| <!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 `crates/hir-ty/src/drop.rs`."><title>drop.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-77263533.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="hir_ty" data-themes="" data-resource-suffix="" data-rustdoc-version="1.94.0 (4a4ef493e 2026-03-02)" data-channel="1.94.0" data-search-js="search-9e2438ea.js" data-stringdex-js="stringdex-b897f86f.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-7bab91a1.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-ffcac47a.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">hir_ty/</div>drop.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="doccomment">//! Utilities for computing drop info about types. |
| <a href=#2 id=2 data-nosnippet>2</a> |
| <a href=#3 id=3 data-nosnippet>3</a></span><span class="kw">use </span>hir_def::{AdtId, signatures::StructFlags}; |
| <a href=#4 id=4 data-nosnippet>4</a><span class="kw">use </span>rustc_hash::FxHashSet; |
| <a href=#5 id=5 data-nosnippet>5</a><span class="kw">use </span>rustc_type_ir::inherent::{AdtDef, IntoKind}; |
| <a href=#6 id=6 data-nosnippet>6</a><span class="kw">use </span>stdx::never; |
| <a href=#7 id=7 data-nosnippet>7</a> |
| <a href=#8 id=8 data-nosnippet>8</a><span class="kw">use </span>crate::{ |
| <a href=#9 id=9 data-nosnippet>9</a> InferenceResult, consteval, |
| <a href=#10 id=10 data-nosnippet>10</a> method_resolution::TraitImpls, |
| <a href=#11 id=11 data-nosnippet>11</a> next_solver::{ |
| <a href=#12 id=12 data-nosnippet>12</a> DbInterner, ParamEnv, SimplifiedType, Ty, TyKind, |
| <a href=#13 id=13 data-nosnippet>13</a> infer::{InferCtxt, traits::ObligationCause}, |
| <a href=#14 id=14 data-nosnippet>14</a> obligation_ctxt::ObligationCtxt, |
| <a href=#15 id=15 data-nosnippet>15</a> }, |
| <a href=#16 id=16 data-nosnippet>16</a>}; |
| <a href=#17 id=17 data-nosnippet>17</a> |
| <a href=#18 id=18 data-nosnippet>18</a><span class="kw">fn </span>has_destructor(interner: DbInterner<<span class="lifetime">'_</span>>, adt: AdtId) -> bool { |
| <a href=#19 id=19 data-nosnippet>19</a> <span class="kw">let </span>db = interner.db; |
| <a href=#20 id=20 data-nosnippet>20</a> <span class="kw">let </span>module = <span class="kw">match </span>adt { |
| <a href=#21 id=21 data-nosnippet>21</a> AdtId::EnumId(id) => db.lookup_intern_enum(id).container, |
| <a href=#22 id=22 data-nosnippet>22</a> AdtId::StructId(id) => db.lookup_intern_struct(id).container, |
| <a href=#23 id=23 data-nosnippet>23</a> AdtId::UnionId(id) => db.lookup_intern_union(id).container, |
| <a href=#24 id=24 data-nosnippet>24</a> }; |
| <a href=#25 id=25 data-nosnippet>25</a> <span class="kw">let </span><span class="prelude-val">Some</span>(drop_trait) = interner.lang_items().Drop <span class="kw">else </span>{ |
| <a href=#26 id=26 data-nosnippet>26</a> <span class="kw">return </span><span class="bool-val">false</span>; |
| <a href=#27 id=27 data-nosnippet>27</a> }; |
| <a href=#28 id=28 data-nosnippet>28</a> <span class="kw">let </span>impls = <span class="kw">match </span>module.block(db) { |
| <a href=#29 id=29 data-nosnippet>29</a> <span class="prelude-val">Some</span>(block) => <span class="kw">match </span>TraitImpls::for_block(db, block) { |
