c++/790: Linking errors on attempts to access static members of classes and structs

[hoopak at hotmail dot com]

>Number:         790
>Category:       c++
>Synopsis:       Linking errors on attempts to access static members of classes and structs
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Mon Nov 13 14:06:01 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     Chad Simmons
>Release:        gcc version 2.96 20000731 (Red Hat Linux 7.0)
>Organization:
>Environment:
Red Hat Linux version 7.0
GCC was installed via RPM from the standard Red Hat Distribution
>Description:
The linker generates an error when the code tries to access static members of structures and classes. I've double checked the C++ syntax for declaring and accessing them (because at first I just assumed I was doing it wrong) but all the C++ books I found said that I was using the static members properly.


>How-To-Repeat:
Here is the file I used to repeat the error

test.cpp
==========================================================
struct A
{
        private:

                static int struct_private;

        public:
                static int struct_public;

                A() { struct_private++; }
                ~A() { struct_private--; }
};

class B
{
        private:

                static int class_private;

        public:

                static int class_public;

                B() { class_private++; }
                ~B() { class_private--; }
};

static int global;

int main()
{
        static int local;

        A::struct_public = 1;
        B::class_public = 1;

        A testA;
        B testB;

        global = 1;
        local =1;

        return 0;

}

==========================================================


Compiler/Linker Output
**********************************************************
$ g++ -Wall test.cpp -o test --save-temps

test.o: In function `main':
test.o(.text+0x8): undefined reference to `A::struct_public'
test.o(.text+0x12): undefined reference to `B::class_public'
test.o: In function `A::A(void)':
test.o(.A::gnu.linkonce.t.(void)+0x8): undefined reference to `A::struct_private'
test.o: In function `A::~A(void)':
test.o(.gnu.linkonce.t._._1A+0xb): undefined reference to `A::struct_private'
test.o: In function `B::B(void)':
test.o(.B::gnu.linkonce.t.(void)+0x8): undefined reference to `B::class_private'
test.o: In function `B::~B(void)':
test.o(.gnu.linkonce.t._._1B+0xb): undefined reference to `B::class_private'
collect2: ld returned 1 exit status

$
**********************************************************


>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: