20.3.4.1 Class template out_ptr_t [out.ptr.t] C++N4910:2022 (478) p618.cpp

# はじめに(Introduction)

N4910  Working Draft, Standard for Programming Language C++

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/n4910.pdf

n4910は、ISO/IEC JTC1 SC22 WG21の作業原案(Working Draft)です。
公式のISO/IEC 14882原本ではありません。
ISO/IEC JTC1 SC22 WG21では、可能な限り作業文書を公開し、幅広い意見を求めています。
一連の記事はコード断片をコンパイルできる形にする方法を検討してコンパイル、リンク、実行して、規格案の原文と処理系(g++, Clang++)との違いを確認し、技術内容を検討し、ISO/IEC JTC1 SC22 WG21にフィードバックするために用います。
また、CERT C++, MISRA C++等のコーディング標準のコード断片をコンパイルする際の参考にさせていただこうと考えています。CERT C++, MISRA C++が標準化の動きとの時間的なずれがあれば確認できれば幸いです。また、boostライブラリとの関連、Linux OS, TOPPERSカーネル、g++(GCC), clang++(LLVM）との関係も調査中です。
何か、抜け漏れ、耳より情報がありましたらおしらせくださると幸いです。

 <この項は書きかけです。順次追記します。>

## 背景(back ground)
C/C++でコンパイルエラーが出ると、途方にくれることがしばしばあります。
何回かに１回は、該当するエラーが検索できます。
ただ、条件が違っていて、そこでの修正方法では目的を達成しないこともしばしばです。いろいろな条件のコンパイルエラーとその対応方法について、広く記録することによって、いつか同じエラーに遭遇した時にやくに立つことを目指しています。

この半年の間で、三度、自分のネットでの記録に助けられたことがあります。
また過去に解決できなかった記録を１０種類以上、最近になって解決できたことがあります。それは、主に次の３つの情報に基づいています。

https://stackoverflow.com
https://cpprefjp.github.io
http://ja.cppreference.com/

また
https://researchmap.jp/joub9b3my-1797580/#_1797580
に記載したサイトのお世話になっています。

## 作業方針(sequence)
Clang++では-std=c++03, C++2bの2種類
g++では-std=c++03, c++2bの２種類
でコンパイルし、

１）コンパイルエラーを収集する。
２）コンパイルエラーをなくす方法を検討する。
コンパイルエラーになる例を示すだけが目的のコードは、コンパイルエラーをなくすのではなく、コンパイルエラーの種類を収集するだけにする。
文法を示すのが目的のコード場合に、コンパイルエラーをなくすのに手間がかかる場合は、順次作業します。
３）リンクエラーをなくす方法を検討する。
文法を示すのが目的のコード場合に、リンクエラーをなくすのに手間がかかる場合は、順次作業します。
４）意味のある出力を作る。
コンパイル、リンクが通っても、意味のある出力を示そうとすると、コンパイル・リンクエラーが出て収拾できそうにない場合がある。順次作業します。

１）だけのものから４）まで進んだものと色々ある状態です。一歩でも前に進むご助言をお待ちしています。「検討事項」の欄に現状を記録するようにしています。

### C++N4910:2022 Standard Working Draft on ISO/IEC 14882(0) sample code compile list  

https://qiita.com/kaizen_nagoya/items/fc957ddddd402004bb91

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

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

### C++N3242, 2011 sample code compile list on clang++ and g++
https://qiita.com/kaizen_nagoya/items/685b5c1a2c17c1bf1318

## 編纂器(Compiler)
### clang++ --version
> Debian clang version 14.0.5-++20220610033153+c12386ae247c-1~exp1~20220610153237.151
Target: x86_64-pc-linux-gnu, Thread model: posix, InstalledDir: /usr/bin

