20.3.2.2.2 Constructors [util.smartptr.shared.const] C++N4910:2022 (457) p605.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.

# 20.3.2.2.2 Constructors [util.smartptr.shared.const] C++N4910:2022 (457) p605.cpp

## 算譜(source code)

```c++:p605.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 = "20.3.2.2.2 Constructors [util.smartptr.shared.const] C++N4910:2022 (457) p605.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 <typeinfo>

using namespace std;

// Example 1
if (p != nullptr && p->weak_this.expired())
    p->weak_this = shared_ptr<remove_cv_t<Y>>(*this, const_cast<remove_cv_t<Y>*>(p));
//The assignment to the weak_this member is not atomic and conflicts with any potentially concurrent access to the same object (6.9.2).
constexpr shared_ptr() noexcept;
// Postconditions: use_count() == 0 && get() == nullptr. template<class Y> explicit shared_ptr(Y* p)
// Constraints: When T is an array type, the expression delete[] p is well-formed and either T is U[N] and Y(*)[N] is convertible to T*, or T is U[] and Y(*)[] is convertible to T*. When T is not an array type, the expression delete p is well-formed and Y* is convertible to T*.
// Mandates: Y is a complete type.
// Preconditions: The expression delete[] p, when T is an array type, or delete p, when T is not an array type, has well-defined behavior, and does not throw exceptions.
// Effects: When T is not an array type, constructs a shared_ptr object that owns the pointer p. Otherwise, constructs a shared_ptr that owns p and a deleter of an unspecified type that calls delete[] p. When T is not an array type, enables shared_from_this with p. If an exception is thrown, delete p is called when T is not an array type, delete[] p otherwise.
// Postconditions: use_count() == 1 && get() == p.
// Throws: bad_alloc, or an implementation-defined exception when a resource other than memory cannot be obtained.
template<class Y, class D> shared_ptr(Y* p, D d);
template<class Y, class D, class A> shared_ptr(Y* p, D d, A a);
template<class D> shared_ptr(nullptr_t p, D d);
template<class D, class A> shared_ptr(nullptr_t p, D d, A a);
// Constraints: is_move_constructible_v<D> is true, and d(p) is a well-formed expression. For the first two overloads:
// — If T is an array type, then either T is U[N] and Y(*)[N] is convertible to T*, or T is U[] and Y(*)[] is convertible to T*.
// — If T is not an array type, then Y* is convertible to T*.
// Preconditions: Construction of d and a deleter of type D initialized with std::move(d) do not throw exceptions. The expression d(p) has well-defined behavior and does not throw exceptions. A meets the Cpp17Allocator requirements (16.4.4.6.1).
// Effects: Constructs a shared_ptr object that owns the object p and the deleter d. When T is not an array type, the first and second constructors enable shared_from_this with p. The second and fourth constructors shall use a copy of a to allocate memory for internal use. If an exception is thrown, d(p) is called.
// Postconditions: use_count() == 1 && get() == p.
// Throws: bad_alloc, or an implementation-defined exception when a resource other than memory cannot be obtained.
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
// Effects: Constructs a shared_ptr instance that stores p and shares ownership with the initial value of r.
// Postconditions: get() == p. For the second overload, r is empty and r.get() == nullptr.
// [Note 1: Use of this constructor leads to a dangling pointer unless p remains valid at least until the ownership group of r is destroyed.
// [Note 2: This constructor allows creation of an empty shared_ptr instance with a non-null stored pointer.
shared_ptr(const shared_ptr& r) noexcept;
template<class Y> shared_ptr(const shared_ptr<Y>& r) noexcept;
// Constraints: For the second constructor, Y* is compatible with T*.
// Effects: If r is empty, constructs an empty shared_ptr object; otherwise, constructs a shared_ptr
object that shares ownership with r.
// Postconditions: get() == r.get() && use_count() == r.use_count().
shared_ptr(shared_ptr&& r) noexcept;
template<class Y> shared_ptr(shared_ptr<Y>&& r) noexcept;
// Constraints: For the second constructor, Y* is compatible with T*.
// Effects: Move constructs a shared_ptr instance from r.
// Postconditions: *this contains the old value of r. r is empty, and r.get() == nullptr.
template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
// Constraints: Y* is compatible with T*.
// Effects: Constructs a shared_ptr object that shares ownership with r and stores a copy of the pointerstored in r. If an exception is thrown, the constructor has no effect. Postconditions: use_count() == r.use_count().
// Throws: bad_weak_ptr when r.expired().
template<class Y, class D> shared_ptr(unique_ptr<Y, D>&& r);
// Constraints: Y* is compatible with T* and unique_ptr<Y, D>::pointer is convertible to element_- type*.
