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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - false positive: static analyzer does not detect full case"
href="http://llvm.org/bugs/show_bug.cgi?id=16615">16615</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>false positive: static analyzer does not detect full case
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>3.2
</td>
</tr>
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<th>Hardware</th>
<td>Macintosh
</td>
</tr>
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<th>OS</th>
<td>MacOS X
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Static Analyzer
</td>
</tr>
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<th>Assignee</th>
<td>kremenek@apple.com
</td>
</tr>
<tr>
<th>Reporter</th>
<td>pat.pannuto@gmail.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=10877" name="attach_10877" title="Minimum working example">attachment 10877</a> <a href="attachment.cgi?id=10877&action=edit" title="Minimum working example">[details]</a></span>
Minimum working example
$ clang --version
Apple LLVM version 4.2 (clang-425.0.28) (based on LLVM 3.2svn)
Target: x86_64-apple-darwin12.4.0
checker-275 pre-compiled bundle for mac.
-----
The static analyzer does not detect case statements that are full, that is all
possible values are explicitly listed as cases and a default block is
unnecessary / impossible to reach:
For the following MWE, out is always well-defined despite the static analyzer's
protestations to the contrary:
1 #include <stdio.h>
2
3 int main(int argc, char **argv) {
4 int val = argc;
5 int out;
1
'out' declared without an initial value
→
6
7 switch (val & 0x3) {
2
←
'Default' branch taken. Execution continues on line 25
→
8 case 0x0:
9 out = 0;
10 break;
11
12 case 0x1:
13 out = 1;
14 break;
15
16 case 0x2:
17 out = 2;
18 break;
19
20 case 0x3:
21 out = 3;
22 break;
23 }
24
25 printf("Out is %d\n", out);
3
←
Function call argument is an uninitialized value
26 }</pre>
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