https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64816
Bug ID: 64816
Summary: gcc claims that constructor is private when it should
be accessible
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: thakis at chromium dot org
I came across this while trying to build chromium for android with libc++ and
gcc. Here's an attempt at a reduction:
$ cat repro2.cc
namespace std {
template <class _Iter> class __wrap_iter {
private:
__wrap_iter(_Iter __x) {}
template <class _CharT> friend class basic_string;
template <class _Tp> friend class vector;
};
template <class _CharT> class basic_string {
public:
typedef const char *const_pointer;
typedef __wrap_iter<const_pointer> const_iterator;
const_iterator begin() const {return const_iterator(const_pointer(0));}
};
typedef basic_string<char> string;
template <class _Tp> class vector {
public:
typedef const _Tp *const_pointer;
typedef __wrap_iter<const_pointer> const_iterator;
const_iterator begin() const {return const_iterator(const_pointer(0));}
};
} // namespace std
void g(const std::vector<char> &v) { v.begin(); }
# gcc doesn't like this (also broken in 4.4 and 4.9):
$ gcc-4.8.1 -c repro2.cc
gcc-4.8.1: warning: couldn’t understand kern.osversion ‘14.0.0
repro2.cc: In instantiation of ‘std::vector<_Tp>::const_iterator
std::vector<_Tp>::begin() const [with _Tp = char;
std::vector<_Tp>::const_iterator = std::__wrap_iter<const char*>]’:
repro2.cc:30:46: required from here
repro2.cc:5:3: error: ‘std::__wrap_iter<_Iter>::__wrap_iter(_Iter) [with _Iter
= const char*]’ is private
__wrap_iter(_Iter __x) {}
^
repro2.cc:25:71: error: within this context
const_iterator begin() const {return const_iterator(const_pointer(0));}
^
It's true that the constructor is private, but vector is also a friend.
clang likes it (icc too):
$ bin/clang -c repro2.cc
To make this more mysterious, gcc stops rejecting the problem if:
1.) I change `typedef const char *const_pointer;` to `typedef const _CharT
*const_pointer;`
2.) or I declare `template <class _Tp> class vector;` before class __wrap_iter
3.) or I remove class basic_string (and typedef string) -- even though they
aren't referenced anywhere.
