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Apply patch from #8408.

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Fixes #8408.

[SVN r83958]
This commit is contained in:
John Maddock
2013-04-18 17:50:17 +00:00
parent 1f5100001f
commit bffa0772d8
8 changed files with 126 additions and 22 deletions
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doc/html/boost_config/boost_macro_reference.html
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<p>
<code class="computeroutput"><span class="identifier">BOOST_FALLTHROUGH</span></code>
</p>
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<td>
<p>
The BOOST_FALLTHROUGH macro can be used to annotate implicit fall-through
between switch labels:
</p>
<pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="keyword">switch</span> <span class="special">(</span><span class="identifier">x</span><span class="special">)</span> <span class="special">{</span>
<span class="keyword">case</span> <span class="number">40</span><span class="special">:</span>
<span class="keyword">case</span> <span class="number">41</span><span class="special">:</span>
<span class="keyword">if</span> <span class="special">(</span><span class="identifier">truth_is_out_there</span><span class="special">)</span> <span class="special">{</span>
<span class="special">++</span><span class="identifier">x</span><span class="special">;</span>
<span class="identifier">BOOST_FALLTHROUGH</span><span class="special">;</span> <span class="comment">// Use instead of/along with annotations in </span>
<span class="comment">// comments. </span>
<span class="special">}</span> <span class="keyword">else</span> <span class="special">{</span>
<span class="keyword">return</span> <span class="identifier">x</span><span class="special">;</span>
<span class="special">}</span>
<span class="keyword">case</span> <span class="number">42</span><span class="special">:</span>
<span class="special">...</span>
</pre>
<p>
As shown in the example above, the BOOST_FALLTHROUGH macro should
be followed by a semicolon. It is designed to mimic control-flow
statements like 'break;', so it can be placed in most places where
'break;' can, but only if there are no statements on the execution
path between it and the next switch label.
</p>
<p>
When compiled with Clang &gt;3.2 in C++11 mode, the BOOST_FALLTHROUGH
macro is expanded to <code class="computeroutput"><span class="special">[[</span><span class="identifier">clang</span><span class="special">::</span><span class="identifier">fallthrough</span><span class="special">]]</span></code>
attribute, which is analysed when performing switch labels fall-through
diagnostic ('-Wimplicit-fallthrough'). See clang <a href="http://clang.llvm.org/docs/LanguageExtensions.html#clang__fallthrough" target="_top">documentation
on language extensions for details.</a>
</p>
<p>
When used with unsupported compilers, the BOOST_FALLTHROUGH macro
has no effect on diagnostics.
</p>
<p>
In either case this macro has no effect on runtime behavior and
performance of code.
</p>
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<p>
<code class="computeroutput"><span class="identifier">BOOST_EXPLICIT_TEMPLATE_TYPE</span><span class="special">(</span><span class="identifier">t</span><span class="special">)</span></code> <code class="computeroutput"><span class="identifier">BOOST_EXPLICIT_TEMPLATE_NON_TYPE</span><span class="special">(</span><span class="identifier">t</span><span class="special">,</span><span class="identifier">v</span><span class="special">)</span></code> <code class="computeroutput"><span class="identifier">BOOST_APPEND_EXPLICIT_TEMPLATE_TYPE</span><span class="special">(</span><span class="identifier">t</span><span class="special">)</span></code> <code class="computeroutput"><span class="identifier">BOOST_APPEND_EXPLICIT_TEMPLATE_NON_TYPE</span><span class="special">(</span><span class="identifier">t</span><span class="special">,</span><span class="identifier">v</span><span class="special">)</span></code>