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* [Bug libstdc++/17948] New: iterator increment bug in _Rb_tree::erase(it,it)
@ 2004-10-12 16:29 gcc-bugzilla at gcc dot gnu dot org
2004-10-12 16:33 ` [Bug libstdc++/17948] " pinskia at gcc dot gnu dot org
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: gcc-bugzilla at gcc dot gnu dot org @ 2004-10-12 16:29 UTC (permalink / raw)
To: gcc-bugs
I expect the following program to produce the following output:
a 2
b 1 1
i.e, two elements go into the set, we delete one, and one remains.
However, when i compile this with the current cvs head, the program
actually does the following:
$ g++ -g -o x x.cc
$ ./x
a 2
b 0 1
$
i.e., two elements go in, take away one, and none are left.
Someone's arithmetic is bad...
It looks like the problem is in this function in stl_tree.h:
template<typename _Key, typename _Val, typename _KeyOfValue,
typename _Compare, typename _Alloc>
void
_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
erase(iterator __first, iterator __last)
{
if (__first == begin() && __last == end())
clear();
else
for (; __first != __last; ++__first)
erase(__first);
}
Note that in the loop, the iterator __first is referenced in the
increment _after_ it has been erased from the container --- which
is undefined behavior.
Below is an attempt to fix this. With this patch, the test behaves
as expected.
Environment:
System: Linux karma 2.6.8.1 #20 Mon Sep 13 23:48:47 EDT 2004 i686 i686 i386 GNU/Linux
Architecture: i686
<machine, os, target, libraries (multiple lines)>
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: /home/sss/gcc/gcc/configure --prefix=/usr/local/gcc --enable-threads=posix --enable-long-long --enable-languages=c,c++,f95
How-To-Repeat:
-------------------------------------------
#include <set>
void test2 ()
{
std::set<int> s;
s.insert(2);
s.insert(3);
printf ("a %d\n", s.size());
int x = s.erase (3);
printf ("b %d %d\n", s.size(), x);
}
int main ()
{
test2 ();
return 0;
}
-------------------------------------------
------- Additional Comments From snyder at fnal dot gov 2004-10-12 16:29 -------
Fix:
2004-10-11 scott snyder <snyder@fnal.gov>
* include/bits/stl_tree.h (erase(iterator,iterator)): Fix iterator
loop.
--- libstdc++-v3/include/bits/stl_tree.h-orig 2004-10-11 23:17:30.096014584 -0400
+++ libstdc++-v3/include/bits/stl_tree.h 2004-10-11 23:19:39.688313560 -0400
@@ -1087,8 +1087,12 @@
if (__first == begin() && __last == end())
clear();
else
- for (; __first != __last; ++__first)
+ for (iterator __next = __first; __first != __last; __first = __next)
+ {
+ ++__next;
erase(__first);
+ }
+
}
template<typename _Key, typename _Val, typename _KeyOfValue,
--
Summary: iterator increment bug in _Rb_tree::erase(it,it)
Product: gcc
Version: 0.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: snyder at fnal dot gov
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17948
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/17948] iterator increment bug in _Rb_tree::erase(it,it)
2004-10-12 16:29 [Bug libstdc++/17948] New: iterator increment bug in _Rb_tree::erase(it,it) gcc-bugzilla at gcc dot gnu dot org
@ 2004-10-12 16:33 ` pinskia at gcc dot gnu dot org
2004-10-12 16:59 ` pcarlini at suse dot de
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2004-10-12 16:33 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Version|0.0 |4.0.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17948
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/17948] iterator increment bug in _Rb_tree::erase(it,it)
2004-10-12 16:29 [Bug libstdc++/17948] New: iterator increment bug in _Rb_tree::erase(it,it) gcc-bugzilla at gcc dot gnu dot org
2004-10-12 16:33 ` [Bug libstdc++/17948] " pinskia at gcc dot gnu dot org
@ 2004-10-12 16:59 ` pcarlini at suse dot de
2004-10-12 17:22 ` pcarlini at suse dot de
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: pcarlini at suse dot de @ 2004-10-12 16:59 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pcarlini at suse dot de 2004-10-12 16:57 -------
I'm guilty of this, sorry, your patch looks correct. Will deal with this later
today.
