310 lines
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310 lines
34 KiB
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<!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 `/home/newkirk/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/zerofrom-derive-0.1.6/src/lib.rs`."><title>lib.rs - source</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2"href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-ca0dd0c4.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="zerofrom_derive" data-themes="" data-resource-suffix="" data-rustdoc-version="1.93.1 (01f6ddf75 2026-02-11) (Arch Linux rust 1:1.93.1-1)" data-channel="1.93.1" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-a3946164.js" data-settings-js="settings-c38705f0.js" ><script src="../../static.files/storage-e2aeef58.js"></script><script defer src="../../static.files/src-script-813739b1.js"></script><script defer src="../../src-files.js"></script><script defer src="../../static.files/main-a410ff4d.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-263c88ec.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-eab170b8.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-044be391.svg"></head><body class="rustdoc src"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="src-sidebar-title"><h2>Files</h2></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><section id="main-content" class="content"><div class="main-heading"><h1><div class="sub-heading">zerofrom_derive/</div>lib.rs</h1><rustdoc-toolbar></rustdoc-toolbar></div><div class="example-wrap digits-3"><pre class="rust"><code><a href=#1 id=1 data-nosnippet>1</a><span class="comment">// This file is part of ICU4X. For terms of use, please see the file
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<a href=#2 id=2 data-nosnippet>2</a>// called LICENSE at the top level of the ICU4X source tree
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<a href=#3 id=3 data-nosnippet>3</a>// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
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<a href=#4 id=4 data-nosnippet>4</a>
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<a href=#5 id=5 data-nosnippet>5</a></span><span class="doccomment">//! Custom derives for `ZeroFrom` from the `zerofrom` crate.
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<a href=#6 id=6 data-nosnippet>6</a>
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<a href=#7 id=7 data-nosnippet>7</a></span><span class="comment">// https://github.com/unicode-org/icu4x/blob/main/documents/process/boilerplate.md#library-annotations
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<a href=#8 id=8 data-nosnippet>8</a></span><span class="attr">#![cfg_attr(
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<a href=#9 id=9 data-nosnippet>9</a> not(test),
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<a href=#10 id=10 data-nosnippet>10</a> deny(
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<a href=#11 id=11 data-nosnippet>11</a> clippy::indexing_slicing,
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<a href=#12 id=12 data-nosnippet>12</a> clippy::unwrap_used,
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<a href=#13 id=13 data-nosnippet>13</a> clippy::expect_used,
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<a href=#14 id=14 data-nosnippet>14</a> clippy::panic,
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<a href=#15 id=15 data-nosnippet>15</a> clippy::exhaustive_structs,
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<a href=#16 id=16 data-nosnippet>16</a> clippy::exhaustive_enums,
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<a href=#17 id=17 data-nosnippet>17</a> clippy::trivially_copy_pass_by_ref,
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<a href=#18 id=18 data-nosnippet>18</a> missing_debug_implementations,
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<a href=#19 id=19 data-nosnippet>19</a> )
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<a href=#20 id=20 data-nosnippet>20</a>)]
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<a href=#21 id=21 data-nosnippet>21</a>
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<a href=#22 id=22 data-nosnippet>22</a></span><span class="kw">use </span>core::mem;
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<a href=#23 id=23 data-nosnippet>23</a><span class="kw">use </span>proc_macro::TokenStream;
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<a href=#24 id=24 data-nosnippet>24</a><span class="kw">use </span>proc_macro2::{Span, TokenStream <span class="kw">as </span>TokenStream2};
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<a href=#25 id=25 data-nosnippet>25</a><span class="kw">use </span>quote::quote;
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<a href=#26 id=26 data-nosnippet>26</a><span class="kw">use </span>std::collections::{HashMap, HashSet};
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<a href=#27 id=27 data-nosnippet>27</a><span class="kw">use </span>syn::fold::{<span class="self">self</span>, Fold};
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<a href=#28 id=28 data-nosnippet>28</a><span class="kw">use </span>syn::punctuated::Punctuated;
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<a href=#29 id=29 data-nosnippet>29</a><span class="kw">use </span>syn::spanned::Spanned;
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<a href=#30 id=30 data-nosnippet>30</a><span class="kw">use </span>syn::{
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<a href=#31 id=31 data-nosnippet>31</a> parse_macro_input, parse_quote, DeriveInput, Ident, Lifetime, MetaList, Token,
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<a href=#32 id=32 data-nosnippet>32</a> TraitBoundModifier, Type, TypeParamBound, TypePath, WherePredicate,
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<a href=#33 id=33 data-nosnippet>33</a>};
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<a href=#34 id=34 data-nosnippet>34</a><span class="kw">use </span>synstructure::Structure;
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<a href=#35 id=35 data-nosnippet>35</a><span class="kw">mod </span>visitor;
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<a href=#36 id=36 data-nosnippet>36</a>
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<a href=#37 id=37 data-nosnippet>37</a><span class="doccomment">/// Custom derive for `zerofrom::ZeroFrom`,
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<a href=#38 id=38 data-nosnippet>38</a>///
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<a href=#39 id=39 data-nosnippet>39</a>/// This implements `ZeroFrom<Ty> for Ty` for types
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<a href=#40 id=40 data-nosnippet>40</a>/// without a lifetime parameter, and `ZeroFrom<Ty<'data>> for Ty<'static>`
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<a href=#41 id=41 data-nosnippet>41</a>/// for types with a lifetime parameter.
