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From: Graham.Parrington@newcastle.ac.uk (Graham D. Parrington)
Newsgroups: comp.lang.c++
Subject: Overloaded Function Ambiguity Resolution Problems
Message-ID: <1991Feb27.084909.5063@newcastle.ac.uk>
Date: 27 Feb 91 08:49:09 GMT
Sender: news@newcastle.ac.uk
Organization: University of Newcastle upon Tyne, UK, NE1 7RU
Lines: 53

Consider the following code fragment:

#include "stream.h"
class Base
{
public:
    Base() { cout << "Base::Base()\n"; }
    Base(char *) { cout << "Base::Base(char *)\n"; }
    void func(char*) { cout << "Base::func(char *)\n"; }
};

class Derived:public Base
{
public:
    Derived() { cout << "Derived::Derived()\n"; }
    void func(const Base&){ cout << "Derived::func(const Base&)\n"; } 

};

main()
{
    Derived *d = new Derived();

    d->func("hello");
}

What should it output? 
Cfront 2.1 (<<AT&T C++ Translator 2.1.0 03/31/90>>) gives:
	Base::Base()
	Derived::Derived()
	Base::Base(char *)
	Derived::func(const Base&)

while g++ (version 1.39.0 beta (based on GCC 1.39)) gives:
	Base::Base()
	Derived::Derived()
	Base::func(char *)

That is, g++ considers Base::func(char*) to be the correct match to the call
while cfront prefers to construct a Base first and then use Derived::func(Base)

My reading of the ARM pp318-> makes me believe that g++ is correct in this case
since there is an exact match on argument type (rule 1), whereas cfront appears
to apply rule 4 (user defined conversion). I suspect the differences lie in
search strategies in the two compilers, that is, g++ applies the rules in order
over the entire hierachy, while cfront applies the rules first on the current
class and then on its parents etc.
What do other compilers make of this example (Zortech, Glockenspiel, etc), and
more importantly which is the CORRECT behaviour??

EMAIL = Graham.Parrington@newcastle.ac.uk
POST  = Computing Laboratory, The University, Newcastle upon Tyne, UK NE1 7RU
VOICE = +44 91 222 8067		FAX = +44-91-222-8232