13.3 Names of template specializations [temp.names] C++N4910:2022 (199) p359.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.

# 13.3 Names of template specializations [temp.names] C++N4910:2022 (199) p359.cpp

## 算譜(source code)

```c++:p359.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 = "13.3 Names of template specializations [temp.names] C++N4910:2022 (199) p359.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
struct X {
    template<std::size_t> X* alloc();
    template<std::size_t> static X* adjust();
};
template<class T> void f(T* p) {
    T* p1 = p->alloc<200>();
    T* p2 = p->template alloc<200>();
    T::adjust<100>();
    T::template adjust<100>();
// error: < means less than
// OK, < starts template argument list // error: < means less than
// OK, < starts template argument list
}
// [Example 2:
template<int i> class X { /* ... */
};
X< 1>2 > x1; // syntax error X<(1>2)> x2; // OK
template<class T> class Y { /* ... */
};
Y<X<1>> x3;
Y<X<6>>1>> x4;
Y<X<(6>>1)>> x5;
// OK, same as Y<X<1> > x3;
// syntax error
// OK
// [Example 3:
template <class T> struct A {
    void f(int);
    template <class U> void f(U);
};
template <class T> void f(T t) {
    A<T> a;
    a.template f<>(t);
    a.template f(t);
    template <class T> struct B {
        template <class T2> struct C { };
    };
// OK, calls template
// error: not a template-id
}
// deprecated: T::C is assumed to name a class template:
template <class T, template <class X> class TT = T::template C> struct D { };
D<B<int> > db;
// [Example 4:
template<class T, T::type n = 0> class X;
struct S {
    using type = int;
};
using T1 = X<S, int, int>;
using T2 = X<>;
using T3 = X<1>;
using T4 = X<int>;
using T5 = X<S>;
// error: too many arguments
// error: no default argument for first template parameter
// error: value 1 does not match type-parameter
// error: substitution failure for second template parameter
// OK
// [Example 5:
template<typename T> concept C1 = sizeof(T) != sizeof(int);
template<C1 T> struct S1 { };
template<C1 T> using Ptr = T*;
S1<int>* p;
Ptr<int> p;
template<typename T>
struct S2 {
    Ptr<int>
    x;
};
// error: constraints not satisfied
// error: constraints not satisfied
// ill-formed, no diagnostic required
// OK, satisfaction is not required
// error: constraints not satisfied
// ill-formed, no diagnostic required
template<typename T>
struct S3 {
    Ptr<T> x;
};
S3<int> x;
template<template<C1 T> class X>
struct S4 {
    X<int> x;
};
template<typename T> concept C2 = sizeof(T) == 1;
template<C2 T> struct S { };
template struct S<char[2]>;
template<> struct S<char[2]> { };
// error: constraints not satisfied // error: constraints not satisfied
// [Example 6:
template<typename T> concept C = true;
static_assert(C<int>); // OK
int main() {
    cout  <<  n4910 << endl;
    return EXIT_SUCCESS;
}
```

## 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
```
## 編纂・実行結果(compile and go)

```ubuntu:bash
# ./clgc.sh p359
rm: cannot remove 'p359l': No such file or directory
rm: cannot remove 'p359g': No such file or directory
$ clang++ p359.cpp -std=c++03 -o p359l -I. -Wall
In file included from p359.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 \
 ^
p359.cpp:31:16: error: missing 'template' keyword prior to dependent template name 'alloc'
    T* p1 = p->alloc<200>();
               ^    ~~~~~
p359.cpp:33:8: error: missing 'template' keyword prior to dependent template name 'adjust'
    T::adjust<100>();
       ^     ~~~~~
p359.cpp:40:23: error: redefinition of 'X' as different kind of symbol
template<int i> class X { /* ... */ };
                      ^
p359.cpp:26:10: note: previous definition is here
  struct X {
         ^
p359.cpp:41:2: error: expected unqualified-id
X< 1>2 > x1; // syntax error X<(1>2)> x2; // OK
 ^
p359.cpp:43:6: error: expected '>'
