The following code does not compile. According to the compiler,
't' is overloaded ambiguously.
#include <vector>
struct T {
typedef std::vector<int> Vector;
typedef Vector::iterator iterator;
typedef Vector::const_iterator const_iterator;
int t( iterator f) { return *f; }
int t( const_iterator f) const { return *f; }
};
int main(int, char*[])
{
std::vector<int> v;
T t;
T::const_iterator i = v.begin();
t.t(i);
return 0;
}
We've seen this on gcc 3.2.2., 3.4.3, 4.0.1. Basically, the
const_iterator matches both the iterator and the const_iterator at function
resolution time. This seems to stem from the implementation of iterator in
std::vector using __normal_iterator. There is a template copy constructor that
appears to allow this illegal conversion.
Error on: gcc version 4.0.1 20050727 (Red Hat 4.0.1-5)
----------
test.cc: In function int main(int, char**):
test.cc:18: error: ISO C++ says that these are ambiguous, even though
the
worst conversion for the first is better than the worst conversion for
the
second:
test.cc:10: note: candidate 1: int
T::t(__gnu_cxx::__normal_iterator<const
int*, std::vector<int, std::allocator<int> > >) const
test.cc:9: note: candidate 2: int
T::t(__gnu_cxx::__normal_iterator<int*,
std::vector<int, std::allocator<int> > >)
--
Summary: std::vector iterator implementation wrong
Product: gcc
Version: 4.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: afra at cs dot stanford dot edu
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23767
