<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/124912>124912</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [TySan] Can't build LLVM; many reports from llvm::cl::opt
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          gbMattN
      </td>
    </tr>
</table>

<pre>
    When building clang with TySan, there are many runtime errors of the form
```
==15386==ERROR: TypeSanitizer: type-aliasing-violation on address 0x64ca90a27e18 (pc 0x64ca900c2ff1 bp 0x7ffcdb1ca690 sp 0x7ffcdb1c9e38 tid 15386)
READ of size 8 at 0x64ca90a27e18 with type p1 omnipotent char (in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > at offset 0) accesses part of an existing object of type llvm::cl::opt<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, false, llvm::cl::parser<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > that starts at offset -160
    #0 0x64ca900c2ff0 in llvm::cl::opt<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>, false, llvm::cl::parser<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>>>::~opt() (/home/gbmatt/Documents/upstream/llvm-project/build/bin/clang-tblgen+0x42dff0
```

These are _probably_ false positives, so it would be good to understand them
</pre>
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