LI77191: INCORRECT EVALUATION OF SIZEOF IN TEMPLATES

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • When compiling the test case below, the compiler issues an
    incorrect error message.
    
    The diagnostic refers to this line:
    typedef char staticassert_type[sizeof(Type) == 2 ? 2 : 0]; //
    But this is NOT !!
    indicating that sizeof(Type) is not 2.
    
    The line just above it
    /// char staticassert_var[sizeof(Type) == 2 ? 2 : 0];
    
    is accepted, when uncommented.  If you uncommend line 4,
    and comment line 5 instead, the program compiles and links.
    When you
    run it, the value it returns is 2 (sizeof(Resolver<int>::Type)).
    
    
    ===== COMPILE COMMAND:
    xlC test.cpp
    
    
    ===== TESTCASE:
    $ cat test.cpp
    template <typename T>
    struct Resolver {
        typedef struct { char a[2]; } Type;
    //    char staticassert_var[sizeof(Type) == 2 ? 2 : 0];      //
    This is accepted
        typedef char staticassert_type[sizeof(Type) == 2 ? 2 : 0];
    // But this is NOT !!!
    };
    
    int main()
    {
        return sizeof(Resolver<int>::Type);
    }
    $
    
    
    ===== ACTUAL OUTPUT:
    $ xlC test.cpp
    "test.cpp", line 5.54: 1540-0135 (S) The array bound cannot be
    zero.
    $
    
    ===== EXPECTED OUTPUT:
    Clean compile
    

Local fix

  • n/a
    

Problem summary

  • USERS AFFECTED:
    The problem can be seen when a sizeof expression is used to
    compute an array bound inside a template definition.
    
    PROBLEM DESCRIPTION:
    The compiler was incorrectly evaluating a sizeof expression
    inside a template definition and reporting an error.
    

Problem conclusion

  • The compiler has been fixed to resolve the above issue.
    

Temporary fix

Comments

APAR Information

  • APAR number

    LI77191

  • 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

    2013-02-21

  • Closed date

    2013-02-21

  • Last modified date

    2013-02-21

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

    IV33977

  • 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 #:

LI77191

Modified date:

2013-02-21

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