<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="API documentation for the Rust `Error` trait in crate `std`."><meta name="keywords" content="rust, rustlang, rust-lang, Error"><title>std::error::Error - Rust</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script src="../../storage.js"></script><link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico"></head><body class="rustdoc trait"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../std/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a><p class='location'>Trait Error</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#provided-methods">Provided Methods</a><div class="sidebar-links"><a href="#method.description">description</a><a href="#method.cause">cause</a></div><a class="sidebar-title" href="#foreign-impls">Implementations on Foreign Types</a><div class="sidebar-links"><a href="#impl-Error">TryFromSliceError</a></div><a class="sidebar-title" href="#implementors">Implementors</a><a class="sidebar-title" href="#methods">Methods</a><div class="sidebar-links"><a href="#method.is">is</a><a href="#method.downcast_ref">downcast_ref</a><a href="#method.downcast_mut">downcast_mut</a><a href="#method.is">is</a><a href="#method.downcast_ref">downcast_ref</a><a href="#method.downcast_mut">downcast_mut</a><a href="#method.is">is</a><a href="#method.downcast_ref">downcast_ref</a><a href="#method.downcast_mut">downcast_mut</a><a href="#method.downcast">downcast</a><a href="#method.downcast">downcast</a><a href="#method.downcast">downcast</a></div></div><p class='location'><a href='../index.html'>std</a>::<wbr><a href='index.html'>error</a></p><script>window.sidebarCurrent = {name: 'Error', ty: 'trait', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><a id="settings-menu" href="../../settings.html"><img src="../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='in-band'>Trait <a href='../index.html'>std</a>::<wbr><a href='index.html'>error</a>::<wbr><a class="trait" href=''>Error</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>−</span>]</a></span><a class='srclink' href='../../src/std/error.rs.html#54-150' title='goto source code'>[src]</a></span></h1><div class="docblock type-decl"><pre class='rust trait'>pub trait Error: <a class="trait" href="../../std/fmt/trait.Debug.html" title="trait std::fmt::Debug">Debug</a> + <a class="trait" href="../../std/fmt/trait.Display.html" title="trait std::fmt::Display">Display</a> {
fn <a href='#method.description' class='fnname'>description</a>(&self) -> &<a class="primitive" href="../primitive.str.html">str</a> { ... }
<div class='item-spacer'></div> fn <a href='#method.cause' class='fnname'>cause</a>(&self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><&<a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a>> { ... }
}</pre></div><div class='docblock'><p><code>Error</code> is a trait representing the basic expectations for error values,
i.e. values of type <code>E</code> in <a href="../result/enum.Result.html"><code>Result<T, E></code></a>. Errors must describe
themselves through the <a href="../fmt/trait.Display.html"><code>Display</code></a> and <a href="../../std/fmt/trait.Debug.html" title="`Debug`"><code>Debug</code></a> traits, and may provide
cause chain information:</p>
<p>The <a href="trait.Error.html#method.cause"><code>cause</code></a> method is generally used when errors cross "abstraction
boundaries", i.e. when a one module must report an error that is "caused"
by an error from a lower-level module. This setup makes it possible for the
high-level module to provide its own errors that do not commit to any
particular implementation, but also reveal some of its implementation for
debugging via <a href="trait.Error.html#method.cause"><code>cause</code></a> chains.</p>
</div>
<h2 id='provided-methods' class='small-section-header'>
Provided Methods<a href='#provided-methods' class='anchor'></a>
</h2>
<div class='methods'>
<h3 id='method.description' class='method'><span id='description.v' class='invisible'><code>fn <a href='#method.description' class='fnname'>description</a>(&self) -> &<a class="primitive" href="../primitive.str.html">str</a></code></span></h3><div class='docblock'><p><strong>This method is soft-deprecated.</strong></p>
<p>Although using it won’t cause compilation warning,
new code should use <a href="../fmt/trait.Display.html"><code>Display</code></a> instead
and new <code>impl</code>s can omit it.</p>
<p>To obtain error description as a string, use <code>to_string()</code>.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">match</span> <span class="string">"xc"</span>.<span class="ident">parse</span>::<span class="op"><</span><span class="ident">u32</span><span class="op">></span>() {
<span class="prelude-val">Err</span>(<span class="ident">e</span>) <span class="op">=></span> {
<span class="comment">// Print `e` itself, not `e.description()`.</span>
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"Error: {}"</span>, <span class="ident">e</span>);
}
<span class="kw">_</span> <span class="op">=></span> <span class="macro">println</span><span class="macro">!</span>(<span class="string">"No error"</span>),
