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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - -Wexpansion-to-defined enabled without -pedantic"
href="https://llvm.org/bugs/show_bug.cgi?id=28901">28901</a>
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<th>Summary</th>
<td>-Wexpansion-to-defined enabled without -pedantic
</td>
</tr>
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<th>Product</th>
<td>clang
</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>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Frontend
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
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<th>Reporter</th>
<td>bonzini@gnu.org
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<th>Classification</th>
<td>Unclassified
</td>
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<p>
<div>
<pre>Macros that expand to "defined" are undefined behavior according to the C
standard, but clang, as a language extension, is implementing it by always
treating "defined" as the preprocessor operator.
While it is a good idea to add a separate warning flag for
-Wexpansion-to-defined, it should only be enabled by default if -pedantic or
perhaps -Wextra (and of course -Weverything) is provided. It should not be
enabled by -Wall.</pre>
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</p>
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