++:A7-2-1.cpp
//Guidelines for the use of the C++14 language in critical and safety-related systems
const char* msg="Rule A7-2-1 (required, implementation, automated)An expression with enum underlying type shall only have values corresponding to the enumerators of the enumeration.(64)A7-2-1.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

using namespace std;/// @line add using

///start AUTOSAR: From here to the "///end AUTOSAR" is from AUTOSAR without code having /// comment in line.
// $Id: A5-0-3.cpp 271687 2017-03-23 08:57:35Z piotr.tanski $
#include <cstdint>
using IntPtr = std::int8_t*;
struct S
{
  std::int8_t* s1; // Compliant
  std::int8_t** s2; // Compliant
  std::int8_t*** s3; // Non-compliant
};
S* ps1; // Compliant
S** ps2; // Compliant
S*** ps3; // Non-compliant

std::int8_t** (*pfunc1)(); // Compliant
std::int8_t** (**pfunc2)(); // Compliant
std::int8_t** (***pfunc3)(); // Non-compliant
std::int8_t*** (**pfunc4)(); // Non-compliant

void fn(std::int8_t* par1, // Compliant
        std::int8_t** par2, // Compliant
        std::int8_t*** par3, // Non-compliant
        IntPtr* par4, // Compliant
        IntPtr* const* const par5, // Non-compliant
        std::int8_t* par6[], // Compliant
        std::int8_t** par7[]) // Non-compliant
{
  std::int8_t* ptr1=par1; // Compliant
  std::int8_t** ptr2=par2; // Compliant
  std::int8_t*** ptr3=par3; // Non-compliant
  IntPtr* ptr4=par4; // Compliant
  IntPtr* const* const ptr5 = nullptr; // Non-compliant
  std::int8_t* ptr6[10]= {par1,*par2,*par4}; // Compliant
  std::int8_t** ptr7[10]= {par2,*par3,par4}; // Compliant
  cout <<"*ptr1="<<*ptr1<<" **ptr2="<<**ptr2<<" ***ptr3="<<***ptr3<<" ptr4="<<ptr4<<" &ptr5="<<&ptr5<<" *ptr6[0]="<<*ptr6[0]<<" **ptr7[0]="<<**ptr7[0]<<endl;
}
// Explanation of types
// 1) par1 and ptr1 are of type pointer to std::int8_t.
// 2) par2 and ptr2 are of type pointer to pointer to std::int8_t.
// 3) par3 and ptr3 are of type pointer to a pointer to a pointer
// to std::int8_t.
// This is three levels and is non-compliant.
// 4) par4 and ptr4 are expanded to a type of pointer to a pointer to
// std::int8_t.
// 5) par5 and ptr5 are expanded to a type of const pointer to a const
// pointer
// to a pointer to std::int8_t. This is three levels and is non-compliant.
// 6) par6 is of type pointer to pointer to std::int8_t because arrays
// are converted
// to a pointer to the initial element of the array.
// 7) ptr6 is of type pointer to array of std::int8_t.
// 8) par7 is of type pointer to pointer to pointer to
// std::int8_t because arrays are
// converted to a pointer to the initial element of the array. This is
// three
// levels and is non-compliant.
// 9) ptr7 is of type array of pointer to pointer to std::int8_t. This
// is compliant.
///end AUTOSAR
int start() { /// @{} for start
  int8_t i=127;
  int8_t* par1=&i; // Compliant
  int8_t** par2=&par1; // Compliant
  int8_t*** par3 =&par2;// Non-compliant
  IntPtr* par4=par2; // Compliant
  IntPtr* const* const par5=&par4; // Non-compliant
  int8_t* par6[10]= {par1,*par2,*par4}; // Compliant
  int8_t** par7[10]= {par2,*par3,par4}; // Non-compliant
  fn(par1,par2,par3,par4,par5,par6,par7);
  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 a7-2-1
$ clang++ a7-2-1.cpp -I./ -std=c++14 -Wall
*ptr1= **ptr2= ***ptr3= ptr4=0x7ffee5d5c680 &ptr5=0x7ffee5d5c508 *ptr6[0]= **ptr7[0]=
Rule A7-2-1 (required, implementation, automated)An expression with enum underlying type shall only have values corresponding to the enumerators of the enumeration.(64)A7-2-1.cpp
$ clang++ a7-2-1.cpp  -I./ -std=c++17 -Wall
*ptr1= **ptr2= ***ptr3= ptr4=0x7ffee32f8680 &ptr5=0x7ffee32f8508 *ptr6[0]= **ptr7[0]=
Rule A7-2-1 (required, implementation, automated)An expression with enum underlying type shall only have values corresponding to the enumerators of the enumeration.(64)A7-2-1.cpp
$ clang++ a7-2-1.cpp  -I./ -std=c++2a -Wall
*ptr1= **ptr2= ***ptr3= ptr4=0x7ffee8580680 &ptr5=0x7ffee8580508 *ptr6[0]= **ptr7[0]=
Rule A7-2-1 (required, implementation, automated)An expression with enum underlying type shall only have values corresponding to the enumerators of the enumeration.(64)A7-2-1.cpp

$ g++-8 a7-2-1.cpp  -I./ -std=c++14  -Wall
*ptr1= **ptr2= ***ptr3= ptr4=0x7ffeea791730 &ptr5=0x7ffeea791638 *ptr6[0]= **ptr7[0]=
Rule A7-2-1 (required, implementation, automated)An expression with enum underlying type shall only have values corresponding to the enumerators of the enumeration.(64)A7-2-1.cpp
$ g++-8 a7-2-1.cpp  -I./ -std=c++17  -Wall
*ptr1= **ptr2= ***ptr3= ptr4=0x7ffeec547730 &ptr5=0x7ffeec547638 *ptr6[0]= **ptr7[0]=
Rule A7-2-1 (required, implementation, automated)An expression with enum underlying type shall only have values corresponding to the enumerators of the enumeration.(64)A7-2-1.cpp
$ g++-8 a7-2-1.cpp  -I./ -std=c++2a  -Wall
*ptr1= **ptr2= ***ptr3= ptr4=0x7ffee5729730 &ptr5=0x7ffee5729638 *ptr6[0]= **ptr7[0]=
Rule A7-2-1 (required, implementation, automated)An expression with enum underlying type shall only have values corresponding to the enumerators of the enumeration.(64)A7-2-1.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)
###C++N4741 2018
Working Draft, Standard for Programming Language C++
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/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/

#文書履歴
ver 0.10 初稿 20180611