C++N4606 (201)14.8.1 Explicit template argument specification [temp.arg.explicit] p406


はじめに

N4606 Working Draft, Standard for Programming Language C++
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/#mailing2016-11
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4606.pdf

n4606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。

作業方針

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。

list

N4606 Working Draft 2016, ISO/IEC 14882, C++ standard(1) coding list
https://qiita.com/kaizen_nagoya/items/df5d62c35bd6ed1c3d43/

Compiler

clang++ --version

clang version 6.0.0 (tags/RELEASE_600/final)
Target: x86_64-apple-darwin17.4.0

g++-7 --version

g++-7 (Homebrew GCC 7.3.0_1) 7.3.0
Copyright (C) 2017 Free Software Foundation, Inc.

(201)14.8.1 Explicit template argument specification [temp.arg.explicit] p406

p406.cpp
// N4606 Committee Draft, Standard for Programming Language C++
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/n4606.pdf
#define msg "(201)14.8.1 Explicit template argument specification [temp.arg.explicit] p406.cpp"
// Edited by Dr. Ogawa Kiyoshi. Compile procedure and results record.

#include <iostream>


template<class T> void sort(Array<T>& v);
void f(Array<dcomplex>& cv, Array<int>& ci) {
sort<dcomplex>(cv); // sort(Array<dcomplex>&)
sort<int>(ci); // sort(Array<int>&)
}

template<class U, class V> U convert(V v);
void g(double d) {
int i = convert<int,double>(d); // int convert(double)
char c = convert<char,double>(d); // char convert(double)
}

template<class X, class Y> X f(Y);
template<class X, class Y, class ... Z> X g(Y);
void h() {
int i = f<int>(5.6); // Y is deduced to be double
int j = f(5.6); // ill-formed: X cannot be deduced
f<void>(f<int, bool>); // Y for outer f deduced to be
// int (*)(bool)
f<void>(f<int>); // ill-formed: f<int> does not denote a
// single function template specialization
int k = g<int>(5.6); // Y is deduced to be double, Z is deduced to an empty sequence
f<void>(g<int, bool>); // Y for outer f is deduced to be
// int (*)(bool), Z is deduced to an empty sequence
}

template <class T> int f(T); // #1
int f(int); // #2
int k = f(1); // uses #2
int l = f<>(1); // uses #1

template<class X, class Y, class Z> X f(Y,Z);
template<class ... Args> void f2();
void g() {
f<int,const char*,double>("aa",3.0);
f<int,const char*>("aa",3.0); // Z is deduced to be double
f<int>("aa",3.0); // Y is deduced to be const char*, and
// Z is deduced to be double
f("aa",3.0); // error: X cannot be deduced
f2<char, short, int, long>(); // OK
}

template<class T> void f(T);
class Complex {
Complex(double);
};
void g() {
f<Complex>(1); // OK, means f<Complex>(Complex(1))
}

namespace A {
struct B { };
template<int X> void f(B);
}
namespace C {
template<class T> void f(T t);
}
void g(A::B b) {
f<3>(b); // ill-formed: not a function call
A::f<3>(b); // well-formed
C::f<3>(b); // ill-formed; argument dependent lookup
// applies only to unqualified names
using C::f;
f<3>(b); // well-formed because C::f is visible; then
// A::f is found by argument dependent lookup
}

template<class ... Types> void f(Types ... values);
void g() {
f<int*, float*>(0, 0, 0); // Types is deduced to the sequence int*, float*, int
}


