| <!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="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/memoffset-0.8.0/src/raw_field.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>raw_field.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../memoffset/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../memoffset/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="comment">// Copyright (c) 2020 Gilad Naaman, Ralf Jung |
| // |
| // Permission is hereby granted, free of charge, to any person obtaining a copy |
| // of this software and associated documentation files (the "Software"), to deal |
| // in the Software without restriction, including without limitation the rights |
| // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| // copies of the Software, and to permit persons to whom the Software is |
| // furnished to do so, subject to the following conditions: |
| // |
| // The above copyright notice and this permission notice shall be included in all |
| // copies or substantial portions of the Software. |
| // |
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
| // SOFTWARE. |
| |
| </span><span class="doccomment">/// `addr_of!`, or just ref-then-cast when that is not available. |
| </span><span class="attribute">#[cfg(raw_ref_macros)] |
| #[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>_memoffset__addr_of { |
| (<span class="macro-nonterminal">$path</span>:expr) => {{ |
| <span class="macro-nonterminal">$</span><span class="macro">crate::__priv::ptr::addr_of!</span>(<span class="macro-nonterminal">$path</span>) |
| }}; |
| } |
| <span class="attribute">#[cfg(not(raw_ref_macros))] |
| #[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>_memoffset__addr_of { |
| (<span class="macro-nonterminal">$path</span>:expr) => {{ |
| <span class="comment">// This is UB because we create an intermediate reference to uninitialized memory. |
| // Nothing we can do about that without `addr_of!` though. |
| </span><span class="kw-2">&</span><span class="macro-nonterminal">$path </span><span class="kw">as </span><span class="kw-2">*const </span><span class="kw">_ |
| </span>}}; |
| } |
| |
| <span class="doccomment">/// Deref-coercion protection macro. |
| /// |
| /// Prevents complilation if the specified field name is not a part of the |
| /// struct definition. |
| /// |
| /// ```compile_fail |
| /// use memoffset::_memoffset__field_check; |
| /// |
| /// struct Foo { |
| /// foo: i32, |
| /// } |
| /// |
| /// type BoxedFoo = Box<Foo>; |
| /// |
| /// _memoffset__field_check!(BoxedFoo, foo); |
| /// ``` |
| </span><span class="attribute">#[cfg(allow_clippy)] |
| #[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>_memoffset__field_check { |
| (<span class="macro-nonterminal">$</span><span class="kw">type</span>:<span class="macro-nonterminal">path</span>, <span class="macro-nonterminal">$field</span>:tt) => { |
| <span class="comment">// Make sure the field actually exists. This line ensures that a |
| // compile-time error is generated if $field is accessed through a |
| // Deref impl. |
| </span><span class="attribute">#[allow(clippy::unneeded_field_pattern)] |
| </span><span class="kw">let </span><span class="macro-nonterminal">$</span><span class="kw">type </span>{ <span class="macro-nonterminal">$field</span>: <span class="kw">_</span>, .. }; |
| }; |
| } |
| <span class="attribute">#[cfg(not(allow_clippy))] |
| #[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>_memoffset__field_check { |
| (<span class="macro-nonterminal">$</span><span class="kw">type</span>:<span class="macro-nonterminal">path</span>, <span class="macro-nonterminal">$field</span>:tt) => { |
| <span class="comment">// Make sure the field actually exists. This line ensures that a |
| // compile-time error is generated if $field is accessed through a |
| // Deref impl. |
| </span><span class="kw">let </span><span class="macro-nonterminal">$</span><span class="kw">type </span>{ <span class="macro-nonterminal">$field</span>: <span class="kw">_</span>, .. }; |
| }; |
| } |
| |
| <span class="doccomment">/// Deref-coercion protection macro. |
| /// |
| /// Prevents complilation if the specified type is not a tuple. |
| /// |
| /// ```compile_fail |
| /// use memoffset::_memoffset__field_check_tuple; |
| /// |
| /// _memoffset__field_check_tuple!(i32, 0); |
| /// ``` |
| </span><span class="attribute">#[cfg(allow_clippy)] |
| #[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>_memoffset__field_check_tuple { |
| (<span class="macro-nonterminal">$</span><span class="kw">type</span>:<span class="macro-nonterminal">ty</span>, <span class="macro-nonterminal">$field</span>:tt) => { |
| <span class="comment">// Make sure the type argument is a tuple |
| </span><span class="attribute">#[allow(clippy::unneeded_wildcard_pattern)] |
| </span><span class="kw">let </span>(<span class="kw">_</span>, ..): <span class="macro-nonterminal">$</span><span class="kw">type</span>; |
| }; |
| } |
| <span class="attribute">#[<span class="macro-nonterminal">cfg</span>(not(allow_clippy))] |
| #[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>_memoffset__field_check_tuple { |
| (<span class="macro-nonterminal">$</span><span class="kw">type</span>:<span class="macro-nonterminal">ty</span>, <span class="macro-nonterminal">$field</span>:tt) => { |
| <span class="comment">// Make sure the type argument is a tuple |
| </span><span class="kw">let </span>(<span class="kw">_</span>, ..): <span class="macro-nonterminal">$</span><span class="kw">type</span>; |
| }; |
| } |
| |
| <span class="doccomment">/// Deref-coercion protection macro for unions. |
| /// Unfortunately accepts single-field structs as well, which is not ideal, |
| /// but ultimately pretty harmless. |
| /// |
| /// ```compile_fail |
| /// use memoffset::_memoffset__field_check_union; |
| /// |
| /// union Foo { |
| /// variant_a: i32, |
| /// } |
| /// |
| /// type BoxedFoo = Box<Foo>; |
| /// |
| /// _memoffset__field_check_union!(BoxedFoo, variant_a); |
| /// ``` |
| </span><span class="attribute">#[<span class="macro-nonterminal">cfg</span>(allow_clippy)] |
| #[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>_memoffset__field_check_union { |
| (<span class="macro-nonterminal">$</span><span class="kw">type</span>:<span class="macro-nonterminal">path</span>, <span class="macro-nonterminal">$field</span>:tt) => { |
| <span class="comment">// Make sure the field actually exists. This line ensures that a |
| // compile-time error is generated if $field is accessed through a |
| // Deref impl. |
| </span><span class="attribute">#[allow(clippy::unneeded_wildcard_pattern)] |
| </span><span class="comment">// rustc1.19 requires unsafe here for the pattern; not needed in newer versions |
| </span><span class="attribute">#[allow(unused_unsafe)] |
| </span><span class="kw">unsafe </span>{ |
| <span class="kw">let </span><span class="macro-nonterminal">$</span><span class="kw">type </span>{ <span class="macro-nonterminal">$field</span>: <span class="kw">_ </span>}; |
| } |
| }; |
| } |
| <span class="attribute">#[cfg(not(allow_clippy))] |
| #[macro_export] |
| #[doc(hidden)] |
| </span><span class="macro">macro_rules! </span>_memoffset__field_check_union { |
| (<span class="macro-nonterminal">$</span><span class="kw">type</span>:<span class="macro-nonterminal">path</span>, <span class="macro-nonterminal">$field</span>:tt) => { |
| <span class="comment">// Make sure the field actually exists. This line ensures that a |
| // compile-time error is generated if $field is accessed through a |
| // Deref impl. |
| // rustc1.19 requires unsafe here for the pattern; not needed in newer versions |
| </span><span class="attribute">#[allow(unused_unsafe)] |
| </span><span class="kw">unsafe </span>{ |
| <span class="kw">let </span><span class="macro-nonterminal">$</span><span class="kw">type </span>{ <span class="macro-nonterminal">$field</span>: <span class="kw">_ </span>}; |
| } |
| }; |
| } |
| |
| <span class="doccomment">/// Computes a const raw pointer to the given field of the given base pointer |
| /// to the given parent type. |
| /// |
| /// The `base` pointer *must not* be dangling, but it *may* point to |
| /// uninitialized memory. |
| </span><span class="attribute">#[macro_export(local_inner_macros)] |
| </span><span class="macro">macro_rules! </span>raw_field { |
| (<span class="macro-nonterminal">$base</span>:expr, <span class="macro-nonterminal">$parent</span>:path, <span class="macro-nonterminal">$field</span>:tt) => {{ |
| <span class="macro">_memoffset__field_check!</span>(<span class="macro-nonterminal">$parent</span>, <span class="macro-nonterminal">$field</span>); |
