| <!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/pin-project-internal-1.1.0/src/pin_project/derive.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>derive.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="../../../pin_project_internal/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="../../../pin_project_internal/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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| <span id="1076">1076</span> |
| <span id="1077">1077</span> |
| <span id="1078">1078</span> |
| <span id="1079">1079</span> |
| <span id="1080">1080</span> |
| <span id="1081">1081</span> |
| <span id="1082">1082</span> |
| <span id="1083">1083</span> |
| <span id="1084">1084</span> |
| <span id="1085">1085</span> |
| <span id="1086">1086</span> |
| <span id="1087">1087</span> |
| <span id="1088">1088</span> |
| <span id="1089">1089</span> |
| <span id="1090">1090</span> |
| <span id="1091">1091</span> |
| <span id="1092">1092</span> |
| <span id="1093">1093</span> |
| <span id="1094">1094</span> |
| <span id="1095">1095</span> |
| <span id="1096">1096</span> |
| <span id="1097">1097</span> |
| <span id="1098">1098</span> |
| <span id="1099">1099</span> |
| <span id="1100">1100</span> |
| <span id="1101">1101</span> |
| <span id="1102">1102</span> |
| <span id="1103">1103</span> |
| <span id="1104">1104</span> |
| <span id="1105">1105</span> |
| <span id="1106">1106</span> |
| <span id="1107">1107</span> |
| <span id="1108">1108</span> |
| <span id="1109">1109</span> |
| <span id="1110">1110</span> |
| <span id="1111">1111</span> |
| <span id="1112">1112</span> |
| <span id="1113">1113</span> |
| <span id="1114">1114</span> |
| <span id="1115">1115</span> |
| <span id="1116">1116</span> |
| <span id="1117">1117</span> |
| <span id="1118">1118</span> |
| <span id="1119">1119</span> |
| <span id="1120">1120</span> |
| <span id="1121">1121</span> |
| <span id="1122">1122</span> |
| </pre><pre class="rust"><code><span class="kw">use </span>proc_macro2::{Delimiter, Group, Span, TokenStream}; |
| <span class="kw">use </span>quote::{format_ident, quote, quote_spanned, ToTokens}; |
| <span class="kw">use </span>syn::{ |
| parse_quote, punctuated::Punctuated, token, visit_mut::VisitMut, Attribute, Data, DataEnum, |
| DeriveInput, Error, Field, Fields, FieldsNamed, FieldsUnnamed, Generics, Ident, Index, |
| Lifetime, LifetimeParam, Meta, <span class="prelude-ty">Result</span>, Token, Type, Variant, Visibility, WhereClause, |
| }; |
| |
| <span class="kw">use super</span>::{ |
| args::{parse_args, Args, ProjReplace, UnpinImpl}, |
| PIN, |
| }; |
| <span class="kw">use </span><span class="kw">crate</span>::utils::{ |
| determine_lifetime_name, determine_visibility, insert_lifetime_and_bound, ReplaceReceiver, |
| SliceExt, Variants, |
| }; |
| |
| <span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">fn </span>parse_derive(input: TokenStream) -> <span class="prelude-ty">Result</span><TokenStream> { |
| <span class="kw">let </span><span class="kw-2">mut </span>input: DeriveInput = syn::parse2(input)<span class="question-mark">?</span>; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>cx; |
| <span class="kw">let </span><span class="kw-2">mut </span>generate = GenerateTokens::default(); |
| |
| <span class="kw">let </span>ident = <span class="kw-2">&</span>input.ident; |
| <span class="kw">let </span>ty_generics = input.generics.split_for_impl().<span class="number">1</span>; |
| <span class="kw">let </span>self_ty = <span class="macro">parse_quote!</span>(#ident #ty_generics); |
| <span class="kw">let </span><span class="kw-2">mut </span>visitor = ReplaceReceiver(<span class="kw-2">&</span>self_ty); |
| visitor.visit_generics_mut(<span class="kw-2">&mut </span>input.generics); |
| visitor.visit_data_mut(<span class="kw-2">&mut </span>input.data); |
| |
| <span class="kw">match </span><span class="kw-2">&</span>input.data { |
| Data::Struct(data) => { |
| cx = Context::new(<span class="kw-2">&</span>input.attrs, <span class="kw-2">&</span>input.vis, ident, <span class="kw-2">&mut </span>input.generics, Struct)<span class="question-mark">?</span>; |
| parse_struct(<span class="kw-2">&mut </span>cx, <span class="kw-2">&</span>data.fields, <span class="kw-2">&mut </span>generate)<span class="question-mark">?</span>; |
| } |
| Data::Enum(data) => { |
| cx = Context::new(<span class="kw-2">&</span>input.attrs, <span class="kw-2">&</span>input.vis, ident, <span class="kw-2">&mut </span>input.generics, Enum)<span class="question-mark">?</span>; |
| parse_enum(<span class="kw-2">&mut </span>cx, data, <span class="kw-2">&mut </span>generate)<span class="question-mark">?</span>; |
| } |
| Data::Union(<span class="kw">_</span>) => { |
| <span class="macro">bail!</span>(input, <span class="string">"#[pin_project] attribute may only be used on structs or enums"</span>); |
| } |
| } |
| |
| <span class="prelude-val">Ok</span>(generate.into_tokens(<span class="kw-2">&</span>cx)) |
| } |
| |
| <span class="attribute">#[derive(Default)] |
| </span><span class="kw">struct </span>GenerateTokens { |
| exposed: TokenStream, |
| scoped: TokenStream, |
| } |
| |
| <span class="kw">impl </span>GenerateTokens { |
| <span class="kw">fn </span>extend(<span class="kw-2">&mut </span><span class="self">self</span>, expose: bool, tokens: TokenStream) { |
| <span class="kw">if </span>expose { |
| <span class="self">self</span>.exposed.extend(tokens); |
| } <span class="kw">else </span>{ |
| <span class="self">self</span>.scoped.extend(tokens); |
| } |
| } |
| |
| <span class="kw">fn </span>into_tokens(<span class="self">self</span>, cx: <span class="kw-2">&</span>Context<<span class="lifetime">'_</span>>) -> TokenStream { |
| <span class="kw">let </span><span class="kw-2">mut </span>tokens = <span class="self">self</span>.exposed; |
| <span class="kw">let </span>scoped = <span class="self">self</span>.scoped; |
| |
| <span class="kw">let </span>unpin_impl = make_unpin_impl(cx); |
| <span class="kw">let </span>drop_impl = make_drop_impl(cx); |
| <span class="kw">let </span>allowed_lints = global_allowed_lints(); |
| |
| tokens.extend(<span class="macro">quote! </span>{ |
| <span class="comment">// All items except projected types are generated inside a `const` scope. |
| // This makes it impossible for user code to refer to these types. |
| // However, this prevents Rustdoc from displaying docs for any |
| // of our types. In particular, users cannot see the |
| // automatically generated `Unpin` impl for the '__UnpinStruct' types |
| // |
| // Previously, we provided a flag to correctly document the |
| // automatically generated `Unpin` impl by using def-site hygiene, |
| // but it is now removed. |
| // |
| // Refs: |
| // - https://github.com/rust-lang/rust/issues/63281 |
| // - https://github.com/taiki-e/pin-project/pull/53#issuecomment-525906867 |
| // - https://github.com/taiki-e/pin-project/pull/70 |
| </span>#allowed_lints |
| <span class="attribute">#[allow(unused_qualifications)] |
| #[allow(clippy::semicolon_if_nothing_returned)] |
| #[allow(clippy::use_self)] |
| #[allow(clippy::used_underscore_binding)] |
| </span><span class="kw">const _</span>: () = { |
| <span class="attribute">#[allow(unused_extern_crates)] |
| </span><span class="kw">extern crate </span>pin_project <span class="kw">as </span>_pin_project; |
| #scoped |
| #unpin_impl |
| #drop_impl |
| }; |
| }); |
| tokens |
| } |
| } |
| |
| <span class="doccomment">/// Returns attributes that should be applied to all generated code. |
| </span><span class="kw">fn </span>global_allowed_lints() -> TokenStream { |
| <span class="macro">quote! </span>{ |
| <span class="attribute">#[allow(box_pointers)] </span><span class="comment">// This lint warns use of the `Box` type. |
