CERT C:Rec.EXP05-C

Do not cast away a const qualification

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描述

规则定义

Do not cast away a const qualification.¹

Polyspace 实现

规则检查项检查是否存在去除 const 限定符的指针类型转换。

示例

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将类型转换为指针并去除 `const` 限定符

问题

Polyspace^® 标记违反此规则的隐式和显式转换。

风险

此规则禁止将指向 const 对象的指针转换为不指向 const 对象的指针。

此类转换违反类型限定。例如，const 修饰符表示对象的只读状态。如果转换删除了限定符，则对象不再为只读。

示例 - 删除限定符的转换

void foo(void) {

    /* Cast on simple type */
    unsigned short           x;
    unsigned short * const   cpi = &x;  /* const pointer */
    unsigned short * const  *pcpi;   /* pointer to const pointer */
    unsigned short **ppi;
    const unsigned short    *pci;    /* pointer to const */
    unsigned short          *pi;

    pi = cpi;                        /* Compliant - no cast required */
    pi  = (unsigned short *)  pci;   /* Non-compliant */
    ppi = (unsigned short **)pcpi;   /* Non-compliant */
}

在此示例中，变量 pci 和 pcpi 的类型中包含限定符 const。当变量被转换为不具有 const 修饰符的类型时，该规则被违反。

尽管 cpi 的类型中包含 const 限定符，但在语句 p=cpi; 中并未违反该规则。该赋值操作不会引发类型转换，因为 p 和 cpi 的类型均为 unsigned short。

检查信息

组：Rec.03.表达式 (EXP)

版本历史记录

在 R2019a 中推出

另请参阅

检查 SEI CERT-C (-cert-c)

主题

检查并审查编码标准违规

外部网站

EXP05-C

¹ This software has been created by MathWorks incorporating portions of: the “SEI CERT-C Website,” © 2017 Carnegie Mellon University, the SEI CERT-C++ Web site © 2017 Carnegie Mellon University, ”SEI CERT C Coding Standard – Rules for Developing safe, Reliable and Secure systems – 2016 Edition,” © 2016 Carnegie Mellon University, and “SEI CERT C++ Coding Standard – Rules for Developing safe, Reliable and Secure systems in C++ – 2016 Edition” © 2016 Carnegie Mellon University, with special permission from its Software Engineering Institute.

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