### g++- --version
> g++ (GCC) 12.1.0  Copyright (C) 2022 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.

# 20.3.4.1 Class template out_ptr_t [out.ptr.t] C++N4910:2022 (478) p618.cpp

## 算譜(source code)

```c++:p618.cpp
// C++N4910 Committee Draft, Standard for Programming Language C++
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/n4910.pdf
const char * n4910 = "20.3.4.1 Class template out_ptr_t [out.ptr.t] C++N4910:2022 (478) p618.cpp";
// Debian clang version 14.0.5-++20220610033153+c12386ae247c-
// g++ (GCC) 12.1.0 Copyright (C) 2022 Free Software Foundation, Inc.
// Edited by Dr. OGAWA Kiyoshi. Compile procedure and results record.
// C++N4910:2022 Standard Working Draft on ISO/IEC 14882(0) sample code compile list
// https://qiita.com/kaizen_nagoya/items/fc957ddddd402004bb91

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cassert>
#include <coroutine>
#include <vector>
#include <complex>
#include <map>
#include <atomic>
#include <unordered_map>
#include <memory>
#include <typeinfo>

using namespace std;

// Example 1
#include <memory>
#include <cstdio>
int fopen_s(std::FILE** f, const char* name, const char* mode);
struct fclose_deleter {
    void operator()(std::FILE* f) const noexcept {
        std::fclose(f);
    }
};
int main(int, char*[]) {
    constexpr const char* file_name = "ow.o";
    std::unique_ptr<std::FILE, fclose_deleter> file_ptr;
    int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
    if (err != 0)
        cout  <<  n4910 << endl;
    return EXIT_SUCCESS;
    return 1;
// *file_ptr is valid return 0;
}
// unique_ptr can be used with out_ptr to be passed into an output pointer-style function, without needing to hold onto an intermediate pointer value and manually delete it on error or failure.
namespace std {
template<class Smart, class Pointer, class... Args>
class out_ptr_t {
public:
    explicit out_ptr_t(Smart&, Args...);
    out_ptr_t(const out_ptr_t&) = delete;
    ~out_ptr_t();
    operator Pointer*() const noexcept;
    operator void**() const noexcept;
    if (p) {
        apply([&](auto&&... args) {
            s.reset(static_cast<SP>(p), std::forward<Args>(args)...);
        }, std::move(a));
    }
// if the expression s.reset(static_cast<SP>(p), std::forward<Args>(args)...) is well- formed; otherwise,
    if (p) {
        apply([&](auto&&... args) {
            s = Smart(static_cast<SP>(p), std::forward<Args>(args)...);
        }, std::move(a));
    }
// if is_constructible_v<Smart, SP, Args...> is true; otherwise, the program is ill-formed.
private:
    Smart& s;
    tuple<Args...> a;
    Pointer p;
};
}
// exposition only // exposition only // exposition only
// Pointer shall meet the Cpp17NullablePointer requirements. If Smart is a specialization of shared_ptr and sizeof...(Args) == 0, the program is ill-formed.
// [Note 1: It is typically a user error to reset a shared_ptr without specifying a deleter, as shared_ptr will replace a custom deleter upon usage of reset, as specified in 20.3.2.2.5.
//  Program-defined specializations of out_ptr_t that depend on at least one program-defined type need not meet the requirements for the primary template.
// Evaluations of the conversion functions on the same object may conflict (6.9.2.2).
explicit out_ptr_t(Smart& smart, Args... args);
// Effects: Initializes s with smart, a with std::forward<Args>(args)..., and value-initializes p.
// [Note 2: The constructor is not noexcept to allow for a variety of non-terminating and safe implementation strategies. For example, an implementation can allocate a shared_ptr’s internal node in the constructor and let implementation-defined exceptions escape safely. The destructor can then move the allocated control block in directly and avoid any other exceptions.
~out_ptr_t();
// Let SP be POINTER_OF_OR (Smart, Pointer) (20.2.1).
// Effects: Equivalent to:
operator Pointer*() const noexcept;
// Preconditions: operator void**() has not been called on *this.
// Returns: addressof(const_cast<Pointer&>(p)).
operator void**() const noexcept;
// Constraints: is_same_v<Pointer, void*> is false.
// Mandates: is_pointer_v<Pointer> is true.
// Preconditions: operator Pointer*() has not been called on *this.
// Returns: A pointer value v such that:
// — the initial value *v is equivalent to static_cast<void*>(p) and
// — any modification of *v that is not followed by a subsequent modification of *this affects the value of p during the destruction of *this, such that static_cast<void*>(p) == *v. Remarks: Accessing *v outside the lifetime of *this has undefined behavior.
// [Note 3: reinterpret_cast<void**>(static_cast<Pointer*>(*this)) can be a viable implementation strat- egy for some implementations.
```