| </span><span class="attribute">#[allow(deprecated)] |
| #[allow(explicit_outlives_requirements)] </span><span class="comment">// https://github.com/rust-lang/rust/issues/60993 |
| </span><span class="attribute">#[allow(single_use_lifetimes)] </span><span class="comment">// https://github.com/rust-lang/rust/issues/55058 |
| </span><span class="attribute">#[allow(unreachable_pub)] </span><span class="comment">// This lint warns `pub` field in private struct. |
| </span><span class="attribute">#[allow(unused_tuple_struct_fields)] |
| </span><span class="comment">// This lint warns of `clippy::*` generated by external macros. |
| // We allow this lint for compatibility with older compilers. |
| </span><span class="attribute">#[allow(clippy::unknown_clippy_lints)] |
| #[allow(clippy::pattern_type_mismatch)] |
| #[allow(clippy::redundant_pub_crate)] </span><span class="comment">// This lint warns `pub(crate)` field in private struct. |
| </span><span class="attribute">#[allow(clippy::type_repetition_in_bounds)] </span><span class="comment">// https://github.com/rust-lang/rust-clippy/issues/4326 |
| </span>} |
| } |
| |
| <span class="doccomment">/// Returns attributes used on projected types. |
| </span><span class="kw">fn </span>proj_allowed_lints(cx: <span class="kw-2">&</span>Context<<span class="lifetime">'_</span>>) -> (TokenStream, TokenStream, TokenStream) { |
| <span class="kw">let </span>large_enum_variant = <span class="kw">if </span>cx.kind == Enum { |
| <span class="prelude-val">Some</span>(<span class="macro">quote! </span>{ |
| <span class="attribute">#[allow(variant_size_differences)] |
| #[allow(clippy::large_enum_variant)] |
| </span>}) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">None |
| </span>}; |
| <span class="kw">let </span>global_allowed_lints = global_allowed_lints(); |
| <span class="kw">let </span>proj_mut_allowed_lints = <span class="kw">if </span>cx.project { <span class="prelude-val">Some</span>(<span class="kw-2">&</span>global_allowed_lints) } <span class="kw">else </span>{ <span class="prelude-val">None </span>}; |
| <span class="kw">let </span>proj_mut = <span class="macro">quote! </span>{ |
| #proj_mut_allowed_lints |
| <span class="attribute">#[allow(dead_code)] </span><span class="comment">// This lint warns unused fields/variants. |
| </span><span class="attribute">#[allow(clippy::mut_mut)] </span><span class="comment">// This lint warns `&mut &mut <ty>`. |
| </span>}; |
| <span class="kw">let </span>proj_ref_allowed_lints = <span class="kw">if </span>cx.project_ref { <span class="prelude-val">Some</span>(<span class="kw-2">&</span>global_allowed_lints) } <span class="kw">else </span>{ <span class="prelude-val">None </span>}; |
| <span class="kw">let </span>proj_ref = <span class="macro">quote! </span>{ |
| #proj_ref_allowed_lints |
| <span class="attribute">#[allow(dead_code)] </span><span class="comment">// This lint warns unused fields/variants. |
| </span><span class="attribute">#[allow(clippy::ref_option_ref)] </span><span class="comment">// This lint warns `&Option<&<ty>>`. |
| </span>}; |
| <span class="kw">let </span>proj_own_allowed_lints = |
| <span class="kw">if </span>cx.project_replace.ident().is_some() { <span class="prelude-val">Some</span>(<span class="kw-2">&</span>global_allowed_lints) } <span class="kw">else </span>{ <span class="prelude-val">None </span>}; |
| <span class="kw">let </span>proj_own = <span class="macro">quote! </span>{ |
| #proj_own_allowed_lints |
| <span class="attribute">#[allow(dead_code)] </span><span class="comment">// This lint warns unused fields/variants. |
| </span>#large_enum_variant |
| }; |
| (proj_mut, proj_ref, proj_own) |
| } |
| |
| <span class="kw">struct </span>Context<<span class="lifetime">'a</span>> { |
| <span class="doccomment">/// The original type. |
| </span>orig: OriginalType<<span class="lifetime">'a</span>>, |
| <span class="doccomment">/// The projected types. |
| </span>proj: ProjectedType, |
| <span class="doccomment">/// Types of the pinned fields. |
| </span>pinned_fields: Vec<<span class="kw-2">&</span><span class="lifetime">'a </span>Type>, |
| <span class="doccomment">/// Kind of the original type: struct or enum |
| </span>kind: TypeKind, |
| |
| <span class="doccomment">/// `PinnedDrop` argument. |
| </span>pinned_drop: <span class="prelude-ty">Option</span><Span>, |
| <span class="doccomment">/// `UnsafeUnpin` or `!Unpin` argument. |
| </span>unpin_impl: UnpinImpl, |
| <span class="doccomment">/// `project` argument. |
| </span>project: bool, |
| <span class="doccomment">/// `project_ref` argument. |
| </span>project_ref: bool, |
| <span class="doccomment">/// `project_replace [= <ident>]` argument. |
| </span>project_replace: ProjReplace, |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>> Context<<span class="lifetime">'a</span>> { |
| <span class="kw">fn </span>new( |
| attrs: <span class="kw-2">&</span><span class="lifetime">'a </span>[Attribute], |
| vis: <span class="kw-2">&</span><span class="lifetime">'a </span>Visibility, |
| ident: <span class="kw-2">&</span><span class="lifetime">'a </span>Ident, |
| generics: <span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>Generics, |
| kind: TypeKind, |
| ) -> <span class="prelude-ty">Result</span><<span class="self">Self</span>> { |
| <span class="kw">let </span>Args { pinned_drop, unpin_impl, project, project_ref, project_replace } = |
| parse_args(attrs)<span class="question-mark">?</span>; |
| |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(name) = [project.as_ref(), project_ref.as_ref(), project_replace.ident()] |
| .iter() |
| .filter_map(Option::as_ref) |
| .find(|name| <span class="kw-2">**</span>name == ident) |
| { |
| <span class="macro">bail!</span>(name, <span class="string">"name `{}` is the same as the original type name"</span>, name); |
| } |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>lifetime_name = String::from(<span class="string">"'pin"</span>); |
| determine_lifetime_name(<span class="kw-2">&mut </span>lifetime_name, generics); |
| <span class="kw">let </span>lifetime = Lifetime::new(<span class="kw-2">&</span>lifetime_name, Span::call_site()); |
| |
| <span class="kw">let </span>ty_generics = generics.split_for_impl().<span class="number">1</span>; |
| <span class="kw">let </span>ty_generics_as_generics = <span class="macro">parse_quote!</span>(#ty_generics); |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_generics = generics.clone(); |
| <span class="kw">let </span>pred = insert_lifetime_and_bound( |
| <span class="kw-2">&mut </span>proj_generics, |
| lifetime.clone(), |
| <span class="kw-2">&</span>ty_generics_as_generics, |
| ident, |
| ); |
| <span class="kw">let </span><span class="kw-2">mut </span>where_clause = generics.make_where_clause().clone(); |
| where_clause.predicates.push(pred); |
| |
| <span class="kw">let </span>own_ident = project_replace |
| .ident() |
| .cloned() |
| .unwrap_or_else(|| <span class="macro">format_ident!</span>(<span class="string">"__{}ProjectionOwned"</span>, ident)); |
| |
| <span class="prelude-val">Ok</span>(<span class="self">Self </span>{ |
| kind, |
| pinned_drop, |
| unpin_impl, |
| project: project.is_some(), |
| project_ref: project_ref.is_some(), |
| project_replace, |
| proj: ProjectedType { |
| vis: determine_visibility(vis), |
| mut_ident: project.unwrap_or_else(|| <span class="macro">format_ident!</span>(<span class="string">"__{}Projection"</span>, ident)), |
| ref_ident: project_ref.unwrap_or_else(|| <span class="macro">format_ident!</span>(<span class="string">"__{}ProjectionRef"</span>, ident)), |
| own_ident, |
| lifetime, |
| generics: proj_generics, |
| where_clause, |
| }, |
| orig: OriginalType { attrs, vis, ident, generics }, |
| pinned_fields: Vec::new(), |
| }) |
| } |
