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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - specialization of template template parameter considered ill-formed if parameter is an alias template"
href="https://llvm.org/bugs/show_bug.cgi?id=31263">31263</a>
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<th>Summary</th>
<td>specialization of template template parameter considered ill-formed if parameter is an alias template
</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>Linux
</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++
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>kretz@kde.org
</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>
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<p>
<div>
<pre>Testcase:
```
template <template <typename...> class T> struct Template {
template <typename... Us> using type = T<Us...>;
};
template <class T> struct X { static constexpr T value = T(); };
template <class T> using alias = X<T>;
int main() { return Template<alias>::type<int>::value; }
```
GCC and EDG accept the code.
Clang accepts the code if `X` is used directly or if `alias` is declared as
`template <class... Ts> using alias = X<Ts...>`.</pre>
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