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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Using declaration refers into C, which is a base class (alias) of D, but it is not recognized as valid."
href="https://llvm.org/bugs/show_bug.cgi?id=27961">27961</a>
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<th>Summary</th>
<td>Using declaration refers into C, which is a base class (alias) of D, but it is not recognized as valid.
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>3.8
</td>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>C++11
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>michele.caini@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Consider the following code:
struct B { };
template<typename...>
struct D;
template<typename T, typename U, typename... A>
struct D<T, U, A...>: D<U, A...> {
using C = D<U, A...>; // (1)
// using D<U, A...>::D; // (2)
// using C::C // (3)
using C::D;
};
template<typename T>
struct D<T>: T { using T::T; };
int main() {
D<int, double, B> d{};
}
Lines (2) and (3) work as expected, while (1) gives the following errors:
11 : error: dependent using declaration resolved to type without 'typename'
using C::D;
[...]
11 : error: using declaration refers into 'C::', which is not a base class
of 'D<int, double, B>'
using C::D;
C is an alias of D<U, A...>, that is a base class of D<T, U, A...>, thus even
(1) should compile.
Actually, GCC compiles the example above without errors.</pre>
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