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* [Bug libstdc++/50501] New: Insertion of complex into a stream may fail without invalidating the stream
@ 2011-09-24 0:35 giecrilj at stegny dot 2a.pl
2011-09-24 4:12 ` [Bug libstdc++/50501] " paolo.carlini at oracle dot com
2011-09-24 4:25 ` redi at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: giecrilj at stegny dot 2a.pl @ 2011-09-24 0:35 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50501
Bug #: 50501
Summary: Insertion of complex into a stream may fail without
invalidating the stream
Classification: Unclassified
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: giecrilj@stegny.2a.pl
Host: x86_64-suse-linux
Target: x86_64-suse-linux
Build: x86_64-suse-linux
I can see the following implementation in <complex>:
/// Insertion operator for complex values.
template<typename _Tp, typename _CharT, class _Traits>
basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const complex<_Tp>& __x)
{
basic_ostringstream<_CharT, _Traits> __s;
__s.flags(__os.flags());
__s.imbue(__os.getloc());
__s.precision(__os.precision());
__s << '(' << __x.real() << ',' << __x.imag() << ')'; // This can fail!
return __os << __s.str(); // And then this may be empty!
}
This implementation may cause the following test case to fail:
#include <cstdlib>
#include <cassert>
#include <iostream>
#include <complex>
int main () { float const a_f ((01));
::std:: complex < float > a_c ((a_f)); std:: stringstream a_s;
assert
(!(a_s << a_c) || ((a_c = float ()) == float () && a_s >> a_c && a_c == a_f));
return +EXIT_SUCCESS; }
I cannot reproduce the failure because I do not know how to inject a memory
allocation failure. However, I imagine it is possible.
I suggest that the implementation be modified:
/// Insertion operator for complex values.
template<typename _Tp, typename _CharT, class _Traits>
basic_ostream<_CharT, _Traits>&
operator<<(basic_ostream<_CharT, _Traits>& __os, const complex<_Tp>& __x)
{
basic_ostringstream<_CharT, _Traits> __s;
__s.flags(__os.flags());
__s.imbue(__os.getloc());
__s.precision(__os.precision());
__s << '(' << __x.real() << ',' << __x.imag() << ')';
__os. setstate(__s.rdstate()) ;
return __os << __s.str();
}
Thank you for your consideration.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug libstdc++/50501] Insertion of complex into a stream may fail without invalidating the stream
2011-09-24 0:35 [Bug libstdc++/50501] New: Insertion of complex into a stream may fail without invalidating the stream giecrilj at stegny dot 2a.pl
@ 2011-09-24 4:12 ` paolo.carlini at oracle dot com
2011-09-24 4:25 ` redi at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: paolo.carlini at oracle dot com @ 2011-09-24 4:12 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50501
Paolo Carlini <paolo.carlini at oracle dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |INVALID
--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-09-23 23:58:54 UTC ---
The Standard is very precise here, and nothing changed for C++11. It says,
literally:
Effects: inserts the complex number x onto the stream o as if it were
implemented as follows:
template<class T, class charT, class traits>
basic_ostream<charT, traits>&
operator<<(basic_ostream<charT, traits>& o, const complex<T>& x) {
basic_ostringstream<charT, traits> s;
s.flags(o.flags());
s.imbue(o.getloc());
s.precision(o.precision());
s << ’(’ << x.real() << "," << x.imag() << ’)’;
return o << s.str();
}
thus, I don't see how we could to something else, like what you are suggesting,
and remain conforming.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug libstdc++/50501] Insertion of complex into a stream may fail without invalidating the stream
2011-09-24 0:35 [Bug libstdc++/50501] New: Insertion of complex into a stream may fail without invalidating the stream giecrilj at stegny dot 2a.pl
2011-09-24 4:12 ` [Bug libstdc++/50501] " paolo.carlini at oracle dot com
@ 2011-09-24 4:25 ` redi at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: redi at gcc dot gnu.org @ 2011-09-24 4:25 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50501
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-09-24 00:35:13 UTC ---
What failure scenario are you talking about?
Surely if there's a memory allocation failure it will throw a bad_alloc
exception, so __s.str() will never get called?
^ permalink raw reply [flat|nested] 3+ messages in thread
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2011-09-24 0:35 [Bug libstdc++/50501] New: Insertion of complex into a stream may fail without invalidating the stream giecrilj at stegny dot 2a.pl
2011-09-24 4:12 ` [Bug libstdc++/50501] " paolo.carlini at oracle dot com
2011-09-24 4:25 ` redi at gcc dot gnu.org
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