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+    <h1 id="firstHeading" class="firstHeading">C attribute: nodiscard <span class="t-mark-rev t-since-c23">(since C23)</span>
+</h1>            <p>If a function declared <code>nodiscard</code> or a function returning a struct/union/enum declared <code>nodiscard</code> by value is called from a <a href="../expressions" title="c/language/expressions">discarded-value expression</a> other than a cast to <code>void</code>, the compiler is encouraged to issue a warning.</p>
+<h3 id="Syntax"> Syntax</h3> <table class="t-sdsc-begin">  <tr class="t-sdsc"> <td> <code>[[</code> <code>nodiscard</code> <code>]]</code><br><code>[[</code> <code>__nodiscard__</code> <code>]]</code> </td> <td> (1) </td> <td class="t-sdsc-nopad"> </td>
+</tr>  <tr class="t-sdsc"> <td> <code>[[</code> <code>nodiscard</code> <code>(</code> <span class="t-spar">string-literal</span> <code>)</code> <code>]]</code><br><code>[[</code> <code>__nodiscard__</code> <code>(</code> <span class="t-spar">string-literal</span> <code>)</code> <code>]]</code> </td> <td> (2) </td> <td class="t-sdsc-nopad"> </td>
+</tr> 
+</table> <table class="t-par-begin"> <tr class="t-par"> <td> <span class="t-spar">string-literal</span> </td> <td> - </td> <td> text that could be used to explain the rationale for why the result should not be discarded </td>
+</tr>
+</table> <h3 id="Explanation"> Explanation</h3> <p>Appears in a function declaration, enumeration declaration, or struct/union declaration.</p>
+<p>If, from a <a href="../expressions" title="c/language/expressions">discarded-value expression</a> other than a cast to <code>void</code>,</p>
+<ul>
+<li> a function declared <code>nodiscard</code> is called, or </li>
+<li> a function returning a struct/union/enum declared <code>nodiscard</code> is called, </li>
+</ul> <p>the compiler is encouraged to issue a warning.</p>
+<p>The <span class="t-spar">string-literal</span>, if specified, is usually included in the warnings.</p>
+<h3 id="Example"> Example</h3> <div class="t-example"> <div class="c source-c"><pre data-language="c">struct [[nodiscard]] error_info { int status; /*...*/ };
+struct error_info enable_missile_safety_mode() { /*...*/ return (struct error_info){0}; }
+void launch_missiles() { /*...*/ }
+void test_missiles() {
+   enable_missile_safety_mode(); // compiler may warn on discarding a nodiscard value
+   launch_missiles();
+}
+struct error_info* foo() { static struct error_info e; /*...*/ return &amp;e; }
+void f1() {
+    foo(); // nodiscard type itself is not returned, no warning
+}
+// nodiscard( string-literal ):
+[[nodiscard("PURE FUN")]] int strategic_value(int x, int y) { return x ^ y; }
+ 
+int main()
+{
+    strategic_value(4,2); // compiler may warn on discarding a nodiscard value
+    int z = strategic_value(0,0); // OK: return value is not discarded
+    return z;
+}</pre></div> <p>Possible output:</p>
+<div class="text source-text"><pre data-language="c">game.cpp:5:4: warning: ignoring return value of function declared with 'nodiscard' attribute
+game.cpp:17:5: warning: ignoring return value of function declared with 'nodiscard' attribute: PURE FUN</pre></div> </div> <h3 id="See_also"> See also</h3> <table class="t-dsc-begin"> <tr class="t-dsc"> <td colspan="2"> <span><a href="https://en.cppreference.com/w/cpp/language/attributes/nodiscard" title="cpp/language/attributes/nodiscard">C++ documentation</a></span> for <code>nodiscard</code> </td>
+</tr> </table>           <div class="_attribution">
+  <p class="_attribution-p">
+    &copy; cppreference.com<br>Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.<br>
+    <a href="https://en.cppreference.com/w/c/language/attributes/nodiscard" class="_attribution-link">https://en.cppreference.com/w/c/language/attributes/nodiscard</a>
+  </p>
+</div>