<html>
    <head>
      <base href="http://llvm.org/bugs/" />
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW --- - __USER_LABEL_PREFIX__ incompatibility between clang and gcc on Debian GNU/kFreeBSD"
   href="http://llvm.org/bugs/show_bug.cgi?id=17890">17890</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>__USER_LABEL_PREFIX__ incompatibility between clang and gcc on Debian GNU/kFreeBSD
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>3.0
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>FreeBSD
          </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>-New Bugs
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedclangbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>joel@lopes-da-silva.com
          </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>__USER_LABEL_PREFIX__ incompatibility between clang and gcc on Debian
GNU/kFreeBSD

Whenever I use sscanf on Debian GNU/kFreeBSD Wheezy 7.2, I get the following
error: undefined reference to `___isoc99_sscanf'

In case you're not familiar with this system, Debian GNU/kFreeBSD is a special
variant of the Debian distribution using the FreeBSD kernel with the GNU stack
from Debian GNU/Linux. I guess the relevant difference between Debian
GNU/kFreeBSD and the more common FreeBSD is that Debian GNU/kFreeBSD uses the
GNU version of the C library.


I believe this is essentially the same bug as another one you guys previously
fixed for Linux: <a class="bz_bug_link 
          bz_status_CLOSED  bz_closed"
   title="CLOSED FIXED - __USER_LABEL_PREFIX__ incompabitibility"
   href="show_bug.cgi?id=2824">http://llvm.org/bugs/show_bug.cgi?id=2824</a>

I'm gathering some of the information you guys requested for that older bug
report:

$ gcc -E -o - -dM -x c - < /dev/null | grep USER_LABEL
#define __USER_LABEL_PREFIX__ 
$ clang -E -o - -dM -x c - < /dev/null | grep USER_LABEL
#define __USER_LABEL_PREFIX__ _


Here's some more information you may find relevant:

$ uname -a
GNU/kFreeBSD machine.domain.tld 9.0-2-amd64 #0 Tue Sep 10 18:35:20 CEST 2013
x86_64 amd64 Intel(R) Core(TM) i7-2620M CPU @ 2.70GHz GNU/kFreeBSD

$ gcc --version 
gcc (Debian 4.7.2-5) 4.7.2
Copyright (C) 2012 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ clang --version
Debian clang version 3.0-6.2 (tags/RELEASE_30/final) (based on LLVM 3.0)
Target: x86_64-pc-kfreebsd-gnu
Thread model: posix


I verified that adding the following code at the very top of the compilation
unit where I used sscanf did fix the compilation error:

    #undef __USER_LABEL_PREFIX__
    #define __USER_LABEL_PREFIX__</pre>
        </div>
      </p>
      <hr>
      <span>You are receiving this mail because:</span>
      
      <ul>
          <li>You are on the CC list for the bug.</li>
      </ul>
    </body>
</html>