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Using the same class definitions as the noncompliant code example, this compliant solution modifies the definition of f() to require raw pointers to the object, removing the slicing problem:.

Code Block
bgColor#ccccff
langcpp
// Remainder of code unchanged...
 
void f(const Employee *e) {
  if (e) {
    std::cout << *e;
  }
}

int main() {
  Employee coder("Joe Smith");
  Employee typist("Bill Jones");
  Manager designer("Jane Doe", typist);
  
  f(&coder);
  f(&typist);
  f(&designer);
}

This compliant solution also complies with EXP34-C. Do not dereference null pointers in the implementation of f(). With this definition, the the program correctly outputs :the following.

Code Block
Employee: Joe Smith
Employee: Bill Jones
Manager: Jane Doe
Assistant: 
	Employee: Bill Jones

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An improved compliant solution, which does not require guarding against null pointers within f(), uses references instead of pointers:.

Code Block
bgColor#ccccff
langcpp
// ... Remainder of code unchanged ...
 
void f(const Employee &e) {
  std::cout << e;
}

int main() {
  Employee coder("Joe Smith");
  Employee typist("Bill Jones");
  Manager designer("Jane Doe", typist);
  
  f(coder);
  f(typist);
  f(designer);
}

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This compliant solution uses a vector of std::unique_ptr objects, which eliminates the slicing problem:.

Code Block
bgColor#ccccff
langcpp
#include <iostream>
#include <memory>
#include <string>
#include <vector>

void f(const std::vector<std::unique_ptr<Employee>> &v) {
  for (const auto &e : v) {
    std::cout << *e;
  }
}

int main() {
  std::vector<std::unique_ptr<Employee>> v;
  
  v.emplace_back(new Employee("Joe Smith"));
  v.emplace_back(new Employee("Bill Jones"));
  v.emplace_back(new Manager("Jane Doe", *v.front()));
  
  f(v);
}

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Slicing results in information loss, which could lead to abnormal program execution or denial-of-service attacks.

Rule

Severity

Likelihood

Remediation Cost

Priority

Level

OOP51-CPP

Low

Probable

Medium

P4

L3

Automated Detection

Tool

Version

Checker

Description

CodeSonar
Include Page
CodeSonar_V
CodeSonar_V

LANG.CAST.OBJSLICE

Object Slicing

Helix QAC

Include Page
Helix QAC_V
Helix QAC_V

C++3072
Parasoft C/C++test
9.5OOP-02, JSF-117_a 

 PRQA QA-C++

  Include PagePRQA QA-C++_VPRQA QA-C++_V

3072, 3073

 
Include Page
Parasoft_V
Parasoft_V

CERT_CPP-OOP51-a

Avoid slicing function arguments / return value

Polyspace Bug Finder

Include Page
Polyspace Bug Finder_V
Polyspace Bug Finder_V

CERT C++: OOP51-CPPChecks for object slicing (rule partially covered)
PVS-Studio

Include Page
PVS-Studio_V
PVS-Studio_V

V1054

Related Vulnerabilities

Search for other vulnerabilities resulting from the violation of this rule on the CERT website.

Related Guidelines

Bibliography

[Dewhurst
03
2002]Gotcha #38, "Slicing"
[ISO/IEC 14882-2014]Subclause 12.8, "Copying and Moving Class Objects"
[Sutter
00
2000]Item 40, "Object Lifetimes—Part I"

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