Autosar Guidelines C++14 example code compile list(8)Rule A2-5-1Trigraphs shall not be used.

Guidelines for the use of the C++14 language in critical and
safety-related systems Sample code compile list(8)
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。

# A2-5-1.cpp
## 算譜(source code)

```c++:A2-5-1.cpp
//Guidelines for the use of the C++14 language in critical and safety-related systems
const char* msg= "Rule A2-5-1 (required, implementation, automated)Trigraphs shall not be used.(8)A2-5-1.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.

/// This rule is nonsense. Because trigraphs is only the tool for the system it can not present the characters '{' and '}' and so on. Trigraph can be use at the system. But the transfer to the system it can present the characters '{' and '}' , trigraph shall change the original characters.

///start AUTOSAR: From here to the "///end AUTOSAR" is from AUTOSAR without code having /// comment in line.
//% $Id: A2-5-1.cpp 270728 2017-03-16 10:38:20Z piotr.tanski $
#include "autosar.h"/// add header file https://qiita.com/kaizen_nagoya/items/4bde8f21ab059b96cf2a
#include <cstdint>

using namespace std;/// add using

#include <iostream>
void fn1()
{
  std::cout << "Enter date ??/??/??"; // Non-compliant, ??/??/?? becomes \\??
// after trigraph translation
}
void fn2()
{
  std::cout << "Enter date dd/mm/yy"; // Compliant
}

///end AURORAS
int start() {
  fn1();
  fn2();
  cout<< msg << endl;
  ShutdownOS()  EXIT_SUCCESS;
/// Autosar OS 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 a2-5-1
$ clang++ a2-5-1.cpp -std=c++14 -Wall
a2-5-1.cpp:20:26: warning: trigraph converted to '\' character [-Wtrigraphs]
std::cout << "Enter date ??/??/??"; // Non-compliant, ??/??/?? becomes \\??
                         ^
a2-5-1.cpp:20:29: warning: trigraph converted to '\' character [-Wtrigraphs]
std::cout << "Enter date ??/??/??"; // Non-compliant, ??/??/?? becomes \\??
                            ^
2 warnings generated.
Enter date \??Enter date dd/mm/yyRule Rule A2-5-1 (required, implementation, automated)Trigraphs shall not be used.(88)A2-5-1.cpp
rm: a2-5-1l13: No such file or directory
$ clang++ a2-5-1.cpp -std=c++17 -Wall
a2-5-1.cpp:20:26: warning: trigraph ignored [-Wtrigraphs]
std::cout << "Enter date ??/??/??"; // Non-compliant, ??/??/?? becomes \\??
                         ^
a2-5-1.cpp:20:29: warning: trigraph ignored [-Wtrigraphs]
std::cout << "Enter date ??/??/??"; // Non-compliant, ??/??/?? becomes \\??
                            ^
2 warnings generated.
Enter date ??/??/??Enter date dd/mm/yyRule Rule A2-5-1 (required, implementation, automated)Trigraphs shall not be used.(88)A2-5-1.cpp
$ clang++ a2-5-1.cpp -std=c++2a -Wall
a2-5-1.cpp:20:26: warning: trigraph ignored [-Wtrigraphs]
std::cout << "Enter date ??/??/??"; // Non-compliant, ??/??/?? becomes \\??
                         ^
a2-5-1.cpp:20:29: warning: trigraph ignored [-Wtrigraphs]
std::cout << "Enter date ??/??/??"; // Non-compliant, ??/??/?? becomes \\??
                            ^
2 warnings generated.
Enter date ??/??/??Enter date dd/mm/yyRule Rule A2-5-1 (required, implementation, automated)Trigraphs shall not be used.(88)A2-5-1.cpp

$ g++-8 a2-5-1.cpp -std=c++14  -Wall
a2-5-1.cpp:20:26: warning: trigraph ??/ converted to \ [-Wtrigraphs]
 std::cout << "Enter date ??/??/??"; // Non-compliant, ??/??/?? becomes \\??
                           
a2-5-1.cpp:20:27: warning: trigraph ??/ converted to \ [-Wtrigraphs]
Enter date \??Enter date dd/mm/yyRule Rule A2-5-1 (required, implementation, automated)Trigraphs shall not be used.(88)A2-5-1.cpp
$ g++-8 a2-5-1.cpp -std=c++17  -Wall
a2-5-1.cpp:20:26: warning: trigraph ??/ ignored, use -trigraphs to enable [-Wtrigraphs]
 std::cout << "Enter date ??/??/??"; // Non-compliant, ??/??/?? becomes \\??
                           
a2-5-1.cpp:20:29: warning: trigraph ??/ ignored, use -trigraphs to enable [-Wtrigraphs]
Enter date ??/??/??Enter date dd/mm/yyRule Rule A2-5-1 (required, implementation, automated)Trigraphs shall not be used.(88)A2-5-1.cpp
$ g++-8 a2-5-1.cpp -std=c++2a  -Wall
a2-5-1.cpp:20:26: warning: trigraph ??/ ignored, use -trigraphs to enable [-Wtrigraphs]
 std::cout << "Enter date ??/??/??"; // Non-compliant, ??/??/?? becomes \\??
                           
a2-5-1.cpp:20:29: warning: trigraph ??/ ignored, use -trigraphs to enable [-Wtrigraphs]
Enter date ??/??/??Enter date dd/mm/yyRule Rule A2-5-1 (required, implementation, automated)Trigraphs shall not be used.(88)A2-5-1.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 Trigraph
Trigraphは、C言語で使う文字が表示できないシステムのための拡張であり、使いたくて使うものではない。そのため、この規則は矛盾している。
Trigraphを使っても、Trigraphじゃなくても良いシステムではTrigraphから戻すようにという規則だと理解すると良い。
Digraphの方が、まだTrigraphよりも可読性が高いかもしれない。

#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
ver 0.10 初稿 20180606
ver 0.11 一覧追記 20180613
ver 0.12 参考文献欄追記 20180616
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