value computed is not used

[Shigeya Suzuki <shigeya at foretune dot co dot jp>]

Since I built first egcs last year, I'm getting following warning if I 
use -Wall:

	value computed is not used.

Actually, the value is computed and used.

Following snippet demonstrates this:

------------------------------

class Cx {
private:
    int m_v;
public:
    Cx() : m_v(0) { };

    void set(int z) { m_v = z; }
    int eval(void) { return m_v; }
};

class Cy {
private:
    Cx* m_x1;
    Cx* m_x2;
    Cx* m_x3;
    
public:
    Cy() : m_x1(0), m_x2(0), m_x3(0) { };

    void setx1(Cx* v) { m_x1 = v; }
    void setx2(Cx* v) { m_x1 = v; }
    void setx3(Cx* v) { m_x1 = v; }
    
    void exec() {
	for (m_x1 != 0 && m_x1->eval();
	     m_x2 != 0 && m_x2->eval();
	     m_x3 != 0 && m_x3->eval()) {
	}
    }
};

------------------------------

dream 18% g++ -Wall -c z.cpp
z.cpp: In method `void Cy::exec()':
z.cpp:25: warning: value computed is not used
z.cpp:28: warning: value computed is not used

	
------------------------------


Why this happen?


Shigeya Suzuki						shigeya@foretune.co.jp