| <a href=#30 id=30 data-nosnippet>30</a> <span class="prelude-val">Some</span>(it) => <span class="kw-2">&**</span>it, |
| <a href=#31 id=31 data-nosnippet>31</a> <span class="prelude-val">None </span>=> <span class="kw">return </span><span class="bool-val">false</span>, |
| <a href=#32 id=32 data-nosnippet>32</a> }, |
| <a href=#33 id=33 data-nosnippet>33</a> <span class="prelude-val">None </span>=> TraitImpls::for_crate(db, module.krate(db)), |
| <a href=#34 id=34 data-nosnippet>34</a> }; |
| <a href=#35 id=35 data-nosnippet>35</a> !impls.for_trait_and_self_ty(drop_trait, <span class="kw-2">&</span>SimplifiedType::Adt(adt.into())).<span class="number">0</span>.is_empty() |
| <a href=#36 id=36 data-nosnippet>36</a>} |
| <a href=#37 id=37 data-nosnippet>37</a> |
| <a href=#38 id=38 data-nosnippet>38</a><span class="attr">#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)] |
| <a href=#39 id=39 data-nosnippet>39</a></span><span class="kw">pub enum </span>DropGlue { |
| <a href=#40 id=40 data-nosnippet>40</a> <span class="comment">// Order of variants is important. |
| <a href=#41 id=41 data-nosnippet>41</a> </span><span class="prelude-val">None</span>, |
| <a href=#42 id=42 data-nosnippet>42</a> <span class="doccomment">/// May have a drop glue if some type parameter has it. |
| <a href=#43 id=43 data-nosnippet>43</a> /// |
| <a href=#44 id=44 data-nosnippet>44</a> /// For the compiler this is considered as a positive result, IDE distinguishes this from "yes". |
| <a href=#45 id=45 data-nosnippet>45</a> </span>DependOnParams, |
| <a href=#46 id=46 data-nosnippet>46</a> HasDropGlue, |
| <a href=#47 id=47 data-nosnippet>47</a>} |
| <a href=#48 id=48 data-nosnippet>48</a> |
| <a href=#49 id=49 data-nosnippet>49</a><span class="kw">pub fn </span>has_drop_glue<<span class="lifetime">'db</span>>(infcx: <span class="kw-2">&</span>InferCtxt<<span class="lifetime">'db</span>>, ty: Ty<<span class="lifetime">'db</span>>, env: ParamEnv<<span class="lifetime">'db</span>>) -> DropGlue { |
| <a href=#50 id=50 data-nosnippet>50</a> has_drop_glue_impl(infcx, ty, env, <span class="kw-2">&mut </span>FxHashSet::default()) |
| <a href=#51 id=51 data-nosnippet>51</a>} |
| <a href=#52 id=52 data-nosnippet>52</a> |
| <a href=#53 id=53 data-nosnippet>53</a><span class="kw">fn </span>has_drop_glue_impl<<span class="lifetime">'db</span>>( |
| <a href=#54 id=54 data-nosnippet>54</a> infcx: <span class="kw-2">&</span>InferCtxt<<span class="lifetime">'db</span>>, |
| <a href=#55 id=55 data-nosnippet>55</a> ty: Ty<<span class="lifetime">'db</span>>, |
| <a href=#56 id=56 data-nosnippet>56</a> env: ParamEnv<<span class="lifetime">'db</span>>, |
| <a href=#57 id=57 data-nosnippet>57</a> visited: <span class="kw-2">&mut </span>FxHashSet<Ty<<span class="lifetime">'db</span>>>, |
| <a href=#58 id=58 data-nosnippet>58</a>) -> DropGlue { |
| <a href=#59 id=59 data-nosnippet>59</a> <span class="kw">let </span><span class="kw-2">mut </span>ocx = ObligationCtxt::new(infcx); |
| <a href=#60 id=60 data-nosnippet>60</a> <span class="kw">let </span>ty = ocx.structurally_normalize_ty(<span class="kw-2">&</span>ObligationCause::dummy(), env, ty).unwrap_or(ty); |
