<html>
<head>
<base href="https://llvm.org/bugs/" />
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - False positive: analyzer believes a value is garbage/undefined"
href="https://llvm.org/bugs/show_bug.cgi?id=28338">28338</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>False positive: analyzer believes a value is garbage/undefined
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>3.8
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Static Analyzer
</td>
</tr>
<tr>
<th>Assignee</th>
<td>kremenek@apple.com
</td>
</tr>
<tr>
<th>Reporter</th>
<td>mactalla.obair@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16645" name="attach_16645" title="False positive test case">attachment 16645</a> <a href="attachment.cgi?id=16645&action=edit" title="False positive test case">[details]</a></span>
False positive test case
When reading an individual byte from a larger value, the static analyzer is
fine if:
a) reading any byte if the source is a uint32_t
b) reading the first byte if the source is a uint32_t[1]
But it falsely reports a problem if reading a subsequent byte from uint32_t[1]
The attached test case demonstrates good (silent) behaviour with VARIANT= 1, 2
and 3. And exposes the false positive with VARIANT=4.
I also tested with clang-3.7 and clang-3.6, so it's not a regression.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>