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List:       gcc-bugs
Subject:    libstdc++/6886: bit vector iterator uses wrong 1 constant
From:       meissner () suse ! de
Date:       2002-05-31 12:12:31
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> Number:         6886
> Category:       libstdc++
> Synopsis:       bit vector iterator uses wrong 1 constant
> Confidential:   no
> Severity:       critical
> Priority:       medium
> Responsible:    unassigned
> State:          open
> Class:          sw-bug
> Submitter-Id:   net
> Arrival-Date:   Fri May 31 05:16:00 PDT 2002
> Closed-Date:
> Last-Modified:
> Originator:     Marcus Meissner <meissner@suse.de>
> Release:        3.1 20020410 (prerelease)
> Organization:
SuSE Linux AG
> Environment:
System: Linux gershwin 2.4.18-SMP #1 SMP Mon May 13 09:48:57 UTC 2002 x86_64 unknown
Architecture: x86_64

host: x86_64-unknown-linux-gnu
build: x86_64-unknown-linux-gnu
target: x86_64-unknown-linux-gnu
configured with: /home/hammer/gcc/configure --prefix=/usr --host=x86_64-unknown-linux \
--build=x86_64-unknown-linux --libdir=/usr/lib64 --enable-languages=c,c++ \
--enable-threads=posix --disable-nls
> Description:


The stl bitvector implementation contains in both the iterator and
const_iterator implementation the code:

  reference operator*() const { return reference(_M_p, 1U << _M_offset); }

Since the bit_type is an unsigned long, it should be 1UL here.

I have attached a testcase exhibiting the problem and a fix in 
the Fix section.

Ciao, Marcus

> How-To-Repeat:

#include <assert.h>
#include <vector>

typedef std::vector<bool> bvec;

int
main() {
	int	i, num = 0;

	bvec v;

	v.resize(66);

	for (i = 0 ; i < 66 ; i++)
		v[i] = 0;

	v[1]	= 1;
	v[33]	= 1;
	v[49]	= 1;
	v[65]	= 1;

	for (bvec::iterator j = v.begin() ; j < v.end() ; j++) {
		if (bool(*j)) num++;
	}
	assert (num == 4);
	return 0;
}

> Fix:

--- libstdc++-v3/include/bits/stl_bvector.h.long	Fri May 31 11:35:24 2002
+++ libstdc++-v3/include/bits/stl_bvector.h	Fri May 31 11:35:36 2002
@@ -166,7 +166,7 @@
   _Bit_iterator(_Bit_type * __x, unsigned int __y) 
     : _Bit_iterator_base(__x, __y) {}
 
-  reference operator*() const { return reference(_M_p, 1U << _M_offset); }
+  reference operator*() const { return reference(_M_p, 1UL << _M_offset); }
   iterator& operator++() {
     _M_bump_up();
     return *this;
@@ -223,7 +223,7 @@
     : _Bit_iterator_base(__x._M_p, __x._M_offset) {}
 
   const_reference operator*() const {
-    return _Bit_reference(_M_p, 1U << _M_offset);
+    return _Bit_reference(_M_p, 1UL << _M_offset);
   }
   const_iterator& operator++() {
     _M_bump_up();
> Release-Note:
> Audit-Trail:
> Unformatted:


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