LI80776: DESTRUCTOR IS NOT BEING CALLED WITH RETURN IN TRY BLOCK

APAR status

• Closed as program error.

Error description

• If a return is used in a nested try block, then the destructors
  of objects are on the stack will not be called. This is shown
  with the testcase below:
  
  ===== COMPILE COMMAND:
  xlclang++ test.cpp
  
  ===== TESTCASE:
  $ cat test.cpp
  #include <iostream>
  
  using namespace std;
  class Line {
     public:
        void setLength( double len );
        double getLength( void );
        Line();   // This is the constructor declaration
        ~Line();  // This is the destructor: declaration
  
     private:
        double length;
  };
  
  // Member functions definitions including constructor
  Line::Line(void) {
     cout << "Object is being created" << endl;
  }
  Line::~Line(void) {
     cout << "Object is being deleted" << endl;
  }
  void Line::setLength( double len ) {
     length = len;
  }
  double Line::getLength( void ) {
     return length;
  }
  
  
  void  try_1()
  {
     Line line1;
     try {
             line1.setLength(96.0);
         return;}
         catch ( ... ) {
         cerr << "Catch 2"; }
  }
  void  try_nested()
  {
     Line line1;
     {
       {
         try {
             line1.setLength(96.0);
         return;}
         catch ( ... ) {
             cerr << "Catch 2";
         }
       }
     }
  }
  
  
  void  try_try()
  {
     Line line2;
     try {
             line2.setLength(96.0);
          try {
  
             line2.setLength(196.0);
  //           line2.~Line();
              return;
                 }
         catch ( ... ) {
         cerr << "Catch 1" ;}
         }
         catch ( ... ) {
         cerr << "Catch 2"; }
  
  
  }
  
  
  // Main function for the program
  int main() {
  
     cout << "               " <<endl;
     cout << "               " <<endl;
     cout << " BEGIN: single try with return" <<endl;
     cout << "-------->  Expectartion: Constructor/Destructor is
  called " <<endl;
  
     try_1();
     cout << " END:   single try with return" <<endl;
  ////////////
     cout << "             --------   " <<endl;
     cout << "               " <<endl;
     cout << "               " <<endl;
     cout << " BEGIN: nested  try with return" <<endl;
     cout << "-------->  Expectartion: Constructor/Destructor is
  called " <<endl;
  
     try_nested();
  
     cout << " END:   nested try with return" <<endl;
  ///////////
     cout << "               " <<endl;
     cout << "               " <<endl;
     cout << " BEGIN: try in a try with return" <<endl;
     cout << "-------->  Expectartion: Constructor/Destructor is
  called " <<endl;
  
     try_try();
  
     cout << " END:  try in a try with return" <<endl;
     // cout << "Length of line : " << line.getLength()+1 <<endl;
     return 0;
  }
  
  
  $
  
  
  ===== ACTUAL OUTPUT:
  $ ./a.out
  
  
  BEGIN: single try with return
  -------->  Expectartion: Constructor/Destructor is called
  Object is being created
  Object is being deleted
  END:   single try with return
               --------
  
  
  BEGIN: nested  try with return
  -------->  Expectartion: Constructor/Destructor is called
  Object is being created
  END:   nested try with return
  
  
  BEGIN: try in a try with return
  -------->  Expectartion: Constructor/Destructor is called
  Object is being created
  END:  try in a try with return
  $
  
  ===== EXPECTED OUTPUT:
  $ ./a.out
  
  
  BEGIN: single try with return
  -------->  Expectartion: Constructor/Destructor is called
  Object is being created
  Object is being deleted
  END:   single try with return
               --------
  
  
  BEGIN: nested  try with return
  -------->  Expectartion: Constructor/Destructor is called
  Object is being created
  Object is being deleted
  END:   nested try with return
  
  
  BEGIN: try in a try with return
  -------->  Expectartion: Constructor/Destructor is called
  Object is being created
  Object is being deleted
  END:  try in a try with return
  $
  

Local fix

• N/A
  

Problem summary

• USERS AFFECTED:
  Users who have return statements within try-catch blocks may be
  affected by this issue.
  
  PROBLEM DESCRIPTION:
  The C++ runtime exception handling was not correctly
  processing/cleaning the exceptions when try-catches contained
  return statements.
  

Problem conclusion

• We are now correctly walking the enclosing try/catch blocks of
  the return and emitting the correct actions before the return.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  IJ15509

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  XL C/C++ LINUX

• Fixed component ID

  5725C7310

Applicable component levels