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<a href=#42 id=42 data-nosnippet>42</a>///
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<a href=#43 id=43 data-nosnippet>43</a>/// Apply the `#[zerofrom(clone)]` attribute to a field if it doesn't implement
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<a href=#44 id=44 data-nosnippet>44</a>/// Copy or ZeroFrom; this data will be cloned when the struct is zero_from'ed.
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<a href=#45 id=45 data-nosnippet>45</a>///
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<a href=#46 id=46 data-nosnippet>46</a>/// Apply the `#[zerofrom(maybe_borrow(T, U, V))]` attribute to the struct to indicate
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<a href=#47 id=47 data-nosnippet>47</a>/// that certain type parameters may themselves contain borrows (by default
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<a href=#48 id=48 data-nosnippet>48</a>/// the derives assume that type parameters perform no borrows and can be copied or cloned).
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<a href=#49 id=49 data-nosnippet>49</a>///
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<a href=#50 id=50 data-nosnippet>50</a>/// In rust versions where [this issue](https://github.com/rust-lang/rust/issues/114393) is fixed,
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<a href=#51 id=51 data-nosnippet>51</a>/// `#[zerofrom(may_borrow)]` can be applied directly to type parameters.
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<a href=#52 id=52 data-nosnippet>52</a></span><span class="attr">#[proc_macro_derive(ZeroFrom, attributes(zerofrom))]
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<a href=#53 id=53 data-nosnippet>53</a></span><span class="kw">pub fn </span>zf_derive(input: TokenStream) -> TokenStream {
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<a href=#54 id=54 data-nosnippet>54</a> <span class="kw">let </span>input = <span class="macro">parse_macro_input!</span>(input <span class="kw">as </span>DeriveInput);
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<a href=#55 id=55 data-nosnippet>55</a> TokenStream::from(zf_derive_impl(<span class="kw-2">&</span>input))
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<a href=#56 id=56 data-nosnippet>56</a>}
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<a href=#57 id=57 data-nosnippet>57</a>
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<a href=#58 id=58 data-nosnippet>58</a><span class="kw">fn </span>has_attr(attrs: <span class="kw-2">&</span>[syn::Attribute], name: <span class="kw-2">&</span>str) -> bool {
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<a href=#59 id=59 data-nosnippet>59</a> attrs.iter().any(|a| {
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<a href=#60 id=60 data-nosnippet>60</a> <span class="kw">if let </span><span class="prelude-val">Ok</span>(i) = a.parse_args::<Ident>() {
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<a href=#61 id=61 data-nosnippet>61</a> <span class="kw">if </span>i == name {
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<a href=#62 id=62 data-nosnippet>62</a> <span class="kw">return </span><span class="bool-val">true</span>;
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<a href=#63 id=63 data-nosnippet>63</a> }
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<a href=#64 id=64 data-nosnippet>64</a> }
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<a href=#65 id=65 data-nosnippet>65</a> <span class="bool-val">false
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<a href=#66 id=66 data-nosnippet>66</a> </span>})
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<a href=#67 id=67 data-nosnippet>67</a>}
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<a href=#68 id=68 data-nosnippet>68</a>
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<a href=#69 id=69 data-nosnippet>69</a><span class="comment">// Collects all idents from #[zerofrom(may_borrow(A, B, C, D))]
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<a href=#70 id=70 data-nosnippet>70</a>// needed since #[zerofrom(may_borrow)] doesn't work yet
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<a href=#71 id=71 data-nosnippet>71</a>// (https://github.com/rust-lang/rust/issues/114393)
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<a href=#72 id=72 data-nosnippet>72</a></span><span class="kw">fn </span>get_may_borrow_attr(attrs: <span class="kw-2">&</span>[syn::Attribute]) -> <span class="prelude-ty">Result</span><HashSet<Ident>, Span> {
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<a href=#73 id=73 data-nosnippet>73</a> <span class="kw">let </span><span class="kw-2">mut </span>params = HashSet::new();
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<a href=#74 id=74 data-nosnippet>74</a> <span class="kw">for </span>attr <span class="kw">in </span>attrs {
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<a href=#75 id=75 data-nosnippet>75</a> <span class="kw">if let </span><span class="prelude-val">Ok</span>(list) = attr.parse_args::<MetaList>() {
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<a href=#76 id=76 data-nosnippet>76</a> <span class="kw">if </span>list.path.is_ident(<span class="string">"may_borrow"</span>) {
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<a href=#77 id=77 data-nosnippet>77</a> <span class="kw">if let </span><span class="prelude-val">Ok</span>(list) =
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<a href=#78 id=78 data-nosnippet>78</a> list.parse_args_with(Punctuated::<Ident, <span class="macro">Token!</span>[,]>::parse_terminated)