| <a href=#61 id=61 data-nosnippet>61</a> |
| <a href=#62 id=62 data-nosnippet>62</a> <span class="kw">if </span>!visited.insert(ty) { |
| <a href=#63 id=63 data-nosnippet>63</a> <span class="comment">// Recursive type. |
| <a href=#64 id=64 data-nosnippet>64</a> </span><span class="kw">return </span>DropGlue::None; |
| <a href=#65 id=65 data-nosnippet>65</a> } |
| <a href=#66 id=66 data-nosnippet>66</a> |
| <a href=#67 id=67 data-nosnippet>67</a> <span class="kw">let </span>db = infcx.interner.db; |
| <a href=#68 id=68 data-nosnippet>68</a> <span class="kw">match </span>ty.kind() { |
| <a href=#69 id=69 data-nosnippet>69</a> TyKind::Adt(adt_def, subst) => { |
| <a href=#70 id=70 data-nosnippet>70</a> <span class="kw">let </span>adt_id = adt_def.def_id().<span class="number">0</span>; |
| <a href=#71 id=71 data-nosnippet>71</a> <span class="kw">if </span>has_destructor(infcx.interner, adt_id) { |
| <a href=#72 id=72 data-nosnippet>72</a> <span class="kw">return </span>DropGlue::HasDropGlue; |
| <a href=#73 id=73 data-nosnippet>73</a> } |
| <a href=#74 id=74 data-nosnippet>74</a> <span class="kw">match </span>adt_id { |
| <a href=#75 id=75 data-nosnippet>75</a> AdtId::StructId(id) => { |
| <a href=#76 id=76 data-nosnippet>76</a> <span class="kw">if </span>db |
| <a href=#77 id=77 data-nosnippet>77</a> .struct_signature(id) |
| <a href=#78 id=78 data-nosnippet>78</a> .flags |
| <a href=#79 id=79 data-nosnippet>79</a> .intersects(StructFlags::IS_MANUALLY_DROP | StructFlags::IS_PHANTOM_DATA) |
| <a href=#80 id=80 data-nosnippet>80</a> { |
| <a href=#81 id=81 data-nosnippet>81</a> <span class="kw">return </span>DropGlue::None; |
| <a href=#82 id=82 data-nosnippet>82</a> } |
| <a href=#83 id=83 data-nosnippet>83</a> db.field_types(id.into()) |
| <a href=#84 id=84 data-nosnippet>84</a> .iter() |
| <a href=#85 id=85 data-nosnippet>85</a> .map(|(<span class="kw">_</span>, field_ty)| { |
| <a href=#86 id=86 data-nosnippet>86</a> has_drop_glue_impl( |
| <a href=#87 id=87 data-nosnippet>87</a> infcx, |
| <a href=#88 id=88 data-nosnippet>88</a> field_ty.get().instantiate(infcx.interner, subst), |
| <a href=#89 id=89 data-nosnippet>89</a> env, |
| <a href=#90 id=90 data-nosnippet>90</a> visited, |
| <a href=#91 id=91 data-nosnippet>91</a> ) |
| <a href=#92 id=92 data-nosnippet>92</a> }) |
| <a href=#93 id=93 data-nosnippet>93</a> .max() |
| <a href=#94 id=94 data-nosnippet>94</a> .unwrap_or(DropGlue::None) |
| <a href=#95 id=95 data-nosnippet>95</a> } |
| <a href=#96 id=96 data-nosnippet>96</a> <span class="comment">// Unions cannot have fields with destructors. |
| <a href=#97 id=97 data-nosnippet>97</a> </span>AdtId::UnionId(<span class="kw">_</span>) => DropGlue::None, |
| <a href=#98 id=98 data-nosnippet>98</a> AdtId::EnumId(id) => id |
| <a href=#99 id=99 data-nosnippet>99</a> .enum_variants(db) |
| <a href=#100 id=100 data-nosnippet>100</a> .variants |
| <a href=#101 id=101 data-nosnippet>101</a> .iter() |
| <a href=#102 id=102 data-nosnippet>102</a> .map(|<span class="kw-2">&</span>(variant, <span class="kw">_</span>, <span class="kw">_</span>)| { |
| <a href=#103 id=103 data-nosnippet>103</a> db.field_types(variant.into()) |
| <a href=#104 id=104 data-nosnippet>104</a> .iter() |
