//  (C) Copyright Alisdair Meredith 2007.
//  Use, modification and distribution are subject to the
//  Boost Software License, Version 1.0. (See accompanying file
//  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

//  See http://www.boost.org/libs/config for most recent version.

//  MACRO:         BOOST_NO_IMPLICIT_BOOL_CONVERSION
//  TITLE:         Implicit bool conversion
//  DESCRIPTION:   The compliler should implicitly convert values
//                 in specific contexts, such as the condition
//                 inside an if/while clause, or when evaluating
//                 logical operators && ||.
//                 The convertible-to-unspecified-bool-type idiom
//                 relies on this.  Non-conforming compilers can
//                 be helped out with explicit conversion to bool
//                 in these contexts, preferably with static_cast 

namespace boost_no_implicit_bool_conversion {

struct false_value {
    typedef int const false_value::* unspecified_bool;

    operator unspecified_bool() const {
        return  unspecified_bool();
    }
};

struct true_value {
    typedef int (true_value::* unspecified_bool)();

    operator unspecified_bool() const {
        return  &true_value::hidden;
    }
private:
    int hidden();
};

int test()
{
    true_value True;
    false_value False;
    int count_fails = 0;
    if( False ) {
        ++count_fails;
    }

    if( !True ) {
        ++count_fails;
    }

    if( True && False ) {
        ++count_fails;
    }

    if( !(True || False) ) {
        ++count_fails;
    }

    count_fails += True
                ?  0
                :  1;

    count_fails += False
                ?  1
                :  0;

    while( false_value f = False ) {}
    do {} while( False );
    for( ; False ; ) {}

    return count_fails;
}

}