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    <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 - some problematic casts applied to NULL are not diagnosed"
   href="https://bugs.llvm.org/show_bug.cgi?id=40725">40725</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>some problematic casts applied to NULL are not diagnosed
          </td>
        </tr>

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

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

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

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

        <tr>
          <th>Reporter</th>
          <td>richard-llvm@metafoo.co.uk
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Testcase:

#define NULL __null

int *p = reinterpret_cast<int*>(NULL); // #1
enum E {}; E e = static_cast<E>(NULL); // #2
float f = static_cast<float>(NULL); // #3

This produces no diagnostics. All marked lines should result in a warning:

 -- #1 does not necessarily produce a null pointer; it produces a pointer whose
value is all-zero-bits. We should suggest replacing reinterpret_cast with
static_cast here.
 -- #2 and #3 don't make any sense; they're using NULL as an integer rather
than as a pointer. We should suggest replacing NULL with 0 here.

Generally, we should probably warn on any use of NULL where nullptr would not
be valid or would mean something else.</pre>
        </div>
      </p>


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