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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - false negative of -Winteger-overflow"
href="https://llvm.org/bugs/show_bug.cgi?id=22899">22899</a>
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<th>Summary</th>
<td>false negative of -Winteger-overflow
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
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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>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Frontend
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>chengniansun@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Clang warns on integer overflow in variable initialization but not assignment.
For example, there is warning on
int a = ((uint16_t)0xE570L * (uint16_t)(-1L));
But if I split the statement into two, Clang will not warn:
int b;
b = ((uint16_t)0xE570L * (uint16_t)(-1L));
$: cat t.c
#include <stdint.h>
int main(void) {
int a = ((uint16_t)0xE570L * (uint16_t)(-1L));
int b;
b = ((uint16_t)0xE570L * (uint16_t)(-1L));
return 0;
}
$: clang-trunk -Wconversion t.c
t.c:3:30: warning: overflow in expression; result is -445703536 with type 'int'
[-Winteger-overflow]
int a = ((uint16_t)0xE570L * (uint16_t)(-1L));
^
1 warning generated.
$: gcc-trunk -Wconversion t.c
t.c: In function ‘main’:
t.c:3:30: warning: integer overflow in expression [-Woverflow]
int a = ((uint16_t)0xE570L * (uint16_t)(-1L));
^
t.c:5:26: warning: integer overflow in expression [-Woverflow]
b = ((uint16_t)0xE570L * (uint16_t)(-1L));
^
$:</pre>
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