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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Use of auto template parameters breaks partial specialization"
href="https://bugs.llvm.org/show_bug.cgi?id=50496">50496</a>
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<th>Summary</th>
<td>Use of auto template parameters breaks partial specialization
</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
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<th>Component</th>
<td>C++17
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>eniebler@boost.org
</td>
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<th>CC</th>
<td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>The following code fails to compile, but should:
inline constexpr struct S {} C {};
template <class S>
struct traits;
template <auto& A>
struct odd {};
template <auto& A>
struct traits<odd<A>> {};
int main() {
traits<odd<C>> t; // ERROR HERE
}
The commented line in main generated the following error:
error: implicit instantiation of undefined template 'traits<odd<C>>'
traits<odd<C>> t;
^
The partial specialization with the auto template parameter fails to match the
instantiation.
GCC accepts the code. A slight tweak causes clang to accept the code (replacing
`auto&` with `const auto&`.
<a href="https://godbolt.org/z/M7Y9nvva3">https://godbolt.org/z/M7Y9nvva3</a></pre>
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