FIX: Bad Code Is Generated with /Og Enabled (281424)

SYMPTOMS

With the global optimizations (/Og) compiler option enabled, the Visual C++ 6.0 Service Pack 4 (SP4) compiler may generate incorrect code for return values to functions. See the "More Information" section for a detailed reproducible sample.

RESOLUTION

To work around this bug, do one of the following:

Replace the following line in the sample code

Test (MyClass::Testfunc(), y, z);

with the following:

MyClass x = MyClass::Testfunc();
Test (x , y, z);

-or-

In the sample code, use #pragma optimize("g", off) before the main function to disable the optimizations only in main.

MORE INFORMATION

Steps to Reproduce Behavior

// Test.cpp<BR/>
// Command line : cl test.cpp /Og

#include <iostream.h>

class MyClass
{
public:
   unsigned long mID;
   MyClass(unsigned long id);
   MyClass(const MyClass & other);
   MyClass & operator = (const MyClass & other) ;
   unsigned long getID()
   {
	   return mID;
   }
   static MyClass Testfunc()
   {
	   return 0;
   };
};



MyClass::MyClass (unsigned long id /* = 0 */)
{
   mID = id;
}


MyClass::MyClass(const MyClass & other) : mID(other.mID) 
{
   cout << "In Copy Constructor" << endl;
}

MyClass & MyClass::operator = (const MyClass & other) 
{
    cout << "In Operator =" << endl;
    mID = other.mID;
    return *this;
}


void Test (MyClass x, int y, int z)
{
   cout << "In Function Test" << endl;
   cout << x.getID() << ' ' << y << ' ' << z << endl;
}

int main ()
{
   int y = 1;
   int z = 2;
   Test (MyClass::Testfunc(), y, z);
   // expected output is 0 1 2
   return 0;
}

The following is the expected output:

In Function Test
0 1 2

Actual Output:

In Function Test
1245052 0 2