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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Clang hangs in template instantiation after diagnosing C++11 narrowing in NTTP."
href="https://llvm.org/bugs/show_bug.cgi?id=25856">25856</a>
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<th>Summary</th>
<td>Clang hangs in template instantiation after diagnosing C++11 narrowing in NTTP.
</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>All
</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
</td>
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<th>Component</th>
<td>C++11
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
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<th>Reporter</th>
<td>eric@efcs.ca
</td>
</tr>
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<th>CC</th>
<td>dgregor@apple.com, llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=15473" name="attach_15473" title="reproducer.cpp">attachment 15473</a> <a href="attachment.cgi?id=15473&action=edit" title="reproducer.cpp">[details]</a></span>
reproducer.cpp
The attached reproducer causes clang to hang after in instantiates the `__make`
template with `-3`. Clang will emit a C++11 narrowing error before silently
hanging. My guess is that clang trys to instantiate the base class of
`__parity` with the converted value 4294967293.
metaprogramming often uses an integer NTTP to control the number of
instantiations. If clang instantiates a template with a narrowed NTTP it could
be in for a long ride.
I would be willing to work on a fix if somebody could offer direction on the
solution.</pre>
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