我有一个类，在代码剪辑中我把它的部分贴在我认为问题所在的地方。

class SubtreeExplorer : public AbstractTask {
 public:
  SubtreeExplorer(Threadpool& tp, SudokuBoard&& sudoku)
      : tp(tp), sudoku(std::move(sudoku)) {}

 ...

 private:
  Threadpool& tp;
  SudokuBoard sudoku;
 
  bool sudoku_backtracking_search(SudokuBoard& s) {
   ...
   while(...){
      ...
      // let another thread explore the subtree
      tp.submit(make_shared<SubtreeExplorer>(tp, SudokuBoard(sudoku)));
   }
  }
};

当我尝试编译它时，它给出了一个错误:

/Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/memory:4325:5: error: static_assert failed due to requirement 'is_constructible<SubtreeExplorer,
      Threadpool &, SudokuBoard &>::value' "Can't construct object in make_shared"
    static_assert( is_constructible<_Tp, _Args...>::value, "Can't construct object in make_shared" );

我使用的是VS代码，在IDE中没有突出显示错误。 这个问题很可能是由make_shared引起的，但是我不能确定构造函数中的内容（SubtreeExplorer类）。

SudokuBoard（sudoku)从给定的棋盘返回一个新的棋盘，只需进行少量修改。 我想把这个新板移动到新的子树资源管理器中。

在谷歌上，我写的构造函数应该把板子移到里面，但我还是收到了我写的编译错误，还有一长串难以阅读的注释:

/Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/memory:2259:9: note: in instantiation of function template specialization
      'std::__1::__compressed_pair_elem<SubtreeExplorer, 1, false>::__compressed_pair_elem<Threadpool &, SudokuBoard &, 0, 1>' requested here
        _Base2(__pc, _VSTD::move(__second_args),
        ^ /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/memory:3672:16: note: in instantiation of function template specialization
      'std::__1::__compressed_pair<std::__1::allocator<SubtreeExplorer>, SubtreeExplorer>::__compressed_pair<std::__1::allocator<SubtreeExplorer> &,
      Threadpool &, SudokuBoard &>' requested here
            :  __data_(piecewise_construct, _VSTD::forward_as_tuple(__a),
               ^ /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/memory:4331:26: note: in instantiation of function template specialization
      'std::__1::__shared_ptr_emplace<SubtreeExplorer, std::__1::allocator<SubtreeExplorer>
>::__shared_ptr_emplace<Threadpool &, SudokuBoard &>' requested
      here
    ::new(__hold2.get()) _CntrlBlk(__a2, _VSTD::forward<_Args>(__args)...);
                         ^ /Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/memory:4710:29: note: in instantiation of function template specialization
      'std::__1::shared_ptr<SubtreeExplorer>::make_shared<Threadpool &, SudokuBoard &>' requested here
    return shared_ptr<_Tp>::make_shared(_VSTD::forward<_Args>(__args)...);
                            ^ src/sudoku_parallel.cpp:119:13: note: in instantiation of function template specialization 'std::__1::make_shared<SubtreeExplorer, Threadpool &, SudokuBoard
      &>' requested here   tp.submit(make_shared<SubtreeExplorer>(tp, sudoku));
            ^ src/sudoku_parallel.cpp:41:3: note: candidate constructor not viable: no known conversion from 'SudokuBoard' to 'SudokuBoard &&' for 2nd argument   SubtreeExplorer(Threadpool& tp, SudokuBoard&& sudoku)   ^ src/sudoku_parallel.cpp:39:7: note: candidate constructor (the implicit copy constructor) not viable: requires 1 argument, but 2 were provided class SubtreeExplorer : public AbstractTask {
      ^ src/sudoku_parallel.cpp:39:7: note: candidate constructor (the implicit move constructor) not viable: requires 1 argument, but 2 were provided

这让我产生了这样的想法:我向构造函数传递了错误数量的参数，尽管它需要两个参数，而我传递了这两个参数，一个线程池和一个数独板。

基本上，SubtreeExplorer是在sudoku_backtracking_search函数的主体中创建的:

int main() {
   ...
   SubokuBoard sudoku(filepath);
   tp.submit(make_shared<SubtreeExplorer>(tp, sudoku));
   ...
}

编辑:tp是一个线程池，它的submit方法具有以下签名:

bool submit(std::shared_ptr<AbstractTask> task);

而AbstractTask类如下所示:

struct AbstractTask {
  virtual ~AbstractTask() = default;
  virtual void run() = 0;
};