| } |
| |
| <span class="attribute">#[derive(Copy, Clone, PartialEq)] |
| </span><span class="kw">enum </span>TypeKind { |
| Enum, |
| Struct, |
| } |
| |
| <span class="kw">use </span>TypeKind::{Enum, Struct}; |
| |
| <span class="kw">struct </span>OriginalType<<span class="lifetime">'a</span>> { |
| <span class="doccomment">/// Attributes of the original type. |
| </span>attrs: <span class="kw-2">&</span><span class="lifetime">'a </span>[Attribute], |
| <span class="doccomment">/// Visibility of the original type. |
| </span>vis: <span class="kw-2">&</span><span class="lifetime">'a </span>Visibility, |
| <span class="doccomment">/// Name of the original type. |
| </span>ident: <span class="kw-2">&</span><span class="lifetime">'a </span>Ident, |
| <span class="doccomment">/// Generics of the original type. |
| </span>generics: <span class="kw-2">&</span><span class="lifetime">'a </span>Generics, |
| } |
| |
| <span class="kw">struct </span>ProjectedType { |
| <span class="doccomment">/// Visibility of the projected types. |
| </span>vis: Visibility, |
| <span class="doccomment">/// Name of the projected type returned by `project` method. |
| </span>mut_ident: Ident, |
| <span class="doccomment">/// Name of the projected type returned by `project_ref` method. |
| </span>ref_ident: Ident, |
| <span class="doccomment">/// Name of the projected type returned by `project_replace` method. |
| </span>own_ident: Ident, |
| <span class="doccomment">/// Lifetime on the generated projected types. |
| </span>lifetime: Lifetime, |
| <span class="doccomment">/// Generics of the projected types. |
| </span>generics: Generics, |
| <span class="doccomment">/// `where` clause of the projected types. This has an additional |
| /// bound generated by `insert_lifetime_and_bound` |
| </span>where_clause: WhereClause, |
| } |
| |
| <span class="kw">struct </span>ProjectedVariants { |
| proj_variants: TokenStream, |
| proj_ref_variants: TokenStream, |
| proj_own_variants: TokenStream, |
| proj_arms: TokenStream, |
| proj_ref_arms: TokenStream, |
| proj_own_arms: TokenStream, |
| } |
| |
| <span class="attribute">#[derive(Default)] |
| </span><span class="kw">struct </span>ProjectedFields { |
| proj_pat: TokenStream, |
| proj_body: TokenStream, |
| proj_own_body: TokenStream, |
| proj_fields: TokenStream, |
| proj_ref_fields: TokenStream, |
| proj_own_fields: TokenStream, |
| } |
| |
| <span class="kw">fn </span>validate_struct(ident: <span class="kw-2">&</span>Ident, fields: <span class="kw-2">&</span>Fields) -> <span class="prelude-ty">Result</span><()> { |
| <span class="kw">if </span>fields.is_empty() { |
| <span class="kw">let </span>msg = <span class="string">"#[pin_project] attribute may not be used on structs with zero fields"</span>; |
| <span class="kw">if let </span>Fields::Unit = fields { |
| <span class="macro">bail!</span>(ident, msg) |
| } |
| <span class="macro">bail!</span>(fields, msg) |
| } |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="kw">fn </span>validate_enum(brace_token: token::Brace, variants: <span class="kw-2">&</span>Variants) -> <span class="prelude-ty">Result</span><()> { |
| <span class="kw">if </span>variants.is_empty() { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(Error::new( |
| brace_token.span.join(), |
| <span class="string">"#[pin_project] attribute may not be used on enums without variants"</span>, |
| )); |
| } |
| <span class="kw">let </span>has_field = variants.iter().try_fold(<span class="bool-val">false</span>, |has_field, v| { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>((<span class="kw">_</span>, e)) = <span class="kw-2">&</span>v.discriminant { |
| <span class="macro">bail!</span>(e, <span class="string">"#[pin_project] attribute may not be used on enums with discriminants"</span>); |
| } <span class="kw">else if let </span><span class="prelude-val">Some</span>(attr) = v.attrs.find(PIN) { |
| <span class="macro">bail!</span>(attr, <span class="string">"#[pin] attribute may only be used on fields of structs or variants"</span>); |
| } <span class="kw">else if </span>v.fields.is_empty() { |
| <span class="prelude-val">Ok</span>(has_field) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Ok</span>(<span class="bool-val">true</span>) |
| } |
| })<span class="question-mark">?</span>; |
| <span class="kw">if </span>has_field { |
| <span class="prelude-val">Ok</span>(()) |
| } <span class="kw">else </span>{ |
| <span class="macro">bail!</span>(variants, <span class="string">"#[pin_project] attribute may not be used on enums with zero fields"</span>); |
| } |
| } |
| |
| <span class="kw">fn </span>parse_struct<<span class="lifetime">'a</span>>( |
| cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'a</span>>, |
| fields: <span class="kw-2">&</span><span class="lifetime">'a </span>Fields, |
| generate: <span class="kw-2">&mut </span>GenerateTokens, |
| ) -> <span class="prelude-ty">Result</span><()> { |
| <span class="comment">// Do this first for a better error message. |
| </span><span class="kw">let </span>packed_check = ensure_not_packed(<span class="kw-2">&</span>cx.orig, <span class="prelude-val">Some</span>(fields))<span class="question-mark">?</span>; |
| |
| validate_struct(cx.orig.ident, fields)<span class="question-mark">?</span>; |
| |
| <span class="kw">let </span>ProjectedFields { |
| proj_pat, |
| proj_body, |
| proj_fields, |
| proj_ref_fields, |
| proj_own_fields, |
| proj_own_body, |
| } = <span class="kw">match </span>fields { |
| Fields::Named(<span class="kw">_</span>) => visit_fields(cx, <span class="prelude-val">None</span>, fields, Delimiter::Brace)<span class="question-mark">?</span>, |
| Fields::Unnamed(<span class="kw">_</span>) => visit_fields(cx, <span class="prelude-val">None</span>, fields, Delimiter::Parenthesis)<span class="question-mark">?</span>, |
| Fields::Unit => <span class="macro">unreachable!</span>(), |
| }; |
| |
| <span class="kw">let </span>proj_ident = <span class="kw-2">&</span>cx.proj.mut_ident; |
| <span class="kw">let </span>proj_ref_ident = <span class="kw-2">&</span>cx.proj.ref_ident; |
| <span class="kw">let </span>proj_own_ident = <span class="kw-2">&</span>cx.proj.own_ident; |
| <span class="kw">let </span>vis = <span class="kw-2">&</span>cx.proj.vis; |
| <span class="kw">let </span><span class="kw-2">mut </span>orig_generics = cx.orig.generics.clone(); |
| <span class="kw">let </span>orig_where_clause = orig_generics.where_clause.take(); |
| <span class="kw">let </span>proj_generics = <span class="kw-2">&</span>cx.proj.generics; |
| <span class="kw">let </span>proj_where_clause = <span class="kw-2">&</span>cx.proj.where_clause; |
| |
| <span class="comment">// For tuple structs, we need to generate `(T1, T2) where Foo: Bar` |
| // For non-tuple structs, we need to generate `where Foo: Bar { field1: T }` |
| </span><span class="kw">let </span>(where_clause_fields, where_clause_ref_fields, where_clause_own_fields) = <span class="kw">match </span>fields { |
| Fields::Named(<span class="kw">_</span>) => ( |
| <span class="macro">quote!</span>(#proj_where_clause #proj_fields), |
| <span class="macro">quote!</span>(#proj_where_clause #proj_ref_fields), |
| <span class="macro">quote!</span>(#orig_where_clause #proj_own_fields), |
| ), |
| Fields::Unnamed(<span class="kw">_</span>) => ( |
| <span class="macro">quote!</span>(#proj_fields #proj_where_clause;), |
| <span class="macro">quote!</span>(#proj_ref_fields #proj_where_clause;), |
| <span class="macro">quote!</span>(#proj_own_fields #orig_where_clause;), |
| ), |
| Fields::Unit => <span class="macro">unreachable!</span>(), |
| }; |
| |
| <span class="kw">let </span>(proj_attrs, proj_ref_attrs, proj_own_attrs) = proj_allowed_lints(cx); |
| generate.extend(cx.project, <span class="macro">quote! </span>{ |