## 編纂・実行結果(compile and go)

```ubuntu:bash
$ clang++ p618.cpp -std=c++03 -o p618l -I. -Wall
In file included from p618.cpp:19:
In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/atomic:38:
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/c++0x_warning.h:32:2: error: This file requires compiler and library support for the ISO C++ 2011 standard. This support must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
#error This file requires compiler and library support \
 ^
p618.cpp:31:43: error: expected ';' at end of declaration list
       void operator()(std::FILE* f) const noexcept {
                                          ^
                                          ;
p618.cpp:36:8: error: unknown type name 'constexpr'
       constexpr const char* file_name = "ow.o";
       ^
p618.cpp:37:13: error: no member named 'unique_ptr' in namespace 'std'
       std::unique_ptr<std::FILE, fclose_deleter> file_ptr;
       ~~~~~^
p618.cpp:37:33: error: expected '(' for function-style cast or type construction
       std::unique_ptr<std::FILE, fclose_deleter> file_ptr;
                       ~~~~~~~~~^
p618.cpp:38:31: error: no template named 'out_ptr' in namespace 'std'; did you mean 'auto_ptr'?
       int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
                         ~~~~~^~~~~~~
                              auto_ptr
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward/auto_ptr.h:89:11: note: 'auto_ptr' declared here
    class auto_ptr
          ^
p618.cpp:38:51: error: use of undeclared identifier 'file_ptr'
       int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
                                                  ^
p618.cpp:47:47: warning: variadic templates are a C++11 extension [-Wc++11-extensions]
    template<class Smart, class Pointer, class... Args>
                                              ^
p618.cpp:51:37: warning: deleted function definitions are a C++11 extension [-Wc++11-extensions]
      out_ptr_t(const out_ptr_t&) = delete;
                                    ^
p618.cpp:53:26: error: expected ';' at end of declaration list
operator Pointer*() const noexcept;
                         ^
                         ;
p618.cpp:54:30: error: expected ';' at end of declaration list
      operator void**() const noexcept;
                             ^
                             ;
p618.cpp:55:3: error: expected member name or ';' after declaration specifiers
  if (p) {
  ^
p618.cpp:67:5: error: no template named 'tuple'
    tuple<Args...> a;
    ^
p618.cpp:75:23: error: unknown type name 'Smart'
   explicit out_ptr_t(Smart& smart, Args... args);
                      ^
p618.cpp:75:37: error: unknown type name 'Args'
   explicit out_ptr_t(Smart& smart, Args... args);
                                    ^
p618.cpp:75:41: error: type 'int' of function parameter pack does not contain any unexpanded parameter packs
   explicit out_ptr_t(Smart& smart, Args... args);
                                    ~~~~^~~~~~~~
p618.cpp:75:13: error: C++ requires a type specifier for all declarations
   explicit out_ptr_t(Smart& smart, Args... args);
   ~~~~~~~~ ^
p618.cpp:78:2: error: identifier 'out_ptr_t' after '~' in destructor name does not name a type
~out_ptr_t();
 ^
p618.cpp:48:11: note: non-type declaration found by destructor name lookup
    class out_ptr_t {
          ^
p618.cpp:81:10: error: unknown type name 'Pointer'
operator Pointer*() const noexcept;
         ^
p618.cpp:84:31: error: expected function body after function declarator
      operator void**() const noexcept;
                              ^
2 warnings and 18 errors generated.
rm: cannot remove 'p618l': No such file or directory
$ clang++ p618.cpp -std=c++2b -o p618l -I. -Wall
p618.cpp:38:31: error: no template named 'out_ptr' in namespace 'std'; did you mean 'auto_ptr'?
       int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
                         ~~~~~^~~~~~~
                              auto_ptr
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward/auto_ptr.h:89:11: note: 'auto_ptr' declared here
    class auto_ptr
          ^
