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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Pack expansion failure with template lambda and std::index_sequence"
href="https://bugs.llvm.org/show_bug.cgi?id=49387">49387</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Pack expansion failure with template lambda and std::index_sequence
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>C++2a
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>vittorio.romeo@outlook.com
</td>
</tr>
<tr>
<th>CC</th>
<td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
</td>
</tr></table>
<p>
<div>
<pre>#include <utility>
struct S
{
template <int> using N = int;
static constexpr int size = 5;
};
static void f()
{
const auto l = [&]<typename>() {};
[&]<std::size_t... Is>(std::index_sequence<Is...>)
{
((l
.template operator()<typename S::template N<Is>>()),
...);
}
(std::make_index_sequence<S::size> {});
}
The code above results in an incorrect compilation failure with the following
message:
<source>:17:13: error: pack expansion does not contain any unexpanded parameter
packs
...);
^
1 error generated.
Compiler returned: 1
The code should instead compile. Live on Compiler Explorer:
<a href="https://gcc.godbolt.org/z/rMvY3o">https://gcc.godbolt.org/z/rMvY3o</a></pre>
</div>
</p>
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