<html>
    <head>
      <base href="https://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 --- - promise/future deadlock"
   href="https://llvm.org/bugs/show_bug.cgi?id=24692">24692</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>promise/future deadlock
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libc++
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </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>kaballo86@hotmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>The following test case results in a deadlock:

    #include <chrono>
    #include <future>
    #include <iostream>
    #include <utility>

    template <typename T>
    struct weird {
      std::future<weird<T>> f;

      explicit weird(std::future<weird<T>> f) : f(std::move(f)) {}

      weird(weird&& other)
        : f(std::move(other.f))
      {
        if (f.wait_for(std::chrono::seconds(1)) == std::future_status::timeout)
{
          std::cout << "Moving but the future is not ready yet\n";
        }
      }
    };

    int main() {
      std::promise<weird<int>> p;
      weird<int> w(p.get_future());
      p.set_value(std::move(w));
    }

This is caused by executing arbitrary user code under a lock.</pre>
        </div>
      </p>
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