p618.cpp:38:26: error: no matching conversion for functional-style cast from 'std::unique_ptr<std::FILE, fclose_deleter>' (aka 'unique_ptr<_IO_FILE, fclose_deleter>') to 'std::auto_ptr<std::FILE *>' (aka 'auto_ptr<_IO_FILE *>')
       int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward/auto_ptr.h:105:7: note: candidate constructor not viable: no known conversion from 'std::unique_ptr<std::FILE, fclose_deleter>' (aka 'unique_ptr<_IO_FILE, fclose_deleter>') to 'std::auto_ptr<_IO_FILE *>::element_type *' (aka '_IO_FILE **') for 1st argument
      auto_ptr(element_type* __p = 0) throw() : _M_ptr(__p) { }
      ^
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward/auto_ptr.h:114:7: note: candidate constructor not viable: no known conversion from 'std::unique_ptr<std::FILE, fclose_deleter>' (aka 'unique_ptr<_IO_FILE, fclose_deleter>') to 'std::auto_ptr<_IO_FILE *> &' for 1st argument
      auto_ptr(auto_ptr& __a) throw() : _M_ptr(__a.release()) { }
      ^
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward/auto_ptr.h:266:7: note: candidate constructor not viable: no known conversion from 'std::unique_ptr<std::FILE, fclose_deleter>' (aka 'unique_ptr<_IO_FILE, fclose_deleter>') to 'auto_ptr_ref<std::auto_ptr<_IO_FILE *>::element_type>' (aka 'auto_ptr_ref<_IO_FILE *>') for 1st argument
      auto_ptr(auto_ptr_ref<element_type> __ref) throw()
      ^
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward/auto_ptr.h:127:9: note: candidate template ignored: could not match 'auto_ptr' against 'unique_ptr'
        auto_ptr(auto_ptr<_Tp1>& __a) throw() : _M_ptr(__a.release()) { }
        ^
p618.cpp:38:18: error: no matching function for call to 'fopen_s'
       int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
                 ^~~~~~~
p618.cpp:29:10: note: candidate function not viable: no known conversion from 'std::auto_ptr<std::FILE *>' (aka 'auto_ptr<_IO_FILE *>') to 'std::FILE **' (aka '_IO_FILE **') for 1st argument
     int fopen_s(std::FILE** f, const char* name, const char* mode);
         ^
p618.cpp:38:31: warning: 'auto_ptr<_IO_FILE *>' is deprecated [-Wdeprecated-declarations]
       int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
                              ^
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward/auto_ptr.h:287:7: note: 'auto_ptr<_IO_FILE *>' has been explicitly marked deprecated here
    } _GLIBCXX_DEPRECATED;
      ^
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10/bits/c++config.h:88:46: note: expanded from macro '_GLIBCXX_DEPRECATED'
# define _GLIBCXX_DEPRECATED __attribute__ ((__deprecated__))
                                             ^
p618.cpp:55:3: error: expected member name or ';' after declaration specifiers
  if (p) {
  ^
p618.cpp:75:23: error: unknown type name 'Smart'
   explicit out_ptr_t(Smart& smart, Args... args);
                      ^
p618.cpp:75:37: error: unknown type name 'Args'
   explicit out_ptr_t(Smart& smart, Args... args);
                                    ^
p618.cpp:75:41: error: type 'int' of function parameter pack does not contain any unexpanded parameter packs
   explicit out_ptr_t(Smart& smart, Args... args);
                                    ~~~~^~~~~~~~
p618.cpp:75:13: error: deduction guide must be declared in the same scope as template 'std::out_ptr_t'
   explicit out_ptr_t(Smart& smart, Args... args);
            ^
p618.cpp:48:11: note: template is declared here
    class out_ptr_t {
          ^
p618.cpp:75:13: error: deduction guide declaration without trailing return type
   explicit out_ptr_t(Smart& smart, Args... args);
            ^
p618.cpp:78:2: error: identifier 'out_ptr_t' after '~' in destructor name does not name a type
~out_ptr_t();
 ^
p618.cpp:48:11: note: non-type declaration found by destructor name lookup
    class out_ptr_t {
          ^
p618.cpp:81:10: error: unknown type name 'Pointer'
operator Pointer*() const noexcept;
         ^
p618.cpp:84:25: error: non-member function cannot have 'const' qualifier
      operator void**() const noexcept;
                        ^~~~~~
p618.cpp:84:7: error: conversion function must be a non-static member function
      operator void**() const noexcept;
      ^
1 warning and 13 errors generated.

