c++ - 通过引用访问是否违反了严格的别名规则？

Question

我知道 int* ptr = (int*)buffer(其中 buffer 是 char*)中断严格别名规则。

这个语法 int& ref = (int&)(*buffer) 是否也违反了规则？

我had一些由于违反严格的别名规则而导致的 SEGFAULT，此语法已将其消除。虽然可能仍然不正确，是吗？

Answer 1

这不行(假设您要使用所述引用来访问该值)。 § 3.10 [basic.lval] ¶ C++14 标准的第 10 条(引用 N4140)说(强调我的):

If a program attempts to access the stored value of an object through a glvalue of other than one of the following types the behavior is undefined:

• the dynamic type of the object,
• a cv-qualified version of the dynamic type of the object,
• a type similar (as defined in 4.4) to the dynamic type of the object,
• a type that is the signed or unsigned type corresponding to the dynamic type of the object,
• a type that is the signed or unsigned type corresponding to a cv-qualified version of the dynamic type of the object,
• an aggregate or union type that includes one of the aforementioned types among its elements or non-static data members (including, recursively, an element or non-static data member of a subaggregate or contained union),
• a type that is a (possibly cv-qualified) base class type of the dynamic type of the object,
• a char or unsigned char type.

尝试通过指针还是引用访问并不重要。对于 char 类型的存储对象，没有任何要点适用于允许将其作为 int 进行访问。

最后一个要点仅表示您可以将任何 other 类型别名为 char，但反之则不行。这是有道理的，因为 char 是具有最弱对齐要求的最小可寻址单元。

如果您愿意，使用指针与使用引用是一样的，只是您需要显式取消引用才能访问该值。