LANG.TYPE.MI.TMPBC : Multiple Inheritance with Too Many Protected Base Classes

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CodeSonar^® 9.2p0

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CodeSecure Inc

C and C++

LANG.TYPE.MI.TMPBC : Multiple Inheritance with Too Many Protected Base Classes

Summary

A class inherits two or more non-interface classes as protected.

A class C is considered an interface class if either of the following is true.

C has at least one method, and all methods of C are pure virtual, and C has at most one scalar data member.
or
C is inherited as a "mixin" class: an instantiation of a template with at least one parameter that is the inheriting class. This is sometimes referred to as the Curiously Repeating Template Pattern (CRTP).

Properties

Class Name

Multiple Inheritance with Too Many Protected Base Classes

Significance

style

Mnemonic

LANG.TYPE.MI.TMPBC

Categories

AUTOSARC++14	AUTOSARC++14:A10-1-1	Class shall not be derived from more than one base class which is not an interface class.
CWE	CWE:1055	Multiple Inheritance from Concrete Classes
JSF++	JSF++:88	Multiple inheritance shall only be allowed in the following restricted form: n interfaces plus m private implementations, plus at most one protected implementation.

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="Multiple Inheritance with Too Many Protected Base Classes"

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 base0 {};

class base1 {};

// interface0 is always considered an interface class:
// - It has at least one method.
// - All methods are pure virtual.
// - It has no more than one scalar data member.
class interface0 {
  public:
    char *id;
    virtual void start(void) = 0;
};

class derivedA :     // 'Multiple Inheritance with Too Many Protected Base Classes' warning issued here
  protected base0,
  protected base1
{};

class derivedB:                                 // only one base class inherited as protected
  protected base0,
  private base1
{};

class derivedC:                                 // only one non-interface inherited
                                                // ('Multiple Inheritance with Protected Interface Class'
                                                //  warning issued here if enabled)
  protected base0,
  protected interface0
{
  void start(void) {};
};

Relevant Configuration File Parameters

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

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