<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Nested std::bind with a custom placeholder fails to compile"
href="https://bugs.llvm.org/show_bug.cgi?id=51753">51753</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Nested std::bind with a custom placeholder fails to compile
</td>
</tr>
<tr>
<th>Product</th>
<td>libc++
</td>
</tr>
<tr>
<th>Version</th>
<td>12.0
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>All Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>pdimov@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
</td>
</tr></table>
<p>
<div>
<pre>The code
```
#include <functional>
template<int I> struct lambda2_arg
{
};
constexpr lambda2_arg<1> _1{};
namespace std
{
template<int I> struct is_placeholder< lambda2_arg<I> >: integral_constant<int,
I>
{
};
} // namespace std
struct plus_equal
{
template<class T1, class T2> decltype(auto) operator()(T1&& t1, T2&& t2)
const
{
return std::forward<T1>(t1) += std::forward<T2>(t2);
}
};
struct X
{
int m;
};
int main()
{
X x{ 1 };
return std::bind( plus_equal(), std::bind( &X::m, _1 ), 1 )( x );
}
```
(<a href="https://godbolt.org/z/8h1Td56c7">https://godbolt.org/z/8h1Td56c7</a>)
fails to compile. Other standard libraries work. Using std::placeholders::_1
instead of _1 works.
(This bind expression is produced by Boost.Lambda2.)</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>