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Amatch%20%22xc%22.parse%3A%3A%3Cu32%3E()%20%7B%0A%20%20%20%20Err(e)%20%3D%3E%20%7B%0A%20%20%20%20%20%20%20%20%2F%2F%20Print%20%60e%60%20itself%2C%20not%20%60e.description()%60.%0A%20%20%20%20%20%20%20%20println!(%22Error%3A%20%7B%7D%22%2C%20e)%3B%0A%20%20%20%20%7D%0A%20%20%20%20_%20%3D%3E%20println!(%22No%20error%22)%2C%0A%7D%0A%7D">Run</a></pre>
</div><h3 id='method.cause' class='method'><span id='cause.v' class='invisible'><code>fn <a href='#method.cause' class='fnname'>cause</a>(&self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><&<a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a>></code></span></h3><div class='docblock'><p>The lower-level cause of this error, if any.</p>
<h1 id="examples-1" class="section-header"><a href="#examples-1">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">error</span>::<span class="ident">Error</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>;
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">struct</span> <span class="ident">SuperError</span> {
<span class="ident">side</span>: <span class="ident">SuperErrorSideKick</span>,
}
<span class="kw">impl</span> <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="kw">for</span> <span class="ident">SuperError</span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="macro">write</span><span class="macro">!</span>(<span class="ident">f</span>, <span class="string">"SuperError is here!"</span>)
}
}
<span class="kw">impl</span> <span class="ident">Error</span> <span class="kw">for</span> <span class="ident">SuperError</span> {
<span class="kw">fn</span> <span class="ident">description</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">str</span> {
<span class="string">"I'm the superhero of errors"</span>
}
<span class="kw">fn</span> <span class="ident">cause</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">Error</span><span class="op">></span> {
<span class="prelude-val">Some</span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="ident">side</span>)
}
}
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">struct</span> <span class="ident">SuperErrorSideKick</span>;
<span class="kw">impl</span> <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="kw">for</span> <span class="ident">SuperErrorSideKick</span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="macro">write</span><span class="macro">!</span>(<span class="ident">f</span>, <span class="string">"SuperErrorSideKick is here!"</span>)
}
}
<span class="kw">impl</span> <span class="ident">Error</span> <span class="kw">for</span> <span class="ident">SuperErrorSideKick</span> {
<span class="kw">fn</span> <span class="ident">description</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">str</span> {
<span class="string">"I'm SuperError side kick"</span>
}
}
<span class="kw">fn</span> <span class="ident">get_super_error</span>() <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">SuperError</span><span class="op">></span> {
<span class="prelude-val">Err</span>(<span class="ident">SuperError</span> { <span class="ident">side</span>: <span class="ident">SuperErrorSideKick</span> })
}
<span class="kw">fn</span> <span class="ident">main</span>() {
<span class="kw">match</span> <span class="ident">get_super_error</span>() {
<span class="prelude-val">Err</span>(<span class="ident">e</span>) <span class="op">=></span> {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"Error: {}"</span>, <span class="ident">e</span>.<span class="ident">description</span>());
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"Caused by: {}"</span>, <span class="ident">e</span>.<span class="ident">cause</span>().<span class="ident">unwrap</span>());
}
<span class="kw">_</span> <span class="op">=></span> <span class="macro">println</span><span class="macro">!</span>(<span class="string">"No error"</span>),
}
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Ause%20std%3A%3Aerror%3A%3AError%3B%0Ause%20std%3A%3Afmt%3B%0A%0A%23%5Bderive(Debug)%5D%0Astruct%20SuperError%20%7B%0A%20%20%20%20side%3A%20SuperErrorSideKick%2C%0A%7D%0A%0Aimpl%20fmt%3A%3ADisplay%20for%20SuperError%20%7B%0A%20%20%20%20fn%20fmt(%26self%2C%20f%3A%20%26mut%20fmt%3A%3AFormatter)%20-%3E%20fmt%3A%3AResult%20%7B%0A%20%20%20%20%20%20%20%20write!(f%2C%20%22SuperError%20is%20here!%22)%0A%20%20%20%20%7D%0A%7D%0A%0Aimpl%20Error%20for%20SuperError%20%7B%0A%20%20%20%20fn%20description(%26self)%20-%3E%20%26str%20%7B%0A%20%20%20%20%20%20%20%20%22I'm%20the%20superhero%20of%20errors%22%0A%20%20%20%20%7D%0A%0A%20%20%20%20fn%20cause(%26self)%20-%3E%20Option%3C%26Error%3E%20%7B%0A%20%20%20%20%20%20%20%20Some(%26self.side)%0A%20%20%20%20%7D%0A%7D%0A%0A%23%5Bderive(Debug)%5D%0Astruct%20SuperErrorSideKick%3B%0A%0Aimpl%20fmt%3A%3ADisplay%20for%20SuperErrorSideKick%20%7B%0A%20%20%20%20fn%20fmt(%26self%2C%20f%3A%20%26mut%20fmt%3A%3AFormatter)%20-%3E%20fmt%3A%3AResult%20%7B%0A%20%20%20%20%20%20%20%20write!(f%2C%20%22SuperErrorSideKick%20is%20here!