LI77348: INCORRECT ERROR MESSAGE OF USE BEFORE DEFINED

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • ===== DESCRIPTION:
    The compiler is mistakenly generating an error related to "use
    before defined" for templates when it shouldn't.
    
    ===== Compile command:
    xlC -c test.cpp
    
    ========Testcase:
    $ cat test.cpp
    #include <iostream>
    #include <vector>
    
    namespace LibGeoDecomp {
    
    template<int DIM>
    class Coord
    {
    public:
        Coord(int x, int y)
        {
            pos[0] = x;
            pos[1] = y;
        }
    
        int pos[DIM];
    };
    
    class Stencils
    {
    public:
        template<int DIM, int RADIUS>
        class Moore
        {
            static const int dim = DIM;
            static const int radius = RADIUS;
        };
    };
    
    class TopologiesHelpers
    {
    public:
        template<int DIM, bool WRAP_X=false, bool WRAP_Y=false, bool
    WRAP_Z=false>
        class Topology
        {
        public:
            static const int dim = DIM;
            static const int wrapX = WRAP_X;
            static const int wrapY = WRAP_Y;
            static const int wrapZ = WRAP_Z;
        };
    };
    
    template<int DIM=2, typename STENCIL=Stencils::Moore<2, 1>,
    typename TOPOLOGY=TopologiesHelpers::Topology<2, 0, 0, 0> >
    class TestCell
    {
    public:
        typedef STENCIL Stencil;
        typedef TOPOLOGY Topology;
        static const int dim = DIM;
    };
    
    template<typename CELL, typename
    TOPOLOGY=TopologiesHelpers::Topology<2, 0, 0, 0> >
    class Grid
    {
    public:
        typedef CELL Cell;
        typedef TOPOLOGY Topology;
        static const int DIM = CELL::Topology::dim;
    
        Grid(Coord<DIM> c) :
            dim(c)
        {
            std::cout << "Grid(" << c.pos[0] << ", " << c.pos[1] <<
    ")\n";
        };
    
        Coord<DIM> getDimensions()
        {
            return dim;
        }
    
    private:
        Coord<DIM> dim;
    };
    
    template<typename CELL_TYPE>
    class Simulator
    {
    public:
        typedef typename CELL_TYPE::Topology Topology;
        typedef Grid<CELL_TYPE, Topology> GridType;
    
        virtual void step() = 0;
        virtual void run() = 0;
    };
    
    template<typename CELL_TYPE>
    class MonolithicSimulator : public Simulator<CELL_TYPE>
    {
    public:
        inline MonolithicSimulator() : Simulator<CELL_TYPE>()
        {}
    
        virtual const typename Simulator<CELL_TYPE>::GridType
    *getGrid() = 0;
    };
    
    class MockSimulator : public MonolithicSimulator<TestCell<2> >
    {
    public:
        typedef TestCell<2> MyTestCell;
        typedef Grid<MyTestCell> MyType;
    
        MockSimulator() :
            MonolithicSimulator<TestCell<2> >()
        {}
    
        void step() {}
        void run() {}
        MyType *getGrid() { return 0; }
    };
    
    // enable this code to make the error go away:
    
    // typedef
    LibGeoDecomp::Grid<LibGeoDecomp::TestCell<2,LibGeoDecomp::Stenci
    ls::Moore<2,1>,LibGeoDecomp::TopologiesHelpers::Topology<2,0,0,0
    > >,LibGeoDecomp::TopologiesHelpers::Topology<2,0,0,0> >
    TestGrid;
    // TestGrid dummy(LibGeoDecomp::Coord<2>(10, 20));
    
    }
    
    int main()
    {
        LibGeoDecomp::MockSimulator a;
        std::cout << sizeof(a) << "\n";
        return 0;
    }
    
    
    
    
    
    ===== ACTUAL OUTPUT:
    $
    /gsa/tlbgsa/projects/x/xlcmpbld/run/vacpp/121_com/bgq/daily/late
    st/bin/xlC -c test.cpp
    $ "test.cpp", line 54.7: 1540-0253 (S) This use of undefined
    class
    "LibGeoDecomp::Grid<LibGeoDecomp::TestCell<2,LibGeoDecomp::Stenc
    ils::Moore<2,1>,LibGeoDecomp::TopologiesHelpers::Topology<2,0,0,
    0> >,LibGeoDecomp::TopologiesHelpers::Topology<2,0,0,0> >" is
    not valid.
    
    
    
    ===== EXPECTED OUTPUT:
    Should compile clean.
    

Local fix

  • Explicitly declare the template function as follows:
    
    typedef
    LibGeoDecomp::Grid<LibGeoDecomp::TestCell<2,LibGeoDecomp::Stenci
    ls::Moore<2,1>,LibGeoDecomp::TopologiesHelpers::Topology<2,0,0,0
    > >,LibGeoDecomp::TopologiesHelpers::Topology<2,0,0,0> >
    TestGrid;
    TestGrid dummy(LibGeoDecomp::Coord<2>(10, 20));
    

Problem summary

  • USERS AFFECTED:
    User code with virtual function's return type declared as the
    combination of template and typedefs are affected by this
    issue.
    
    PROBLEM DESCRIPTION:
    The compiler mistakenly treats the two virtual functions as
    functions with covariant return types, and object model fails
    to find the information of handling covariant return functions.
    

Problem conclusion

  • Modified the object model code to recognize the virtual
    function's return types are the same instead of treating them
    as covariant return functions.
    

Temporary fix

Comments

APAR Information

  • APAR number

    LI77348

  • 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

    2013-05-13

  • Closed date

    2013-09-11

  • Last modified date

    2013-09-11

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

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

    IV49568 LI77573

Fix information

  • Fixed component name

    XL C/C++ FOR BG

  • Fixed component ID

    5799AG100

Applicable component levels

  • RC10 PSY

       UP



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Document information


More support for:

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

Software version:

12.1

Reference #:

LI77348

Modified date:

2013-09-11

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