| #proj_attrs |
| #vis <span class="kw">struct </span>#proj_ident #proj_generics #where_clause_fields |
| }); |
| generate.extend(cx.project_ref, <span class="macro">quote! </span>{ |
| #proj_ref_attrs |
| #vis <span class="kw">struct </span>#proj_ref_ident #proj_generics #where_clause_ref_fields |
| }); |
| <span class="kw">if </span>cx.project_replace.span().is_some() { |
| generate.extend(cx.project_replace.ident().is_some(), <span class="macro">quote! </span>{ |
| #proj_own_attrs |
| #vis <span class="kw">struct </span>#proj_own_ident #orig_generics #where_clause_own_fields |
| }); |
| } |
| |
| <span class="kw">let </span>proj_mut_body = <span class="macro">quote! </span>{ |
| <span class="kw">let </span><span class="self">Self </span>#proj_pat = <span class="self">self</span>.get_unchecked_mut(); |
| #proj_ident #proj_body |
| }; |
| <span class="kw">let </span>proj_ref_body = <span class="macro">quote! </span>{ |
| <span class="kw">let </span><span class="self">Self </span>#proj_pat = <span class="self">self</span>.get_ref(); |
| #proj_ref_ident #proj_body |
| }; |
| <span class="kw">let </span>proj_own_body = <span class="macro">quote! </span>{ |
| <span class="kw">let </span><span class="self">Self </span>#proj_pat = <span class="kw-2">&mut *</span>__self_ptr; |
| #proj_own_body |
| }; |
| generate.extend(<span class="bool-val">false</span>, make_proj_impl(cx, <span class="kw-2">&</span>proj_mut_body, <span class="kw-2">&</span>proj_ref_body, <span class="kw-2">&</span>proj_own_body)); |
| |
| generate.extend(<span class="bool-val">false</span>, packed_check); |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="kw">fn </span>parse_enum<<span class="lifetime">'a</span>>( |
| cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'a</span>>, |
| DataEnum { brace_token, variants, .. }: <span class="kw-2">&</span><span class="lifetime">'a </span>DataEnum, |
| generate: <span class="kw-2">&mut </span>GenerateTokens, |
| ) -> <span class="prelude-ty">Result</span><()> { |
| <span class="kw">if let </span>ProjReplace::Unnamed { span } = <span class="kw-2">&</span>cx.project_replace { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(Error::new( |
| <span class="kw-2">*</span>span, |
| <span class="string">"`project_replace` argument requires a value when used on enums"</span>, |
| )); |
| } |
| |
| <span class="comment">// #[repr(packed)] cannot be apply on enums and will be rejected by rustc. |
| // However, we should not rely on the behavior of rustc that rejects this. |
| // https://github.com/taiki-e/pin-project/pull/324#discussion_r612388001 |
| // |
| // Do this first for a better error message. |
| </span>ensure_not_packed(<span class="kw-2">&</span>cx.orig, <span class="prelude-val">None</span>)<span class="question-mark">?</span>; |
| |
| validate_enum(<span class="kw-2">*</span>brace_token, variants)<span class="question-mark">?</span>; |
| |
| <span class="kw">let </span>ProjectedVariants { |
| proj_variants, |
| proj_ref_variants, |
| proj_own_variants, |
| proj_arms, |
| proj_ref_arms, |
| proj_own_arms, |
| } = visit_variants(cx, variants)<span class="question-mark">?</span>; |
| |
| <span class="kw">let </span>proj_ident = <span class="kw-2">&</span>cx.proj.mut_ident; |
| <span class="kw">let </span>proj_ref_ident = <span class="kw-2">&</span>cx.proj.ref_ident; |
| <span class="kw">let </span>proj_own_ident = <span class="kw-2">&</span>cx.proj.own_ident; |
| <span class="kw">let </span>vis = <span class="kw-2">&</span>cx.proj.vis; |
| <span class="kw">let </span><span class="kw-2">mut </span>orig_generics = cx.orig.generics.clone(); |
| <span class="kw">let </span>orig_where_clause = orig_generics.where_clause.take(); |
| <span class="kw">let </span>proj_generics = <span class="kw-2">&</span>cx.proj.generics; |
| <span class="kw">let </span>proj_where_clause = <span class="kw-2">&</span>cx.proj.where_clause; |
| |
| <span class="kw">let </span>(proj_attrs, proj_ref_attrs, proj_own_attrs) = proj_allowed_lints(cx); |
| <span class="kw">if </span>cx.project { |
| generate.extend(<span class="bool-val">true</span>, <span class="macro">quote! </span>{ |
| #proj_attrs |
| #vis <span class="kw">enum </span>#proj_ident #proj_generics #proj_where_clause { |
| #proj_variants |
| } |
| }); |
| } |
| <span class="kw">if </span>cx.project_ref { |
| generate.extend(<span class="bool-val">true</span>, <span class="macro">quote! </span>{ |
| #proj_ref_attrs |
| #vis <span class="kw">enum </span>#proj_ref_ident #proj_generics #proj_where_clause { |
| #proj_ref_variants |
| } |
| }); |
| } |
| <span class="kw">if </span>cx.project_replace.ident().is_some() { |
| generate.extend(<span class="bool-val">true</span>, <span class="macro">quote! </span>{ |
| #proj_own_attrs |
| #vis <span class="kw">enum </span>#proj_own_ident #orig_generics #orig_where_clause { |
| #proj_own_variants |
| } |
| }); |
| } |
| |
| <span class="kw">let </span>proj_mut_body = <span class="macro">quote! </span>{ |
| <span class="kw">match </span><span class="self">self</span>.get_unchecked_mut() { |
| #proj_arms |
| } |
| }; |
| <span class="kw">let </span>proj_ref_body = <span class="macro">quote! </span>{ |
| <span class="kw">match </span><span class="self">self</span>.get_ref() { |
| #proj_ref_arms |
| } |
| }; |
| <span class="kw">let </span>proj_own_body = <span class="macro">quote! </span>{ |
| <span class="kw">match </span><span class="kw-2">&mut *</span>__self_ptr { |
| #proj_own_arms |
| } |
| }; |
| generate.extend(<span class="bool-val">false</span>, make_proj_impl(cx, <span class="kw-2">&</span>proj_mut_body, <span class="kw-2">&</span>proj_ref_body, <span class="kw-2">&</span>proj_own_body)); |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="kw">fn </span>visit_variants<<span class="lifetime">'a</span>>(cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'a</span>>, variants: <span class="kw-2">&</span><span class="lifetime">'a </span>Variants) -> <span class="prelude-ty">Result</span><ProjectedVariants> { |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_variants = TokenStream::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_ref_variants = TokenStream::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_own_variants = TokenStream::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_arms = TokenStream::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_ref_arms = TokenStream::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_own_arms = TokenStream::new(); |
| |
| <span class="kw">for </span>Variant { ident, fields, .. } <span class="kw">in </span>variants { |
| <span class="kw">let </span>ProjectedFields { |
| proj_pat, |
| proj_body, |
| proj_fields, |
| proj_ref_fields, |
| proj_own_fields, |
| proj_own_body, |
| } = <span class="kw">match </span>fields { |
| Fields::Named(<span class="kw">_</span>) => visit_fields(cx, <span class="prelude-val">Some</span>(ident), fields, Delimiter::Brace)<span class="question-mark">?</span>, |
| Fields::Unnamed(<span class="kw">_</span>) => visit_fields(cx, <span class="prelude-val">Some</span>(ident), fields, Delimiter::Parenthesis)<span class="question-mark">?</span>, |
| Fields::Unit => ProjectedFields { |
| proj_own_body: proj_own_body(cx, <span class="prelude-val">Some</span>(ident), <span class="prelude-val">None</span>, <span class="kw-2">&</span>[]), |
| ..Default::default() |
| }, |
| }; |
| |
| <span class="kw">let </span>proj_ident = <span class="kw-2">&</span>cx.proj.mut_ident; |
| <span class="kw">let </span>proj_ref_ident = <span class="kw-2">&</span>cx.proj.ref_ident; |
| proj_variants.extend(<span class="macro">quote! </span>{ |
| #ident #proj_fields, |
| }); |
| proj_ref_variants.extend(<span class="macro">quote! </span>{ |
| #ident #proj_ref_fields, |
| }); |
