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Node:<a name="Deprecated%20Features">Deprecated Features</a>,
Next:<a rel="next" accesskey="n" href="Backwards-Compatibility.html#Backwards%20Compatibility">Backwards Compatibility</a>,
Previous:<a rel="previous" accesskey="p" href="Java-Exceptions.html#Java%20Exceptions">Java Exceptions</a>,
Up:<a rel="up" accesskey="u" href="C---Extensions.html#C++%20Extensions">C++ Extensions</a>
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<h3 class="section">Deprecated Features</h3>
<p>In the past, the GNU C++ compiler was extended to experiment with new
features, at a time when the C++ language was still evolving. Now that
the C++ standard is complete, some of those features are superseded by
superior alternatives. Using the old features might cause a warning in
some cases that the feature will be dropped in the future. In other
cases, the feature might be gone already.
<p>While the list below is not exhaustive, it documents some of the options
that are now deprecated:
<dl>
<dt><code>-fexternal-templates</code>
<dd><dt><code>-falt-external-templates</code>
<dd>These are two of the many ways for g++ to implement template
instantiation. See <a href="Template-Instantiation.html#Template%20Instantiation">Template Instantiation</a>. The C++ standard clearly
defines how template definitions have to be organized across
implementation units. g++ has an implicit instantiation mechanism that
should work just fine for standard-conforming code.
<br><dt><code>-fstrict-prototype</code>
<dd><dt><code>-fno-strict-prototype</code>
<dd>Previously it was possible to use an empty prototype parameter list to
indicate an unspecified number of parameters (like C), rather than no
parameters, as C++ demands. This feature has been removed, except where
it is required for backwards compatibility See <a href="Backwards-Compatibility.html#Backwards%20Compatibility">Backwards Compatibility</a>.
</dl>
<p>The named return value extension has been deprecated, and is now
removed from g++.
<p>The use of initializer lists with new expressions has been deprecated,
and is now removed from g++.
<p>Floating and complex non-type template parameters have been deprecated,
and are now removed from g++.
<p>The implicit typename extension has been deprecated and will be removed
from g++ at some point. In some cases g++ determines that a dependent
type such as <code>TPL<T>::X</code> is a type without needing a
<code>typename</code> keyword, contrary to the standard.
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