  Y<X<1>> x3;
     ^
p359.cpp:43:4: note: to match this '<'
  Y<X<1>> x3;
   ^
p359.cpp:43:6: error: expected unqualified-id
  Y<X<1>> x3;
     ^
p359.cpp:44:6: error: expected '>'
  Y<X<6>>1>> x4;
     ^
p359.cpp:44:4: note: to match this '<'
  Y<X<6>>1>> x4;
   ^
p359.cpp:44:6: error: expected unqualified-id
  Y<X<6>>1>> x4;
     ^
p359.cpp:45:6: error: expected '>'
  Y<X<(6>>1)>> x5;
     ^
p359.cpp:45:4: note: to match this '<'
  Y<X<(6>>1)>> x5;
   ^
p359.cpp:45:6: error: expected unqualified-id
  Y<X<(6>>1)>> x5;
     ^
p359.cpp:58:3: error: expected expression
  template <class T> struct B {
  ^
p359.cpp:65:81: error: use of undeclared identifier 'B'
template <class T, template <class X> class TT = T::template C> struct D { }; D<B<int> > db;
                                                                                ^
p359.cpp:67:21: error: missing 'typename' prior to dependent type name 'T::type'
  template<class T, T::type n = 0> class X;
                    ^~~~~~~
                    typename 
p359.cpp:67:42: error: redefinition of 'X' as different kind of symbol
  template<class T, T::type n = 0> class X;
                                         ^
p359.cpp:26:10: note: previous definition is here
  struct X {
         ^
p359.cpp:69:18: warning: alias declarations are a C++11 extension [-Wc++11-extensions]
    using type = int;
                 ^
p359.cpp:71:14: warning: alias declarations are a C++11 extension [-Wc++11-extensions]
  using T1 = X<S, int, int>;
             ^
p359.cpp:71:15: error: expected ';' after alias declaration
  using T1 = X<S, int, int>;
              ^
              ;
p359.cpp:72:14: warning: alias declarations are a C++11 extension [-Wc++11-extensions]
  using T2 = X<>;
             ^
p359.cpp:72:15: error: expected ';' after alias declaration
  using T2 = X<>;
              ^
              ;
p359.cpp:73:14: warning: alias declarations are a C++11 extension [-Wc++11-extensions]
  using T3 = X<1>;
             ^
p359.cpp:73:15: error: expected ';' after alias declaration
  using T3 = X<1>;
              ^
              ;
p359.cpp:74:14: warning: alias declarations are a C++11 extension [-Wc++11-extensions]
  using T4 = X<int>;
             ^
p359.cpp:74:15: error: expected ';' after alias declaration
  using T4 = X<int>;
              ^
              ;
p359.cpp:75:14: warning: alias declarations are a C++11 extension [-Wc++11-extensions]
  using T5 = X<S>;
             ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
6 warnings and 20 errors generated.
rm: cannot remove 'p359l': No such file or directory
$ clang++ p359.cpp -std=c++2b -o p359l -I. -Wall
p359.cpp:31:16: error: missing 'template' keyword prior to dependent template name 'alloc'
    T* p1 = p->alloc<200>();
               ^    ~~~~~
p359.cpp:33:8: error: missing 'template' keyword prior to dependent template name 'adjust'
    T::adjust<100>();
       ^     ~~~~~
p359.cpp:40:23: error: redefinition of 'X' as different kind of symbol
template<int i> class X { /* ... */ };
                      ^
p359.cpp:26:10: note: previous definition is here
  struct X {
         ^
p359.cpp:41:2: error: expected unqualified-id
X< 1>2 > x1; // syntax error X<(1>2)> x2; // OK
 ^
p359.cpp:43:6: error: expected '>'
  Y<X<1>> x3;
     ^
p359.cpp:43:4: note: to match this '<'
  Y<X<1>> x3;
   ^
p359.cpp:43:6: error: expected unqualified-id
  Y<X<1>> x3;
     ^
p359.cpp:44:6: error: expected '>'
  Y<X<6>>1>> x4;
     ^
p359.cpp:44:4: note: to match this '<'
  Y<X<6>>1>> x4;
   ^
p359.cpp:44:6: error: expected unqualified-id
  Y<X<6>>1>> x4;
     ^
p359.cpp:45:6: error: expected '>'
  Y<X<(6>>1)>> x5;
     ^
p359.cpp:45:4: note: to match this '<'
  Y<X<(6>>1)>> x5;
   ^
p359.cpp:45:6: error: expected unqualified-id
  Y<X<(6>>1)>> x5;
     ^
p359.cpp:58:3: error: expected expression
