禁用“错误函数转换”警告 [英] Disabling "bad function cast" warning

问题描述

我收到以下警告：

warning: converting from 'void (MyClass::*)(byte)' to 'void (*)(byte)'

这是因为我需要传递作为参数a成员函数而不是普通函数。但是程序运行正常。

This is because I need to pass as argument a member function instead of an ordinary function. But the program is running correctly.

我想禁用此警告（Wno-bad-function-cast不适用于C ++）或实现不同的

I'd like to disable this warning (Wno-bad-function-cast doesn't work for C++) or to implement a different way to pass a member function.

推荐答案

否。认真对待这个警告。

No. Take this warning seriously. You should rather change your code to handle this scenario.

指向成员函数的指针（ void（MyClass :: *）（byte））和正常函数指针（ void（*）（byte））完全不同。 请参阅此链接。你不能像这样施放他们。

Pointer to member function(void (MyClass::*)(byte)) and normal function pointer (void (*)(byte)) are entirely different. See this link. You cannot cast them just like that. It results in undefined behavior or crash.

看到这里，它们是如何不同：

See here, how they are different:

void foo (byte); // normal function
struct MyClass {
  void foo (byte); // member function 
}

现在你可能会觉得 foo（byte）和 MyClass :: foo（byte）有相同的签名，那么为什么他们的函数指针不相同。这是因为 MyClass :: foo（byte）在某种程度上被内部解析为，

Now you may feel that, foo(byte) and MyClass::foo(byte) have same signature, then why their function pointers are NOT same. It's because, MyClass::foo(byte) is internally resolved somewhat as,

void foo(MyClass* const this, byte);

现在你可以闻到它们之间的区别。

Now you can smell the difference between them.

将成员函数的指针声明为

Declare pointer to member function as,

void (MyClass::*ptr)(byte) = &MyClass::foo;

您必须使用 ptr 对象 MyClass ，例如：

You have to use this ptr with the object of MyClass, such as:

MyClass obj;
obj.*ptr('a');

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