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        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - Combining CHECK-DAG and CHECK-NOT sometimes causes an incorrect error-less failure"
   href="http://llvm.org/bugs/show_bug.cgi?id=16450">16450</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Combining CHECK-DAG and CHECK-NOT sometimes causes an incorrect error-less failure
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>new-bugs
          </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>normal
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>new bugs
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>das@mips.com
          </td>
        </tr>

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

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
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        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=10763" name="attach_10763" title="test.txt">attachment 10763</a> <a href="attachment.cgi?id=10763&action=edit" title="test.txt">[details]</a></span>
test.txt

Overview:
    Using CHECK-NOT between two CHECK-DAG's may result in a failure with no
error emitted. There are two locations in the CHECK-DAG processing that
CHECK-NOT is processed and one of them is handled incorrectly.

    The one that is incorrect is taking the bool returned by CheckNot(),
casting it to size_t, then comparing it to a large unsigned value. This
comparison is always false whether the pattern is matched or not.

    It seems that the testsuite only checks that successful matches of the
CHECK-NOT pattern trigger failures. I didn't find any tests that check that
unsuccessful matches permits successes.

Steps to reproduce:
    * Run 'FileCheck -input-file test.txt test.txt' using the attached file.
    * echo $?

Expected behaviour:
    * No output
    * Exit with 0

Actual behaviour:
    * No output
    * Exit with 1</pre>
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