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* [Bug c++/45082]  New: Static const signed int class member causes undefined symbol.
@ 2010-07-26 15:25 rwitmer at xmission dot com
  2010-07-26 15:32 ` [Bug c++/45082] " jakub at gcc dot gnu dot org
                   ` (5 more replies)
  0 siblings, 6 replies; 7+ messages in thread
From: rwitmer at xmission dot com @ 2010-07-26 15:25 UTC (permalink / raw)
  To: gcc-bugs

A class that has a static const signed int data member when passed to a
function as a const int& parameter will cause the data member to be an
undefined symbol.  If the static const signed int data member is re-typed as
const unsigned int the error goes away.  I've verified this on g++ 3.4.6 and
4.1.2. The following code example illustrates the error.

#include <stdio.h>

static const signed int GLOBAL_BUFF_SIZE=30;

class myclass
{
  public:

    static const          int BUFF_SIZE = 20;  // Causes linker error.
  //static const   signed int BUFF_SIZE = 20;  // Causes linker error.
  //static const unsigned int BUFF_SIZE = 20;  // No     linker error.

    static const          int ANOTHER_BUFF_SIZE;

    int myArray[BUFF_SIZE];

/*  Linker error.
% g++ static2.cpp
Undefined                       first referenced
 symbol                             in file
myclass::BUFF_SIZE                  /var/tmp//cc2IHYwP.o
ld: fatal: Symbol referencing errors. No output written to a.out
collect2: ld returned 1 exit status
% g++ --version
g++ (GCC) 3.4.6
and
g++ (GCC) 4.1.2
% ccppc --version                            
ccppc (Wind River VxWorks G++ DWARF-EH 4.1-131) 4.1.2
*/
};

// This solves the linker problem.  
// Not an option for me.  I need to dimension an array with BUFF_SIZE.
const int myclass::ANOTHER_BUFF_SIZE=20;

// Function that takes a constant reference to an integer.
// When a static const signed int is passed to this function
// that was defined in a class, you get the linker error.
// If that static const is declared unsigned int, you dont get the error.
// When the reference is to a global static, there is no error.
void funky(const int& in)
{
  printf("What came into funky() was %d\n", in);
}

int main()
{
  printf("%d\n", myclass::BUFF_SIZE);  // This doesn't cause the error.
  funky(myclass::BUFF_SIZE);           // This line causes the error.
  funky(myclass::ANOTHER_BUFF_SIZE);   // This doesn't cause the error.
  funky(GLOBAL_BUFF_SIZE);             // This doesn't cause the error.
}


-- 
           Summary: Static const signed int class member causes undefined
                    symbol.
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rwitmer at xmission dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45082


^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2010-07-27 23:55 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2010-07-26 15:25 [Bug c++/45082] New: Static const signed int class member causes undefined symbol rwitmer at xmission dot com
2010-07-26 15:32 ` [Bug c++/45082] " jakub at gcc dot gnu dot org
2010-07-26 15:59 ` rwitmer at xmission dot com
2010-07-26 16:33 ` redi at gcc dot gnu dot org
2010-07-26 16:37 ` redi at gcc dot gnu dot org
2010-07-27 15:27 ` rwitmer at xmission dot com
2010-07-27 23:55 ` redi at gcc dot gnu dot org

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