| <a href=#105 id=105 data-nosnippet>105</a> .map(|(<span class="kw">_</span>, field_ty)| { |
| <a href=#106 id=106 data-nosnippet>106</a> has_drop_glue_impl( |
| <a href=#107 id=107 data-nosnippet>107</a> infcx, |
| <a href=#108 id=108 data-nosnippet>108</a> field_ty.get().instantiate(infcx.interner, subst), |
| <a href=#109 id=109 data-nosnippet>109</a> env, |
| <a href=#110 id=110 data-nosnippet>110</a> visited, |
| <a href=#111 id=111 data-nosnippet>111</a> ) |
| <a href=#112 id=112 data-nosnippet>112</a> }) |
| <a href=#113 id=113 data-nosnippet>113</a> .max() |
| <a href=#114 id=114 data-nosnippet>114</a> .unwrap_or(DropGlue::None) |
| <a href=#115 id=115 data-nosnippet>115</a> }) |
| <a href=#116 id=116 data-nosnippet>116</a> .max() |
| <a href=#117 id=117 data-nosnippet>117</a> .unwrap_or(DropGlue::None), |
| <a href=#118 id=118 data-nosnippet>118</a> } |
| <a href=#119 id=119 data-nosnippet>119</a> } |
| <a href=#120 id=120 data-nosnippet>120</a> TyKind::Tuple(tys) => tys |
| <a href=#121 id=121 data-nosnippet>121</a> .iter() |
| <a href=#122 id=122 data-nosnippet>122</a> .map(|ty| has_drop_glue_impl(infcx, ty, env, visited)) |
| <a href=#123 id=123 data-nosnippet>123</a> .max() |
| <a href=#124 id=124 data-nosnippet>124</a> .unwrap_or(DropGlue::None), |
| <a href=#125 id=125 data-nosnippet>125</a> TyKind::Array(ty, len) => { |
| <a href=#126 id=126 data-nosnippet>126</a> <span class="kw">if </span>consteval::try_const_usize(db, len) == <span class="prelude-val">Some</span>(<span class="number">0</span>) { |
| <a href=#127 id=127 data-nosnippet>127</a> <span class="comment">// Arrays of size 0 don't have drop glue. |
| <a href=#128 id=128 data-nosnippet>128</a> </span><span class="kw">return </span>DropGlue::None; |
| <a href=#129 id=129 data-nosnippet>129</a> } |
| <a href=#130 id=130 data-nosnippet>130</a> has_drop_glue_impl(infcx, ty, env, visited) |
| <a href=#131 id=131 data-nosnippet>131</a> } |
| <a href=#132 id=132 data-nosnippet>132</a> TyKind::Slice(ty) => has_drop_glue_impl(infcx, ty, env, visited), |
| <a href=#133 id=133 data-nosnippet>133</a> TyKind::Closure(closure_id, subst) => { |
| <a href=#134 id=134 data-nosnippet>134</a> <span class="kw">let </span>owner = db.lookup_intern_closure(closure_id.<span class="number">0</span>).<span class="number">0</span>; |
| <a href=#135 id=135 data-nosnippet>135</a> <span class="kw">let </span>infer = InferenceResult::for_body(db, owner); |
| <a href=#136 id=136 data-nosnippet>136</a> <span class="kw">let </span>(captures, <span class="kw">_</span>) = infer.closure_info(closure_id.<span class="number">0</span>); |
| <a href=#137 id=137 data-nosnippet>137</a> <span class="kw">let </span>env = db.trait_environment_for_body(owner); |
| <a href=#138 id=138 data-nosnippet>138</a> captures |
| <a href=#139 id=139 data-nosnippet>139</a> .iter() |
| <a href=#140 id=140 data-nosnippet>140</a> .map(|capture| has_drop_glue_impl(infcx, capture.ty(db, subst), env, visited)) |
| <a href=#141 id=141 data-nosnippet>141</a> .max() |
| <a href=#142 id=142 data-nosnippet>142</a> .unwrap_or(DropGlue::None) |
| <a href=#143 id=143 data-nosnippet>143</a> } |
| <a href=#144 id=144 data-nosnippet>144</a> <span class="comment">// FIXME: Handle coroutines. |
