LI77073: INCORRECT VIRTUAL TEMPLATE ERROR

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • The compiler generates an incorrect virtual template error
    message for the test case mentioned below:
    
    $cat test.cpp
    namespace sc{
    
    template <class T>
    class  Ref {};
    }
    
    
    namespace sc {
    
    
      struct DistArray4Dimensions {
        public:
          static const DistArray4Dimensions& default_dim() { return
    default_dim_; }
    
        private:
          static DistArray4Dimensions default_dim_;
    
      };
    
    
    class DistArray4 {
      public:
        virtual Ref<DistArray4> clone(const DistArray4Dimensions&
    dim = DistArray4Dimensions::default_dim()) =0;
    };
    
    
    }
    
    namespace sc {
    
    class DistArray4_MPIIOFile: public DistArray4 {
    
      protected:
        template <typename Derived> Ref<DistArray4> clone(const
    DistArray4Dimensions& dim =
    
    DistArray4Dimensions::default_dim());
    };
    }
    $
    
    
    ===== ACTUAL OUTPUT:
    $bgxlC -qarch=450d -qtune=450  -c test.cpp
    "test.cpp", line 34.49: 1540-1158 (S) The function template
    "sc::DistArray4_MPIIOFile::clone" must not be declared as
    virtual.
    $
    
    ===== EXPECTED OUTPUT:
    Should compile clean.
    

Local fix

  • n/a
    

Problem summary

  • USERS AFFECTED:
    Users with member function templates which have the same name
    and parameter list as a base class virtual function are
    affected by this issue.
    
    PROBLEM DESCRIPTION:
    A template function which otherwise has the same name and
    parameter list
    as a base class virtual function may be incorrectly rejected
    with a message
    indicating that the template function may not be declared
    virtual.
    
    struct A {
    virtual void foo();
    };
    
    struct B : A {
    template <typename T>
    void foo();  // error message produced for this line
    };
    
    The function is actually not declared virtual; however, it was
    mistakenly
    considered to override the base class virtual function.
    
    Specializations of member template functions should never be
    considered to
    override members of a base class.
    

Problem conclusion

  • A check was implemented to recognize that member function
    templates never override virtual functions.
    

Temporary fix

Comments

APAR Information

  • APAR number

    LI77073

  • Reported component name

    XL C/C++ FOR BG

  • Reported component ID

    5799AG100

  • Reported release

    C10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-11-23

  • Closed date

    2012-11-23

  • Last modified date

    2012-11-23

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

    LI76710

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

Fix information

  • Fixed component name

    XL C/C++ FOR BG

  • Fixed component ID

    5799AG100

Applicable component levels



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Document information


More support for:

XL C/C++ for Blue Gene/Q
Compiler

Software version:

12.1

Reference #:

LI77073

Modified date:

2012-11-23

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