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<title>Using the GNU Compiler Collection (GCC): Symbol-Renaming Pragmas</title>

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<a name="Symbol_002dRenaming-Pragmas"></a>
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Next: <a href="Structure_002dLayout-Pragmas.html#Structure_002dLayout-Pragmas" accesskey="n" rel="next">Structure-Layout Pragmas</a>, Previous: <a href="Solaris-Pragmas.html#Solaris-Pragmas" accesskey="p" rel="prev">Solaris Pragmas</a>, Up: <a href="Pragmas.html#Pragmas" accesskey="u" rel="up">Pragmas</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Symbol_002dRenaming-Pragmas-1"></a>
<h4 class="subsection">6.62.9 Symbol-Renaming Pragmas</h4>

<p>GCC supports a <code>#pragma</code> directive that changes the name used in
assembly for a given declaration. While this pragma is supported on all
platforms, it is intended primarily to provide compatibility with the
Solaris system headers. This effect can also be achieved using the asm
labels extension (see <a href="Asm-Labels.html#Asm-Labels">Asm Labels</a>).
</p>
<dl compact="compact">
<dt><code>redefine_extname <var>oldname</var> <var>newname</var></code></dt>
<dd><a name="index-pragma_002c-redefine_005fextname"></a>

<p>This pragma gives the C function <var>oldname</var> the assembly symbol
<var>newname</var>.  The preprocessor macro <code>__PRAGMA_REDEFINE_EXTNAME</code>
is defined if this pragma is available (currently on all platforms).
</p></dd>
</dl>

<p>This pragma and the asm labels extension interact in a complicated
manner.  Here are some corner cases you may want to be aware of:
</p>
<ol>
<li> This pragma silently applies only to declarations with external
linkage.  Asm labels do not have this restriction.

</li><li> In C++, this pragma silently applies only to declarations with
&ldquo;C&rdquo; linkage.  Again, asm labels do not have this restriction.

</li><li> If either of the ways of changing the assembly name of a
declaration are applied to a declaration whose assembly name has
already been determined (either by a previous use of one of these
features, or because the compiler needed the assembly name in order to
generate code), and the new name is different, a warning issues and
the name does not change.

</li><li> The <var>oldname</var> used by <code>#pragma redefine_extname</code> is
always the C-language name.
</li></ol>


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