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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Possible false NULL dereference warning in doubly-linked list"
href="http://llvm.org/bugs/show_bug.cgi?id=16782">16782</a>
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<th>Summary</th>
<td>Possible false NULL dereference warning in doubly-linked list
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>Macintosh
</td>
</tr>
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<th>OS</th>
<td>MacOS X
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Static Analyzer
</td>
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<th>Assignee</th>
<td>kremenek@apple.com
</td>
</tr>
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<th>Reporter</th>
<td>bugzilla@jwwalker.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=10977" name="attach_10977" title="C++ source and header">attachment 10977</a> <a href="attachment.cgi?id=10977&action=edit" title="C++ source and header">[details]</a></span>
C++ source and header
Overview:
The static analyzer says that in traversing a doubly linked list, a NULL
pointer can be dereferenced, but I can't see how that can happen.
Steps to reproduce:
Analyze the attached source, like:
clang -DDEBUG=1 --analyze micropather.cpp
Actual results:
micropather.h:206:45: warning: Access to field 'next' results in a dereference
of a null pointer (loaded from variable 'it'
Expected results:
No warning.
Build date:
clang version 3.4 (trunk 187678)
Target: x86_64-apple-darwin11.4.2
Thread model: posix
Additional information:
The code is from <<a href="http://sourceforge.net/projects/micropather/">http://sourceforge.net/projects/micropather/</a>>. I don't claim
to be intimately familiar with it. But it appears to me that the next and prev
pointers only become NULL when a node is removed from the doubly linked list,
so traversing the list should not encounter a NULL.</pre>
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