| proj_own_variants.extend(<span class="macro">quote! </span>{ |
| #ident #proj_own_fields, |
| }); |
| proj_arms.extend(<span class="macro">quote! </span>{ |
| <span class="self">Self</span>::#ident #proj_pat => #proj_ident::#ident #proj_body, |
| }); |
| proj_ref_arms.extend(<span class="macro">quote! </span>{ |
| <span class="self">Self</span>::#ident #proj_pat => #proj_ref_ident::#ident #proj_body, |
| }); |
| proj_own_arms.extend(<span class="macro">quote! </span>{ |
| <span class="self">Self</span>::#ident #proj_pat => { #proj_own_body } |
| }); |
| } |
| |
| <span class="prelude-val">Ok</span>(ProjectedVariants { |
| proj_variants, |
| proj_ref_variants, |
| proj_own_variants, |
| proj_arms, |
| proj_ref_arms, |
| proj_own_arms, |
| }) |
| } |
| |
| <span class="kw">fn </span>visit_fields<<span class="lifetime">'a</span>>( |
| cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'a</span>>, |
| variant_ident: <span class="prelude-ty">Option</span><<span class="kw-2">&</span>Ident>, |
| fields: <span class="kw-2">&</span><span class="lifetime">'a </span>Fields, |
| delim: Delimiter, |
| ) -> <span class="prelude-ty">Result</span><ProjectedFields> { |
| <span class="kw">fn </span>surround(delim: Delimiter, tokens: TokenStream) -> TokenStream { |
| Group::new(delim, tokens).into_token_stream() |
| } |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_pat = TokenStream::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_body = TokenStream::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_fields = TokenStream::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_ref_fields = TokenStream::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_own_fields = TokenStream::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_move = TokenStream::new(); |
| <span class="kw">let </span><span class="kw-2">mut </span>pinned_bindings = Vec::with_capacity(fields.len()); |
| |
| <span class="kw">for </span>(i, Field { attrs, vis, ident, colon_token, ty, mutability: <span class="kw">_ </span>}) <span class="kw">in |
| </span>fields.iter().enumerate() |
| { |
| <span class="kw">let </span>binding = ident.clone().unwrap_or_else(|| <span class="macro">format_ident!</span>(<span class="string">"_{}"</span>, i)); |
| proj_pat.extend(<span class="macro">quote!</span>(#binding,)); |
| <span class="kw">let </span>lifetime = <span class="kw-2">&</span>cx.proj.lifetime; |
| <span class="kw">if </span>attrs.position_exact(PIN)<span class="question-mark">?</span>.is_some() { |
| proj_fields.extend(<span class="macro">quote! </span>{ |
| #vis #ident #colon_token ::pin_project::__private::Pin<<span class="kw-2">&</span>#lifetime <span class="kw-2">mut </span>(#ty)>, |
| }); |
| proj_ref_fields.extend(<span class="macro">quote! </span>{ |
| #vis #ident #colon_token ::pin_project::__private::Pin<<span class="kw-2">&</span>#lifetime (#ty)>, |
| }); |
| proj_own_fields.extend(<span class="macro">quote! </span>{ |
| #vis #ident #colon_token ::pin_project::__private::PhantomData<#ty>, |
| }); |
| proj_body.extend(<span class="macro">quote! </span>{ |
| #ident #colon_token _pin_project::__private::Pin::new_unchecked(#binding), |
| }); |
| proj_move.extend(<span class="macro">quote! </span>{ |
| #ident #colon_token _pin_project::__private::PhantomData, |
| }); |
| |
| cx.pinned_fields.push(ty); |
| pinned_bindings.push(binding); |
| } <span class="kw">else </span>{ |
| proj_fields.extend(<span class="macro">quote! </span>{ |
| #vis #ident #colon_token <span class="kw-2">&</span>#lifetime <span class="kw-2">mut </span>(#ty), |
| }); |
| proj_ref_fields.extend(<span class="macro">quote! </span>{ |
| #vis #ident #colon_token <span class="kw-2">&</span>#lifetime (#ty), |
| }); |
| proj_own_fields.extend(<span class="macro">quote! </span>{ |
| #vis #ident #colon_token #ty, |
| }); |
| proj_body.extend(<span class="macro">quote! </span>{ |
| #binding, |
| }); |
| proj_move.extend(<span class="macro">quote! </span>{ |
| #ident #colon_token _pin_project::__private::ptr::read(#binding), |
| }); |
| } |
| } |
| |
| <span class="kw">let </span>proj_pat = surround(delim, proj_pat); |
| <span class="kw">let </span>proj_body = surround(delim, proj_body); |
| <span class="kw">let </span>proj_fields = surround(delim, proj_fields); |
| <span class="kw">let </span>proj_ref_fields = surround(delim, proj_ref_fields); |
| <span class="kw">let </span>proj_own_fields = surround(delim, proj_own_fields); |
| |
| <span class="kw">let </span>proj_move = Group::new(delim, proj_move); |
| <span class="kw">let </span>proj_own_body = proj_own_body(cx, variant_ident, <span class="prelude-val">Some</span>(<span class="kw-2">&</span>proj_move), <span class="kw-2">&</span>pinned_bindings); |
| |
| <span class="prelude-val">Ok</span>(ProjectedFields { |
| proj_pat, |
| proj_body, |
| proj_own_body, |
| proj_fields, |
| proj_ref_fields, |
| proj_own_fields, |
| }) |
| } |
| |
| <span class="doccomment">/// Generates the processing that `project_replace` does for the struct or each variant. |
| /// |
| /// Note: `pinned_fields` must be in declaration order. |
| </span><span class="kw">fn </span>proj_own_body( |
| cx: <span class="kw-2">&</span>Context<<span class="lifetime">'_</span>>, |
| variant_ident: <span class="prelude-ty">Option</span><<span class="kw-2">&</span>Ident>, |
| proj_move: <span class="prelude-ty">Option</span><<span class="kw-2">&</span>Group>, |
| pinned_fields: <span class="kw-2">&</span>[Ident], |
| ) -> TokenStream { |
| <span class="kw">let </span>ident = <span class="kw-2">&</span>cx.proj.own_ident; |
| <span class="kw">let </span>proj_own = <span class="kw">match </span>variant_ident { |
| <span class="prelude-val">Some</span>(variant_ident) => <span class="macro">quote!</span>(#ident::#variant_ident), |
| <span class="prelude-val">None </span>=> <span class="macro">quote!</span>(#ident), |
| }; |
| |
| <span class="comment">// The fields of the struct and the active enum variant are dropped |
| // in declaration order. |
| // Refs: https://doc.rust-lang.org/reference/destructors.html |
| </span><span class="kw">let </span>pinned_fields = pinned_fields.iter().rev(); |
| |
| <span class="macro">quote! </span>{ |
| <span class="comment">// First, extract all the unpinned fields. |
| </span><span class="kw">let </span>__result = #proj_own #proj_move; |
| |
| <span class="comment">// Now create guards to drop all the pinned fields. |
| // |
| // Due to a compiler bug (https://github.com/rust-lang/rust/issues/47949) |
| // this must be in its own scope, or else `__result` will not be dropped |
| // if any of the destructors panic. |
| </span>{ |
| #( |
| <span class="kw">let </span>__guard = _pin_project::__private::UnsafeDropInPlaceGuard::new(#pinned_fields); |
| )* |
| } |
| |
| <span class="comment">// Finally, return the result. |
| </span>__result |
| } |
| } |
| |
| <span class="doccomment">/// Creates `Unpin` implementation for the original type. |
| /// |
| /// The kind of `Unpin` impl generated depends on `unpin_impl` field: |
| /// - `UnpinImpl::Unsafe` - Implements `Unpin` via `UnsafeUnpin` impl. |
| /// - `UnpinImpl::Negative` - Generates `Unpin` impl with bounds that will never be true. |
| /// - `UnpinImpl::Default` - Generates `Unpin` impl that requires `Unpin` for all pinned fields. |
| </span><span class="kw">fn </span>make_unpin_impl(cx: <span class="kw-2">&</span>Context<<span class="lifetime">'_</span>>) -> TokenStream { |
| <span class="kw">match </span>cx.unpin_impl { |
| UnpinImpl::Unsafe(span) => { |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_generics = cx.proj.generics.clone(); |
| <span class="kw">let </span>orig_ident = cx.orig.ident; |
| <span class="kw">let </span>lifetime = <span class="kw-2">&</span>cx.proj.lifetime; |
| |
