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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - No -Wsequence-point warning for undefined behavior in "a[*p] = (*p += 1)""
href="http://llvm.org/bugs/show_bug.cgi?id=18803">18803</a>
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<th>Summary</th>
<td>No -Wsequence-point warning for undefined behavior in "a[*p] = (*p += 1)"
</td>
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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>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Frontend
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>chengniansun@gmail.com
</td>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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</tr></table>
<p>
<div>
<pre>I suppose there should be an undefined behavior on *p. Gcc warns this behavior.
$: cat s.c
void fn(int* p) {
int a[2] = {1, 2};
a[*p] = (*p += 1);
}
$: clang-trunk -Wsequence-point -c s.c
$: gcc-trunk -Wsequence-point -c s.c
s.c: In function ‘fn’:
s.c:3:15: warning: operation on ‘*p’ may be undefined [-Wsequence-point]
a[*p] = (*p += 1);
^
$: clang-trunk --version
clang version 3.5 (trunk 201116)
Target: x86_64-unknown-linux-gnu
Thread model: posix</pre>
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</p>
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