🚀 go-pugleaf

Class Base defines a protected member function f with a function pointer
parameter.  Class Derv defines a public member function f with a different
kind of function pointer parameter.  I get a "contravariance violation"
warning.  I don't think I should;  I'm just overloading a name.  By
comparision, doing the same thing with member function g and non-function
pointer arguments doesn't give a warning.
-------------------- contra.cc --------------------
#include <stream.h>

class Base {}; 
class Derv: public Base {};

typedef int (*BCF)(Base*, Base*);
typedef int (*DCF)(Derv*, Derv*);

class BaseCont {
  protected:
    void f(BCF) { cout << "BaseCont::f()\n"; };
    void g(int*) { cout << "BaseCont::g()\n"; };
    };

class DervCont: public BaseCont {
  public:
    void f(DCF) { cout << "DervCont::f()\n"; };
    void g(char*) { cout << "DervCont::g()\n"; };
    };

int dcf(Derv*, Derv*) { return 0; };

int main() {
    char c;
    DervCont dc;
    dc.f(dcf);			// line 26
    dc.g(&c);
    };
---------------------------------------------------
gcc -v -c contra.cc
gcc version 1.36.9
 /usr/local/lib/gcc-cpp -+ -v -undef -D__GNUC__ -D__GNUG__ -Dvax -Dunix -D__vax__ -D__unix__ contra.cc /usr/tmp/cc010778.cpp
GNU CPP version 1.36.9
 /usr/local/lib/gcc-cc1plus /usr/tmp/cc010778.cpp -quiet -dumpbase contra.cc -version -o /usr/tmp/cc010778.s
GNU C++ version 1.36.1 (based on GCC 1.36) (vax) compiled by GNU C version 1.36.
default target switches: -munix
contra.cc: In function int main ():
contra.cc:26: warning: contravariance violation for method types ignored
 /usr/local/lib/gcc-as -o contra.o /usr/tmp/cc010778.s

Compilation finished at Tue Dec  5 15:16:20

... on a VAX running BSD 4.3

    Glen Ditchfield  gjditchfield@violet.uwaterloo.ca  Office: DC 2517
Dept. of Computer Science, U of Waterloo, Waterloo, Ontario, Canada, N2L 3G1
			 Gorbachev is a CIA mole.