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sdk-toolchain-GNU-ARM-Embedded
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<span id="g_t_005f_005fhas_005fc_005fattribute-1"></span><h4 class="subsection">4.2.8 <code>__has_c_attribute</code></h4>
<span id="index-_005f_005fhas_005fc_005fattribute"></span>

<p>The special operator <code>__has_c_attribute (<var>operand</var>)</code> may be
used in &lsquo;<samp>#if</samp>&rsquo; and &lsquo;<samp>#elif</samp>&rsquo; expressions in C code to test
whether the attribute referenced by its <var>operand</var> is recognized by
GCC in attributes using the &lsquo;<samp>[[]]</samp>&rsquo; syntax.  GNU attributes must
be specified with the scope &lsquo;<samp>gnu</samp>&rsquo; or &lsquo;<samp>__gnu__</samp>&rsquo; with
<code>__has_c_attribute</code>.  When <var>operand</var> designates a supported
standard attribute it evaluates to an integer constant of the form
<code>YYYYMM</code> indicating the year and month when the attribute was
first introduced into the C standard, or when the syntax of operands
to the attribute was extended in the C standard.
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