c++ - `core constant expression` 与 `constant expression`

Question

核心常量表达式的定义取决于常量表达式的概念，如要点 (2.7.1) 和 (2.9.1) 所示N4140 的。

§5.19/2:

A conditional-expression e is a core constant expression unless the evaluation of e, following the rules of the abstract machine (1.9), would evaluate one of the following expressions:

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(2.7.1) — a non-volatile glvalue of integral or enumeration type that refers to a non-volatile const object with a preceding initialization, initialized with a constant expression

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(2.9.1) — it is initialized with a constant expression or

常量表达式的定义依赖于核心常量表达式的概念，如N4140的§5.19/4所示:

A constant expression is either a glvalue core constant expression whose value refers to an object with static storage duration or to a function, or a prvalue core constant expression whose value is an object where, for that object and its subobjects:
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这似乎违背了数理逻辑的基本原则。

Answer 1

定义是相互递归的，但实际上不是循环的。