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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 --- - glibc exposed issue: wide character literal fails to behave as literal of its underlying type in preprocessor conditions"
href="http://llvm.org/bugs/show_bug.cgi?id=19649">19649</a>
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<th>Summary</th>
<td>glibc exposed issue: wide character literal fails to behave as literal of its underlying type in preprocessor conditions
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>3.4
</td>
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<th>Hardware</th>
<td>Other
</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>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Frontend
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>hstong@ca.ibm.com
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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</tr></table>
<p>
<div>
<pre>Certain versions of glibc use conditional inclusion to decide on the definition
of WCHAR_MIN. Clang picks the wrong definition.
According to C99 subclause 6.4.4.4 paragraph 11:
A wide character constant has type wchar_t, an integer type defined in the
<stddef.h> header.
The following source demonstrates that Clang will not treat a wide character
constant in the controlling expression of a preprocessing directive for
conditional inclusion in a way that is consistent with the above.
In particular, wchar_t is a synonym for int on the system in question (as
shown).
L'\0' does not behave consistently with 0 although both have the same type.
### SOURCE:> cat wchar_tPlay.c
extern __typeof__(L'\0') wchar;
extern int wchar;
#if (L'\0' - 1 < 0) != (0 - 1 < 0)
# warning
#endif
Return: 0x00:0
### COMPILER INVOCATION AND OUTPUT:> clang -std=c99 wchar_tPlay.c -c
wchar_tPlay.c:5:3: warning: [-W#warnings]
# warning
^
1 warning generated.
Return: 0x00:0
### VERSION INFO:> clang -v
clang version 3.4 (tags/RELEASE_34/final)
Target: powerpc64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/ppc64-redhat-linux/4.4.4
Found candidate GCC installation: /usr/lib/gcc/ppc64-redhat-linux/4.4.6
Selected GCC installation: /usr/lib/gcc/ppc64-redhat-linux/4.4.6
Return: 0x00:0</pre>
</div>
</p>
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