int main() {
  std::cout<< msg << std::endl;
  return EXIT_SUCCESS;
}
$ ./cppgl17.sh p406
$ clang++ p406.cpp
p406.cpp:10:24: error: variable has incomplete type 'void'
template<class T> void sort(Array<T>& v);
                       ^
p406.cpp:10:29: error: use of undeclared identifier 'Array'
template<class T> void sort(Array<T>& v);
                            ^
p406.cpp:10:35: error: 'T' does not refer to a value
template<class T> void sort(Array<T>& v);
                                  ^
p406.cpp:10:16: note: declared here
template<class T> void sort(Array<T>& v);
               ^
p406.cpp:10:39: error: use of undeclared identifier 'v'
template<class T> void sort(Array<T>& v);
                                      ^
p406.cpp:11:6: error: variable has incomplete type 'void'
void f(Array<dcomplex>& cv, Array<int>& ci) {
     ^
p406.cpp:11:8: error: use of undeclared identifier 'Array'
void f(Array<dcomplex>& cv, Array<int>& ci) {
       ^
p406.cpp:11:14: error: use of undeclared identifier 'dcomplex'
void f(Array<dcomplex>& cv, Array<int>& ci) {
             ^
p406.cpp:11:25: error: use of undeclared identifier 'cv'
void f(Array<dcomplex>& cv, Array<int>& ci) {
                        ^
p406.cpp:11:29: error: use of undeclared identifier 'Array'
void f(Array<dcomplex>& cv, Array<int>& ci) {
                            ^
p406.cpp:11:38: error: expected '(' for function-style cast or type construction
void f(Array<dcomplex>& cv, Array<int>& ci) {
                                  ~~~^
p406.cpp:11:41: error: use of undeclared identifier 'ci'
void f(Array<dcomplex>& cv, Array<int>& ci) {
                                        ^
p406.cpp:11:44: error: expected ';' after top level declarator
void f(Array<dcomplex>& cv, Array<int>& ci) {
                                           ^
                                           ;
p406.cpp:18:9: error: use of undeclared identifier 'convert'
int i = convert<int,double>(d); // int convert(double)
        ^
p406.cpp:18:20: error: expected '(' for function-style cast or type construction
int i = convert<int,double>(d); // int convert(double)
                ~~~^
p406.cpp:18:21: error: expected unqualified-id
int i = convert<int,double>(d); // int convert(double)
                    ^
p406.cpp:18:21: error: expected ';' at end of declaration
int i = convert<int,double>(d); // int convert(double)
                    ^
                    ;
p406.cpp:18:27: error: expected unqualified-id
int i = convert<int,double>(d); // int convert(double)
                          ^
p406.cpp:19:10: error: use of undeclared identifier 'convert'
char c = convert<char,double>(d); // char convert(double)
         ^
p406.cpp:19:22: error: expected '(' for function-style cast or type construction
char c = convert<char,double>(d); // char convert(double)
                 ~~~~^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

$ g++-7 p406.cpp
p406.cpp:10:29: error: variable or field 'sort' declared void
 template<class T> void sort(Array<T>& v);
                             ^~~~~
p406.cpp:10:29: error: 'Array' was not declared in this scope
p406.cpp:10:36: error: expected primary-expression before '>' token
 template<class T> void sort(Array<T>& v);
                                    ^
p406.cpp:10:39: error: 'v' was not declared in this scope
 template<class T> void sort(Array<T>& v);
                                       ^
p406.cpp:11:8: error: variable or field 'f' declared void
 void f(Array<dcomplex>& cv, Array<int>& ci) {
        ^~~~~
p406.cpp:11:8: error: 'Array' was not declared in this scope
p406.cpp:11:14: error: 'dcomplex' was not declared in this scope
 void f(Array<dcomplex>& cv, Array<int>& ci) {
              ^~~~~~~~
p406.cpp:11:14: note: suggested alternative: 'double'
 void f(Array<dcomplex>& cv, Array<int>& ci) {
              ^~~~~~~~
              double
p406.cpp:11:25: error: 'cv' was not declared in this scope
 void f(Array<dcomplex>& cv, Array<int>& ci) {
                         ^~
p406.cpp:11:29: error: 'Array' was not declared in this scope
 void f(Array<dcomplex>& cv, Array<int>& ci) {
                             ^~~~~
p406.cpp:11:35: error: expected primary-expression before 'int'
 void f(Array<dcomplex>& cv, Array<int>& ci) {
                                   ^~~
p406.cpp: In function 'void h()':
p406.cpp:25:9: error: 'f2' was not declared in this scope
 int i = f2<int>(5.6); // Y is deduced to be double
         ^~
p406.cpp:25:9: note: suggested alternative: 'f'
 int i = f2<int>(5.6); // Y is deduced to be double
         ^~
         f
p406.cpp:25:12: error: expected primary-expression before 'int'
 int i = f2<int>(5.6); // Y is deduced to be double
            ^~~
p406.cpp:27:4: error: expected primary-expression before 'void'
 f2<void>(f2<int, bool>); // Y for outer f deduced to be
    ^~~~
p406.cpp:29:4: error: expected primary-expression before 'void'
 f2<void>(f2<int>); // ill-formed: f<int> does not denote a
    ^~~~
p406.cpp:31:10: error: 'g2' was not declared in this scope
 int k2 = g2<int>(5.6); // Y is deduced to be double, Z is deduced to an empty sequence
          ^~
p406.cpp:31:10: note: suggested alternative: 'k2'
 int k2 = g2<int>(5.6); // Y is deduced to be double, Z is deduced to an empty sequence
          ^~
          k2
p406.cpp:31:13: error: expected primary-expression before 'int'
 int k2 = g2<int>(5.6); // Y is deduced to be double, Z is deduced to an empty sequence
             ^~~
p406.cpp:32:4: error: expected primary-expression before 'void'
 f2<void>(g2<int, bool>); // Y for outer f is deduced to be
    ^~~~
p406.cpp: At global scope:
p406.cpp:39:12: error: expected primary-expression before '>' token
 int l = f3<>(1); // uses #1
            ^
p406.cpp: In function 'void ga()':
p406.cpp:48:12: error: no matching function for call to 'fa(const char [3], double)'
 fa("aa",3.0); // error: Xa cannot be deduced
            ^
p406.cpp:41:43: note: candidate: template<class Xa, class Ya, class Za> Xa fa(Ya, Za)
 template<class Xa, class Ya, class Za> Xa fa(Ya,Za);
                                           ^~
p406.cpp:41:43: note:   template argument deduction/substitution failed:
p406.cpp:48:12: note:   couldn't deduce template parameter 'Xa'
 fa("aa",3.0); // error: Xa cannot be deduced
            ^
p406.cpp: In function 'void g4()':
p406.cpp:57:1: error: 'f4' was not declared in this scope
 f4<Complex>(1); // OK, means f<Complex>(Complex(1))
 ^~
p406.cpp:57:1: note: suggested alternative: 'g4'
 f4<Complex>(1); // OK, means f<Complex>(Complex(1))
 ^~
 g4
p406.cpp:57:11: error: expected primary-expression before '>' token
 f4<Complex>(1); // OK, means f<Complex>(Complex(1))
           ^
p406.cpp: In function 'void g5(A::B)':
p406.cpp:68:1: error: 'f5' was not declared in this scope
