PK85126: COMPILER ERROR WHEN USING FRIEND CLASS TO ACCESS PROTECTED MEMB ERS OF A CLASS

APAR status

• Closed as Permanent restriction.

Error description

• Quintus defect :223845
  
  
              Summary:
  ---------
  Compiler error when using friend class to access protected
  members of a class
  
  Description:
  ------------
  The reason that this is a defect is simply that the
  CPP_CG.Class.Friend
  property does not work for parts with the Advanced compiler and
  MS VC6.
  
  The VC6 compiler error is correct according to the specification
  of the
  C++ language.  In 'The C++ Programming Language' by Bjarne
  Stroustrup
  (I'm using the 3rd edition), section C.11.3 'Access to Member
  Class', it
  is clear in the example that an Inner class should be declared
  before it is granted friend access to its Outer class.
  
  The classic code generator
  (CPP_CG.Configuration.CodeGeneratorTool =
  Classic) produces code that compiles OK with VC6 --- this
  problem has
  only arisen with the Advanced code generator.
  
  The defect is that the Advanced compiler should declare all part
  classes
  before friend declarations, as per the C++ language
  specification.
  There are (at least) two possible ways of doing this:
  1. Have forward declarations of all parts, before the friend
  declarations (this is what the classic compiler does), or
  2. Place the friend declarations after the declarations of all
  parts
  (this is like work-around using the specification epilog and not
  friend class property).
  
  Steps to reproduce:
  -------------------
  Create a class Container
  Add a protected operation OpInContainer to this class
  Create a part Object_0 inside Container
  Add an operation OpInObject to this object
  Add association between the two
  In OpInObject accesss mycontainer-?OpInContainer();
  Add object_0 as friend to container
  Build the model in VC6 and observe the error.
  
  Defect: All forward decalarations of parts should come before
  the friend declaration , which doesn happen in this case.
  
  Open project placed in \\ilre-dc\TestCases\Rhapsody\
  Error: Cannot access protected member of a class
  (With cygwin it gives redefinition error since friend class is
  added for the part as well)
  
  Compiles fine in Rhp 7.2
  Does not compile with Rhp 7.4 and higher
  Exception:
  
  Compiles fine with MSVS 2005
  Does not compile with VC6
  
  PMR Number: PMR 61794,019,866
  

Local fix

• CPP_CG.Class.SpecificationEpilog and add code for a
  friend declaration
  after the declaration of the part class
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
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  * PROBLEM DESCRIPTION:                                         *
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  * RECOMMENDATION:                                              *
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  Compiler error when using a friend class to access protected
  members of a class.
  

Problem conclusion

• There are no plans at the moment to change this code
  generation behavior. There are two available workarounds:
  1) Add "class" to the friend declaration. For example,
  instead of using MyClass for the CPP_CG::Class::Friend
  property, use "class MyClass".
  2) Model a ??Friend?? dependency.
  Either of these approaches will result in code that
  compiles.
  

Temporary fix

Comments

APAR Information

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

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

Fix information

Applicable component levels