[Bug c++/48323] New: Lifetime of local variables: global versus member function

["j.v.dijk at tue dot nl" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48323

           Summary: Lifetime of local variables: global versus member
                    function
           Product: gcc
           Version: 4.5.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: j.v.dijk@tue.nl


[First presented on gcc-help. Submitted as per the suggestion of Ian Lance
Taylor, see http://gcc.gnu.org/ml/gcc-help/2011-03/msg00340.html ]

Consider the following shared object:

// g++ -o libtest.so -shared -fPIC dltestlib.cpp

#include <iostream>

int global_f() { static int i=0; return i; }

struct C
{
        int class_scope_f() { static int i=0; return i; }
        C()
        {
                global_f();
//              class_scope_f(); // CULPRIT
        }
        ~C() { std::cout << "Destructor called" << std::endl; }
};

static C c;

Also consider the following test program, which merely loads and unloads this 
library using dlopen/dlclose.

// g++ dltest2.cpp -ldl

#include <dlfcn.h>
#include <iostream>

int main(int argc, const char* argv[])
{
        if (argc!=2) return -1;

        const char* fname = argv[1];
        std::cout << "Opening: " << fname << std::endl;
        void* handle = dlopen( fname, RTLD_NOW | RTLD_LOCAL);
        std::cout << "Handle after dlopen: " << handle << std::endl;
        if(!handle)
        {
                std::cout << dlerror() << std::endl;
        }

        dlclose(handle);
        // do not load. Only check if the file is resident.
        handle = dlopen( fname, RTLD_NOW | RTLD_NOLOAD);
        std::cout << "Handle after dlclose: " << handle << std::endl;
        std::cout << "Exiting..." << std::endl;
}

Providing the abovementioned library as argument, I get the expected result:

./a.out /home/jan/src/gum-cvs/ideas/jan/libtest.so

Opening: /home/jan/src/gum-cvs/ideas/jan/libtest.so
Handle after dlopen: 0x602050
Destructor called
Handle after dlclose: 0
Exiting...

In particular, the library *is* unloaded by dlclose (so the global destructor 
of object c in the library is called before the program is exiting.)

And now for the problem... 
If I comment in line 11 of the library module (marked CULPRIT), thus calling 
class_scope_f(), and try again, the result is:

Opening: /home/jan/src/gum-cvs/ideas/jan/libtest.so
Handle after dlopen: 0x602050
Handle after dlclose: 0x602050
Exiting...
Destructor called

Now the library unloading fails (the handle is still !=0, and indeed the 
destructor of c is not called before the program terminates).

I assume this is because there is a difference in lifetime between local 
static variables in functions in global scope vs. those of member functions. 
Is this the intended behaviour? (I say 'intended', not 'mandated', because I 
know so's are beyond the scope of ISO-C++.) If not, should I file a report?

I am on OpenSuSE 11.4; that is: glibc 2.11.3, gcc 4.5.1, binutils 2.21.