c++致命错误C1001使用可变模板

c++ fatal error C1001 on using variadic template

本文关键字：致命错误 C1001 c++      更新时间：2023-10-16

大家好。在编译代码时，我发现了下一个错误:
致命错误C1001:编译器内部错误。

当我只传递一个参数给"exec"函数时，一切正常。但是当我传递多个参数时，它会发出一个错误。我分别使用vs 2015和visual c++编译器。

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
//using namespace std;
template <class T>
void param_push_(T arg, char ** param) {
  sprintf(*param, "%15.15e", arg);
}
template <class T, class... args>
void param_push_(T first, args... args, char ** param) {
  static int param_No = 0;
  sprintf(param[param_No++], "%15.15e", first);
  param_push(args..., param[param_No]);
}
template <class ... param_types>
void exec(const char * command, const param_types& ...param_values) {
  int arg_count = sizeof...(param_values);
  char ** params = new char*[arg_count];
  for (int i = 0; i < arg_count; ++i) {
    params[i] = new char[22 * sizeof(char)];
  }
  param_push_(param_values..., params); //cast parameters to (char *)  
  for (int i = 0; i < arg_count; ++i) {
    delete[] params[i];
  }
  delete[] params;
}
int main()
{
  double e_restriction = 0.55300000000000000000124124;
  double M_restriction = 5;
  exec("SELECT "M",e from orbital WHERE e < $1::double precision AND "M" < $2::double precision", e_restriction,M_restriction);
  return 0;
}

试试这个-它可以工作。

#include <stdio.h>
#include <iostream>
template <typename ...> struct param_push;
template <class H, class... T>
struct param_push<H,T...> {
   void operator() (H head, T... tail, char** param) {
     sprintf(param[0], "%15.15e", head);
     param_push<T...> one_less;
     one_less(tail..., &param[1]);
   }
};
template <>
struct param_push<> {
  void operator() (char** param) {
    // does nothing, no more args to sprintf
  }
};
template <class ... param_types>
void exec(const char * command, const param_types& ...param_values) {
  int arg_count = sizeof...(param_values);
  char ** params = new char*[arg_count];
  for (int i = 0; i < arg_count; ++i) {
    params[i] = new char[22 * sizeof(char)];
  }
  // param_push_(param_values..., params); //cast parameters to (char *)
  struct param_push<param_types...> functor;
  functor(param_values..., params);
  for (int i = 0; i < arg_count; ++i) {
    std::cout << params[i] << " will be deleted" << std::endl;
    delete[] params[i];
  }
  delete[] params;
}
int main()
{
  double e_restriction = 0.55300000000000000000124124;
  double M_restriction = 5;
  exec("SELECT "M",e from orbital WHERE e < $1::double precision AND "M" < $2::double precision", e_restriction,M_restriction);
  return 0;
}

(现在是Arty Zefirov的作业:找到使用模板结构函数时该技术有效的原因，为什么它不能用于模板化函数并使用发现更新您的问题)

下面是在gcc上编译这段代码的输出:

12 : error: declaration of 'args ... args'
void param_push_(T first, args... args, char ** param) {
^
11 : error: shadows template parm 'class ... args'
template <class T, class... args>
^
/tmp/gcc-explorer-compiler116729-61-oaaqho/example.cpp: In function 'void param_push_(T, args ..., char**)':
12 : error: declaration of 'args ... args'
void param_push_(T first, args... args, char ** param) {
^
11 : error: shadows template parm 'class ... args'
template <class T, class... args>
^
/tmp/gcc-explorer-compiler116729-61-oaaqho/example.cpp: In instantiation of 'void exec(const char*, const param_types& ...) [with param_types = {double, double}]':
41 : required from here
27 : error: no matching function for call to 'param_push_(const double&, const double&, char**&)'
param_push_(param_values..., params); //cast parameters to (char *)
^
7 : note: candidate: template<class T> void param_push_(T, char**)
void param_push_(T arg, char ** param) {
^
7 : note: template argument deduction/substitution failed:
27 : note: cannot convert 'param_values#1' (type 'const double') to type 'char**'
param_push_(param_values..., params); //cast parameters to (char *)
^
12 : note: candidate: template<class T, class ... args> void param_push_(T, args ..., char**)
void param_push_(T first, args... args, char ** param) {
^
12 : note: template argument deduction/substitution failed:
27 : note: cannot convert 'param_values#1' (type 'const double') to type 'char**'
param_push_(param_values..., params); //cast parameters to (char *)
^
Compilation failed

你可能需要重新考虑这个:

template <class T, class... Args>
void param_push_(T first, Args... args, char ** param) {
  //
  // WARNING: param_No will be a different variable for each
  // combination of Args...
  //
  static int param_No = 0;
  sprintf(param[param_No++], "%15.15e", first);
  param_push(args..., param[param_No]);
}

这是一个新的代码。模板函数不改变当前参数。但应该是这样的，不是吗?

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
//using namespace std;
template <class T>
void param_push_(T arg, char ** param) {
  sprintf(*param, "%15.15e", arg);
}
template <class T, class... args>
void param_push_(T first, args... args_temp, char ** param) {
  static int param_No = 0;
  sprintf(param[param_No++], "%15.15e", first);
  param_push_(args_temp..., param[param_No]);
}
template <class ... param_types>
void my_exec(const char * command, const param_types& ...param_values) {
  int arg_count = sizeof...(param_values);
  char ** params = new char*[arg_count];
  for (int i = 0; i < arg_count; ++i) {
    params[i] = new char[22 * sizeof(char)];
  }
  param_push_(param_values..., params); //cast parameters to (char *)  
  for (int i = 0; i < arg_count; ++i) {
    delete[] params[i];
  }
  delete[] params;
}
int main()
{
  double e_restriction = 0.55300000000000000000124124;
  double M_restriction = 5;
  param_push_<double, double, char**>;
  my_exec("SELECT "M",e from orbital WHERE e < $1::double precision AND "M" < $2::double precision", 
    e_restriction, M_restriction);
    return 0;
}
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