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<h1 class='fqn'><span class='in-band'>Constant <a href='../index.html'>std</a>::<wbr><a href='index.html'>boxed</a>::<wbr><a class="constant" href=''>HEAP</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version '></span><span id='render-detail'>
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</span><a class='srclink' href='../../src/alloc/boxed.rs.html#94' title='goto source code'>[src]</a></span></h1>
<pre class='rust const'>pub const HEAP: <a class="struct" href="../../std/boxed/struct.ExchangeHeapSingleton.html" title="struct std::boxed::ExchangeHeapSingleton">ExchangeHeapSingleton</a><code> = </code><code>ExchangeHeapSingleton{_force_singleton: (),}</code></pre><div class='stability'><div class='stab unstable'><details><summary><span class=microscope>🔬</span> This is a nightly-only experimental API. (<code>box_heap </code><a href="https://github.com/rust-lang/rust/issues/27779">#27779</a>)</summary><p>may be renamed; uncertain about custom allocator design</p>
</details></div></div><div class='docblock'><p>A value that represents the heap. This is the default place that the <code>box</code>
keyword allocates into when no place is supplied.</p>
<p>The following two examples are equivalent:</p>
<pre class="rust rust-example-rendered">
<span class="attribute">#![<span class="ident">feature</span>(<span class="ident">box_heap</span>)]</span>
<span class="attribute">#![<span class="ident">feature</span>(<span class="ident">box_syntax</span>, <span class="ident">placement_in_syntax</span>)]</span>
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">boxed</span>::<span class="ident">HEAP</span>;
<span class="kw">fn</span> <span class="ident">main</span>() {
<span class="kw">let</span> <span class="ident">foo</span>: <span class="ident">Box</span><span class="op"><</span><span class="ident">i32</span><span class="op">></span> <span class="op">=</span> <span class="kw">in</span> <span class="ident">HEAP</span> { <span class="number">5</span> };
<span class="kw">let</span> <span class="ident">foo</span> <span class="op">=</span> <span class="kw">box</span> <span class="number">5</span>;
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0A%23!%5Bfeature(box_heap)%5D%0A%0A%23!%5Bfeature(box_syntax%2C%20placement_in_syntax)%5D%0Ause%20std%3A%3Aboxed%3A%3AHEAP%3B%0A%0Afn%20main()%20%7B%0A%20%20%20%20let%20foo%3A%20Box%3Ci32%3E%20%3D%20in%20HEAP%20%7B%205%20%7D%3B%0A%20%20%20%20let%20foo%20%3D%20box%205%3B%0A%7D%0A&version=nightly">Run</a></pre>
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