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<a href=#79 id=79 data-nosnippet>79</a> {
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<a href=#80 id=80 data-nosnippet>80</a> params.extend(list)
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<a href=#81 id=81 data-nosnippet>81</a> } <span class="kw">else </span>{
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<a href=#82 id=82 data-nosnippet>82</a> <span class="kw">return </span><span class="prelude-val">Err</span>(attr.span());
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<a href=#83 id=83 data-nosnippet>83</a> }
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<a href=#84 id=84 data-nosnippet>84</a> }
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<a href=#85 id=85 data-nosnippet>85</a> }
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<a href=#86 id=86 data-nosnippet>86</a> }
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<a href=#87 id=87 data-nosnippet>87</a> <span class="prelude-val">Ok</span>(params)
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<a href=#88 id=88 data-nosnippet>88</a>}
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<a href=#89 id=89 data-nosnippet>89</a>
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<a href=#90 id=90 data-nosnippet>90</a><span class="kw">fn </span>zf_derive_impl(input: <span class="kw-2">&</span>DeriveInput) -> TokenStream2 {
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<a href=#91 id=91 data-nosnippet>91</a> <span class="kw">let </span><span class="kw-2">mut </span>tybounds = input
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<a href=#92 id=92 data-nosnippet>92</a> .generics
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<a href=#93 id=93 data-nosnippet>93</a> .type_params()
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<a href=#94 id=94 data-nosnippet>94</a> .map(|ty| {
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<a href=#95 id=95 data-nosnippet>95</a> <span class="comment">// Strip out param defaults, we don't need them in the impl
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<a href=#96 id=96 data-nosnippet>96</a> </span><span class="kw">let </span><span class="kw-2">mut </span>ty = ty.clone();
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<a href=#97 id=97 data-nosnippet>97</a> ty.eq_token = <span class="prelude-val">None</span>;
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<a href=#98 id=98 data-nosnippet>98</a> ty.default = <span class="prelude-val">None</span>;
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<a href=#99 id=99 data-nosnippet>99</a> ty
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<a href=#100 id=100 data-nosnippet>100</a> })
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<a href=#101 id=101 data-nosnippet>101</a> .collect::<Vec<<span class="kw">_</span>>>();
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<a href=#102 id=102 data-nosnippet>102</a> <span class="kw">let </span>typarams = tybounds
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<a href=#103 id=103 data-nosnippet>103</a> .iter()
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<a href=#104 id=104 data-nosnippet>104</a> .map(|ty| ty.ident.clone())
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<a href=#105 id=105 data-nosnippet>105</a> .collect::<Vec<<span class="kw">_</span>>>();
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<a href=#106 id=106 data-nosnippet>106</a> <span class="kw">let </span>lts = input.generics.lifetimes().count();
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<a href=#107 id=107 data-nosnippet>107</a> <span class="kw">let </span>name = <span class="kw-2">&</span>input.ident;
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<a href=#108 id=108 data-nosnippet>108</a> <span class="kw">let </span>structure = Structure::new(input);
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<a href=#109 id=109 data-nosnippet>109</a>
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<a href=#110 id=110 data-nosnippet>110</a> <span class="kw">let </span>may_borrow_attrs = <span class="kw">match </span>get_may_borrow_attr(<span class="kw-2">&</span>input.attrs) {
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<a href=#111 id=111 data-nosnippet>111</a> <span class="prelude-val">Ok</span>(mb) => mb,
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<a href=#112 id=112 data-nosnippet>112</a> <span class="prelude-val">Err</span>(span) => {
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<a href=#113 id=113 data-nosnippet>113</a> <span class="kw">return </span>syn::Error::new(
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<a href=#114 id=114 data-nosnippet>114</a> span,
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<a href=#115 id=115 data-nosnippet>115</a> <span class="string">"#[zerofrom(may_borrow)] on the struct takes in a comma separated list of type parameters, like so: `#[zerofrom(may_borrow(A, B, C, D)]`"</span>,
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<a href=#116 id=116 data-nosnippet>116</a> ).to_compile_error();
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<a href=#117 id=117 data-nosnippet>117</a> }
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<a href=#118 id=118 data-nosnippet>118</a> };
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<a href=#119 id=119 data-nosnippet>119</a>
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<a href=#120 id=120 data-nosnippet>120</a> <span class="comment">// This contains every generic type introduced in this code.
