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Commit | Line | Data |
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9fa01778 XL |
1 | use crate::ich::{self, StableHashingContext}; |
2 | use crate::traits::specialization_graph; | |
3 | use crate::ty::fast_reject; | |
4 | use crate::ty::fold::TypeFoldable; | |
5 | use crate::ty::{Ty, TyCtxt}; | |
dfeec247 | 6 | use rustc_hir as hir; |
6a06907d | 7 | use rustc_hir::def_id::{CrateNum, DefId, LocalDefId}; |
ba9703b0 | 8 | use rustc_hir::definitions::DefPathHash; |
041b39d2 XL |
9 | |
10 | use rustc_data_structures::fx::FxHashMap; | |
e74abb32 | 11 | use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; |
ba9703b0 | 12 | use rustc_errors::ErrorReported; |
532ac7d7 | 13 | use rustc_macros::HashStable; |
ba9703b0 | 14 | use std::collections::BTreeMap; |
8bb4bdeb | 15 | |
476ff2be | 16 | /// A trait's definition with type information. |
532ac7d7 | 17 | #[derive(HashStable)] |
476ff2be | 18 | pub struct TraitDef { |
532ac7d7 XL |
19 | // We already have the def_path_hash below, no need to hash it twice |
20 | #[stable_hasher(ignore)] | |
476ff2be | 21 | pub def_id: DefId, |
9cc50fc6 | 22 | |
9cc50fc6 SL |
23 | pub unsafety: hir::Unsafety, |
24 | ||
25 | /// If `true`, then this trait had the `#[rustc_paren_sugar]` | |
26 | /// attribute, indicating that it should be used with `Foo()` | |
32a655c1 | 27 | /// sugar. This is a temporary thing -- eventually any trait will |
9cc50fc6 SL |
28 | /// be usable with the sugar (or without it). |
29 | pub paren_sugar: bool, | |
30 | ||
abe05a73 | 31 | pub has_auto_impl: bool, |
8bb4bdeb | 32 | |
0bf4aa26 XL |
33 | /// If `true`, then this trait has the `#[marker]` attribute, indicating |
34 | /// that all its associated items have defaults that cannot be overridden, | |
35 | /// and thus `impl`s of it are allowed to overlap. | |
36 | pub is_marker: bool, | |
37 | ||
ba9703b0 XL |
38 | /// Used to determine whether the standard library is allowed to specialize |
39 | /// on this trait. | |
40 | pub specialization_kind: TraitSpecializationKind, | |
41 | ||
9e0c209e SL |
42 | /// The ICH of this trait's DefPath, cached here so it doesn't have to be |
43 | /// recomputed all the time. | |
7cac9316 | 44 | pub def_path_hash: DefPathHash, |
9cc50fc6 SL |
45 | } |
46 | ||
ba9703b0 XL |
47 | /// Whether this trait is treated specially by the standard library |
48 | /// specialization lint. | |
3dfed10e | 49 | #[derive(HashStable, PartialEq, Clone, Copy, TyEncodable, TyDecodable)] |
ba9703b0 XL |
50 | pub enum TraitSpecializationKind { |
51 | /// The default. Specializing on this trait is not allowed. | |
52 | None, | |
53 | /// Specializing on this trait is allowed because it doesn't have any | |
54 | /// methods. For example `Sized` or `FusedIterator`. | |
55 | /// Applies to traits with the `rustc_unsafe_specialization_marker` | |
56 | /// attribute. | |
57 | Marker, | |
58 | /// Specializing on this trait is allowed because all of the impls of this | |
59 | /// trait are "always applicable". Always applicable means that if | |
60 | /// `X<'x>: T<'y>` for any lifetimes, then `for<'a, 'b> X<'a>: T<'b>`. | |
61 | /// Applies to traits with the `rustc_specialization_trait` attribute. | |
62 | AlwaysApplicable, | |
63 | } | |
64 | ||
5869c6ff | 65 | #[derive(Default, Debug)] |
7cac9316 | 66 | pub struct TraitImpls { |
041b39d2 | 67 | blanket_impls: Vec<DefId>, |
9fa01778 | 68 | /// Impls indexed by their simplified self type, for fast lookup. |
041b39d2 | 69 | non_blanket_impls: FxHashMap<fast_reject::SimplifiedType, Vec<DefId>>, |
7cac9316 | 70 | } |
9cc50fc6 | 71 | |
dc9dc135 | 72 | impl<'tcx> TraitDef { |
dfeec247 XL |
73 | pub fn new( |
74 | def_id: DefId, | |
75 | unsafety: hir::Unsafety, | |
76 | paren_sugar: bool, | |
77 | has_auto_impl: bool, | |
78 | is_marker: bool, | |
ba9703b0 | 79 | specialization_kind: TraitSpecializationKind, |
dfeec247 XL |
80 | def_path_hash: DefPathHash, |
81 | ) -> TraitDef { | |
ba9703b0 XL |
82 | TraitDef { |
83 | def_id, | |
84 | unsafety, | |
85 | paren_sugar, | |
86 | has_auto_impl, | |
87 | is_marker, | |
88 | specialization_kind, | |
89 | def_path_hash, | |
90 | } | |
54a0048b | 91 | } |
9cc50fc6 | 92 | |
dc9dc135 XL |
93 | pub fn ancestors( |
94 | &self, | |
95 | tcx: TyCtxt<'tcx>, | |
96 | of_impl: DefId, | |
ba9703b0 | 97 | ) -> Result<specialization_graph::Ancestors<'tcx>, ErrorReported> { |
7cac9316 | 98 | specialization_graph::ancestors(tcx, self.def_id, of_impl) |