| <span class="comment">// Make the error message highlight `UnsafeUnpin` argument. |
| </span>proj_generics.make_where_clause().predicates.push(<span class="macro">parse_quote_spanned! </span>{ span => |
| _pin_project::__private::Wrapper<#lifetime, <span class="self">Self</span>>: _pin_project::UnsafeUnpin |
| }); |
| |
| <span class="kw">let </span>(impl_generics, <span class="kw">_</span>, where_clause) = proj_generics.split_for_impl(); |
| <span class="kw">let </span>ty_generics = cx.orig.generics.split_for_impl().<span class="number">1</span>; |
| |
| <span class="macro">quote_spanned! </span>{ span => |
| <span class="kw">impl </span>#impl_generics _pin_project::__private::Unpin <span class="kw">for </span>#orig_ident #ty_generics |
| #where_clause |
| { |
| } |
| } |
| } |
| UnpinImpl::Negative(span) => { |
| <span class="kw">let </span><span class="kw-2">mut </span>proj_generics = cx.proj.generics.clone(); |
| <span class="kw">let </span>orig_ident = cx.orig.ident; |
| <span class="kw">let </span>lifetime = <span class="kw-2">&</span>cx.proj.lifetime; |
| |
| proj_generics.make_where_clause().predicates.push(<span class="macro">parse_quote! </span>{ |
| _pin_project::__private::Wrapper< |
| #lifetime, _pin_project::__private::PhantomPinned |
| >: _pin_project::__private::Unpin |
| }); |
| |
| <span class="kw">let </span>(proj_impl_generics, <span class="kw">_</span>, proj_where_clause) = proj_generics.split_for_impl(); |
| <span class="kw">let </span>ty_generics = cx.orig.generics.split_for_impl().<span class="number">1</span>; |
| |
| <span class="comment">// For interoperability with `forbid(unsafe_code)`, `unsafe` token should be |
| // call-site span. |
| </span><span class="kw">let </span>unsafety = <<span class="macro">Token!</span>[<span class="kw">unsafe</span>]>::default(); |
| <span class="macro">quote_spanned! </span>{ span => |
| <span class="kw">impl </span>#proj_impl_generics _pin_project::__private::Unpin |
| <span class="kw">for </span>#orig_ident #ty_generics |
| #proj_where_clause |
| { |
| } |
| |
| <span class="comment">// Generate a dummy impl of `UnsafeUnpin`, to ensure that the user cannot implement it. |
| // |
| // To ensure that users don't accidentally write a non-functional `UnsafeUnpin` |
| // impls, we emit one ourselves. If the user ends up writing an `UnsafeUnpin` |
| // impl, they'll get a "conflicting implementations of trait" error when |
| // coherence checks are run. |
| </span><span class="attribute">#[doc(hidden)] |
| </span>#unsafety <span class="kw">impl </span>#proj_impl_generics _pin_project::UnsafeUnpin |
| <span class="kw">for </span>#orig_ident #ty_generics |
| #proj_where_clause |
| { |
| } |
| } |
| } |
| UnpinImpl::Default => { |
| <span class="kw">let </span><span class="kw-2">mut </span>full_where_clause = cx.orig.generics.where_clause.clone().unwrap(); |
| |
| <span class="comment">// Generate a field in our new struct for every |
| // pinned field in the original type. |
| </span><span class="kw">let </span>fields = cx.pinned_fields.iter().enumerate().map(|(i, ty)| { |
| <span class="kw">let </span>field_ident = <span class="macro">format_ident!</span>(<span class="string">"__field{}"</span>, i); |
| <span class="macro">quote!</span>(#field_ident: #ty) |
| }); |
| |
| <span class="comment">// We could try to determine the subset of type parameters |
| // and lifetimes that are actually used by the pinned fields |
| // (as opposed to those only used by unpinned fields). |
| // However, this would be tricky and error-prone, since |
| // it's possible for users to create types that would alias |
| // with generic parameters (e.g. 'struct T'). |
| // |
| // Instead, we generate a use of every single type parameter |
| // and lifetime used in the original struct. For type parameters, |
| // we generate code like this: |
| // |
| // ```rust |
| // struct AlwaysUnpin<T: ?Sized>(PhantomData<T>) {} |
| // impl<T: ?Sized> Unpin for AlwaysUnpin<T> {} |
| // |
| // ... |
| // _field: AlwaysUnpin<(A, B, C)> |
| // ``` |
| // |
| // This ensures that any unused type parameters |
| // don't end up with `Unpin` bounds. |
| </span><span class="kw">let </span>lifetime_fields = cx.orig.generics.lifetimes().enumerate().map( |
| |(i, LifetimeParam { lifetime, .. })| { |
| <span class="kw">let </span>field_ident = <span class="macro">format_ident!</span>(<span class="string">"__lifetime{}"</span>, i); |
| <span class="macro">quote!</span>(#field_ident: <span class="kw-2">&</span>#lifetime ()) |
| }, |
| ); |
| |
| <span class="kw">let </span>orig_ident = cx.orig.ident; |
| <span class="kw">let </span>struct_ident = <span class="macro">format_ident!</span>(<span class="string">"__{}"</span>, orig_ident); |
| <span class="kw">let </span>vis = cx.orig.vis; |
| <span class="kw">let </span>lifetime = <span class="kw-2">&</span>cx.proj.lifetime; |
| <span class="kw">let </span>type_params = cx.orig.generics.type_params().map(|t| <span class="kw-2">&</span>t.ident); |
| <span class="kw">let </span>proj_generics = <span class="kw-2">&</span>cx.proj.generics; |
| <span class="kw">let </span>(proj_impl_generics, proj_ty_generics, <span class="kw">_</span>) = proj_generics.split_for_impl(); |
| <span class="kw">let </span>(<span class="kw">_</span>, ty_generics, where_clause) = cx.orig.generics.split_for_impl(); |
| |
| full_where_clause.predicates.push(<span class="macro">parse_quote! </span>{ |
| #struct_ident #proj_ty_generics: _pin_project::__private::Unpin |
| }); |
| |
| <span class="macro">quote! </span>{ |
| <span class="comment">// This needs to have the same visibility as the original type, |
| // due to the limitations of the 'public in private' error. |
| // |
| // Our goal is to implement the public trait `Unpin` for |
| // a potentially public user type. Because of this, rust |
| // requires that any types mentioned in the where clause of |
| // our `Unpin` impl also be public. This means that our generated |
| // `__UnpinStruct` type must also be public. |
| // However, we ensure that the user can never actually reference |
| // this 'public' type by creating this type in the inside of `const`. |
| </span><span class="attribute">#[allow(missing_debug_implementations)] |
| </span>#vis <span class="kw">struct </span>#struct_ident #proj_generics #where_clause { |
| __pin_project_use_generics: _pin_project::__private::AlwaysUnpin< |
| #lifetime, (#(_pin_project::__private::PhantomData<#type_params>),<span class="kw-2">*</span>) |
| >, |
| |
| #(#fields,)* |
| #(#lifetime_fields,)* |
| } |
| |
| <span class="kw">impl </span>#proj_impl_generics _pin_project::__private::Unpin |
| <span class="kw">for </span>#orig_ident #ty_generics |
| #full_where_clause |
| { |
| } |
| |
| <span class="comment">// Generate a dummy impl of `UnsafeUnpin`, to ensure that the user cannot implement it. |
| // |
| // To ensure that users don't accidentally write a non-functional `UnsafeUnpin` |
| // impls, we emit one ourselves. If the user ends up writing an `UnsafeUnpin` |
| // impl, they'll get a "conflicting implementations of trait" error when |
| // coherence checks are run. |
| </span><span class="attribute">#[doc(hidden)] |
| </span><span class="kw">unsafe impl </span>#proj_impl_generics _pin_project::UnsafeUnpin |
| <span class="kw">for </span>#orig_ident #ty_generics |
| #full_where_clause |
| { |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Creates `Drop` implementation for the original type. |
| /// |
| /// The kind of `Drop` impl generated depends on `pinned_drop` field: |
| /// - `Some` - implements `Drop` via `PinnedDrop` impl. |
| /// - `None` - generates code that ensures that `Drop` trait is not implemented, |
| /// instead of generating `Drop` impl. |
| </span><span class="kw">fn </span>make_drop_impl(cx: <span class="kw-2">&</span>Context<<span class="lifetime">'_</span>>) -> TokenStream { |
