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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - CallExpr::getArgs violates strict aliasing"
href="https://bugs.llvm.org/show_bug.cgi?id=43344">43344</a>
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<th>Summary</th>
<td>CallExpr::getArgs violates strict aliasing
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>comexk@gmail.com
</td>
</tr>
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>For a CallExpr, the array trailing the object can be accessed in two different
ways:
- As `Stmt **`: getTrailingStmts(), children()
- As `Expr **`: getArgs()
Accessing the same memory using both types is a strict aliasing violation –
it's of course legal to access an `Expr` through a pointer to `Stmt`, but not
to access an `Expr *` through a pointer to `Stmt *` or vice versa.
However, note that Clang itself does not enforce strict aliasing between
pointer types [1], and Clang's build system sets -fno-strict-aliasing when
built with GCC-compatible compilers other than Clang itself [2]. And the other
major C++ compiler, MSVC, does not enforce strict aliasing at all. So for now
this should not cause any problems in practice.
[1]
<a href="https://github.com/llvm-mirror/clang/blob/168f5196982f3aa5abce4e28c75bd6194ce0d9f0/lib/CodeGen/CodeGenTBAA.cpp#L161">https://github.com/llvm-mirror/clang/blob/168f5196982f3aa5abce4e28c75bd6194ce0d9f0/lib/CodeGen/CodeGenTBAA.cpp#L161</a>
[2]
<a href="https://github.com/llvm-mirror/clang/blob/168f5196982f3aa5abce4e28c75bd6194ce0d9f0/CMakeLists.txt#L363">https://github.com/llvm-mirror/clang/blob/168f5196982f3aa5abce4e28c75bd6194ce0d9f0/CMakeLists.txt#L363</a></pre>
</div>
</p>
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