c++ - C89 或 C++03 是否定义了严格的别名规则？

Question

我看过 several assertions C89 和 C++03 定义了严格的别名规则。但是，我无法在标准中找到该特定位。我的理解是 C99 中添加了严格的别名规则。

Answer 1

此文本出现在 C89，§3.3 表达式中:

An object shall have its stored value accessed only by an lvalue that has one of the following types:

• the declared type of the object,

• a qualified version of the declared type of the object,

• a type that is the signed or unsigned type corresponding to the
  declared type of the object,

• a type that is the signed or unsigned type corresponding to a
  qualified version of the declared type of the object,

• an aggregate or union type that includes one of the aforementioned
  types among its members (including, recursively, a member of a
  subaggregate or contained union), or

• a character type.

违反“应”约束会导致未定义的行为，因此可以从此文本中导出一组允许的别名规则。