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<a href=#121 id=121 data-nosnippet>121</a> // If the gneeric type is may_borrow, this additionally contains the identifier corresponding to
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<a href=#122 id=122 data-nosnippet>122</a> // a newly introduced mirror type parameter that we are borrowing from, similar to C in the original trait.
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<a href=#123 id=123 data-nosnippet>123</a> // For convenience, we are calling these "C types"
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<a href=#124 id=124 data-nosnippet>124</a> </span><span class="kw">let </span>generics_env: HashMap<Ident, <span class="prelude-ty">Option</span><Ident>> = tybounds
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<a href=#125 id=125 data-nosnippet>125</a> .iter_mut()
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<a href=#126 id=126 data-nosnippet>126</a> .map(|param| {
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<a href=#127 id=127 data-nosnippet>127</a> <span class="comment">// First one doesn't work yet https://github.com/rust-lang/rust/issues/114393
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<a href=#128 id=128 data-nosnippet>128</a> </span><span class="kw">let </span>maybe_new_param = <span class="kw">if </span>has_attr(<span class="kw-2">&</span>param.attrs, <span class="string">"may_borrow"</span>)
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<a href=#129 id=129 data-nosnippet>129</a> || may_borrow_attrs.contains(<span class="kw-2">&</span>param.ident)
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<a href=#130 id=130 data-nosnippet>130</a> {
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<a href=#131 id=131 data-nosnippet>131</a> <span class="comment">// Remove `?Sized`` bound because we need a param to be Sized in order to take a ZeroFrom of it.
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<a href=#132 id=132 data-nosnippet>132</a> // This only applies to fields marked as `may_borrow`.
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<a href=#133 id=133 data-nosnippet>133</a> </span><span class="kw">let </span><span class="kw-2">mut </span>bounds = core::mem::take(<span class="kw-2">&mut </span>param.bounds);
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<a href=#134 id=134 data-nosnippet>134</a> <span class="kw">while let </span><span class="prelude-val">Some</span>(bound_pair) = bounds.pop() {
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<a href=#135 id=135 data-nosnippet>135</a> <span class="kw">let </span>bound = bound_pair.into_value();
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<a href=#136 id=136 data-nosnippet>136</a> <span class="kw">if let </span>TypeParamBound::Trait(<span class="kw-2">ref </span>trait_bound) = bound {
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<a href=#137 id=137 data-nosnippet>137</a> <span class="kw">if </span>trait_bound.path.get_ident().map(|ident| ident == <span class="string">"Sized"</span>) == <span class="prelude-val">Some</span>(<span class="bool-val">true</span>)
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<a href=#138 id=138 data-nosnippet>138</a> && <span class="macro">matches!</span>(trait_bound.modifier, TraitBoundModifier::Maybe(<span class="kw">_</span>))
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<a href=#139 id=139 data-nosnippet>139</a> {
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<a href=#140 id=140 data-nosnippet>140</a> <span class="kw">continue</span>;
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<a href=#141 id=141 data-nosnippet>141</a> }
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<a href=#142 id=142 data-nosnippet>142</a> }
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<a href=#143 id=143 data-nosnippet>143</a> param.bounds.push(bound);
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<a href=#144 id=144 data-nosnippet>144</a> }
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<a href=#145 id=145 data-nosnippet>145</a> <span class="prelude-val">Some</span>(Ident::new(
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<a href=#146 id=146 data-nosnippet>146</a> <span class="kw-2">&</span><span class="macro">format!</span>(<span class="string">"{}ZFParamC"</span>, param.ident),
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<a href=#147 id=147 data-nosnippet>147</a> param.ident.span(),
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<a href=#148 id=148 data-nosnippet>148</a> ))
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<a href=#149 id=149 data-nosnippet>149</a> } <span class="kw">else </span>{
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<a href=#150 id=150 data-nosnippet>150</a> <span class="prelude-val">None
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<a href=#151 id=151 data-nosnippet>151</a> </span>};
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<a href=#152 id=152 data-nosnippet>152</a> (param.ident.clone(), maybe_new_param)
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<a href=#153 id=153 data-nosnippet>153</a> })
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<a href=#154 id=154 data-nosnippet>154</a> .collect();
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<a href=#155 id=155 data-nosnippet>155</a>
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<a href=#156 id=156 data-nosnippet>156</a> <span class="comment">// Do any of the generics potentially borrow?