$ g++ p618.cpp -std=c++03 -o p618g -I. -Wall
In file included from /usr/local/include/c++/12.1.0/atomic:38,
                 from p618.cpp:19:
/usr/local/include/c++/12.1.0/bits/c++0x_warning.h:32:2: error: #error This file requires compiler and library support for the ISO C++ 2011 standard. This support must be enabled with the -std=c++11 or -std=gnu++11 compiler options.
   32 | #error This file requires compiler and library support \
      |  ^~~~~
p618.cpp:31:44: warning: identifier 'noexcept' is a keyword in C++11 [-Wc++11-compat]
   31 |        void operator()(std::FILE* f) const noexcept {
      |                                            ^~~~~~~~
p618.cpp:36:8: warning: identifier 'constexpr' is a keyword in C++11 [-Wc++11-compat]
   36 |        constexpr const char* file_name = "ow.o";
      |        ^~~~~~~~~
p618.cpp:31:38: error: expected ';' at end of member declaration
   31 |        void operator()(std::FILE* f) const noexcept {
      |                                      ^~~~~
      |                                           ;
p618.cpp:31:44: error: 'noexcept' does not name a type
   31 |        void operator()(std::FILE* f) const noexcept {
      |                                            ^~~~~~~~
p618.cpp:31:44: note: C++11 'noexcept' only available with '-std=c++11' or '-std=gnu++11'
p618.cpp: In function 'int main(int, char**)':
p618.cpp:36:8: error: 'constexpr' was not declared in this scope
   36 |        constexpr const char* file_name = "ow.o";
      |        ^~~~~~~~~
p618.cpp:37:13: error: 'unique_ptr' is not a member of 'std'
   37 |        std::unique_ptr<std::FILE, fclose_deleter> file_ptr;
      |             ^~~~~~~~~~
p618.cpp:37:13: note: 'std::unique_ptr' is only available from C++11 onwards
p618.cpp:37:33: error: expected primary-expression before ',' token
   37 |        std::unique_ptr<std::FILE, fclose_deleter> file_ptr;
      |                                 ^
p618.cpp:37:49: error: expected primary-expression before '>' token
   37 |        std::unique_ptr<std::FILE, fclose_deleter> file_ptr;
      |                                                 ^
p618.cpp:37:51: error: 'file_ptr' was not declared in this scope
   37 |        std::unique_ptr<std::FILE, fclose_deleter> file_ptr;
      |                                                   ^~~~~~~~
p618.cpp:38:31: error: 'out_ptr' is not a member of 'std'; did you mean 'auto_ptr'?
   38 |        int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
      |                               ^~~~~~~
      |                               auto_ptr
p618.cpp:38:48: error: expected primary-expression before '*' token
   38 |        int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
      |                                                ^
p618.cpp:38:49: error: expected primary-expression before '>' token
   38 |        int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
      |                                                 ^
p618.cpp:38:62: error: 'file_name' was not declared in this scope
   38 |        int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
      |                                                              ^~~~~~~~~
p618.cpp: At global scope:
p618.cpp:47:47: warning: variadic templates only available with '-std=c++11' or '-std=gnu++11' [-Wc++11-extensions]
   47 |     template<class Smart, class Pointer, class... Args>
      |                                               ^~~
p618.cpp:50:38: warning: variadic templates only available with '-std=c++11' or '-std=gnu++11' [-Wc++11-extensions]
   50 |       explicit out_ptr_t(Smart&, Args...);
      |                                      ^~~
p618.cpp:51:37: warning: defaulted and deleted functions only available with '-std=c++11' or '-std=gnu++11' [-Wc++11-extensions]
   51 |       out_ptr_t(const out_ptr_t&) = delete;
      |                                     ^~~~~~
p618.cpp:53:21: error: expected ';' at end of member declaration
   53 | operator Pointer*() const noexcept;
      |                     ^~~~~
      |                          ;
p618.cpp:53:27: error: 'noexcept' does not name a type
   53 | operator Pointer*() const noexcept;
      |                           ^~~~~~~~
p618.cpp:53:27: note: C++11 'noexcept' only available with '-std=c++11' or '-std=gnu++11'
p618.cpp:54:25: error: expected ';' at end of member declaration
   54 |       operator void**() const noexcept;
      |                         ^~~~~
      |                              ;
p618.cpp:54:31: error: 'noexcept' does not name a type
   54 |       operator void**() const noexcept;
      |                               ^~~~~~~~
p618.cpp:54:31: note: C++11 'noexcept' only available with '-std=c++11' or '-std=gnu++11'
p618.cpp:55:3: error: expected unqualified-id before 'if'
   55 |   if (p) {
      |   ^~
p618.cpp:60:3: error: expected unqualified-id before 'if'
   60 |   if (p) {
      |   ^~
p618.cpp:67:5: error: 'tuple' does not name a type
   67 |     tuple<Args...> a;
      |     ^~~~~
p618.cpp:75:13: error: ISO C++ forbids declaration of 'out_ptr_t' with no type [-fpermissive]
   75 |    explicit out_ptr_t(Smart& smart, Args... args);
      |             ^~~~~~~~~
p618.cpp:75:4: error: 'explicit' outside class declaration
   75 |    explicit out_ptr_t(Smart& smart, Args... args);
      |    ^~~~~~~~
p618.cpp:75:23: error: 'Smart' was not declared in this scope
   75 |    explicit out_ptr_t(Smart& smart, Args... args);
      |                       ^~~~~
p618.cpp:75:30: error: 'smart' was not declared in this scope
   75 |    explicit out_ptr_t(Smart& smart, Args... args);
      |                              ^~~~~
p618.cpp:75:37: error: 'Args' was not declared in this scope
   75 |    explicit out_ptr_t(Smart& smart, Args... args);
      |                                     ^~~~
p618.cpp:75:49: error: expression list treated as compound expression in initializer [-fpermissive]
   75 |    explicit out_ptr_t(Smart& smart, Args... args);
      |                                                 ^
p618.cpp:78:11: error: expected class-name before '(' token
   78 | ~out_ptr_t();
      |           ^
p618.cpp:81:10: error: 'Pointer' does not name a type
   81 | operator Pointer*() const noexcept;
      |          ^~~~~~~
p618.cpp:84:31: error: expected constructor, destructor, or type conversion before 'noexcept'
   84 |       operator void**() const noexcept;
      |                               ^~~~~~~~
rm: cannot remove 'p618g': No such file or directory