  template <class T> struct B {
  ^
p359.cpp:65:81: error: use of undeclared identifier 'B'
template <class T, template <class X> class TT = T::template C> struct D { }; D<B<int> > db;
                                                                                ^
p359.cpp:67:21: error: missing 'typename' prior to dependent type name 'T::type'
  template<class T, T::type n = 0> class X;
                    ^~~~~~~
                    typename 
p359.cpp:67:42: error: redefinition of 'X' as different kind of symbol
  template<class T, T::type n = 0> class X;
                                         ^
p359.cpp:26:10: note: previous definition is here
  struct X {
         ^
p359.cpp:71:15: error: expected ';' after alias declaration
  using T1 = X<S, int, int>;
              ^
              ;
p359.cpp:72:15: error: expected ';' after alias declaration
  using T2 = X<>;
              ^
              ;
p359.cpp:73:15: error: expected ';' after alias declaration
  using T3 = X<1>;
              ^
              ;
p359.cpp:74:15: error: expected ';' after alias declaration
  using T4 = X<int>;
              ^
              ;
p359.cpp:75:15: error: expected ';' after alias declaration
  using T5 = X<S>;
              ^
              ;
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

$ g++ p359.cpp -std=c++03 -o p359g -I. -Wall
In file included from /usr/local/include/c++/12.1.0/atomic:38,
                 from p359.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 \
      |  ^~~~~
p359.cpp:109:1: warning: identifier 'static_assert' is a keyword in C++11 [-Wc++11-compat]
  109 | static_assert(C<int>); // OK
      | ^~~~~~~~~~~~~
p359.cpp: In function 'void f(T*)':
p359.cpp:31:16: warning: expected 'template' keyword before dependent template name [-Wmissing-template-keyword]
   31 |     T* p1 = p->alloc<200>();
      |                ^~~~~
p359.cpp:31:27: error: expected primary-expression before ')' token
   31 |     T* p1 = p->alloc<200>();
      |                           ^
p359.cpp:33:8: warning: expected 'template' keyword before dependent template name [-Wmissing-template-keyword]
   33 |     T::adjust<100>();
      |        ^~~~~~
p359.cpp:33:20: error: expected primary-expression before ')' token
   33 |     T::adjust<100>();
      |                    ^
p359.cpp: At global scope:
p359.cpp:40:23: error: 'X' is not a template
   40 | template<int i> class X { /* ... */ };
      |                       ^
p359.cpp:26:10: note: previous declaration here
   26 |   struct X {
      |          ^
p359.cpp:41:1: error: 'X' is not a template
   41 | X< 1>2 > x1; // syntax error X<(1>2)> x2; // OK
      | ^
p359.cpp:41:6: error: expected unqualified-id before numeric constant
   41 | X< 1>2 > x1; // syntax error X<(1>2)> x2; // OK
      |      ^
p359.cpp:43:5: error: 'X' is not a template
   43 |   Y<X<1>> x3;
      |     ^
p359.cpp:43:8: warning: '>>' operator is treated as two right angle brackets in C++11 [-Wc++11-compat]
   43 |   Y<X<1>> x3;
      |        ^~
p359.cpp:43:8: note: suggest parentheses around '>>' expression
p359.cpp:43:11: error: 'x3' was not declared in this scope
   43 |   Y<X<1>> x3;
      |           ^~
p359.cpp:43:5: error: template argument 1 is invalid
   43 |   Y<X<1>> x3;
      |     ^
p359.cpp:44:5: error: 'X' is not a template
   44 |   Y<X<6>>1>> x4;
      |     ^
p359.cpp:44:8: warning: '>>' operator is treated as two right angle brackets in C++11 [-Wc++11-compat]
   44 |   Y<X<6>>1>> x4;
      |        ^~
p359.cpp:44:8: note: suggest parentheses around '>>' expression
p359.cpp:44:11: warning: '>>' operator is treated as two right angle brackets in C++11 [-Wc++11-compat]
   44 |   Y<X<6>>1>> x4;
      |           ^~
p359.cpp:44:11: note: suggest parentheses around '>>' expression
p359.cpp:44:14: error: 'x4' was not declared in this scope