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<a href=#157 id=157 data-nosnippet>157</a> </span><span class="kw">let </span>generics_may_borrow = generics_env.values().any(|x| x.is_some());
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<a href=#158 id=158 data-nosnippet>158</a>
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<a href=#159 id=159 data-nosnippet>159</a> <span class="kw">if </span>lts == <span class="number">0 </span>&& !generics_may_borrow {
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<a href=#160 id=160 data-nosnippet>160</a> <span class="kw">let </span>has_clone = structure
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<a href=#161 id=161 data-nosnippet>161</a> .variants()
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<a href=#162 id=162 data-nosnippet>162</a> .iter()
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<a href=#163 id=163 data-nosnippet>163</a> .flat_map(|variant| variant.bindings().iter())
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<a href=#164 id=164 data-nosnippet>164</a> .any(|binding| has_attr(<span class="kw-2">&</span>binding.ast().attrs, <span class="string">"clone"</span>));
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<a href=#165 id=165 data-nosnippet>165</a> <span class="kw">let </span>(clone, clone_trait) = <span class="kw">if </span>has_clone {
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<a href=#166 id=166 data-nosnippet>166</a> (<span class="macro">quote!</span>(this.clone()), <span class="macro">quote!</span>(Clone))
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<a href=#167 id=167 data-nosnippet>167</a> } <span class="kw">else </span>{
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<a href=#168 id=168 data-nosnippet>168</a> (<span class="macro">quote!</span>(<span class="kw-2">*</span>this), <span class="macro">quote!</span>(Copy))
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<a href=#169 id=169 data-nosnippet>169</a> };
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<a href=#170 id=170 data-nosnippet>170</a> <span class="kw">let </span>bounds: Vec<WherePredicate> = typarams
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<a href=#171 id=171 data-nosnippet>171</a> .iter()
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<a href=#172 id=172 data-nosnippet>172</a> .map(|ty| <span class="macro">parse_quote!</span>(#ty: #clone_trait + <span class="lifetime">'static</span>))
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<a href=#173 id=173 data-nosnippet>173</a> .collect();
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<a href=#174 id=174 data-nosnippet>174</a> <span class="macro">quote!</span> {
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<a href=#175 id=175 data-nosnippet>175</a> <span class="kw">impl</span><<span class="lifetime">'zf</span>, #(#tybounds),<span class="kw-2">*</span>> zerofrom::ZeroFrom<<span class="lifetime">'zf</span>, #name<#(#typarams),<span class="kw-2">*</span>>> <span class="kw">for </span>#name<#(#typarams),<span class="kw-2">*</span>> <span class="kw">where </span>#(#bounds),* {
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<a href=#176 id=176 data-nosnippet>176</a> <span class="kw">fn </span>zero_from(this: <span class="kw-2">&</span><span class="lifetime">'zf </span><span class="self">Self</span>) -> <span class="self">Self </span>{
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<a href=#177 id=177 data-nosnippet>177</a> #clone
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<a href=#178 id=178 data-nosnippet>178</a> }
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<a href=#179 id=179 data-nosnippet>179</a> }
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<a href=#180 id=180 data-nosnippet>180</a> }
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<a href=#181 id=181 data-nosnippet>181</a> } <span class="kw">else </span>{
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<a href=#182 id=182 data-nosnippet>182</a> <span class="kw">if </span>lts > <span class="number">1 </span>{
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<a href=#183 id=183 data-nosnippet>183</a> <span class="kw">return </span>syn::Error::new(
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<a href=#184 id=184 data-nosnippet>184</a> input.generics.span(),
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<a href=#185 id=185 data-nosnippet>185</a> <span class="string">"derive(ZeroFrom) cannot have multiple lifetime parameters"</span>,
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<a href=#186 id=186 data-nosnippet>186</a> )
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<a href=#187 id=187 data-nosnippet>187</a> .to_compile_error();
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<a href=#188 id=188 data-nosnippet>188</a> }
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<a href=#189 id=189 data-nosnippet>189</a>
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<a href=#190 id=190 data-nosnippet>190</a> <span class="kw">let </span><span class="kw-2">mut </span>zf_bounds: Vec<WherePredicate> = <span class="macro">vec!</span>[];
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<a href=#191 id=191 data-nosnippet>191</a> <span class="kw">let </span>body = structure.each_variant(|vi| {
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<a href=#192 id=192 data-nosnippet>192</a> vi.construct(|f, i| {
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<a href=#193 id=193 data-nosnippet>193</a> <span class="kw">let </span>binding = <span class="macro">format!</span>(<span class="string">"__binding_{i}"</span>);
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<a href=#194 id=194 data-nosnippet>194</a> <span class="kw">let </span>field = Ident::new(<span class="kw-2">&</span>binding, Span::call_site());