| <span class="kw">let </span>ident = cx.orig.ident; |
| <span class="kw">let </span>(impl_generics, ty_generics, where_clause) = cx.orig.generics.split_for_impl(); |
| |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(span) = cx.pinned_drop { |
| <span class="comment">// For interoperability with `forbid(unsafe_code)`, `unsafe` token should be |
| // call-site span. |
| </span><span class="kw">let </span>unsafety = <<span class="macro">Token!</span>[<span class="kw">unsafe</span>]>::default(); |
| <span class="macro">quote_spanned! </span>{ span => |
| <span class="kw">impl </span>#impl_generics _pin_project::__private::Drop <span class="kw">for </span>#ident #ty_generics |
| #where_clause |
| { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| #unsafety { |
| <span class="comment">// Safety - we're in 'drop', so we know that 'self' will |
| // never move again. |
| </span><span class="kw">let </span>__pinned_self = _pin_project::__private::Pin::new_unchecked(<span class="self">self</span>); |
| <span class="comment">// We call `pinned_drop` only once. Since `PinnedDrop::drop` |
| // is an unsafe method and a private API, it is never called again in safe |
| // code *unless the user uses a maliciously crafted macro*. |
| </span>_pin_project::__private::PinnedDrop::drop(__pinned_self); |
| } |
| } |
| } |
| } |
| } <span class="kw">else </span>{ |
| <span class="comment">// If the user does not provide a `PinnedDrop` impl, |
| // we need to ensure that they don't provide a `Drop` impl of their |
| // own. |
| // Based on https://github.com/upsuper/assert-impl/blob/f503255b292ab0ba8d085b657f4065403cfa46eb/src/lib.rs#L80-L87 |
| // |
| // We create a new identifier for each struct, so that the traits |
| // for different types do not conflict with each other. |
| // |
| // Another approach would be to provide an empty Drop impl, |
| // which would conflict with a user-provided Drop impl. |
| // However, this would trigger the compiler's special handling |
| // of Drop types (e.g. fields cannot be moved out of a Drop type). |
| // This approach prevents the creation of needless Drop impls, |
| // giving users more flexibility. |
| </span><span class="kw">let </span>trait_ident = <span class="macro">format_ident!</span>(<span class="string">"{}MustNotImplDrop"</span>, ident); |
| |
| <span class="macro">quote! </span>{ |
| <span class="comment">// There are two possible cases: |
| // 1. The user type does not implement Drop. In this case, |
| // the first blanked impl will not apply to it. This code |
| // will compile, as there is only one impl of MustNotImplDrop for the user type |
| // 2. The user type does impl Drop. This will make the blanket impl applicable, |
| // which will then conflict with the explicit MustNotImplDrop impl below. |
| // This will result in a compilation error, which is exactly what we want. |
| </span><span class="kw">trait </span>#trait_ident {} |
| <span class="attribute">#[allow(clippy::drop_bounds, drop_bounds)] |
| </span><span class="kw">impl</span><T: _pin_project::__private::Drop> #trait_ident <span class="kw">for </span>T {} |
| <span class="kw">impl </span>#impl_generics #trait_ident <span class="kw">for </span>#ident #ty_generics #where_clause {} |
| |
| <span class="comment">// Generate a dummy impl of `PinnedDrop`, to ensure that the user cannot implement it. |
| // Since the user did not pass `PinnedDrop` to `#[pin_project]`, any `PinnedDrop` |
| // impl will not actually be called. Unfortunately, we can't detect this situation |
| // directly from either the `#[pin_project]` or `#[pinned_drop]` attributes, since |
| // we don't know what other attributes/impl may exist. |
| // |
| // To ensure that users don't accidentally write a non-functional `PinnedDrop` |
| // impls, we emit one ourselves. If the user ends up writing a `PinnedDrop` impl, |
| // they'll get a "conflicting implementations of trait" error when coherence |
| // checks are run. |
| </span><span class="attribute">#[doc(hidden)] |
| </span><span class="kw">impl </span>#impl_generics _pin_project::__private::PinnedDrop <span class="kw">for </span>#ident #ty_generics |
| #where_clause |
| { |
| <span class="kw">unsafe fn </span>drop(<span class="self">self</span>: _pin_project::__private::Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>) {} |
| } |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Creates an implementation of the projection methods. |
| /// |
| /// On structs, both the `project` and `project_ref` methods are always generated, |
| /// and the `project_replace` method is only generated if `ProjReplace::span` is `Some`. |
| /// |
| /// On enums, only methods that the returned projected type is named will be generated. |
| </span><span class="kw">fn </span>make_proj_impl( |
| cx: <span class="kw-2">&</span>Context<<span class="lifetime">'_</span>>, |
| proj_body: <span class="kw-2">&</span>TokenStream, |
| proj_ref_body: <span class="kw-2">&</span>TokenStream, |
| proj_own_body: <span class="kw-2">&</span>TokenStream, |
| ) -> TokenStream { |
| <span class="kw">let </span>vis = <span class="kw-2">&</span>cx.proj.vis; |
| <span class="kw">let </span>lifetime = <span class="kw-2">&</span>cx.proj.lifetime; |
| <span class="kw">let </span>orig_ident = cx.orig.ident; |
| <span class="kw">let </span>proj_ident = <span class="kw-2">&</span>cx.proj.mut_ident; |
| <span class="kw">let </span>proj_ref_ident = <span class="kw-2">&</span>cx.proj.ref_ident; |
| <span class="kw">let </span>proj_own_ident = <span class="kw-2">&</span>cx.proj.own_ident; |
| |
| <span class="kw">let </span>orig_ty_generics = cx.orig.generics.split_for_impl().<span class="number">1</span>; |
| <span class="kw">let </span>proj_ty_generics = cx.proj.generics.split_for_impl().<span class="number">1</span>; |
| <span class="kw">let </span>(impl_generics, ty_generics, where_clause) = cx.orig.generics.split_for_impl(); |
| <span class="comment">// TODO: For enums and project_replace, dead_code warnings should not be |
| // allowed because methods are not generated unless explicitly specified. |
| // However, there is currently no good way to allow warnings for generated |
| // code, so we allow warnings for all methods for now. |
| </span><span class="kw">let </span>allow_dead_code = <span class="macro">quote! </span>{ <span class="attribute">#[allow(dead_code)] </span>}; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>project = <span class="prelude-val">Some</span>(<span class="macro">quote! </span>{ |
| #allow_dead_code |
| #vis <span class="kw">fn </span>project<#lifetime>( |
| <span class="self">self</span>: _pin_project::__private::Pin<<span class="kw-2">&</span>#lifetime <span class="kw-2">mut </span><span class="self">Self</span>>, |
| ) -> #proj_ident #proj_ty_generics { |
| <span class="kw">unsafe </span>{ |
| #proj_body |
| } |
| } |
| }); |
| <span class="kw">let </span><span class="kw-2">mut </span>project_ref = <span class="prelude-val">Some</span>(<span class="macro">quote! </span>{ |
| #allow_dead_code |
| <span class="attribute">#[allow(clippy::missing_const_for_fn)] |
| </span>#vis <span class="kw">fn </span>project_ref<#lifetime>( |
| <span class="self">self</span>: _pin_project::__private::Pin<<span class="kw-2">&</span>#lifetime <span class="self">Self</span>>, |
| ) -> #proj_ref_ident #proj_ty_generics { |
| <span class="kw">unsafe </span>{ |
| #proj_ref_body |
| } |
| } |
| }); |
| <span class="kw">let </span><span class="kw-2">mut </span>project_replace = cx.project_replace.span().map(|span| { |
| <span class="comment">// It is enough to only set the span of the signature. |
| </span><span class="kw">let </span>sig = <span class="macro">quote_spanned! </span>{ span => |