%22)%0A%20%20%20%20%7D%0A%7D%0A%0Aimpl%20Error%20for%20SuperErrorSideKick%20%7B%0A%20%20%20%20fn%20description(%26self)%20-%3E%20%26str%20%7B%0A%20%20%20%20%20%20%20%20%22I'm%20SuperError%20side%20kick%22%0A%20%20%20%20%7D%0A%7D%0A%0Afn%20get_super_error()%20-%3E%20Result%3C()%2C%20SuperError%3E%20%7B%0A%20%20%20%20Err(SuperError%20%7B%20side%3A%20SuperErrorSideKick%20%7D)%0A%7D%0A%0Afn%20main()%20%7B%0A%20%20%20%20match%20get_super_error()%20%7B%0A%20%20%20%20%20%20%20%20Err(e)%20%3D%3E%20%7B%0A%20%20%20%20%20%20%20%20%20%20%20%20println!(%22Error%3A%20%7B%7D%22%2C%20e.description())%3B%0A%20%20%20%20%20%20%20%20%20%20%20%20println!(%22Caused%20by%3A%20%7B%7D%22%2C%20e.cause().unwrap())%3B%0A%20%20%20%20%20%20%20%20%7D%0A%20%20%20%20%20%20%20%20_%20%3D%3E%20println!(%22No%20error%22)%2C%0A%20%20%20%20%7D%0A%7D">Run</a></pre>
</div></div>
<h2 id='methods' class='small-section-header'>
Methods<a href='#methods' class='anchor'></a>
</h2>
<h3 id='impl' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static</code><a href='#impl' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/error.rs.html#370-412' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.is' class="method"><span id='is.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.is' class='fnname'>is</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(&self) -> <a class="primitive" href="../primitive.bool.html">bool</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#374-383' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns true if the boxed type is the same as <code>T</code></p>
</div><h4 id='method.downcast_ref' class="method"><span id='downcast_ref.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.downcast_ref' class='fnname'>downcast_ref</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(&self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.reference.html">&</a>T></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#389-397' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns some reference to the boxed value if it is of type <code>T</code>, or
<code>None</code> if it isn't.</p>
</div><h4 id='method.downcast_mut' class="method"><span id='downcast_mut.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.downcast_mut' class='fnname'>downcast_mut</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(&mut self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.reference.html">&mut </a>T></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#403-411' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns some mutable reference to the boxed value if it is of type <code>T</code>, or
<code>None</code> if it isn't.</p>
</div></div><h3 id='impl-1' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + <a class="trait" href="../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a> + 'static</code><a href='#impl-1' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/error.rs.html#414-435' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.is-1' class="method"><span id='is.v-1' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.is-1' class='fnname'>is</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(&self) -> <a class="primitive" href="../primitive.bool.html">bool</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#418-420' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Forwards to the method defined on the type <code>Any</code>.</p>
</div><h4 id='method.downcast_ref-1' class="method"><span id='downcast_ref.v-1' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.downcast_ref-1' class='fnname'>downcast_ref</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(&self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.reference.html">&</a>T></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#425-427' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Forwards to the method defined on the type <code>Any</code>.</p>
</div><h4 id='method.downcast_mut-1' class="method"><span id='downcast_mut.v-1' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.downcast_mut-1' class='fnname'>downcast_mut</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(&mut self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.reference.html">&mut </a>T></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#432-434' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Forwards to the method defined on the type <code>Any</code>.</p>
</div></div><h3 id='impl-2' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + <a class="trait" href="../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a> + <a class="trait" href="../../std/marker/trait.Sync.html" title="trait std::marker::Sync">Sync</a> + 'static</code><a href='#impl-2' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/error.rs.html#437-458' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.is-2' class="method"><span id='is.v-2' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.is-2' class='fnname'>is</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(&self) -> <a class="primitive" href="../primitive.bool.html">bool</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#441-443' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Forwards to the method defined on the type <code>Any</code>.</p>
</div><h4 id='method.downcast_ref-2' class="method"><span id='downcast_ref.v-2' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.downcast_ref-2' class='fnname'>downcast_ref</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(&self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.reference.html">&</a>T></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#448-450' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Forwards to the method defined on the type <code>Any</code>.</p>
</div><h4 id='method.downcast_mut-2' class="method"><span id='downcast_mut.v-2' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.downcast_mut-2' class='fnname'>downcast_mut</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(&mut self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><<a class="primitive" href="../primitive.reference.html">&mut </a>T></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#455-457' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Forwards to the method defined on the type <code>Any</code>.</p>
</div></div><h3 id='impl-3' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a></code><a href='#impl-3' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/error.rs.html#460-474' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.downcast' class="method"><span id='downcast.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.downcast' class='fnname'>downcast</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(<br> self: <a class="struct" href="../../std/boxed/struct.Box.html" title="struct std::boxed::Box">Box</a><Self><br>) -> <a class="enum" href="../../std/result/enum.Result.html" title="enum std::result::Result">Result</a><<a class="struct" href="../../std/boxed/struct.Box.html" title="struct std::boxed::Box">Box</a><T>, <a class="struct" href="../../std/boxed/struct.Box.html" title="struct std::boxed::Box">Box</a><<a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a>>></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#464-473' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Attempt to downcast the box to a concrete type.</p>
</div></div><h3 id='impl-4' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + <a class="trait" href="../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a></code><a href='#impl-4' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/error.rs.html#476-488' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.downcast-1' class="method"><span id='downcast.v-1' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.downcast-1' class='fnname'>downcast</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(<br> self: <a class="struct" href="../../std/boxed/struct.Box.html" title="struct std::boxed::Box">Box</a><Self><br>) -> <a class="enum" href="../../std/result/enum.Result.html" title="enum std::result::Result">Result</a><<a class="struct" href="../../std/boxed/struct.Box.html" title="struct std::boxed::Box">Box</a><T>, <a class="struct" href="../../std/boxed/struct.Box.html" title="struct std::boxed::Box">Box</a><<a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + <a class="trait" href="../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a>>></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#480-487' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Attempt to downcast the box to a concrete type.</p>
</div></div><h3 id='impl-5' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + <a class="trait" href="../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a> + <a class="trait" href="../../std/marker/trait.Sync.html" title="trait std::marker::Sync">Sync</a></code><a href='#impl-5' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/error.rs.html#490-502' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.downcast-2' class="method"><span id='downcast.v-2' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.downcast-2' class='fnname'>downcast</a><T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> + 'static>(<br> self: <a class="struct" href="../../std/boxed/struct.Box.html" title="struct std::boxed::Box">Box</a><Self><br>) -> <a class="enum" href="../../std/result/enum.Result.html" title="enum std::result::Result">Result</a><<a class="struct" href="../../std/boxed/struct.Box.html" title="struct std::boxed::Box">Box</a><T>, <a class="struct" href="../../std/boxed/struct.Box.html" title="struct std::boxed::Box">Box</a><Self>></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.3.0'>1.3.0</div><a class='srclink' href='../../src/std/error.rs.html#494-501' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Attempt to downcast the box to a concrete type.</p>
</div></div>
<h2 id='foreign-impls' class='small-section-header'>
Implementations on Foreign Types<a href='#foreign-impls' class='anchor'></a>
</h2>