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<a href=#195 id=195 data-nosnippet>195</a>
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<a href=#196 id=196 data-nosnippet>196</a> <span class="kw">if </span>has_attr(<span class="kw-2">&</span>f.attrs, <span class="string">"clone"</span>) {
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<a href=#197 id=197 data-nosnippet>197</a> <span class="macro">quote!</span> {
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<a href=#198 id=198 data-nosnippet>198</a> #field.clone()
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<a href=#199 id=199 data-nosnippet>199</a> }
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<a href=#200 id=200 data-nosnippet>200</a> } <span class="kw">else </span>{
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<a href=#201 id=201 data-nosnippet>201</a> <span class="comment">// the field type
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<a href=#202 id=202 data-nosnippet>202</a> </span><span class="kw">let </span>fty = replace_lifetime(<span class="kw-2">&</span>f.ty, custom_lt(<span class="string">"'zf"</span>));
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<a href=#203 id=203 data-nosnippet>203</a> <span class="comment">// the corresponding lifetimey type we are borrowing from (effectively, the C type)
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<a href=#204 id=204 data-nosnippet>204</a> </span><span class="kw">let </span>lifetime_ty =
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<a href=#205 id=205 data-nosnippet>205</a> replace_lifetime_and_type(<span class="kw-2">&</span>f.ty, custom_lt(<span class="string">"'zf_inner"</span>), <span class="kw-2">&</span>generics_env);
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<a href=#206 id=206 data-nosnippet>206</a>
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<a href=#207 id=207 data-nosnippet>207</a> <span class="kw">let </span>(has_ty, has_lt) = visitor::check_type_for_parameters(<span class="kw-2">&</span>f.ty, <span class="kw-2">&</span>generics_env);
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<a href=#208 id=208 data-nosnippet>208</a> <span class="kw">if </span>has_ty {
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<a href=#209 id=209 data-nosnippet>209</a> <span class="comment">// For types without type parameters, the compiler can figure out that the field implements
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<a href=#210 id=210 data-nosnippet>210</a> // ZeroFrom on its own. However, if there are type parameters, there may be complex preconditions
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<a href=#211 id=211 data-nosnippet>211</a> // to `FieldTy: ZeroFrom` that need to be satisfied. We get them to be satisfied by requiring
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<a href=#212 id=212 data-nosnippet>212</a> // `FieldTy<'zf>: ZeroFrom<'zf, FieldTy<'zf_inner>>`
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<a href=#213 id=213 data-nosnippet>213</a> </span><span class="kw">if </span>has_lt {
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<a href=#214 id=214 data-nosnippet>214</a> zf_bounds
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<a href=#215 id=215 data-nosnippet>215</a> .push(<span class="macro">parse_quote!</span>(#fty: zerofrom::ZeroFrom<<span class="lifetime">'zf</span>, #lifetime_ty>));
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<a href=#216 id=216 data-nosnippet>216</a> } <span class="kw">else </span>{
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<a href=#217 id=217 data-nosnippet>217</a> zf_bounds.push(<span class="macro">parse_quote!</span>(#fty: zerofrom::ZeroFrom<<span class="lifetime">'zf</span>, #fty>));
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<a href=#218 id=218 data-nosnippet>218</a> }
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<a href=#219 id=219 data-nosnippet>219</a> }
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<a href=#220 id=220 data-nosnippet>220</a> <span class="kw">if </span>has_ty || has_lt {
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<a href=#221 id=221 data-nosnippet>221</a> <span class="comment">// By doing this we essentially require ZF to be implemented
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<a href=#222 id=222 data-nosnippet>222</a> // on all fields
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<a href=#223 id=223 data-nosnippet>223</a> </span><span class="macro">quote!</span> {
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<a href=#224 id=224 data-nosnippet>224</a> <#fty <span class="kw">as </span>zerofrom::ZeroFrom<<span class="lifetime">'zf</span>, #lifetime_ty>>::zero_from(#field)
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<a href=#225 id=225 data-nosnippet>225</a> }
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<a href=#226 id=226 data-nosnippet>226</a> } <span class="kw">else </span>{
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<a href=#227 id=227 data-nosnippet>227</a> <span class="comment">// No lifetimes, so we can just copy
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<a href=#228 id=228 data-nosnippet>228</a> </span><span class="macro">quote!</span> { <span class="kw-2">*</span>#field }
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<a href=#229 id=229 data-nosnippet>229</a> }
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<a href=#230 id=230 data-nosnippet>230</a> }
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<a href=#231 id=231 data-nosnippet>231</a> })
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<a href=#232 id=232 data-nosnippet>232</a> });
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<a href=#233 id=233 data-nosnippet>233</a> <span class="comment">// Due to the possibility of generics_may_borrow, we might reach here with no lifetimes on self,
