public inbox for gcc-prs@sourceware.org
help / color / mirror / Atom feed
* libstdc++/10794: std::map's erase method invalidates reverse_iterators
@ 2003-05-14 23:46 gandy
0 siblings, 0 replies; 2+ messages in thread
From: gandy @ 2003-05-14 23:46 UTC (permalink / raw)
To: gcc-gnats
>Number: 10794
>Category: libstdc++
>Synopsis: std::map's erase method invalidates reverse_iterators
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Wed May 14 23:46:01 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator: gandy@abacho.de
>Release: libstdc++5-3.3
>Organization:
>Environment:
debian linux:
ii libstdc++5 3.3-0pre9
ii libstdc++5-3.3-dev 3.3-0pre9
ii libstdc++5-3.3-doc 3.3-0pre9
ii libstdc++5-dev 3.2.3-2
ii g++ 3.2.3-1
ii g++-3.2 3.2.3-2
ii g++-3.3 3.3-0pre9
>Description:
Programm output (g++-3.2 and g++-3.3):
-90
270
-90
-90
Expected output:
-90
-90
-90
-90
Note that the reverse_iterator jt is NOT pointing to the element which is erased.
Citation from SGI STL Docu:
Erasing an element from a map also does not invalidate any iterators, except, of course, for iterators that actually point to the element that is being erased.
I would think that applies to reverse_iterators, too.
>How-To-Repeat:
#include <iostream>
#include <map>
using namespace std;
int main()
{
map<double, double> byloc;
map<double, double>::reverse_iterator jt;
byloc.insert(pair<double, double>(90, 1));
byloc.insert(pair<double, double>(-90, 1));
byloc.insert(pair<double, double>(270, 1));
byloc.insert(pair<double, double>(-270, 1));
jt = byloc.rbegin();
jt++;
jt++;
cout << jt->first << endl;
byloc.erase(90);
cout << jt->first << endl;
byloc.clear();
byloc.insert(pair<double, double>(90, 1));
byloc.insert(pair<double, double>(-90, 1));
byloc.insert(pair<double, double>(270, 1));
jt = byloc.rbegin();
jt++;
jt++;
cout << jt->first << endl;
byloc.erase(90);
cout << jt->first << endl;
return 0;
}
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: libstdc++/10794: std::map's erase method invalidates reverse_iterators
@ 2003-05-15 16:01 paolo
0 siblings, 0 replies; 2+ messages in thread
From: paolo @ 2003-05-15 16:01 UTC (permalink / raw)
To: gandy, gcc-bugs, gcc-prs, nobody
Synopsis: std::map's erase method invalidates reverse_iterators
State-Changed-From-To: open->closed
State-Changed-By: paolo
State-Changed-When: Thu May 15 16:01:23 2003
State-Changed-Why:
Not a bug: see 24.4.1.1 (or Stroustrup, p. 557). In a
nutshell, reverse_iterator is implemented in terms of a
plain iterator (called 'current' in the standard) which
points one position forward. Therefore, in your testcase, upon erase(90), jt 'current' iterator (which points to 90)
is invalidated.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10794
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2003-05-15 16:01 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2003-05-14 23:46 libstdc++/10794: std::map's erase method invalidates reverse_iterators gandy
2003-05-15 16:01 paolo
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).