// Effects: If r.get() == nullptr, equivalent to shared_ptr(). Otherwise, if D is not a reference type, equivalent to shared_ptr(r.release(), std::move(r.get_deleter())). Otherwise, equivalent to shared_ptr(r.release(), ref(r.get_deleter())). If an exception is thrown, the constructor has no effect.
int main() {
    cout  <<  n4910 << endl;
    return EXIT_SUCCESS;
}
```

## 編纂・実行結果(compile and go)

```ubuntu:bash
$ clang++ p605.cpp -std=c++03 -o p605l -I. -Wall
In file included from p605.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 \
 ^
p605.cpp:26:1: error: expected unqualified-id
if (p != nullptr && p->weak_this.expired())
^
p605.cpp:29:4: error: unknown type name 'constexpr'
   constexpr shared_ptr() noexcept;
   ^
p605.cpp:29:27: error: expected function body after function declarator
   constexpr shared_ptr() noexcept;
                          ^
p605.cpp:37:28: error: C++ requires a type specifier for all declarations
template<class Y, class D> shared_ptr(Y* p, D d);
                           ^
p605.cpp:38:37: error: C++ requires a type specifier for all declarations
template<class Y, class D, class A> shared_ptr(Y* p, D d, A a);
                                    ^
p605.cpp:39:30: error: unknown type name 'nullptr_t'
template<class D> shared_ptr(nullptr_t p, D d);
                             ^
p605.cpp:39:19: error: C++ requires a type specifier for all declarations
template<class D> shared_ptr(nullptr_t p, D d);
                  ^
p605.cpp:40:39: error: unknown type name 'nullptr_t'
template<class D, class A> shared_ptr(nullptr_t p, D d, A a);
                                      ^
p605.cpp:40:28: error: C++ requires a type specifier for all declarations
template<class D, class A> shared_ptr(nullptr_t p, D d, A a);
                           ^
p605.cpp:48:36: error: parameter name cannot have template arguments
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                                   ^
p605.cpp:48:36: error: C++ requires a type specifier for all declarations
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                             ~~~~~ ^
p605.cpp:48:49: error: expected ')'
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                                                ^
p605.cpp:48:29: note: to match this '('
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                            ^
p605.cpp:48:19: error: C++ requires a type specifier for all declarations
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                  ^
p605.cpp:48:70: error: expected ';' at end of declaration
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                                                                     ^
                                                                     ;
p605.cpp:48:71: error: C++ requires a type specifier for all declarations
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                                                                      ^
p605.cpp:49:19: error: C++ requires a type specifier for all declarations
template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
                  ^
p605.cpp:49:19: warning: variable templates are a C++14 extension [-Wc++14-extensions]
p605.cpp:49:46: error: use of undeclared identifier 'r'
template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
                                             ^
p605.cpp:49:49: error: use of undeclared identifier 'element_type'
template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
                                                ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
1 warning and 20 errors generated.
rm: cannot remove 'p605l': No such file or directory
$ clang++ p605.cpp -std=c++2b -o p605l -I. -Wall
p605.cpp:26:1: error: expected unqualified-id
if (p != nullptr && p->weak_this.expired())
^
p605.cpp:29:14: error: C++ requires a type specifier for all declarations
   constexpr shared_ptr() noexcept;
   ~~~~~~~~~ ^
p605.cpp:37:28: error: C++ requires a type specifier for all declarations
template<class Y, class D> shared_ptr(Y* p, D d);
                           ^
p605.cpp:38:37: error: C++ requires a type specifier for all declarations
template<class Y, class D, class A> shared_ptr(Y* p, D d, A a);
                                    ^
p605.cpp:39:19: error: C++ requires a type specifier for all declarations
template<class D> shared_ptr(nullptr_t p, D d);
                  ^
p605.cpp:40:28: error: C++ requires a type specifier for all declarations
template<class D, class A> shared_ptr(nullptr_t p, D d, A a);
                           ^
p605.cpp:48:36: error: parameter name cannot have template arguments
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                                   ^
p605.cpp:48:36: error: C++ requires a type specifier for all declarations
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                             ~~~~~ ^
p605.cpp:48:49: error: expected ')'
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                                                ^
p605.cpp:48:29: note: to match this '('
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                            ^
p605.cpp:48:19: error: C++ requires a type specifier for all declarations
template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