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<a href=#234 id=234 data-nosnippet>234</a> // don't accidentally feed them to self later
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<a href=#235 id=235 data-nosnippet>235</a> </span><span class="kw">let </span>(maybe_zf_lifetime, maybe_zf_inner_lifetime) = <span class="kw">if </span>lts == <span class="number">0 </span>{
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<a href=#236 id=236 data-nosnippet>236</a> (<span class="macro">quote!</span>(), <span class="macro">quote!</span>())
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<a href=#237 id=237 data-nosnippet>237</a> } <span class="kw">else </span>{
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<a href=#238 id=238 data-nosnippet>238</a> (<span class="macro">quote!</span>(<span class="lifetime">'zf</span>,), <span class="macro">quote!</span>(<span class="lifetime">'zf_inner</span>,))
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<a href=#239 id=239 data-nosnippet>239</a> };
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<a href=#240 id=240 data-nosnippet>240</a>
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<a href=#241 id=241 data-nosnippet>241</a> <span class="comment">// Array of C types. Only different if generics are allowed to borrow
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<a href=#242 id=242 data-nosnippet>242</a> </span><span class="kw">let </span><span class="kw-2">mut </span>typarams_c = typarams.clone();
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<a href=#243 id=243 data-nosnippet>243</a>
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<a href=#244 id=244 data-nosnippet>244</a> <span class="kw">if </span>generics_may_borrow {
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<a href=#245 id=245 data-nosnippet>245</a> <span class="kw">for </span>typaram_c <span class="kw">in </span><span class="kw-2">&mut </span>typarams_c {
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<a href=#246 id=246 data-nosnippet>246</a> <span class="kw">if let </span><span class="prelude-val">Some</span>(<span class="prelude-val">Some</span>(replacement)) = generics_env.get(typaram_c) {
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<a href=#247 id=247 data-nosnippet>247</a> <span class="comment">// we use mem::replace here so we can be really clear about the C vs the T type
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<a href=#248 id=248 data-nosnippet>248</a> </span><span class="kw">let </span>typaram_t = mem::replace(typaram_c, replacement.clone());
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<a href=#249 id=249 data-nosnippet>249</a> zf_bounds
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<a href=#250 id=250 data-nosnippet>250</a> .push(<span class="macro">parse_quote!</span>(#typaram_c: zerofrom::ZeroFrom<<span class="lifetime">'zf_inner</span>, #typaram_t>));
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<a href=#251 id=251 data-nosnippet>251</a> tybounds.push(<span class="macro">parse_quote!</span>(#typaram_c));
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<a href=#252 id=252 data-nosnippet>252</a> }
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<a href=#253 id=253 data-nosnippet>253</a> }
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<a href=#254 id=254 data-nosnippet>254</a> }
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<a href=#255 id=255 data-nosnippet>255</a>
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<a href=#256 id=256 data-nosnippet>256</a> <span class="macro">quote!</span> {
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<a href=#257 id=257 data-nosnippet>257</a> <span class="kw">impl</span><<span class="lifetime">'zf</span>, <span class="lifetime">'zf_inner</span>, #(#tybounds),<span class="kw-2">*</span>> zerofrom::ZeroFrom<<span class="lifetime">'zf</span>, #name<#maybe_zf_inner_lifetime #(#typarams_c),<span class="kw-2">*</span>>> <span class="kw">for </span>#name<#maybe_zf_lifetime #(#typarams),<span class="kw-2">*</span>>
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<a href=#258 id=258 data-nosnippet>258</a> <span class="kw">where
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<a href=#259 id=259 data-nosnippet>259</a> </span>#(#zf_bounds,)* {
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<a href=#260 id=260 data-nosnippet>260</a> <span class="kw">fn </span>zero_from(this: <span class="kw-2">&</span><span class="lifetime">'zf </span>#name<#maybe_zf_inner_lifetime #(#typarams_c),<span class="kw-2">*</span>>) -> <span class="self">Self </span>{
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<a href=#261 id=261 data-nosnippet>261</a> <span class="kw">match </span><span class="kw-2">*</span>this { #body }
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<a href=#262 id=262 data-nosnippet>262</a> }
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<a href=#263 id=263 data-nosnippet>263</a> }
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<a href=#264 id=264 data-nosnippet>264</a> }
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<a href=#265 id=265 data-nosnippet>265</a> }
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<a href=#266 id=266 data-nosnippet>266</a>}
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<a href=#267 id=267 data-nosnippet>267</a>
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<a href=#268 id=268 data-nosnippet>268</a><span class="kw">fn </span>custom_lt(s: <span class="kw-2">&</span>str) -> Lifetime {
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<a href=#269 id=269 data-nosnippet>269</a> Lifetime::new(s, Span::call_site())
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<a href=#270 id=270 data-nosnippet>270</a>}
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<a href=#271 id=271 data-nosnippet>271</a>