| #allow_dead_code |
| #vis <span class="kw">fn </span>project_replace( |
| <span class="self">self</span>: _pin_project::__private::Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, |
| __replacement: <span class="self">Self</span>, |
| ) -> #proj_own_ident #orig_ty_generics |
| }; |
| <span class="macro">quote! </span>{ |
| #sig { |
| <span class="kw">unsafe </span>{ |
| <span class="kw">let </span>__self_ptr: <span class="kw-2">*mut </span><span class="self">Self </span>= <span class="self">self</span>.get_unchecked_mut(); |
| |
| <span class="comment">// Destructors will run in reverse order, so next create a guard to overwrite |
| // `self` with the replacement value without calling destructors. |
| </span><span class="kw">let </span>__guard = _pin_project::__private::UnsafeOverwriteGuard::new( |
| __self_ptr, |
| __replacement, |
| ); |
| |
| #proj_own_body |
| } |
| } |
| } |
| }); |
| |
| <span class="kw">if </span>cx.kind == Enum { |
| <span class="kw">if </span>!cx.project { |
| project = <span class="prelude-val">None</span>; |
| } |
| <span class="kw">if </span>!cx.project_ref { |
| project_ref = <span class="prelude-val">None</span>; |
| } |
| <span class="kw">if </span>cx.project_replace.ident().is_none() { |
| project_replace = <span class="prelude-val">None</span>; |
| } |
| } |
| |
| <span class="macro">quote! </span>{ |
| <span class="kw">impl </span>#impl_generics #orig_ident #ty_generics #where_clause { |
| #project |
| #project_ref |
| #project_replace |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Checks that the `[repr(packed)]` attribute is not included. |
| /// |
| /// This currently does two checks: |
| /// - Checks the attributes of structs to ensure there is no `[repr(packed)]`. |
| /// - Generates a function that borrows fields without an unsafe block and |
| /// forbidding `unaligned_references` lint. |
| </span><span class="kw">fn </span>ensure_not_packed(orig: <span class="kw-2">&</span>OriginalType<<span class="lifetime">'_</span>>, fields: <span class="prelude-ty">Option</span><<span class="kw-2">&</span>Fields>) -> <span class="prelude-ty">Result</span><TokenStream> { |
| <span class="kw">for </span>attr <span class="kw">in </span>orig.attrs { |
| <span class="kw">if let </span>Meta::List(<span class="kw-2">ref </span>list) = attr.meta { |
| <span class="kw">if </span>list.path.is_ident(<span class="string">"repr"</span>) { |
| <span class="kw">for </span>repr <span class="kw">in </span>list.parse_args_with(Punctuated::<Meta, <span class="macro">Token!</span>[,]>::parse_terminated)<span class="question-mark">? </span>{ |
| <span class="kw">if </span>repr.path().is_ident(<span class="string">"packed"</span>) { |
| <span class="kw">let </span>msg = <span class="kw">if </span>fields.is_none() { |
| <span class="comment">// #[repr(packed)] cannot be apply on enums and will be rejected by rustc. |
| // However, we should not rely on the behavior of rustc that rejects this. |
| // https://github.com/taiki-e/pin-project/pull/324#discussion_r612388001 |
| </span><span class="string">"#[repr(packed)] attribute should be applied to a struct or union" |
| </span>} <span class="kw">else if </span>repr.require_name_value().is_ok() { |
| <span class="comment">// #[repr(packed = "")] is not valid format of #[repr(packed)] and will be |
| // rejected by rustc. |
| // However, we should not rely on the behavior of rustc that rejects this. |
| // https://github.com/taiki-e/pin-project/pull/324#discussion_r612388001 |
| </span><span class="string">"#[repr(packed)] attribute should not be name-value pair" |
| </span>} <span class="kw">else </span>{ |
| <span class="string">"#[pin_project] attribute may not be used on #[repr(packed)] types" |
| </span>}; |
| <span class="macro">bail!</span>(repr, msg); |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="kw">let </span>fields = <span class="kw">match </span>fields { |
| <span class="prelude-val">Some</span>(fields) => fields, |
| <span class="prelude-val">None </span>=> <span class="kw">return </span><span class="prelude-val">Ok</span>(TokenStream::new()), |
| }; |
| |
| <span class="comment">// Workaround for https://github.com/taiki-e/pin-project/issues/32 |
| // Through the tricky use of proc macros, it's possible to bypass |
| // the above check for the `repr` attribute. |
| // To ensure that it's impossible to use pin projections on a `#[repr(packed)]` |
| // struct, we generate code like this: |
| // |
| // ```rust |
| // #[forbid(unaligned_references)] |
| // fn assert_not_repr_packed(val: &MyStruct) { |
| // let _field_1 = &val.field_1; |
| // let _field_2 = &val.field_2; |
| // ... |
| // let _field_n = &val.field_n; |
| // } |
| // ``` |
| // |
| // Taking a reference to a packed field is UB, and applying |
| // `#[forbid(unaligned_references)]` makes sure that doing this is a hard error. |
| // |
| // If the struct ends up having `#[repr(packed)]` applied somehow, |
| // this will generate an (unfriendly) error message. Under all reasonable |
| // circumstances, we'll detect the `#[repr(packed)]` attribute, and generate |
| // a much nicer error above. |
| // |
| // There is one exception: If the type of a struct field has an alignment of 1 |
| // (e.g. u8), it is always safe to take a reference to it, even if the struct |
| // is `#[repr(packed)]`. If the struct is composed entirely of types of |
| // alignment 1, our generated method will not trigger an error if the |
| // struct is `#[repr(packed)]`. |
| // |
| // Fortunately, this should have no observable consequence - `#[repr(packed)]` |
| // is essentially a no-op on such a type. Nevertheless, we include a test |
| // to ensure that the compiler doesn't ever try to copy the fields on |
| // such a struct when trying to drop it - which is reason we prevent |
| // `#[repr(packed)]` in the first place. |
| // |
| // See also https://github.com/taiki-e/pin-project/pull/34. |
| // |
| // Note: |
| // - Lint-based tricks aren't perfect, but they're much better than nothing: |
| // https://github.com/taiki-e/pin-project-lite/issues/26 |
| // |
| // - Enable both unaligned_references and safe_packed_borrows lints |
| // because unaligned_references lint does not exist in older compilers: |
| // https://github.com/taiki-e/pin-project-lite/pull/55 |
| // https://github.com/rust-lang/rust/pull/82525 |
| </span><span class="kw">let </span><span class="kw-2">mut </span>field_refs = <span class="macro">vec!</span>[]; |
| <span class="kw">match </span>fields { |
| Fields::Named(FieldsNamed { named, .. }) => { |
| <span class="kw">for </span>Field { ident, .. } <span class="kw">in </span>named { |
| field_refs.push(<span class="macro">quote!</span>(<span class="kw-2">&</span>this.#ident)); |
| } |
| } |
| Fields::Unnamed(FieldsUnnamed { unnamed, .. }) => { |
| <span class="kw">for </span>(index, <span class="kw">_</span>) <span class="kw">in </span>unnamed.iter().enumerate() { |
| <span class="kw">let </span>index = Index::from(index); |
| field_refs.push(<span class="macro">quote!</span>(<span class="kw-2">&</span>this.#index)); |
| } |
| } |
| Fields::Unit => {} |
| } |
| |
| <span class="kw">let </span>(impl_generics, ty_generics, where_clause) = orig.generics.split_for_impl(); |
| <span class="kw">let </span>ident = orig.ident; |
| <span class="prelude-val">Ok</span>(<span class="macro">quote! </span>{ |
| <span class="attribute">#[forbid(unaligned_references, safe_packed_borrows)] |
| </span><span class="kw">fn </span>__assert_not_repr_packed #impl_generics (this: <span class="kw-2">&</span>#ident #ty_generics) #where_clause { |
| #(<span class="kw">let _ </span>= #field_refs;)* |
| } |
| }) |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="pin_project_internal" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |