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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - No -Wtautological-pointer-compare warning on variables within parentheses, and the column number might be improved"
href="http://llvm.org/bugs/show_bug.cgi?id=20951">20951</a>
</td>
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<tr>
<th>Summary</th>
<td>No -Wtautological-pointer-compare warning on variables within parentheses, and the column number might be improved
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Frontend
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<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 emits a -Wtautological-pointer-compare on the following expressions,
NULL == &a,
but does not on the following one
NULL == (&a)
Moreover, the column of this warning points to the location of the variable a,
but not the location of the comparison expression. Is this deliberate? I find
that a number of Clang warnings point to the operator location.
========================================================================
$: cat t.c
#include <stdlib.h>
int f(short a) {
if (NULL ==
(&a)) { /*no warning here*/
return 0;
} else if (NULL ==
&a) { /*warning here.*/
return 2;
} else
return 1;
}
$: clang-trunk -Wtautological-pointer-compare -c t.c
t.c:7:16: warning: comparison of address of 'a' equal to a null pointer is
always false [-Wtautological-pointer-compare]
&a) { /*warning here.*/
^
1 warning generated.
$: gcc-trunk -Waddress -c t.c
t.c: In function ‘f’:
t.c:3:12: warning: the comparison will always evaluate as ‘false’ for the
address of ‘a’ will never be NULL [-Waddress]
if (NULL ==
^
t.c:6:19: warning: the comparison will always evaluate as ‘false’ for the
address of ‘a’ will never be NULL [-Waddress]
} else if (NULL ==
^
$: clang-trunk -v
clang version 3.6.0 (trunk 217725)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.2
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.1
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Candidate multilib: .;@m64
Selected multilib: .;@m64
$:</pre>
</div>
</p>
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