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[Bug c++/14039] New: bug in std::find
- From: "jsiek at osl dot iu dot edu" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 6 Feb 2004 04:57:08 -0000
- Subject: [Bug c++/14039] New: bug in std::find
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
The expression (*__first == __val) appears in the implementation
std::find. However, __first is only required to be an input iterator,
so *__first is required to be convertible to the value type
but not necessarily comparable with the value type. So
const value_type& x = *__first;
x == __value
would be a valid alternative.
The following program demonstrates the problem.
#include <algorithm>
namespace detail {
class dummy_constructor { };
}
template <class T = int>
class null_archetype {
private:
null_archetype() { }
null_archetype(const null_archetype&) { }
null_archetype& operator=(const null_archetype&) { return *this; }
public:
null_archetype(detail::dummy_constructor) { }
template <class TT>
friend void dummy_friend(); // just to avoid warnings
};
class boolean_archetype {
public:
boolean_archetype(const boolean_archetype&) { }
operator bool() const { return true; }
boolean_archetype(detail::dummy_constructor) { }
private:
boolean_archetype() { }
boolean_archetype& operator=(const boolean_archetype&) { return *this; }
};
template <class T>
class static_object
{
public:
static T& get()
{
static char d[sizeof(T)];
return *reinterpret_cast<T*>(d);
}
};
template <class Base = null_archetype<> >
class equality_comparable2_first_archetype : public Base {
public:
equality_comparable2_first_archetype(detail::dummy_constructor x)
: Base(x) { }
};
template <class Base = null_archetype<> >
class equality_comparable2_second_archetype : public Base {
public:
equality_comparable2_second_archetype(detail::dummy_constructor x)
: Base(x) { }
};
template <class Base1, class Base2>
boolean_archetype
operator==(const equality_comparable2_first_archetype<Base1>&,
const equality_comparable2_second_archetype<Base2>&)
{
return boolean_archetype(static_object<detail::dummy_constructor>::get());
}
template <class Base1, class Base2>
boolean_archetype
operator!=(const equality_comparable2_first_archetype<Base1>&,
const equality_comparable2_second_archetype<Base2>&)
{
return boolean_archetype(static_object<detail::dummy_constructor>::get());
}
template <class T, int I = 0>
class input_iterator_archetype
{
private:
typedef input_iterator_archetype self;
public:
typedef std::input_iterator_tag iterator_category;
typedef T value_type;
struct reference {
operator const value_type&() const { return static_object<T>::get(); }
};
typedef const T* pointer;
typedef std::ptrdiff_t difference_type;
self& operator=(const self&) { return *this; }
bool operator==(const self&) const { return true; }
bool operator!=(const self&) const { return true; }
reference operator*() const { return reference(); }
self& operator++() { return *this; }
self operator++(int) { return *this; }
};
int main()
{
typedef equality_comparable2_first_archetype<> Left;
input_iterator_archetype< Left > in;
detail::dummy_constructor dummy_cons;
equality_comparable2_second_archetype<> value(dummy_cons);
in = std::find(in, in, value);
}
--
Summary: bug in std::find
Product: gcc
Version: 3.1
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: jsiek at osl dot iu dot edu
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14039