doc/html/boost_typeindex/mixing_sources_with_rtti_on_and_.html


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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="boost_typeindex.mixing_sources_with_rtti_on_and_"></a><a class="link" href="mixing_sources_with_rtti_on_and_.html" title="Mixing sources with RTTI on and RTTI off">Mixing
    sources with RTTI on and RTTI off</a>
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<p>
      Linking a binary from source files that were compiled with different RTTI flags
      is not a very good idea and may lead to a lot of surprises. However if there
      is a very strong need, TypeIndex library provides a solution for mixing sources:
      just define <code class="computeroutput"><a class="link" href="../BOOST_TYPE_INDEX_FORCE_NO_RTTI_COMPATIBILITY.html" title="Macro BOOST_TYPE_INDEX_FORCE_NO_RTTI_COMPATIBILITY">BOOST_TYPE_INDEX_FORCE_NO_RTTI_COMPATIBILITY</a></code>
      macro. This would lead to usage of same type_index class (<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">typeindex</span><span class="special">::</span><span class="identifier">ctti_type_index</span></code>
      or <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">typeindex</span><span class="special">::</span><span class="identifier">stl_type_index</span></code>) all around the project.
    </p>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
        Do not forget to rebuild <span class="bold"><strong>all</strong></span> the projects
        with <code class="computeroutput"><span class="identifier">BOOST_TYPE_INDEX_FORCE_NO_RTTI_COMPATIBILITY</span></code>
        macro defined
      </p></td></tr>
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<p>
      You must know that linking RTTI on and RTTI off binaries may succeed even without
      defining the <code class="computeroutput"><span class="identifier">BOOST_TYPE_INDEX_FORCE_NO_RTTI_COMPATIBILITY</span></code>
      macro, but that does not mean that you'll get a working binary. Such actions
      may break the One Definition Rule. Take a look at the table below, that shows
      how the <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">type_index</span> <span class="identifier">get_integer</span><span class="special">();</span></code> function will look like with different RTTI
      flags:
    </p>
<div class="informaltable">
<a name="boost_typeindex.mixing_sources_with_rtti_on_and_.diffs"></a><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
              <p>
                RTTI on
              </p>
            </th>
<th>
              <p>
                RTTI off
              </p>
            </th>
</tr></thead>
<tbody><tr>
<td>
              <p>
                <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">typeindex</span><span class="special">::</span><span class="identifier">stl_type_index</span> <span class="identifier">get_integer</span><span class="special">();</span></code>
              </p>
            </td>
<td>
              <p>
                <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">typeindex</span><span class="special">::</span><span class="identifier">ctti_type_index</span> <span class="identifier">get_integer</span><span class="special">();</span></code>
              </p>
            </td>
</tr></tbody>
</table>
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<p>
      Such differences are usually not detected by linker and lead to errors at runtime.
    </p>
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<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
        Even with <code class="computeroutput"><span class="identifier">BOOST_TYPE_INDEX_FORCE_NO_RTTI_COMPATIBILITY</span></code>
        defined there is no guarantee that everything will be OK. Libraries that
        use their own workarounds for disabled RTTI may fail to link or to work correctly.
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<td align="right"><div class="copyright-footer">Copyright &#169; 2012-2014 Antony Polukhin<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
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