<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/149639>149639</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang 21.1.0-rc1 creates broken executables on Cygwin
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          jeremyd2019
      </td>
    </tr>
</table>

<pre>
    with llvm/clang 20.1.8 (with Cygwin-related patches backported) I am able to build llvm, clang, and lld with clang and am able to strip the resulting executables.

with llvm/clang 21.1.0-rc1 I am able to build with clang but when I attempt to strip executables with llvm-strip I get an error `unexpected associative section index` (#53433) and when I attempt to strip executables with binutils 2.44 strip I get an executable that crashes on startup (I was able to catch it once during pseudo-relocations).

I don't have much detail yet, but I wanted to get this recorded and have a place to track the investigation.  I imagine my next step would be to set up a git bisect operation to try to figure out what's going on.  I don't have any ideas on how to reduce a test case, just that lld.exe and clang.exe are bugged, but simple C and C++ hello world executables are not.

/cc @mstorsjo @tyan0 @kikairoya 
</pre>
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