$ g++ p618.cpp -std=c++2b -o p618g -I. -Wall
p618.cpp: In function 'int main(int, char**)':
p618.cpp:38:31: error: 'out_ptr' is not a member of 'std'; did you mean 'auto_ptr'?
   38 |        int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
      |                               ^~~~~~~
      |                               auto_ptr
p618.cpp:38:48: error: expected primary-expression before '*' token
   38 |        int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
      |                                                ^
p618.cpp:38:49: error: expected primary-expression before '>' token
   38 |        int err = fopen_s(std::out_ptr<std::FILE*>(file_ptr), file_name, "r+b");
      |                                                 ^
p618.cpp: At global scope:
p618.cpp:55:3: error: expected unqualified-id before 'if'
   55 |   if (p) {
      |   ^~
p618.cpp:60:3: error: expected unqualified-id before 'if'
   60 |   if (p) {
      |   ^~
p618.cpp:75:28: error: expected ')' before '&' token
   75 |    explicit out_ptr_t(Smart& smart, Args... args);
      |                      ~     ^
      |                            )
p618.cpp:78:11: error: expected class-name before '(' token
   78 | ~out_ptr_t();
      |           ^
p618.cpp:81:10: error: 'Pointer' does not name a type
   81 | operator Pointer*() const noexcept;
      |          ^~~~~~~
p618.cpp:84:39: error: expected constructor, destructor, or type conversion before ';' token
   84 |       operator void**() const noexcept;
      |                                       ^
```

## 検討事項(agenda)
コンパイルエラーを取るか、コンパイルエラーの理由を解説する。

<!-- リンクエラーの解説をする。clang++とg++の比較。意味のある出力。
コンパイルエラーを取るか、コンパイルエラーの理由を解説する。-->

## Script

