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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - False positive - std::vector<T>::size() won't change in two subsequent invocations"
href="http://llvm.org/bugs/show_bug.cgi?id=21789">21789</a>
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<th>Summary</th>
<td>False positive - std::vector<T>::size() won't change in two subsequent invocations
</td>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>3.5
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
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<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>frerich.raabe+llvmbug@gmail.com
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=13443" name="attach_13443" title="Tiny testcase to trigger the issue">attachment 13443</a> <a href="attachment.cgi?id=13443&action=edit" title="Tiny testcase to trigger the issue">[details]</a></span>
Tiny testcase to trigger the issue
Using 'Debian clang version 3.5.0-1~exp1 (trunk) (based on LLVM 3.5.0)' on the
attached program will emit a 'running scan-build on the following program will
emit a warning saying
foo.cpp:13:16: warning: Dereference of undefined pointer value
(void)(*x + 1);
It appears this is because the analyzer doesn't see that two subsequent
invocations of std::vector<T>::size() will yield the same value, i.e. if the
second if() was hit then the first one must've been hit as well. I suspect this
could be considered a defect since the compiler most certainly saw the
implementation of size()?</pre>
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