IV97585: CONSTRUCTORS NOT CALLED FOR OBJECTS CREATED IN COMMA EXPRESSIONS

XL C/C++ for AIX Fix Pack 9 (June 2017 PTF) for 13.1
XL C/C++ for AIX Fix Pack 10 (February 2018 PTF) for 13.1
XL C/C++ for AIX Fix Pack 11 (November 2018 PTF) for 13.1

APAR status

• Closed as program error.

Error description

• When using comma expressions to create objects, some destructor
  calls are seen without corresponding constructor calls.  The
  missing constructors may cause memory or illegal instruction
  errors.
  
  
     === TEST CASE ===
  
  #include <stdio.h>
  struct Test
  {
      Test()
       { printf("Test() %p\n", this); }
  
      Test(const Test &other)
       { printf("Test(const Test &) %p<-%p\n", this, &other); }
  
      Test &operator=(const Test &other)
        {
         printf("Test &operator=(const Test &) %p=%p\n",
                this, &other);
         return *this;
        }
  
      ~Test()
       { printf("~Test() %p\n", this); }
  };
  
  Test f()
  {
      return Test();
  }
  
  int main()
  {
      Test s;
      s = ( Test(), f() );
  }
  
  
  
  $ xlC test.cpp
  $ ./a.out
  Test() 2ff216a0
  Test() 2ff216a1
  Test() 2ff216a2
  Test(const Test &) 2ff216a3<-2ff216a2
  Test &operator=(const Test &) 2ff216a0=2ff216a3
  ~Test() 2ff216a3
  ~Test() 2ff216a2
  ~Test() 2ff216a1
  ~Test() 2ff216a0
  $
  

Local fix

• In failing scenarios using an intermediate temporary object, the
  issue can be worked around by avoid the tempoarary:
  
  
  Failing Scenario:
        Test s;
        s = ( Test(), f() );
  
  Passing Scenario:
        Test a = ( Test(), f() );
  

Problem summary

• PROBLEM DESCRIPTION:
  Some constructor calls are missing when using comma
  expressions.
  
  USERS AFFECTED:
  Users of comma expressions that create temporaries with
  constructors such as:
  
  container s;
  s = ( container(), f() );
  

Problem conclusion

• The problem has been fixed.
  

Temporary fix

Comments

APAR Information

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

  IV90063

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

Fix information

• Fixed component name

  XL C/C++ FOR AI

• Fixed component ID

  5725C7200

Applicable component levels