constexpr和bizzare错误

问题描述

我有：

constexpr bool is_concurrency_selected()const
    {
        return ConcurrentGBx->isChecked();//GBx is a groupbox with checkbox
    }

'm getting error：

and I'm getting error:

C:\...\Options_Dialog.hpp:129: error: enclosing class of 'bool Options_Dialog::is_concurrency_selected() const' is not a literal type

p>

推荐答案

这意味着你的类不是文字类型...这个程序是无效的，因为 code>不是字面类类型。但 Checker 是一个文字类型。

It means your class is not a literal type... This program is invalid, because Options is not a literal class type. But Checker is a literal type.

struct Checker {
  constexpr bool isChecked() {
    return false;
  }
};

struct Options {
  Options(Checker *ConcurrentGBx)
    :ConcurrentGBx(ConcurrentGBx)
  { }

  constexpr bool is_concurrency_selected()const
  {
      //GBx is a groupbox with checkbox
      return ConcurrentGBx->isChecked();
  }

  Checker *ConcurrentGBx;
};

int main() {
  static Checker c;
  constexpr Options o(&c);
  constexpr bool x = o.is_concurrency_selected();
}

Clang列印

test.cpp:12:18: error: non-literal type 'Options' cannot have constexpr members
    constexpr bool is_concurrency_selected()const
                   ^
test.cpp:7:8: note: 'Options' is not literal because it is not an aggregate and has no constexpr constructors other than copy or move constructors
    struct Options {

如果你解决这个问题，并使选项构造函数 constexpr ，我的示例代码片段编译。类似的事情可能适用于您的代码。

If you fix this and make the Options constructor constexpr, my example snippet compiles. Similar things may apply to your code.

您似乎不明白 constexpr 是什么意思。我建议读一本关于它的书（如果这样的书已经存在，反正）。

You appear to not understand what constexpr means. I recommend reading a book about it (if such a book exists already, anyway).

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