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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - non-type template-parameter of reference type confuses template specialization matching"
href="https://bugs.llvm.org/show_bug.cgi?id=40983">40983</a>
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<th>Summary</th>
<td>non-type template-parameter of reference type confuses template specialization matching
</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
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<th>Component</th>
<td>C++'17
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>tadeus.prastowo@unitn.it
</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>Consider the following MWE:
-- 8< ---------------------
template<typename T, T v>
struct X {
};
template<bool &v>
struct X<bool &, v> {
};
-- 8< ---------------------
As shown in <a href="https://www.godbolt.org/z/HqqLWu">https://www.godbolt.org/z/HqqLWu</a>, the MWE is accepted by GCC when
using C++14 (the compilation switches `-std=c++14 -pedantic-errors') and when
using C++17 (the compilation switches `-std=c++17 -pedantic-errors').
Clang also accepts the MWE when using C++14 but _not_ when using C++17.
A thread in the C++ std-discussion has just been started on this matter (see
<a href="https://groups.google.com/a/isocpp.org/d/msg/std-discussion/etn0e3qhz28/Nmpmz7NwBAAJ">https://groups.google.com/a/isocpp.org/d/msg/std-discussion/etn0e3qhz28/Nmpmz7NwBAAJ</a>),
but no one has replied yet. Nevertheless, I think this is a bug considering
that Clang accepts the MWE in C++14, and I think, there is no change in C++17
that justifies Clang behavior in rejecting the MWE in C++17.
This bug may also be related to this bug:
<a class="bz_bug_link
bz_status_NEW "
title="NEW - template non-type with decltype(auto) placeholder does not work with template specialization when a reference is passed"
href="show_bug.cgi?id=39373">https://bugs.llvm.org/show_bug.cgi?id=39373</a></pre>
</div>
</p>
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