c++ - C++ 标准的哪一部分涵盖通过空指针调用方法？

Question

Stack Overflow 上有很多问题解释了以下是 C++ 中未定义的行为:

MyType* p = nullptr;
p->DoSomething();

但我找不到引用 C++ 标准的内容。 C++11 和/或 C++14 标准的哪一部分规定这是未定义的行为？

Answer 1

C++14 [expr.ref]/2:

The expression E1->E2 is converted to the equivalent form (*(E1)).E2

C++14 [expr.unary.op]/1:

The unary * operator performs indirection: the expression to which it is applied shall be a pointer to an object type, or a pointer to a function type and the result is an lvalue referring to the object or function to which the expression points.

指针不指向对象，因此这句话没有定义*p的行为。标准中的其他地方也没有定义它，因此它是未定义的行为。

关于空指针是否可以说指向一个对象，N4618 [basic.compound]/3将指针值定义为:

Every value of pointer type is one of the following:

• a pointer to an object or function (the pointer is said to point to the object or function), or
• a pointer past the end of an object, or
• the null pointer value for that type, or
• an invalid pointer value.

这表明空指针值不指向对象。