                  ^
p605.cpp:49:19: error: C++ requires a type specifier for all declarations
template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
                  ^
p605.cpp:49:46: error: use of undeclared identifier 'r'
template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
                                             ^
p605.cpp:49:49: error: use of undeclared identifier 'element_type'
template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
                                                ^
p605.cpp:49:63: error: use of undeclared identifier 'p'
template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
                                                              ^
p605.cpp:49:65: error: expected ';' at end of declaration
template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
                                                                ^
                                                                ;
p605.cpp:49:66: error: expected unqualified-id
template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
                                                                 ^
p605.cpp:54:18: error: unknown type name 'shared_ptr'
shared_ptr(const shared_ptr& r) noexcept;
                 ^
p605.cpp:54:1: error: C++ requires a type specifier for all declarations
shared_ptr(const shared_ptr& r) noexcept;
^
p605.cpp:55:36: error: parameter name cannot have template arguments
template<class Y> shared_ptr(const shared_ptr<Y>& r) noexcept;
                                   ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

$ g++ p605.cpp -std=c++03 -o p605g -I. -Wall
In file included from /usr/local/include/c++/12.1.0/atomic:38,
                 from p605.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 \
      |  ^~~~~
p605.cpp:26:10: warning: identifier 'nullptr' is a keyword in C++11 [-Wc++11-compat]
   26 | if (p != nullptr && p->weak_this.expired())
      |          ^~~~~~~
p605.cpp:29:4: warning: identifier 'constexpr' is a keyword in C++11 [-Wc++11-compat]
   29 |    constexpr shared_ptr() noexcept;
      |    ^~~~~~~~~
p605.cpp:29:27: warning: identifier 'noexcept' is a keyword in C++11 [-Wc++11-compat]
   29 |    constexpr shared_ptr() noexcept;
      |                           ^~~~~~~~
p605.cpp:26:1: error: expected unqualified-id before 'if'
   26 | if (p != nullptr && p->weak_this.expired())
      | ^~
p605.cpp:29:4: error: 'constexpr' does not name a type
   29 |    constexpr shared_ptr() noexcept;
      |    ^~~~~~~~~
p605.cpp:29:4: note: C++11 'constexpr' only available with '-std=c++11' or '-std=gnu++11'
p605.cpp:37:49: error: expected constructor, destructor, or type conversion before ';' token
   37 | template<class Y, class D> shared_ptr(Y* p, D d);
      |                                                 ^
p605.cpp:38:63: error: expected constructor, destructor, or type conversion before ';' token
   38 | template<class Y, class D, class A> shared_ptr(Y* p, D d, A a);
      |                                                               ^
p605.cpp:39:29: error: expected constructor, destructor, or type conversion before '(' token
   39 | template<class D> shared_ptr(nullptr_t p, D d);
      |                             ^
p605.cpp:40:38: error: expected constructor, destructor, or type conversion before '(' token
   40 | template<class D, class A> shared_ptr(nullptr_t p, D d, A a);
      |                                      ^
p605.cpp:48:36: error: 'shared_ptr' does not name a type
   48 | template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
      |                                    ^~~~~~~~~~
p605.cpp:48:46: error: expected ',' or '...' before '<' token
   48 | template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
      |                                              ^
p605.cpp:48:71: error: expected constructor, destructor, or type conversion before 'noexcept'
   48 | template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
      |                                                                       ^~~~~~~~
p605.cpp:49:29: error: expected constructor, destructor, or type conversion before '(' token
   49 | template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
      |                             ^
p605.cpp:54:18: error: 'shared_ptr' does not name a type
   54 | shared_ptr(const shared_ptr& r) noexcept;
      |                  ^~~~~~~~~~
p605.cpp:54:33: error: expected constructor, destructor, or type conversion before 'noexcept'
   54 | shared_ptr(const shared_ptr& r) noexcept;
      |                                 ^~~~~~~~
p605.cpp:55:36: error: 'shared_ptr' does not name a type
   55 | template<class Y> shared_ptr(const shared_ptr<Y>& r) noexcept;
      |                                    ^~~~~~~~~~
p605.cpp:55:46: error: expected ',' or '...' before '<' token
   55 | template<class Y> shared_ptr(const shared_ptr<Y>& r) noexcept;
      |                                              ^
p605.cpp:55:54: error: expected constructor, destructor, or type conversion before 'noexcept'
   55 | template<class Y> shared_ptr(const shared_ptr<Y>& r) noexcept;
      |                                                      ^~~~~~~~
p605.cpp:58:1: error: 'object' does not name a type
   58 | object that shares ownership with r.
