Guidelines for the use of the C++14 language in critical and
safety-related systems Sample code compile list(78)
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。
A9-3-1.cpp
算譜(source code)
//Guidelines for the use of the C++14 language in critical and safety-related systems
const char* msg="Rule A9-3-1 (required, implementation, automated)Member functions shall not return non-const “raw” pointers or references to private or protected data owned by the class.(78)A8-2-1.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: A9-3-1.cpp 271927 2017-03-24 12:01:35Z piotr.tanski $
#include <cstdint>
#include <memory>
#include <utility>
class A
{
public:
explicit A(std::int32_t number) : x(number) {}
// Implementation
std::int32_t&
getX() noexcept // Non-compliant - x is a resource owned by the A class
{
return x;
}
private:
std::int32_t x;
};
void fn1() noexcept
{
A a{10};
std::int32_t& number = a.getX();
number = 15; // External modification of private class data
}
class B
{
public:
explicit B(std::shared_ptr<std::int32_t> ptr) : sharedptr(std::move(ptr)) {}
// Implementation
std::shared_ptr<std::int32_t> getSharedPtr() const
noexcept // Compliant - sharedptr is a variable being shared between
// instances
{
return sharedptr;
}
private:
std::shared_ptr<std::int32_t> sharedptr;
};
void fn2() noexcept
{
std::shared_ptr<std::int32_t> ptr = std::make_shared<std::int32_t>(10);
B b1{ptr};
B b2{ptr};
*ptr = 50; // External modification of ptr which shared between b1 and b2
// instances
auto shared = b1.getSharedPtr();
*shared = 100; // External modification of ptr which shared between b1 and
// b2 instances
}
class C
{
public:
explicit C(std::int32_t number)
: ownedptr{std::make_unique<std::int32_t>(number)}
{
}
// Implementation
const std::unique_ptr<std::int32_t>& getOwnedPtr() const
noexcept // Non-compliant - only unique_ptr is const, the object that
// it is pointing to is modifiable
{
return ownedptr;
}
const std::int32_t& getData() const noexcept // Compliant
{
return *ownedptr;
}
private:
std::unique_ptr<std::int32_t> ownedptr;
};
void fn3() noexcept
{
C c{10};
const std::int32_t& data = c.getData();
// data = 20; // Can not modify data, it is a const reference
const std::unique_ptr<std::int32_t>& ptr = c.getOwnedPtr();
*ptr = 20; // Internal data of class C modified
cout<< "data=" << data<<endl;
}
///end AUTOSAR
int start() { /// @{} for start
fn1();
fn2();
fn3();
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)
$ ../cpa.sh a9-3-1
$ clang++ a9-3-1.cpp -I./ -std=c++14 -Wall
data=20
Rule A9-3-1 (required, implementation, automated)Member functions shall not return non-const “raw” pointers or references to private or protected data owned by the class.(78)A9-3-1.cpp
$ clang++ a9-3-1.cpp -I./ -std=c++17 -Wall
data=20
Rule A9-3-1 (required, implementation, automated)Member functions shall not return non-const “raw” pointers or references to private or protected data owned by the class.(78)A9-3-1.cpp
$ clang++ a9-3-1.cpp -I./ -std=c++2a -Wall
data=20
Rule A9-3-1 (required, implementation, automated)Member functions shall not return non-const “raw” pointers or references to private or protected data owned by the class.(78)A9-3-1.cpp
$ g++-8 a9-3-1.cpp -I./ -std=c++14 -Wall
data=20
Rule A9-3-1 (required, implementation, automated)Member functions shall not return non-const “raw” pointers or references to private or protected data owned by the class.(78)A9-3-1.cpp
$ g++-8 a9-3-1.cpp -I./ -std=c++17 -Wall
data=20
Rule A9-3-1 (required, implementation, automated)Member functions shall not return non-const “raw” pointers or references to private or protected data owned by the class.(78)A9-3-1.cpp
$ g++-8 a9-3-1.cpp -I./ -std=c++2a -Wall
data=20
Rule A9-3-1 (required, implementation, automated)Member functions shall not return non-const “raw” pointers or references to private or protected data owned by the class.(78)A9-3-1.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