 f5<3>(b); // ill-formed: not a function call
 ^~
p406.cpp:68:1: note: suggested alternatives:
p406.cpp:62:23: note:   'A::f5'
 template<int X5> void f5(B);
                       ^~
p406.cpp:65:24: note:   'C::f5'
 template<class T> void f5(T t);
                        ^~
p406.cpp:70:11: error: no matching function for call to 'f5<3>(A::B&)'
 C::f5<3>(b); // ill-formed; argument dependent lookup
           ^
p406.cpp:65:24: note: candidate: template<class T> void C::f5(T)
 template<class T> void f5(T t);
                        ^~
p406.cpp:65:24: note:   template argument deduction/substitution failed:
p406.cpp:72:10: error: 'f5' is already declared in this scope
 using C::f5;
          ^~
p406.cpp:68:1: error: previous non-function declaration '<typeprefixerror>f5'
 f5<3>(b); // ill-formed: not a function call
 ^~
p406.cpp:72:10: error: conflicts with function declaration 'template<class T> void C::f5(T)'
 using C::f5;
          ^~
OgawaKiyoshi-no-MacBook-Pro:cpp ogawakiyoshi$ vi p406.cpp
OgawaKiyoshi-no-MacBook-Pro:cpp ogawakiyoshi$ ./cppgl17.sh p406
$ clang++ p406.cpp
p406.cpp:10:24: error: variable has incomplete type 'void'
template<class T> void sort(Array<T>& v);
                       ^
p406.cpp:10:29: error: use of undeclared identifier 'Array'
template<class T> void sort(Array<T>& v);
                            ^
p406.cpp:10:35: error: 'T' does not refer to a value
template<class T> void sort(Array<T>& v);
                                  ^
p406.cpp:10:16: note: declared here
template<class T> void sort(Array<T>& v);
               ^
p406.cpp:10:39: error: use of undeclared identifier 'v'
template<class T> void sort(Array<T>& v);
                                      ^
p406.cpp:11:6: error: variable has incomplete type 'void'
void f(Array<dcomplex>& cv, Array<int>& ci) {
     ^
p406.cpp:11:8: error: use of undeclared identifier 'Array'
void f(Array<dcomplex>& cv, Array<int>& ci) {
       ^
p406.cpp:11:14: error: use of undeclared identifier 'dcomplex'
void f(Array<dcomplex>& cv, Array<int>& ci) {
             ^
p406.cpp:11:25: error: use of undeclared identifier 'cv'
void f(Array<dcomplex>& cv, Array<int>& ci) {
                        ^
p406.cpp:11:29: error: use of undeclared identifier 'Array'
void f(Array<dcomplex>& cv, Array<int>& ci) {
                            ^
p406.cpp:11:38: error: expected '(' for function-style cast or type construction
void f(Array<dcomplex>& cv, Array<int>& ci) {
                                  ~~~^
p406.cpp:11:41: error: use of undeclared identifier 'ci'
void f(Array<dcomplex>& cv, Array<int>& ci) {
                                        ^
p406.cpp:11:44: error: expected ';' after top level declarator
void f(Array<dcomplex>& cv, Array<int>& ci) {
                                           ^
                                           ;
p406.cpp:18:9: error: use of undeclared identifier 'convert'
int i = convert<int,double>(d); // int convert(double)
        ^
p406.cpp:18:20: error: expected '(' for function-style cast or type construction
int i = convert<int,double>(d); // int convert(double)
                ~~~^
p406.cpp:18:21: error: expected unqualified-id
int i = convert<int,double>(d); // int convert(double)
                    ^
p406.cpp:18:21: error: expected ';' at end of declaration
int i = convert<int,double>(d); // int convert(double)
                    ^
                    ;
p406.cpp:18:27: error: expected unqualified-id
int i = convert<int,double>(d); // int convert(double)
                          ^
p406.cpp:19:10: error: use of undeclared identifier 'convert'
char c = convert<char,double>(d); // char convert(double)
         ^
p406.cpp:19:22: error: expected '(' for function-style cast or type construction
char c = convert<char,double>(d); // char convert(double)
                 ~~~~^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.

