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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - __cxa_exception doesn't match Itanium spec."
href="https://bugs.llvm.org/show_bug.cgi?id=41397">41397</a>
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<th>Summary</th>
<td>__cxa_exception doesn't match Itanium spec.
</td>
</tr>
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<th>Product</th>
<td>libc++abi
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>All Bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>eric@efcs.ca
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
</td>
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=21739" name="attach_21739" title="libstdcxx_test.cpp">attachment 21739</a> <a href="attachment.cgi?id=21739&action=edit" title="libstdcxx_test.cpp">[details]</a></span>
libstdcxx_test.cpp
To support C++11 exception point, we added a ref count member at the start of
the `__cxa_exception` type. However, `__cxa_exception` is specified by the
Itanium spec and in the specification it doesn't contain the new member.
Since `__cxa_exception` is part of the ABI specification, users may declare
their own copy of it and then attempt to access in-flight exceptions using
`__cxa_get_globals()`.
When this occurs the members of the `__cxa_exception` objects are at the wrong
offsets and this can break users.
GCC's fixs to this problem was to keep `__cxa_exception`'s layout and put the
refcount in a new type `__cxa_refcounted_exception` [1]. We should consider
doing similar.
[1] <a href="https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38732">https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38732</a></pre>
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