<h3 id='impl-Error' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a> for <a class="struct" href="../../core/array/struct.TryFromSliceError.html" title="struct core::array::TryFromSliceError">TryFromSliceError</a></code><a href='#impl-Error' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/error.rs.html#282-286' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><span class='docblock autohide'><div class='impl-items'><h4 id='method.description-1' class="method"><span id='description.v-1' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='#method.description' class='fnname'>description</a>(&self) -> &<a class="primitive" href="../primitive.str.html">str</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/std/error.rs.html#283-285' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><h4 id='method.cause-1' class="method"><span id='cause.v-1' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='../../std/error/trait.Error.html#method.cause' class='fnname'>cause</a>(&self) -> <a class="enum" href="../../std/option/enum.Option.html" title="enum std::option::Option">Option</a><&<a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a>></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.0.0'>1.0.0</div><a class='srclink' href='../../src/std/error.rs.html#140' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4></div></span>
<h2 id='implementors' class='small-section-header'>
Implementors<a href='#implementors' class='anchor'></a>
</h2>
<ul class='item-list' id='implementors-list'>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="enum" href="../../std/env/enum.VarError.html" title="enum std::env::VarError">VarError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/env.rs.html#277-284' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/env/struct.JoinPathsError.html" title="struct std::env::JoinPathsError">JoinPathsError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/env.rs.html#507-509' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="primitive" href="../primitive.never.html">!</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#224-226' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/alloc/struct.AllocErr.html" title="struct std::alloc::AllocErr">AllocErr</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#231-235' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/alloc/struct.LayoutErr.html" title="struct std::alloc::LayoutErr">LayoutErr</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#240-244' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/alloc/struct.CannotReallocInPlace.html" title="struct std::alloc::CannotReallocInPlace">CannotReallocInPlace</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#249-253' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/str/struct.ParseBoolError.html" title="struct std::str::ParseBoolError">ParseBoolError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#256-258' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/str/struct.Utf8Error.html" title="struct std::str::Utf8Error">Utf8Error</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#261-265' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/num/struct.ParseIntError.html" title="struct std::num::ParseIntError">ParseIntError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#268-272' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/num/struct.TryFromIntError.html" title="struct std::num::TryFromIntError">TryFromIntError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#275-279' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/num/struct.ParseFloatError.html" title="struct std::num::ParseFloatError">ParseFloatError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#289-293' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/string/struct.FromUtf8Error.html" title="struct std::string::FromUtf8Error">FromUtf8Error</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#296-300' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/string/struct.FromUtf16Error.html" title="struct std::string::FromUtf16Error">FromUtf16Error</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#303-307' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="enum" href="../../std/string/enum.ParseError.html" title="enum std::string::ParseError">ParseError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#310-314' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/char/struct.DecodeUtf16Error.html" title="struct std::char::DecodeUtf16Error">DecodeUtf16Error</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#317-321' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl<T: <a class="trait" href="../../std/error/trait.Error.html" title="trait std::error::Error">Error</a>> Error for <a class="struct" href="../../std/boxed/struct.Box.html" title="struct std::boxed::Box">Box</a><T></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#324-332' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for std::fmt::<a class="struct" href="../../std/fmt/struct.Error.html" title="struct std::fmt::Error">Error</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#335-339' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/cell/struct.BorrowError.html" title="struct std::cell::BorrowError">BorrowError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#342-346' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/cell/struct.BorrowMutError.html" title="struct