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

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A pointer to virtual base class is cast to a pointer to a derived class by some means other than dynamic_cast.

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	5.1. 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.

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
}

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

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

Summary

Properties

Example

Relevant Configuration File Parameters