   44 |   Y<X<6>>1>> x4;
      |              ^~
p359.cpp:44:5: error: template argument 1 is invalid
   44 |   Y<X<6>>1>> x4;
      |     ^
p359.cpp:45:5: error: 'X' is not a template
   45 |   Y<X<(6>>1)>> x5;
      |     ^
p359.cpp:45:13: warning: '>>' operator is treated as two right angle brackets in C++11 [-Wc++11-compat]
   45 |   Y<X<(6>>1)>> x5;
      |             ^~
p359.cpp:45:13: note: suggest parentheses around '>>' expression
p359.cpp:45:16: error: 'x5' was not declared in this scope
   45 |   Y<X<(6>>1)>> x5;
      |                ^~
p359.cpp:45:5: error: template argument 1 is invalid
   45 |   Y<X<(6>>1)>> x5;
      |     ^
p359.cpp: In function 'void f(T)':
p359.cpp:58:3: error: a template declaration cannot appear at block scope
   58 |   template <class T> struct B {
      |   ^~~~~~~~
p359.cpp: At global scope:
p359.cpp:65:81: error: 'B' was not declared in this scope
   65 | template <class T, template <class X> class TT = T::template C> struct D { }; D<B<int> > db;
      |                                                                                 ^
p359.cpp:65:86: error: template argument 1 is invalid
   65 | template <class T, template <class X> class TT = T::template C> struct D { }; D<B<int> > db;
      |                                                                                      ^
p359.cpp:65:86: error: template argument 2 is invalid
p359.cpp:65:88: error: expected unqualified-id before '>' token
   65 | template <class T, template <class X> class TT = T::template C> struct D { }; D<B<int> > db;
      |                                                                                        ^
p359.cpp:67:24: error: 'T::type' is not a type
   67 |   template<class T, T::type n = 0> class X;
      |                        ^~~~
p359.cpp:67:42: error: 'X' is not a template
   67 |   template<class T, T::type n = 0> class X;
      |                                          ^
p359.cpp:26:10: note: previous declaration here
   26 |   struct X {
      |          ^
p359.cpp:69:11: error: expected nested-name-specifier before 'type'
   69 |     using type = int;
      |           ^~~~
p359.cpp:71:9: error: expected nested-name-specifier before 'T1'
   71 |   using T1 = X<S, int, int>;
      |         ^~
p359.cpp:72:9: error: expected nested-name-specifier before 'T2'
   72 |   using T2 = X<>;
      |         ^~
p359.cpp:73:9: error: expected nested-name-specifier before 'T3'
   73 |   using T3 = X<1>;
      |         ^~
p359.cpp:74:9: error: expected nested-name-specifier before 'T4'
   74 |   using T4 = X<int>;
      |         ^~
p359.cpp:75:9: error: expected nested-name-specifier before 'T5'
   75 |   using T5 = X<S>;
      |         ^~
p359.cpp:82:22: error: 'concept' does not name a type; did you mean 'const'?
   82 | template<typename T> concept C1 = sizeof(T) != sizeof(int);
      |                      ^~~~~~~
      |                      const
p359.cpp:82:22: note: 'concept' only available with '-std=c++20' or '-fconcepts'
p359.cpp:83:10: error: 'C1' has not been declared
   83 | template<C1 T> struct S1 { };
      |          ^~
p359.cpp:84:10: error: 'C1' has not been declared
   84 | template<C1 T> using Ptr = T*;
      |          ^~
p359.cpp:84:16: error: expected unqualified-id before 'using'
   84 | template<C1 T> using Ptr = T*;
      |                ^~~~~
p359.cpp:86:1: error: 'Ptr' does not name a type
   86 | Ptr<int> p;
      | ^~~
p359.cpp:88:13: error: 'Ptr' does not name a type
   88 | struct S2 { Ptr<int>
      |             ^~~
p359.cpp:97:13: error: 'Ptr' does not name a type
   97 | struct S3 { Ptr<T> x; };
      |             ^~~
p359.cpp:99:19: error: 'C1' has not been declared
   99 | template<template<C1 T> class X>
      |                   ^~
p359.cpp:102:22: error: 'concept' does not name a type; did you mean 'const'?
  102 | template<typename T> concept C2 = sizeof(T) == 1;
      |                      ^~~~~~~
      |                      const
p359.cpp:102:22: note: 'concept' only available with '-std=c++20' or '-fconcepts'
p359.cpp:103:10: error: 'C2' has not been declared
  103 | template<C2 T> struct S { };
      |          ^~
p359.cpp:103:23: error: 'S' is not a template
  103 | template<C2 T> struct S { };
      |                       ^
p359.cpp:68:10: note: previous declaration here
   68 |   struct S {
      |          ^
p359.cpp:104:19: error: 'S' is not a class template
  104 |   template struct S<char[2]>;
      |                   ^
p359.cpp:104:19: error: explicit instantiation of non-template type 'S'
p359.cpp:105:21: error: 'S' is not a class template
  105 |   template<> struct S<char[2]> { };
      |                     ^
p359.cpp:105:30: error: 'S' is not a template
  105 |   template<> struct S<char[2]> { };
      |                              ^
p359.cpp:68:10: note: previous declaration here
   68 |   struct S {
      |          ^
p359.cpp:108:22: error: 'concept' does not name a type; did you mean 'const'?
  108 | template<typename T> concept C = true;
      |                      ^~~~~~~
      |                      const
p359.cpp:108:22: note: 'concept' only available with '-std=c++20' or '-fconcepts'
p359.cpp:109:14: error: expected constructor, destructor, or type conversion before '(' token
  109 | static_assert(C<int>); // OK
      |              ^
rm: cannot remove 'p359g': No such file or directory

$ g++ p359.cpp -std=c++2b -o p359g -I. -Wall
p359.cpp: In function 'void f(T*)':
p359.cpp:31:16: warning: expected 'template' keyword before dependent template name [-Wmissing-template-keyword]
   31 |     T* p1 = p->alloc<200>();
      |                ^~~~~
p359.cpp:31:27: error: expected primary-expression before ')' token
   31 |     T* p1 = p->alloc<200>();
      |                           ^
p359.cpp:33:8: warning: expected 'template' keyword before dependent template name [-Wmissing-template-keyword]
   33 |     T::adjust<100>();
      |        ^~~~~~
p359.cpp:33:20: error: expected primary-expression before ')' token
   33 |     T::adjust<100>();
      |                    ^
p359.cpp: At global scope:
p359.cpp:40:23: error: 'X' is not a template
   40 | template<int i> class X { /* ... */ };
      |                       ^
p359.cpp:26:10: note: previous declaration here
   26 |   struct X {
      |          ^
p359.cpp:41:1: error: 'X' is not a template
   41 | X< 1>2 > x1; // syntax error X<(1>2)> x2; // OK
      | ^
p359.cpp:41:6: error: expected unqualified-id before numeric constant
   41 | X< 1>2 > x1; // syntax error X<(1>2)> x2; // OK
      |      ^
p359.cpp:43:5: error: 'X' is not a template
   43 |   Y<X<1>> x3;
      |     ^
p359.cpp:44:5: error: 'X' is not a template
   44 |   Y<X<6>>1>> x4;
      |     ^
p359.cpp:44:10: error: expected unqualified-id before numeric constant
   44 |   Y<X<6>>1>> x4;
      |          ^
p359.cpp:45:5: error: 'X' is not a template
   45 |   Y<X<(6>>1)>> x5;
      |     ^
p359.cpp: In function 'void f(T)':
p359.cpp:58:3: error: a template declaration cannot appear at block scope
   58 |   template <class T> struct B {
      |   ^~~~~~~~
p359.cpp: At global scope:
p359.cpp:65:81: error: 'B' was not declared in this scope
   65 | template <class T, template <class X> class TT = T::template C> struct D { }; D<B<int> > db;
      |                                                                                 ^
p359.cpp:65:86: error: template argument 1 is invalid
   65 | template <class T, template <class X> class TT = T::template C> struct D { }; D<B<int> > db;
      |                                                                                      ^
p359.cpp:65:86: error: template argument 2 is invalid
p359.cpp:65:88: error: expected unqualified-id before '>' token
   65 | template <class T, template <class X> class TT = T::template C> struct D { }; D<B<int> > db;
      |                                                                                        ^
p359.cpp:67:42: error: 'X' is not a template
   67 |   template<class T, T::type n = 0> class X;
      |                                          ^
p359.cpp:26:10: note: previous declaration here
   26 |   struct X {
      |          ^