--
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |pcarlini at suse dot de
|dot org |
Status|UNCONFIRMED |ASSIGNED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17948
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/17948] iterator increment bug in _Rb_tree::erase(it,it)
2004-10-12 16:29 [Bug libstdc++/17948] New: iterator increment bug in _Rb_tree::erase(it,it) gcc-bugzilla at gcc dot gnu dot org
2004-10-12 16:33 ` [Bug libstdc++/17948] " pinskia at gcc dot gnu dot org
2004-10-12 16:59 ` pcarlini at suse dot de
@ 2004-10-12 17:22 ` pcarlini at suse dot de
2004-10-13 0:11 ` cvs-commit at gcc dot gnu dot org
2004-10-13 0:12 ` pcarlini at suse dot de
4 siblings, 0 replies; 6+ messages in thread
From: pcarlini at suse dot de @ 2004-10-12 17:22 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pcarlini at suse dot de 2004-10-12 17:17 -------
Everything considered, if we have to use an additional iterator next, probably is
better just reverting my stupid change and return to:
while (__first != __last)
erase(__first++);
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17948
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/17948] iterator increment bug in _Rb_tree::erase(it,it)
2004-10-12 16:29 [Bug libstdc++/17948] New: iterator increment bug in _Rb_tree::erase(it,it) gcc-bugzilla at gcc dot gnu dot org
` (2 preceding siblings ...)
2004-10-12 17:22 ` pcarlini at suse dot de
@ 2004-10-13 0:11 ` cvs-commit at gcc dot gnu dot org
2004-10-13 0:12 ` pcarlini at suse dot de
4 siblings, 0 replies; 6+ messages in thread
From: cvs-commit at gcc dot gnu dot org @ 2004-10-13 0:11 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From cvs-commit at gcc dot gnu dot org 2004-10-13 00:11 -------
Subject: Bug 17948
CVSROOT: /cvs/gcc
Module name: gcc
Changes by: paolo@gcc.gnu.org 2004-10-13 00:11:14
Modified files:
libstdc++-v3 : ChangeLog
libstdc++-v3/include/bits: stl_tree.h
Added files:
libstdc++-v3/testsuite/23_containers/set/modifiers: 17948.cc
Log message:
2004-10-12 Paolo Carlini <pcarlini@suse.de>
PR libstdc++/17948
* include/bits/stl_tree.h (erase(iterator, iterator)): Revert
wrong commit of 2004-10-07.
2004-10-12 Scott Snyder <snyder@fnal.gov>
PR libstdc++/17948
* testsuite/23_containers/set/modifiers/17948.cc: New.
Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libstdc++-v3/ChangeLog.diff?cvsroot=gcc&r1=1.2700&r2=1.2701
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libstdc++-v3/include/bits/stl_tree.h.diff?cvsroot=gcc&r1=1.39&r2=1.40
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libstdc++-v3/testsuite/23_containers/set/modifiers/17948.cc.diff?cvsroot=gcc&r1=NONE&r2=1.1
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17948
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug libstdc++/17948] iterator increment bug in _Rb_tree::erase(it,it)
2004-10-12 16:29 [Bug libstdc++/17948] New: iterator increment bug in _Rb_tree::erase(it,it) gcc-bugzilla at gcc dot gnu dot org
` (3 preceding siblings ...)
2004-10-13 0:11 ` cvs-commit at gcc dot gnu dot org
@ 2004-10-13 0:12 ` pcarlini at suse dot de
4 siblings, 0 replies; 6+ messages in thread
From: pcarlini at suse dot de @ 2004-10-13 0:12 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From pcarlini at suse dot de 2004-10-13 00:12 -------
Fixed.
--
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
Target Milestone|--- |4.0.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17948
^ permalink raw reply [flat|nested] 6+ messages in thread
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2004-10-12 16:29 [Bug libstdc++/17948] New: iterator increment bug in _Rb_tree::erase(it,it) gcc-bugzilla at gcc dot gnu dot org
2004-10-12 16:33 ` [Bug libstdc++/17948] " pinskia at gcc dot gnu dot org
2004-10-12 16:59 ` pcarlini at suse dot de
2004-10-12 17:22 ` pcarlini at suse dot de
2004-10-13 0:11 ` cvs-commit at gcc dot gnu dot org
2004-10-13 0:12 ` pcarlini at suse dot de
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