std::cell::BorrowMutError">BorrowMutError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#349-353' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/char/struct.CharTryFromError.html" title="struct std::char::CharTryFromError">CharTryFromError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#356-360' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/char/struct.ParseCharError.html" title="struct std::char::ParseCharError">ParseCharError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/error.rs.html#363-367' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/ffi/struct.NulError.html" title="struct std::ffi::NulError">NulError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/ffi/c_str.rs.html#821-823' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/ffi/struct.FromBytesWithNulError.html" title="struct std::ffi::FromBytesWithNulError">FromBytesWithNulError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/ffi/c_str.rs.html#841-850' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/ffi/struct.IntoStringError.html" title="struct std::ffi::IntoStringError">IntoStringError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/ffi/c_str.rs.html#881-889' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl<W: <a class="trait" href="../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a> + <a class="trait" href="../../std/fmt/trait.Debug.html" title="trait std::fmt::Debug">Debug</a>> Error for <a class="struct" href="../../std/io/struct.IntoInnerError.html" title="struct std::io::IntoInnerError">IntoInnerError</a><W></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/io/buffered.rs.html#705-709' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for std::io::<a class="struct" href="../../std/io/struct.Error.html" title="struct std::io::Error">Error</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/io/error.rs.html#546-561' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="enum" href="../../std/io/enum.CharsError.html" title="enum std::io::CharsError">CharsError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/io/mod.rs.html#2077-2090' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/net/struct.AddrParseError.html" title="struct std::net::AddrParseError">AddrParseError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/net/parser.rs.html#413-417' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/path/struct.StripPrefixError.html" title="struct std::path::StripPrefixError">StripPrefixError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/path.rs.html#2705-2707' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl<T: <a class="trait" href="../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a>> Error for <a class="struct" href="../../std/sync/mpsc/struct.SendError.html" title="struct std::sync::mpsc::SendError">SendError</a><T></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/sync/mpsc/mod.rs.html#1636-1644' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl<T: <a class="trait" href="../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a>> Error for <a class="enum" href="../../std/sync/mpsc/enum.TrySendError.html" title="enum std::sync::mpsc::TrySendError">TrySendError</a><T></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/sync/mpsc/mod.rs.html#1671-1687' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/sync/mpsc/struct.RecvError.html" title="struct std::sync::mpsc::RecvError">RecvError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/sync/mpsc/mod.rs.html#1706-1715' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="enum" href="../../std/sync/mpsc/enum.TryRecvError.html" title="enum std::sync::mpsc::TryRecvError">TryRecvError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/sync/mpsc/mod.rs.html#1732-1748' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="enum" href="../../std/sync/mpsc/enum.RecvTimeoutError.html" title="enum std::sync::mpsc::RecvTimeoutError">RecvTimeoutError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/sync/mpsc/mod.rs.html#1774-1789' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl Error for <a class="struct" href="../../std/time/struct.SystemTimeError.html" title="struct std::time::SystemTimeError">SystemTimeError</a></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/time.rs.html#458-460' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl<T> Error for <a class="struct" href="../../std/sync/struct.PoisonError.html" title="struct std::sync::PoisonError">PoisonError</a><T></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/sys_common/poison.rs.html#162-166' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
<li><table class='table-display'><tbody><tr><td><code>impl<T> Error for <a class="enum" href="../../std/sync/enum.TryLockError.html" title="enum std::sync::TryLockError">TryLockError</a><T></code><td><div class='out-of-band'><a class='srclink' href='../../src/std/sys_common/poison.rs.html#246-260' title='goto source code'>[src]</a></div></td></tr></tbody></table></li>
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