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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Feature request: Suppressing -Wformat-nonliteral warning with va_list format argument"
href="http://llvm.org/bugs/show_bug.cgi?id=18982">18982</a>
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<th>Summary</th>
<td>Feature request: Suppressing -Wformat-nonliteral warning with va_list format argument
</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>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>chengniansun@gmail.com
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>For the following code, clang emits a -Wformat-nonliteral warning.
------------------------------------
$: cat s.c
#include <stdarg.h>
#include <stdio.h>
void foo (const char *msg, ...) {
va_list ap;
va_start (ap, msg);
vfprintf (stderr, msg, ap);
va_end (ap);
}
------------------------------------
$: clang-trunk -Wformat-nonliteral s.c -c
s.c:6:21: warning: format string is not a string literal [-Wformat-nonliteral]
vfprintf (stderr, msg, ap);
^~~
1 warning generated.
$: gcc-trunk -Wformat=2 -c s.c
$
IMHO, since it is a wrapper function to printf, it is better to suppress this
warning. I also checked the gcc manual, and gcc specially handles such case.
-Wformat-nonliteral
If -Wformat is specified, also warn if the format string is not a string
literal and so cannot be checked, unless the format function takes its format
arguments as a va_list.</pre>
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