/*
Spurious "might be used uninitialized" warning in STL use.
The following short program produces a spurious warning.
The quoted function in stl_uninitialized.h is
template<typename _InputIterator, typename _ForwardIterator>
inline _ForwardIterator
__uninitialized_copy_aux(_InputIterator __first, _InputIterator __last,
_ForwardIterator __result,
__false_type)
{
_ForwardIterator __cur = __result; // this is line 82
try
{
for ( ; __first != __last; ++__first, ++__cur)
std::_Construct(&*__cur, *__first);
return __cur;
}
catch(...)
{
std::_Destroy(__result, __cur);
__throw_exception_again;
}
}
We see this warning in other circumstances on several gcc versions,
always in STL headers and usually in very simple statements of the
form "sometype a = b;" where 'a' is reported a uninitialized (sic!).
The sample given here compiles without warnings with -O1, but
this is not generally the case.
Any solutions or work-arounds?
*/
#include <iostream>
#include <ostream>
#include "boost/format.hpp"
int main()
{
std::cout << boost::format("0x%04x ") % 42 << std::endl;
}
/*
$ uname -a
CYGWIN_NT-5.1 1.5.24(0.156/4/2) 2007-01-31 10:57 i686 Cygwin
$ gcc --version
gcc (GCC) 3.4.4 (cygming special, gdc 0.12, using dmd 0.125)
$ g++ -ansi -Wall -O2 -I/cygdrive/d/Info/boost_1_32_0/ simpleformat.cpp
/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_uninitialized.h:
In member function
`void std::vector<_Tp, _Alloc>::_M_fill_insert(
__gnu_cxx::__normal_iterator<typename _Alloc::pointer, std::vector<_Tp,
_Alloc> >,
size_t, const _Tp&)
[with _Tp = boost::io::detail::format_item<char, std::char_traits<char>,
std::allocator<char> >,
_Alloc = std::allocator<boost::io::detail::format_item<char,
std::char_traits<char>,
std::allocator<char> > >]':
/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_uninitialized.h:82:
warning: '__cur' might be used uninitialized in this function
/usr/lib/gcc/i686-pc-cygwin/3.4.4/include/c++/bits/stl_uninitialized.h:82:
warning: '__cur' might be used uninitialized in this function
*/
--
Summary: Spurious "might be used uninitialized" warning in STL
use.
Product: gcc
Version: 3.4.4
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: hartog at best dot ms dot philips dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30680
