Error: cannot define 'enum class std::align_val_t' in different module

Question

我是一名 C++ 初学者，正在寻找创建模块的机会。我遵循了几个指南并想用类测试模块。当我尝试通过 g++-11 -c -std=c++20 -fmodules-ts func.cxx 运行第一个模块时，出现以下错误：

In file included from /usr/local/Cellar/gcc/11.2.0_3/include/c++/11/bits/stl_iterator.h:82,
                 from /usr/local/Cellar/gcc/11.2.0_3/include/c++/11/bits/stl_algobase.h:67,
                 from /usr/local/Cellar/gcc/11.2.0_3/include/c++/11/bits/char_traits.h:39,
                 from /usr/local/Cellar/gcc/11.2.0_3/include/c++/11/string:40,
                 from func.cxx:2:
/usr/local/Cellar/gcc/11.2.0_3/include/c++/11/new:89:27: error: cannot define 'enum class std::align_val_t' in different module
   89 |   enum class align_val_t: size_t {};
      |                           ^~~~~~
<built-in>: note: declared here
/usr/local/Cellar/gcc/11.2.0_3/include/c++/11/new:89: confused by earlier errors, bailing out

以下是文件，在此先感谢。

main.cpp

#include <iostream>
import airline_ticket;


int main()
{
  std::cout << "Hello" << std::endl;
  return 0;
}

func.cxx

export module airline_ticket;
#include <string>

export class AirlineTicket
{

public:

AirlineTicket();
~AirlineTicket();

double calculatePriceInDollars(); std::string getPassengerName();

void setPassengerName(std::string name);

int getNumberOfMiles();
void setNumberOfMiles(int miles);

bool hasEliteSuperRewardsStatus();
void setHasEliteSuperRewardsStatus(bool status);

private:
std::string m_passengerName;
int m_numberOfMiles;
bool m_hasEliteSuperRewardsStatus;

};

func_impl.cxx

module airline_ticket;

AirlineTicket::AirlineTicket()
{
// Initialize data members.
m_passengerName = "Unknown Passenger";
m_numberOfMiles = 0;
m_hasEliteSuperRewardsStatus = false;
}

Answer 1

func.cxx 中的 include 指令需要在全局模块片段区域中。否则你会得到重新定义。

即

module;
#include <string>
export module .....
...

Error: cannot define 'enum class std::align_val_t' in different module

Error: cannot define 'enum class std::align_val_t' in different module

c++

c++20

c++-modules