如何处理clang中的全局构造函数警告？ [英] How to deal with global-constructor warning in clang?

问题描述

Clang警告（当使用 -Weverything 或 Wglobal-constructors ）关于静态对象的构造函数。 >

Clang warns (when using -Weverything or Wglobal-constructors) about constructors for static objects.

warning: declaration requires a global constructor
      [-Wglobal-constructors]
A A::my_A; // triggers said warning
     ^~~~

为什么这是相关的，处理此警告？

Why is this relevant and how should one deal with this warning?

简单示例代码：

class A {
  // ...
  static A my_A;
  A();
};

A A::my_A; // triggers said warning

推荐答案

触发相同的警告：

class A {
public:
  // ...
  A();
};

A my_A; // triggers said warning


test.cpp:7:3: warning: declaration requires a global constructor [-Wglobal-constructors]
A my_A; // triggers said warning
  ^~~~
1 warning generated.

这是完全合法且安全的C ++。

This is perfectly legal and safe C++.

但是对于每一个非平凡的全局构造函数，你的应用程序的启动时间都会受到影响。警告只是一种让您了解这种潜在性能问题的方法。

However for every non-trivial global constructor you have, launch time of your application suffers. The warning is simply a way of letting you know about this potential performance problem.

您可以使用-Wno-global-constructors禁用警告。或者，您可以改为像这样的延迟初始化方案：

You can disable the warning with -Wno-global-constructors. Or you can change to a lazy initialization scheme like this:

A&
my_A()
{
    static A a;
    return a;
}

可以完全避免问题（并禁止警告）。

which avoids the issue entirely (and suppresses the warning).

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