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<a href=#272 id=272 data-nosnippet>272</a><span class="doccomment">/// Replace all lifetimes in a type with a specified one
|
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<a href=#273 id=273 data-nosnippet>273</a></span><span class="kw">fn </span>replace_lifetime(x: <span class="kw-2">&</span>Type, lt: Lifetime) -> Type {
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<a href=#274 id=274 data-nosnippet>274</a> <span class="kw">struct </span>ReplaceLifetime(Lifetime);
|
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<a href=#275 id=275 data-nosnippet>275</a>
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<a href=#276 id=276 data-nosnippet>276</a> <span class="kw">impl </span>Fold <span class="kw">for </span>ReplaceLifetime {
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<a href=#277 id=277 data-nosnippet>277</a> <span class="kw">fn </span>fold_lifetime(<span class="kw-2">&mut </span><span class="self">self</span>, <span class="kw">_</span>: Lifetime) -> Lifetime {
|
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<a href=#278 id=278 data-nosnippet>278</a> <span class="self">self</span>.<span class="number">0</span>.clone()
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<a href=#279 id=279 data-nosnippet>279</a> }
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<a href=#280 id=280 data-nosnippet>280</a> }
|
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<a href=#281 id=281 data-nosnippet>281</a> ReplaceLifetime(lt).fold_type(x.clone())
|
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<a href=#282 id=282 data-nosnippet>282</a>}
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<a href=#283 id=283 data-nosnippet>283</a>
|
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<a href=#284 id=284 data-nosnippet>284</a><span class="doccomment">/// Replace all lifetimes in a type with a specified one, AND replace all types that have a corresponding C type
|
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<a href=#285 id=285 data-nosnippet>285</a>/// with the C type
|
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<a href=#286 id=286 data-nosnippet>286</a></span><span class="kw">fn </span>replace_lifetime_and_type(
|
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<a href=#287 id=287 data-nosnippet>287</a> x: <span class="kw-2">&</span>Type,
|
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<a href=#288 id=288 data-nosnippet>288</a> lt: Lifetime,
|
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<a href=#289 id=289 data-nosnippet>289</a> generics_env: <span class="kw-2">&</span>HashMap<Ident, <span class="prelude-ty">Option</span><Ident>>,
|
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<a href=#290 id=290 data-nosnippet>290</a>) -> Type {
|
|
<a href=#291 id=291 data-nosnippet>291</a> <span class="kw">struct </span>ReplaceLifetimeAndTy<<span class="lifetime">'a</span>>(Lifetime, <span class="kw-2">&</span><span class="lifetime">'a </span>HashMap<Ident, <span class="prelude-ty">Option</span><Ident>>);
|
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<a href=#292 id=292 data-nosnippet>292</a>
|
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<a href=#293 id=293 data-nosnippet>293</a> <span class="kw">impl </span>Fold <span class="kw">for </span>ReplaceLifetimeAndTy<<span class="lifetime">'_</span>> {
|
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<a href=#294 id=294 data-nosnippet>294</a> <span class="kw">fn </span>fold_lifetime(<span class="kw-2">&mut </span><span class="self">self</span>, <span class="kw">_</span>: Lifetime) -> Lifetime {
|
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<a href=#295 id=295 data-nosnippet>295</a> <span class="self">self</span>.<span class="number">0</span>.clone()
|
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<a href=#296 id=296 data-nosnippet>296</a> }
|
|
<a href=#297 id=297 data-nosnippet>297</a> <span class="kw">fn </span>fold_type_path(<span class="kw-2">&mut </span><span class="self">self</span>, i: TypePath) -> TypePath {
|
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<a href=#298 id=298 data-nosnippet>298</a> <span class="kw">if </span>i.qself.is_none() {
|
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<a href=#299 id=299 data-nosnippet>299</a> <span class="kw">if let </span><span class="prelude-val">Some</span>(ident) = i.path.get_ident() {
|
|
<a href=#300 id=300 data-nosnippet>300</a> <span class="kw">if let </span><span class="prelude-val">Some</span>(<span class="prelude-val">Some</span>(replacement)) = <span class="self">self</span>.<span class="number">1</span>.get(ident) {
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<a href=#301 id=301 data-nosnippet>301</a> <span class="kw">return </span><span class="macro">parse_quote!</span>(#replacement);
|
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<a href=#302 id=302 data-nosnippet>302</a> }
|
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<a href=#303 id=303 data-nosnippet>303</a> }
|
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<a href=#304 id=304 data-nosnippet>304</a> }
|
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<a href=#305 id=305 data-nosnippet>305</a> fold::fold_type_path(<span class="self">self</span>, i)
|
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<a href=#306 id=306 data-nosnippet>306</a> }
|
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<a href=#307 id=307 data-nosnippet>307</a> }
|
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<a href=#308 id=308 data-nosnippet>308</a> ReplaceLifetimeAndTy(lt, generics_env).fold_type(x.clone())
|
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<a href=#309 id=309 data-nosnippet>309</a>}
|
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</code></pre></div></section></main></body></html> |