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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Incorrect clang warning -Wconstant-conversion on unsigned types"
href="https://bugs.llvm.org/show_bug.cgi?id=37771">37771</a>
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<th>Summary</th>
<td>Incorrect clang warning -Wconstant-conversion on unsigned types
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</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>-New Bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>manojgupta@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, rtrieu@google.com
</td>
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<p>
<div>
<pre>Found when building Linux kernel 4.14 with clang:
(<a href="https://bugs.chromium.org/p/chromium/issues/detail?id=849780">https://bugs.chromium.org/p/chromium/issues/detail?id=849780</a>).
Reduced test cases:
unsigned char test_char(void)
{
const unsigned char w = 128;
return ~w;
}
../build/char_warn.c:5:10: error: implicit conversion from 'int' to 'unsigned
char' changes value from -129 to 127
[-Werror,-Wconstant-conversion]
return ~w;
unsigned short test_short(void)
{
const unsigned short w = 0x8000;
return ~w;
}
../build/short_warn.c:5:10: error: implicit conversion from 'int' to 'unsigned
short' changes value from -32769 to 32767
[-Werror,-Wconstant-conversion]
return ~w;</pre>
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