<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 --- - parser crash for overloaded operator++ and ?:"
   href="http://llvm.org/bugs/show_bug.cgi?id=15628">15628</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>parser crash for overloaded operator++ and ?:
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>3.2
          </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>Frontend
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>llvm@brianandresen.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=10257" name="attach_10257" title="test case">attachment 10257</a> <a href="attachment.cgi?id=10257&action=edit" title="test case">[details]</a></span>
test case

Clang 3.2 crashed while parsing some code, which compiles okay using GCC 4.7.2
and Visual Studio 2010/2012.

I distilled out a simpler test case.  The key problem seems to be an expression
with an overloaded operator++, given directly as the guard expression for the
ternary operator ?:.  I found several workarounds, described below.

---

class BlockInputIter
{
public:
  void* operator++(int);
  void* next();
};


bool f()
{
  BlockInputIter nextInput;
  return nextInput++ ? false : true;  // *** clang 3.2 parser failure ***
}

// Adding an explicit comparison to 0 is a workaround.
bool workaround1()
{
  BlockInputIter nextInput;
  return ( nextInput++ != 0 ) ? false : true;
}

// Even just adding parentheses around the "nextInput++" expression works.
bool workaround2()
{
  BlockInputIter nextInput;
  return ( nextInput++ ) ? false : true;
}

// If a function is used, instead of an operator overload, there's no problem.
bool workaround3()
{
  BlockInputIter nextInput;
  return nextInput.next() ? false : true;
}</pre>
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