[Bug c++/27955] New: friend members produce different results

[julien dot durand dot 1981 at gmail dot com]

I've encoutered a problem with a friend function embedded into a class
declaration AND with the optimisation flag -O2. I have discovered that two
successive identical call to cout<<value;  in the main program do not yield the
same value!!! removing the function definition from the declaration solve the
problem, as well as compiling with no optimisation.

tested on two different machines and two different g++ versions:

configuration A:
    machine: Intel Centrino (IA32)
    OS : windows XP professional
    compiler : g++ 3.4.4 for cygwin

configuration B:
    machine: Intel Pentium IV (IA32)
    OS : linux fedora core 5 (2.6)
    compiler : g++ 4.1.1 

command:
g++ -O2 test.cpp -o test

(see below the source code)

is it a mistake on my side or a known/expected behaviour ?

cheers,

Julien

source code:

#include <iostream>

class A{
        friend void load (A* a, float& t){
                reinterpret_cast<unsigned int&>(t) = 1077936128; //binary float
value of 3
        }
};

class B{
        friend void load (B* b, float& t);
};

void load (B* b, float& t) {
        reinterpret_cast<unsigned int&>(t) = 1077936128; //binary float value
of 3
}

int main(){
        float testValue = -1;

        //OK
        load(new A(), testValue);
        std::cout<<testValue<<std::endl;
        std::cout<<testValue<<std::endl;

        //FAIL
        load(new B(), testValue);
        std::cout<<testValue<<std::endl;
        std::cout<<testValue<<std::endl; //output a different value!!!!

        return 0;
}


-- 
           Summary: friend members produce different results
           Product: gcc
           Version: 3.4.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: julien dot durand dot 1981 at gmail dot com
 GCC build triplet: i686-gnu-linux2.6
  GCC host triplet: i686-gnu-linux2.6
GCC target triplet: i686-gnu-linux2.6


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27955