p359.cpp:71:14: error: 'X' is not a template
   71 |   using T1 = X<S, int, int>;
      |              ^
p359.cpp:72:14: error: 'X' is not a template
   72 |   using T2 = X<>;
      |              ^
p359.cpp:73:14: error: 'X' is not a template
   73 |   using T3 = X<1>;
      |              ^
p359.cpp:74:14: error: 'X' is not a template
   74 |   using T4 = X<int>;
      |              ^
p359.cpp:75:14: error: 'X' is not a template
   75 |   using T5 = X<S>;
      |              ^
p359.cpp:85:7: error: template constraint failure for 'template<class T>  requires  C1<T> struct S1'
   85 | S1<int>* p;
      |       ^
p359.cpp:85:7: note: constraints not satisfied
p359.cpp: In substitution of 'template<class T>  requires  C1<T> struct S1 [with T = int]':
p359.cpp:85:7:   required from here
p359.cpp:82:30:   required for the satisfaction of 'C1<T>' [with T = int]
p359.cpp:82:45: note: the expression 'sizeof (T) != sizeof (int) [with T = int]' evaluated to 'false'
   82 | template<typename T> concept C1 = sizeof(T) != sizeof(int);
      |                                   ~~~~~~~~~~^~~~~~~~~~~~~~
p359.cpp:86:8: error: template constraint failure for 'template<class T>  requires  C1<T> using Ptr = T*'
   86 | Ptr<int> p;
      |        ^
p359.cpp:86:8: note: constraints not satisfied
p359.cpp: In substitution of 'template<class T>  requires  C1<T> using Ptr = T* [with T = int]':
p359.cpp:86:8:   required from here
p359.cpp:82:30:   required for the satisfaction of 'C1<T>' [with T = int]
p359.cpp:82:45: note: the expression 'sizeof (T) != sizeof (int) [with T = int]' evaluated to 'false'
   82 | template<typename T> concept C1 = sizeof(T) != sizeof(int);
      |                                   ~~~~~~~~~~^~~~~~~~~~~~~~
p359.cpp:86:10: error: conflicting declaration 'int p'
   86 | Ptr<int> p;
      |          ^
p359.cpp:85:10: note: previous declaration as 'int* p'
   85 | S1<int>* p;
      |          ^
p359.cpp:88:20: error: template constraint failure for 'template<class T>  requires  C1<T> using Ptr = T*'
   88 | struct S2 { Ptr<int>
      |                    ^
p359.cpp:88:20: note: constraints not satisfied
p359.cpp: In substitution of 'template<class T>  requires  C1<T> using Ptr = T* [with T = int]':
p359.cpp:88:20:   required from here
p359.cpp:82:30:   required for the satisfaction of 'C1<T>' [with T = int]
p359.cpp:82:45: note: the expression 'sizeof (T) != sizeof (int) [with T = int]' evaluated to 'false'
   82 | template<typename T> concept C1 = sizeof(T) != sizeof(int);
      |                                   ~~~~~~~~~~^~~~~~~~~~~~~~
p359.cpp: In instantiation of 'struct S3<int>':
p359.cpp:98:9:   required from here
p359.cpp:97:20: error: template constraint failure for 'template<class T>  requires  C1<T> using Ptr = T*'
   97 | struct S3 { Ptr<T> x; };
      |                    ^
p359.cpp:97:20: note: constraints not satisfied
p359.cpp: In substitution of 'template<class T>  requires  C1<T> using Ptr = T* [with T = int]':
p359.cpp:97:20:   required from 'struct S3<int>'
p359.cpp:98:9:   required from here
p359.cpp:82:30:   required for the satisfaction of 'C1<T>' [with T = int]
p359.cpp:82:45: note: the expression 'sizeof (T) != sizeof (int) [with T = int]' evaluated to 'false'
   82 | template<typename T> concept C1 = sizeof(T) != sizeof(int);
      |                                   ~~~~~~~~~~^~~~~~~~~~~~~~
p359.cpp:103:23: error: 'S' is not a template
  103 | template<C2 T> struct S { };
      |                       ^
p359.cpp:68:10: note: previous declaration here
   68 |   struct S {
      |          ^
p359.cpp:104:19: error: 'S' is not a class template
  104 |   template struct S<char[2]>;
      |                   ^
p359.cpp:104:19: error: explicit instantiation of non-template type 'S'
p359.cpp:105:21: error: 'S' is not a class template
  105 |   template<> struct S<char[2]> { };
      |                     ^
p359.cpp:105:30: error: 'S' is not a template
  105 |   template<> struct S<char[2]> { };
      |                              ^
p359.cpp:68:10: note: previous declaration here
   68 |   struct S {
      |          ^
```

## 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。-->


# 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

## 自己参照(self reference)

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 　20220702