<html>
    <head>
      <base href="http://llvm.org/bugs/" />
    </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 --- - Crash while capture template std::function in lambdas"
   href="http://llvm.org/bugs/show_bug.cgi?id=21664">21664</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Crash while capture template std::function in lambdas
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>3.4
          </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>normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>C++11
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedclangbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>kamil.rojewski@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>When trying to capture a template std::function alias in a lambda by value, I
am experiencing a crash in the resulting binary. Here is a code snippet showing
this error:

#include <functional>

template<class T>
using Callback = std::function<void (T)>;

std::function<void ()> f(const Callback<int> &callback)
{
    return [=] {
        callback(0); // crash here
    };
}

int main()
{
    auto lambda = f([](int) { });
    lambda();
    return 0;
}

This also happens when explicitly capturing "callback". To work around the
crash, the variable needs to be captured using generalized capture:

#include <functional>

template<class T>
using Callback = std::function<void (T)>;

std::function<void ()> f(const Callback<int> &callback)
{
    return [=, callback = callback] {
        callback(0);                   // no crash now
    };
}

int main()
{
    auto lambda = f([](int) { });
    lambda();
    return 0;
}</pre>
        </div>
      </p>
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