| <a href=#145 id=145 data-nosnippet>145</a> </span>TyKind::Coroutine(..) | TyKind::CoroutineWitness(..) | TyKind::CoroutineClosure(..) => { |
| <a href=#146 id=146 data-nosnippet>146</a> DropGlue::None |
| <a href=#147 id=147 data-nosnippet>147</a> } |
| <a href=#148 id=148 data-nosnippet>148</a> TyKind::Ref(..) |
| <a href=#149 id=149 data-nosnippet>149</a> | TyKind::RawPtr(..) |
| <a href=#150 id=150 data-nosnippet>150</a> | TyKind::FnDef(..) |
| <a href=#151 id=151 data-nosnippet>151</a> | TyKind::Str |
| <a href=#152 id=152 data-nosnippet>152</a> | TyKind::Never |
| <a href=#153 id=153 data-nosnippet>153</a> | TyKind::Bool |
| <a href=#154 id=154 data-nosnippet>154</a> | TyKind::Char |
| <a href=#155 id=155 data-nosnippet>155</a> | TyKind::Int(<span class="kw">_</span>) |
| <a href=#156 id=156 data-nosnippet>156</a> | TyKind::Uint(<span class="kw">_</span>) |
| <a href=#157 id=157 data-nosnippet>157</a> | TyKind::Float(<span class="kw">_</span>) |
| <a href=#158 id=158 data-nosnippet>158</a> | TyKind::FnPtr(..) |
| <a href=#159 id=159 data-nosnippet>159</a> | TyKind::Foreign(<span class="kw">_</span>) |
| <a href=#160 id=160 data-nosnippet>160</a> | TyKind::Error(<span class="kw">_</span>) |
| <a href=#161 id=161 data-nosnippet>161</a> | TyKind::Bound(..) |
| <a href=#162 id=162 data-nosnippet>162</a> | TyKind::Placeholder(..) => DropGlue::None, |
| <a href=#163 id=163 data-nosnippet>163</a> TyKind::Dynamic(..) => DropGlue::HasDropGlue, |
| <a href=#164 id=164 data-nosnippet>164</a> TyKind::Alias(..) => { |
| <a href=#165 id=165 data-nosnippet>165</a> <span class="kw">if </span>infcx.type_is_copy_modulo_regions(env, ty) { |
| <a href=#166 id=166 data-nosnippet>166</a> DropGlue::None |
| <a href=#167 id=167 data-nosnippet>167</a> } <span class="kw">else </span>{ |
| <a href=#168 id=168 data-nosnippet>168</a> DropGlue::HasDropGlue |
| <a href=#169 id=169 data-nosnippet>169</a> } |
| <a href=#170 id=170 data-nosnippet>170</a> } |
| <a href=#171 id=171 data-nosnippet>171</a> TyKind::Param(<span class="kw">_</span>) => { |
| <a href=#172 id=172 data-nosnippet>172</a> <span class="kw">if </span>infcx.type_is_copy_modulo_regions(env, ty) { |
| <a href=#173 id=173 data-nosnippet>173</a> DropGlue::None |
| <a href=#174 id=174 data-nosnippet>174</a> } <span class="kw">else </span>{ |
| <a href=#175 id=175 data-nosnippet>175</a> DropGlue::DependOnParams |
| <a href=#176 id=176 data-nosnippet>176</a> } |
| <a href=#177 id=177 data-nosnippet>177</a> } |
| <a href=#178 id=178 data-nosnippet>178</a> TyKind::Infer(..) => <span class="macro">unreachable!</span>(<span class="string">"inference vars shouldn't exist out of inference"</span>), |
| <a href=#179 id=179 data-nosnippet>179</a> TyKind::Pat(..) | TyKind::UnsafeBinder(..) => { |
| <a href=#180 id=180 data-nosnippet>180</a> <span class="macro">never!</span>(<span class="string">"we do not handle pattern and unsafe binder types"</span>); |
| <a href=#181 id=181 data-nosnippet>181</a> DropGlue::None |
| <a href=#182 id=182 data-nosnippet>182</a> } |
| <a href=#183 id=183 data-nosnippet>183</a> } |
| <a href=#184 id=184 data-nosnippet>184</a>} |
| </code></pre></div></section></main></body></html> |