```bash:clgc.sh
#!/bin/sh
rm $1l
rm $1g
echo "$ clang++ $1.cpp -std=03 -o $1l -I. -Wall" 
clang++ $1.cpp -std=c++03 -o $1l -I. -Wall
if [  -e $1l ]; then
./$1l 
fi
rm $1l
echo "$ clang++ $1.cpp -std=2b -o $1l -I. -Wall"
clang++ $1.cpp -std=c++2b -o $1l -I. -Wall
if [  -e $1l ]; then
./$1l
fi
echo "\r"
echo "$ g++ $1.cpp -std=03 -o $1g -I. -Wall"
g++ $1.cpp -std=c++03 -o $1g -I. -Wall
if [ -e $1g ]; then
./$1g
fi
rm $1g
echo "\r"
echo "$ g++ $1.cpp -std=2b -o $1g -I. -Wall"
g++ $1.cpp -std=c++2b -o $1g -I. -Wall
if [ -e $1g ]; then
./$1g 
fi
```

# 参考資料(reference)

cpprefjp - C++日本語リファレンス

https://cpprefjp.github.io/

コンパイラの実装状況

https://cpprefjp.github.io/implementation-status.html


typedef は C++11 ではオワコン

https://qiita.com/Linda_pp/items/44a67c64c14cba00eef1

C99からC++14を駆け抜けるC++講座

https://qiita.com/yumetodo/items/e49a673afd9a3ecb81a8


@kazuo_reve 私が効果を確認した「小川メソッド」

https://qiita.com/kazuo_reve/items/a3ea1d9171deeccc04da

## 自己参照(self reference)

C++N4910:2022 tag follower 200人超えました。ありがとうございます。

https://qiita.com/kaizen_nagoya/items/a63fb96d351ac5c16ff7

DoCAP（ドゥーキャップ）って何ですか？

https://qiita.com/kaizen_nagoya/items/47e0e6509ab792c43327


小川メソッド　覚え（書きかけ）

https://qiita.com/kaizen_nagoya/items/3593d72eca551742df68

C++N4910:2022 tag follower 200人超えました。ありがとうございます。

https://qiita.com/kaizen_nagoya/items/a63fb96d351ac5c16ff7

コピペコンパイルエラーあるある

https://qiita.com/kaizen_nagoya/items/29c832de9d762aed2761

C++ Error Message Collection(1)does not name a type, 11 articles

https://qiita.com/kaizen_nagoya/items/acb9f1a9b5aad6df06bd

dockerにclang

https://qiita.com/kaizen_nagoya/items/8829ffeee397eda50e80

docker gnu(gcc/g++) and llvm(clang/clang++)

https://qiita.com/drafts/059874ea39c4de64c0f7

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

Compare the contents of C++N4910:2022, C++N4741:2018 and C++N4606:2015

https://qiita.com/kaizen_nagoya/items/483246d40f98abff7ded

C++ sample list

https://qiita.com/kaizen_nagoya/items/54ad75b73825b7c04f86


clang++, g++コンパイルエラー方針の違いの例

https://qiita.com/kaizen_nagoya/items/ea6e5009fe126d270a82

astyle 使ってみた

https://qiita.com/kaizen_nagoya/items/3c9a87a781d53a1a23f3

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

Clang/Clang++(LLVM) gcc/g++(GNU) コンパイラ警告等比較
https://qiita.com/kaizen_nagoya/items/9a82b958cc3aeef0403f

C++2003とC++2017でコンパイルエラーになるならない事例集
https://qiita.com/kaizen_nagoya/items/a13ea3823441c430edff

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

cpprefjpのdecltypeをコンパイル試験
https://qiita.com/kaizen_nagoya/items/090909af702f0d5d8a67

MISRA C++ 5-0-16
https://qiita.com/kaizen_nagoya/items/7df2d4e05db724752a74

C++ Templates Part1 BASICS Chapter 3. Class Templates 3.2 Use of Class Template Stack stack1test.cpp
https://qiita.com/kaizen_nagoya/items/cd5fc49106fad5a4e9ed

ISO/IEC TS 17961:2013 C Secure Coding Rules(1) All list(to be confirmed)
https://qiita.com/kaizen_nagoya/items/54e056195c4f11b850a1

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

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

'wchar.h' file not found で困った clang++ macOS
https://qiita.com/kaizen_nagoya/items/de15cd46d657517fac11

Open POSIX Test Suiteの使い方を調べはじめました
https://qiita.com/kaizen_nagoya/items/644d5e407f5faf96e6dc

MISRA-C 2012 Referenceに掲載している文献の入手可能性を確認
https://qiita.com/kaizen_nagoya/items/96dc8b125e462d5575bb

どうやって MISRA Example Suiteをコンパイルするか
https://qiita.com/kaizen_nagoya/items/fbdbff5ff696e2ca7f00

MISRA C まとめ #include <misra_c.h>
https://qiita.com/kaizen_nagoya/items/f1a79a7cbd281607c7c9

「C++完全理解ガイド」の同意できること上位10
https://qiita.com/kaizen_nagoya/items/aa5744e0c4a8618c7671


 ＜この記事は個人の過去の経験に基づく個人の感想です。現在所属する組織、業務とは関係がありません。＞

# 文書履歴(document history)
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