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CodeSonar® 9.2p0 CONFIDENTIAL CodeSecure Inc
C and C++

LANG.CAST.PC.VBASE : Cast: Virtual Base to Derived

Summary

A pointer to virtual base class is cast to a pointer to a derived class by reinterpret_cast.

Properties

Class Name Cast: Virtual Base to Derived
Significance reliability
Mnemonic LANG.CAST.PC.VBASE
Categories
Misra2004 Misra2004:11.4 A cast should not be performed between a pointer to object type and a different pointer to object type
AUTOSARC++14 AUTOSARC++14:M5-2-2 A pointer to a virtual base class shall only be cast to a pointer to a derived class by means of dynamic_cast.
  AUTOSARC++14:A5-2-4 reinterpret_cast shall not be used.
MisraC++2008 MisraC++2008:5-2-2 A pointer to a virtual base class shall only be cast to a pointer to a derived class by means of dynamic_cast.
  MisraC++2008:5-2-7 An object with pointer type shall not be converted to an unrelated pointer type, either directly or indirectly.
MisraC++2023 MisraC++2023:8.2.1 A virtual base class shall only be cast to a derived class by means of dynamic_cast
  MisraC++2023:8.2.5 reinterpret_cast shall not be used
CWE CWE:704 Incorrect Type Conversion or Cast
TS17961 TS17961:5.1-ptrcomp Accessing an object through a pointer to an incompatible type
CERT-C CERT-C:EXP36-C Do not cast pointers into more strictly aligned pointer types
JSF++ JSF++:178 Down casting (casting from base to derived class) shall only be allowed through certain mechanisms.
  JSF++:179 A pointer to a virtual base class shall not be converted to a pointer to a derived class.
  JSF++:182 Type casting from any type to or from pointers shall not be used.
  JSF++:183 Every possible measure should be taken to avoid type casting.
Availability Available for C++ only (not C).
Enabling Checks for this warning class are disabled by default, and require the unnormalized C ASTs for the project. To enable them, add the following WARNING_FILTER rule and RETAIN_UNNORMALIZED_C_AST specification to the project configuration file. 
RETAIN_UNNORMALIZED_C_AST = Yes
WARNING_FILTER += allow class="Cast: Virtual Base to Derived"
Note that retaining the unnormalized ASTs will increase the disk space used to store the project representation, and may make the analysis take longer.

Example 

class Base {
  public:
    virtual void polymorphic(void);
};

class Derived : public virtual Base { };

Derived d;
Derived *pD1;
Derived *pD2;

void virtual_base_cast(void) {
    Base * pB = &d;
    pD1 = reinterpret_cast< Derived * >( pB ); // 'Cast: Virtual Base to Derived' warning issued here
    pD2 = dynamic_cast< Derived * >( pB );                   // ok: casting with dynamic_cast
}

Relevant Configuration File Parameters

The following configuration file parameters affect checks for this warning class.

 

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