c++/5116: operator resolution in template class

[binder@iue.tuwien.ac.at]

>Number:         5116
>Category:       c++
>Synopsis:       operator resolution in template class
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Fri Dec 14 07:56:00 PST 2001
>Closed-Date:
>Last-Modified:
>Originator:     binder@iue.tuwien.ac.at
>Release:        3.0.2
>Organization:
>Environment:
g++ version:

Reading specs from /home/binder2/gcc3/bin/../lib/gcc-lib/i686-pc-linux-gnu/3.0.2/specs
Configured with: ../gcc-3.0.2-src/configure --prefix=/home/binder2/gcc --enable-shared --enable-threads=posix
Thread model: posix
gcc version 3.0.2

OS: RedHat Linux 7.2, kernel 2.4.16


libc version:

GNU C Library stable release version 2.2.4, by Roland McGrath et al.
Copyright (C) 1992-1999, 2000, 2001 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.
Compiled by GNU CC version 2.96 20000731 (Red Hat Linux 7.1 2.96-98).
Compiled on a Linux 2.4.9-0.17smp system on 2001-10-03.
Available extensions:
        GNU libio by Per Bothner
        crypt add-on version 2.1 by Michael Glad and others
        The C stubs add-on version 2.1.2.
        linuxthreads-0.9 by Xavier Leroy
        BIND-8.2.3-T5B
        NIS(YP)/NIS+ NSS modules 0.19 by Thorsten Kukuk
        Glibc-2.0 compatibility add-on by Cristian Gafton 
        libthread_db work sponsored by Alpha Processor Inc
Report bugs using the `glibcbug' script to <bugs@gnu.org>.
>Description:
In the attached code g++ invokes operator bool() of the template class before the invokation of operator<<() takes place. 

This results in printing "1 in operator<<....." to stdout instead of printing "in operator<<..." twice.


#include <iostream>
using namespace std;

template <class T> struct Handle
{
	Handle(T* p)
	{}
	
	operator bool() const { return true; }
	
	friend ostream& operator<<(ostream& ostr, const Handle& r)
	{
		return ostr << "in operator<<(ostream&, const Handle&)";
	}
};

struct Buggy
{
	Buggy()
	{}
};

typedef Handle<Buggy>	Buggy_h;

struct BuggyCmp
{
	bool operator()(const Buggy_h& b1, const Buggy_h& b2) const
	{
		cout << b1 << " " << b2 << endl;
		return false;
	}
};


int main()
{
	BuggyCmp	cmp;

	cmp(new Buggy(), new Buggy());
}



>How-To-Repeat:
compile and run the attached program
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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