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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Preprocessor generates bad code"
href="http://llvm.org/bugs/show_bug.cgi?id=20144">20144</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Preprocessor generates bad code
</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>
<tr>
<th>OS</th>
<td>All
</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>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>pelle@morth.org
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>clang -O2 -E generates bad code for this code:
#include <stdio.h>
#include <string.h>
int main(int argc, char *argv[]) {
if (argc > 3) {
if (strcmp(argv[1], "-4") == 0) {
printf("wat\n");
}
}
return 0;
}
It seems to believe sizeof("-4") is 4 rather than 3.
Might be a duplicate of 11536, not sure.
Steps to reproduce:
clang -O2 -E bug.c | clang -Werror -x c -
Expected result:
bug.o generated
Actual result:
dummy.c:6:2109: error: array index 3 is past the end of the array (which
contains 3 elements) [-Werror,-Warray-bounds]
...> 2 && __result == 0) __result = (__s1[3] - ((__const unsigned char *)
(__const char *) ("-4"))[3]); } } __result; }))) : __...
^ ~
1 error generated.
Version info:
clang version 3.5.0 (<a href="http://llvm.org/git/clang.git">http://llvm.org/git/clang.git</a>
db5f8b25707a23dd5852a35539775f7e8cf8896e) (<a href="http://llvm.org/git/llvm.git">http://llvm.org/git/llvm.git</a>
0263debd04a3a827ac0e11968082d1c6fe0a9902)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation:
/opt/rh/devtoolset-2/root/usr/lib/gcc/x86_64-redhat-linux/4.8.2
Selected GCC installation:
/opt/rh/devtoolset-2/root/usr/lib/gcc/x86_64-redhat-linux/4.8.2
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64
on CentOS.
Also tested with 3.4 release.</pre>
</div>
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