| <span class="kw">let </span>base = <span class="macro-nonterminal">$base</span>; <span class="comment">// evaluate $base outside the `unsafe` block |
| |
| // Get the field address. |
| // Crucially, we know that this will not trigger a deref coercion because |
| // of the field check we did above. |
| </span><span class="attribute">#[allow(unused_unsafe)] </span><span class="comment">// for when the macro is used in an unsafe block |
| </span><span class="kw">unsafe </span>{ |
| <span class="macro">_memoffset__addr_of!</span>((<span class="kw-2">*</span>(base <span class="kw">as </span><span class="kw-2">*const </span><span class="macro-nonterminal">$parent</span>)).<span class="macro-nonterminal">$field</span>) |
| } |
| }}; |
| } |
| |
| <span class="doccomment">/// Computes a const raw pointer to the given field of the given base pointer |
| /// to the given parent tuple typle. |
| /// |
| /// The `base` pointer *must not* be dangling, but it *may* point to |
| /// uninitialized memory. |
| </span><span class="attribute">#[cfg(tuple_ty)] |
| #[macro_export(local_inner_macros)] |
| </span><span class="macro">macro_rules! </span>raw_field_tuple { |
| (<span class="macro-nonterminal">$base</span>:expr, <span class="macro-nonterminal">$parent</span>:ty, <span class="macro-nonterminal">$field</span>:tt) => {{ |
| <span class="macro">_memoffset__field_check_tuple!</span>(<span class="macro-nonterminal">$parent</span>, <span class="macro-nonterminal">$field</span>); |
| <span class="kw">let </span>base = <span class="macro-nonterminal">$base</span>; <span class="comment">// evaluate $base outside the `unsafe` block |
| |
| // Get the field address. |
| // Crucially, we know that this will not trigger a deref coercion because |
| // of the field check we did above. |
| </span><span class="attribute">#[allow(unused_unsafe)] </span><span class="comment">// for when the macro is used in an unsafe block |
| </span><span class="kw">unsafe </span>{ |
| <span class="macro">_memoffset__addr_of!</span>((<span class="kw-2">*</span>(base <span class="kw">as </span><span class="kw-2">*const </span><span class="macro-nonterminal">$parent</span>)).<span class="macro-nonterminal">$field</span>) |
| } |
| }}; |
| } |
| |
| <span class="doccomment">/// Computes a const raw pointer to the given field of the given base pointer |
| /// to the given parent tuple typle. |
| /// |
| /// The `base` pointer *must not* be dangling, but it *may* point to |
| /// uninitialized memory. |
| /// |
| /// ## Note |
| /// This macro is the same as `raw_field`, except for a different Deref-coercion check that |
| /// supports unions. |
| /// Due to macro_rules limitations, this check will accept structs with a single field as well as unions. |
| /// This is not a stable guarantee, and future versions of this crate might fail |
| /// on any use of this macro with a struct, without a semver bump. |
| </span><span class="attribute">#[macro_export(local_inner_macros)] |
| </span><span class="macro">macro_rules! </span>raw_field_union { |
| (<span class="macro-nonterminal">$base</span>:expr, <span class="macro-nonterminal">$parent</span>:path, <span class="macro-nonterminal">$field</span>:tt) => {{ |
| <span class="macro">_memoffset__field_check_union!</span>(<span class="macro-nonterminal">$parent</span>, <span class="macro-nonterminal">$field</span>); |
| <span class="kw">let </span>base = <span class="macro-nonterminal">$base</span>; <span class="comment">// evaluate $base outside the `unsafe` block |
| |
| // Get the field address. |
| // Crucially, we know that this will not trigger a deref coercion because |
| // of the field check we did above. |
| </span><span class="attribute">#[allow(unused_unsafe)] </span><span class="comment">// for when the macro is used in an unsafe block |
| </span><span class="kw">unsafe </span>{ |
| <span class="macro">_memoffset__addr_of!</span>((<span class="kw-2">*</span>(base <span class="kw">as </span><span class="kw-2">*const </span><span class="macro-nonterminal">$parent</span>)).<span class="macro-nonterminal">$field</span>) |
| } |
| }}; |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="memoffset" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