$ g++-7 p406.cpp
p406.cpp:10:29: error: variable or field 'sort' declared void
 template<class T> void sort(Array<T>& v);
                             ^~~~~
p406.cpp:10:29: error: 'Array' was not declared in this scope
p406.cpp:10:36: error: expected primary-expression before '>' token
 template<class T> void sort(Array<T>& v);
                                    ^
p406.cpp:10:39: error: 'v' was not declared in this scope
 template<class T> void sort(Array<T>& v);
                                       ^
p406.cpp:11:8: error: variable or field 'f' declared void
 void f(Array<dcomplex>& cv, Array<int>& ci) {
        ^~~~~
p406.cpp:11:8: error: 'Array' was not declared in this scope
p406.cpp:11:14: error: 'dcomplex' was not declared in this scope
 void f(Array<dcomplex>& cv, Array<int>& ci) {
              ^~~~~~~~
p406.cpp:11:14: note: suggested alternative: 'double'
 void f(Array<dcomplex>& cv, Array<int>& ci) {
              ^~~~~~~~
              double
p406.cpp:11:25: error: 'cv' was not declared in this scope
 void f(Array<dcomplex>& cv, Array<int>& ci) {
                         ^~
p406.cpp:11:25: note: suggested alternative: 'gcvt'
 void f(Array<dcomplex>& cv, Array<int>& ci) {
                         ^~
                         gcvt
p406.cpp:11:29: error: 'Array' was not declared in this scope
 void f(Array<dcomplex>& cv, Array<int>& ci) {
                             ^~~~~
p406.cpp:11:35: error: expected primary-expression before 'int'
 void f(Array<dcomplex>& cv, Array<int>& ci) {
                                   ^~~
p406.cpp: In function 'void h()':
p406.cpp:25:9: error: 'f2' was not declared in this scope
 int i = f2<int>(5.6); // Y is deduced to be double
         ^~
p406.cpp:25:9: note: suggested alternative: 'f'
 int i = f2<int>(5.6); // Y is deduced to be double
         ^~
         f
p406.cpp:25:12: error: expected primary-expression before 'int'
 int i = f2<int>(5.6); // Y is deduced to be double
            ^~~
p406.cpp:27:4: error: expected primary-expression before 'void'
 f2<void>(f2<int, bool>); // Y for outer f deduced to be
    ^~~~
p406.cpp:29:4: error: expected primary-expression before 'void'
 f2<void>(f2<int>); // ill-formed: f<int> does not denote a
    ^~~~
p406.cpp:31:10: error: 'g2' was not declared in this scope
 int k2 = g2<int>(5.6); // Y is deduced to be double, Z is deduced to an empty sequence
          ^~
p406.cpp:31:10: note: suggested alternative: 'k2'
 int k2 = g2<int>(5.6); // Y is deduced to be double, Z is deduced to an empty sequence
          ^~
          k2
p406.cpp:31:13: error: expected primary-expression before 'int'
 int k2 = g2<int>(5.6); // Y is deduced to be double, Z is deduced to an empty sequence
             ^~~
p406.cpp:32:4: error: expected primary-expression before 'void'
 f2<void>(g2<int, bool>); // Y for outer f is deduced to be
    ^~~~
p406.cpp: At global scope:
p406.cpp:39:12: error: expected primary-expression before '>' token
 int l = f3<>(1); // uses #1
            ^
p406.cpp: In function 'void ga()':
p406.cpp:48:12: error: no matching function for call to 'fa(const char [3], double)'
 fa("aa",3.0); // error: Xa cannot be deduced
            ^
p406.cpp:41:43: note: candidate: template<class Xa, class Ya, class Za> Xa fa(Ya, Za)
 template<class Xa, class Ya, class Za> Xa fa(Ya,Za);
                                           ^~
p406.cpp:41:43: note:   template argument deduction/substitution failed:
p406.cpp:48:12: note:   couldn't deduce template parameter 'Xa'
 fa("aa",3.0); // error: Xa cannot be deduced
            ^
p406.cpp: In function 'void g4()':
p406.cpp:57:1: error: 'f4' was not declared in this scope
 f4<Complex>(1); // OK, means f<Complex>(Complex(1))
 ^~
p406.cpp:57:1: note: suggested alternative: 'g4'
 f4<Complex>(1); // OK, means f<Complex>(Complex(1))
 ^~
 g4
p406.cpp:57:11: error: expected primary-expression before '>' token
 f4<Complex>(1); // OK, means f<Complex>(Complex(1))
           ^
p406.cpp: In function 'void g5(A::B)':
p406.cpp:68:1: error: 'f5' was not declared in this scope
 f5<3>(b); // ill-formed: not a function call
 ^~
p406.cpp:68:1: note: suggested alternatives:
p406.cpp:62:23: note:   'A::f5'
 template<int X5> void f5(B);
                       ^~
p406.cpp:65:24: note:   'C::f5'
 template<class T> void f5(T t);
                        ^~
p406.cpp:70:11: error: no matching function for call to 'f5<3>(A::B&)'
 C::f5<3>(b); // ill-formed; argument dependent lookup
           ^
p406.cpp:65:24: note: candidate: template<class T> void C::f5(T)
 template<class T> void f5(T t);
                        ^~
p406.cpp:65:24: note:   template argument deduction/substitution failed:
p406.cpp:72:10: error: 'f5' is already declared in this scope
 using C::f5;
          ^~
p406.cpp:68:1: error: previous non-function declaration '<typeprefixerror>f5'
 f5<3>(b); // ill-formed: not a function call
 ^~
p406.cpp:72:10: error: conflicts with function declaration 'template<class T> void C::f5(T)'
 using C::f5;
          ^~


タブを2つの空白に変換しているスクリプトは下記。

a.sh
#!/bin/bash
astyle -s2 -c < $1.cpp > $1s2.cpp
cat $1s2.cpp

検討事項

コンパイルエラーを修正する方法
 complex
convert
役に立つまたは意味のある出力

参考資料

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

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

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

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