Compiling the following code with
   /home/veksler/gcc-4.0.0/bin/g++ -Wall -O2 -c bug.cpp
(Works fine with -O0 or with gcc-3.4.3)

Gives:
  bug.cpp: In function 'bool foo(bar*, bar*)':
  bug.cpp:19: warning: control may reach end of non-void function 'bool
bar_less::operator()(bar*, bar*)' being inlined

Which:
1. Is obviously incorrect.
2. Does not give a line number inside bar_less::operator()

---------- bug.cpp ---
struct bar;
bool operator<(const bar&, const bar&);
class bar_less
{
public:
    bool operator()(bar* x, bar* y)
    {
        bool validX = x, validY = y;
        if(validX && validY)
            return (*x < *y);
        else
            return false;
    }
};

bool foo(bar *x, bar *y)
{
    bar_less comp;
    return comp(x,y);
}