      | ^~~~~~
p605.cpp:61:29: error: expected constructor, destructor, or type conversion before '(' token
   61 | template<class Y> shared_ptr(shared_ptr<Y>&& r) noexcept;
      |                             ^
p605.cpp:65:45: error: 'weak_ptr' does not name a type
   65 | template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
      |                                             ^~~~~~~~
p605.cpp:65:53: error: expected ',' or '...' before '<' token
   65 | template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
      |                                                     ^
p605.cpp:65:28: error: ISO C++ forbids declaration of 'shared_ptr' with no type [-fpermissive]
   65 | template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
      |                            ^~~~~~~~~~
p605.cpp:65:19: error: 'explicit' outside class declaration
   65 | template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
      |                   ^~~~~~~~
p605.cpp:69:43: error: expected constructor, destructor, or type conversion before '(' token
   69 |      template<class Y, class D> shared_ptr(unique_ptr<Y, D>&& r);
      |                                           ^
rm: cannot remove 'p605g': No such file or directory

$ g++ p605.cpp -std=c++2b -o p605g -I. -Wall
p605.cpp:26:1: error: expected unqualified-id before 'if'
   26 | if (p != nullptr && p->weak_this.expired())
      | ^~
p605.cpp:29:14: error: ISO C++ forbids declaration of 'shared_ptr' with no type [-fpermissive]
   29 |    constexpr shared_ptr() noexcept;
      |              ^~~~~~~~~~
p605.cpp:37:49: error: expected constructor, destructor, or type conversion before ';' token
   37 | template<class Y, class D> shared_ptr(Y* p, D d);
      |                                                 ^
p605.cpp:38:63: error: expected constructor, destructor, or type conversion before ';' token
   38 | template<class Y, class D, class A> shared_ptr(Y* p, D d, A a);
      |                                                               ^
p605.cpp:39:47: error: expected constructor, destructor, or type conversion before ';' token
   39 | template<class D> shared_ptr(nullptr_t p, D d);
      |                                               ^
p605.cpp:40:61: error: expected constructor, destructor, or type conversion before ';' token
   40 | template<class D, class A> shared_ptr(nullptr_t p, D d, A a);
      |                                                             ^
p605.cpp:48:49: error: expected '(' after template-argument-list
   48 | template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
      |                                                 ^
p605.cpp:48:36: error: 'shared_ptr' does not name a type
   48 | template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
      |                                    ^~~~~~~~~~
p605.cpp:48:54: error: 'element_type' has not been declared
   48 | template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
      |                                                      ^~~~~~~~~~~~
p605.cpp:48:79: error: expected constructor, destructor, or type conversion before ';' token
   48 | template<class Y> shared_ptr(const shared_ptr<Y>& r, element_type* p) noexcept;
      |                                                                               ^
p605.cpp:49:43: error: expected '(' after template-argument-list
   49 | template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
      |                                           ^~
p605.cpp:49:29: error: expected constructor, destructor, or type conversion before '(' token
   49 | template<class Y> shared_ptr(shared_ptr<Y>&& r, element_type* p) noexcept;
      |                             ^
p605.cpp:54:18: error: 'shared_ptr' does not name a type
   54 | shared_ptr(const shared_ptr& r) noexcept;
      |                  ^~~~~~~~~~
p605.cpp:54:41: error: expected constructor, destructor, or type conversion before ';' token
   54 | shared_ptr(const shared_ptr& r) noexcept;
      |                                         ^
p605.cpp:55:49: error: expected '(' after template-argument-list
   55 | template<class Y> shared_ptr(const shared_ptr<Y>& r) noexcept;
      |                                                 ^
p605.cpp:55:36: error: 'shared_ptr' does not name a type
   55 | template<class Y> shared_ptr(const shared_ptr<Y>& r) noexcept;
      |                                    ^~~~~~~~~~
p605.cpp:55:62: error: expected constructor, destructor, or type conversion before ';' token
   55 | template<class Y> shared_ptr(const shared_ptr<Y>& r) noexcept;
      |                                                              ^
p605.cpp:58:1: error: 'object' does not name a type
   58 | object that shares ownership with r.
      | ^~~~~~
p605.cpp:61:43: error: expected '(' after template-argument-list
   61 | template<class Y> shared_ptr(shared_ptr<Y>&& r) noexcept;
      |                                           ^~
p605.cpp:61:29: error: expected constructor, destructor, or type conversion before '(' token
   61 | template<class Y> shared_ptr(shared_ptr<Y>&& r) noexcept;
      |                             ^
p605.cpp:65:45: error: 'weak_ptr' does not name a type
   65 | template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
      |                                             ^~~~~~~~
p605.cpp:65:53: error: expected ',' or '...' before '<' token
   65 | template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
      |                                                     ^
p605.cpp:65:28: error: ISO C++ forbids declaration of 'shared_ptr' with no type [-fpermissive]
   65 | template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
      |                            ^~~~~~~~~~
p605.cpp:65:19: error: 'explicit' outside class declaration
   65 | template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
      |                   ^~~~~~~~
p605.cpp:69:43: error: expected constructor, destructor, or type conversion before '(' token
   69 |      template<class Y, class D> shared_ptr(unique_ptr<Y, D>&& r);
      |                                           ^
```

## 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)
ver. 0.01 初稿 　20220720