8bb4bdeb | 99 | } |
041b39d2 | 100 | } |
8bb4bdeb | 101 | |
dc9dc135 | 102 | impl<'tcx> TyCtxt<'tcx> { |
041b39d2 XL |
103 | pub fn for_each_impl<F: FnMut(DefId)>(self, def_id: DefId, mut f: F) { |
104 | let impls = self.trait_impls_of(def_id); | |
105 | ||
106 | for &impl_def_id in impls.blanket_impls.iter() { | |
9cc50fc6 SL |
107 | f(impl_def_id); |
108 | } | |
041b39d2 XL |
109 | |
110 | for v in impls.non_blanket_impls.values() { | |
111 | for &impl_def_id in v { | |
112 | f(impl_def_id); | |
113 | } | |
114 | } | |
9cc50fc6 SL |
115 | } |
116 | ||
117 | /// Iterate over every impl that could possibly match the | |
9fa01778 | 118 | /// self type `self_ty`. |
dfeec247 XL |
119 | pub fn for_each_relevant_impl<F: FnMut(DefId)>( |
120 | self, | |
121 | def_id: DefId, | |
122 | self_ty: Ty<'tcx>, | |
123 | mut f: F, | |
124 | ) { | |
29967ef6 XL |
125 | let _: Option<()> = self.find_map_relevant_impl(def_id, self_ty, |did| { |
126 | f(did); | |
127 | None | |
128 | }); | |
129 | } | |
130 | ||
131 | /// Applies function to every impl that could possibly match the self type `self_ty` and returns | |
132 | /// the first non-none value. | |
133 | pub fn find_map_relevant_impl<T, F: FnMut(DefId) -> Option<T>>( | |
134 | self, | |
135 | def_id: DefId, | |
136 | self_ty: Ty<'tcx>, | |
137 | mut f: F, | |
138 | ) -> Option<T> { | |
041b39d2 XL |
139 | let impls = self.trait_impls_of(def_id); |
140 | ||
141 | for &impl_def_id in impls.blanket_impls.iter() { | |
29967ef6 XL |
142 | if let result @ Some(_) = f(impl_def_id) { |
143 | return result; | |
144 | } | |
041b39d2 XL |
145 | } |
146 | ||
9cc50fc6 SL |
147 | // simplify_type(.., false) basically replaces type parameters and |
148 | // projections with infer-variables. This is, of course, done on | |
149 | // the impl trait-ref when it is instantiated, but not on the | |
150 | // predicate trait-ref which is passed here. | |
151 | // | |
152 | // for example, if we match `S: Copy` against an impl like | |
153 | // `impl<T:Copy> Copy for Option<T>`, we replace the type variable | |
154 | // in `Option<T>` with an infer variable, to `Option<_>` (this | |
155 | // doesn't actually change fast_reject output), but we don't | |
156 | // replace `S` with anything - this impl of course can't be | |
157 | // selected, and as there are hundreds of similar impls, | |
158 | // considering them would significantly harm performance. | |
7cac9316 | 159 | |
041b39d2 XL |
160 | // This depends on the set of all impls for the trait. That is |
161 | // unfortunate. When we get red-green recompilation, we would like | |
162 | // to have a way of knowing whether the set of relevant impls | |
163 | // changed. The most naive | |
164 | // way would be to compute the Vec of relevant impls and see whether | |
165 | // it differs between compilations. That shouldn't be too slow by | |
166 | // itself - we do quite a bit of work for each relevant impl anyway. | |
167 | // | |
168 | // If we want to be faster, we could have separate queries for | |
169 | // blanket and non-blanket impls, and compare them separately. | |
170 | // | |
171 | // I think we'll cross that bridge when we get to it. | |
172 | if let Some(simp) = fast_reject::simplify_type(self, self_ty, true) { | |
173 | if let Some(impls) = impls.non_blanket_impls.get(&simp) { | |
174 | for &impl_def_id in impls { | |
29967ef6 XL |
175 | if let result @ Some(_) = f(impl_def_id) { |
176 | return result; | |
177 | } | |
041b39d2 XL |
178 | } |
179 | } | |
180 | } else { | |
0bf4aa26 | 181 | for &impl_def_id in impls.non_blanket_impls.values().flatten() { |
29967ef6 XL |
182 | if let result @ Some(_) = f(impl_def_id) { |
183 | return result; | |
184 | } | |
041b39d2 | 185 | } |
9cc50fc6 | 186 | } |
29967ef6 XL |
187 | |
188 | None | |
9cc50fc6 | 189 | } |
0bf4aa26 | 190 | |
1b1a35ee | 191 | /// Returns an iterator containing all impls |
ba9703b0 XL |
192 | pub fn all_impls(self, def_id: DefId) -> impl Iterator<Item = DefId> + 'tcx { |
193 | let TraitImpls { blanket_impls, non_blanket_impls } = self.trait_impls_of(def_id); | |
0bf4aa26 | 194 | |
f9f354fc | 195 | blanket_impls.iter().chain(non_blanket_impls.iter().map(|(_, v)| v).flatten()).cloned() |
0bf4aa26 | 196 | } |
9cc50fc6 SL |
197 | } |
198 | ||
ba9703b0 XL |
199 | // Query provider for `all_local_trait_impls`. |
200 | pub(super) fn all_local_trait_impls<'tcx>( | |
201 | tcx: TyCtxt<'tcx>, | |
202 | krate: CrateNum, | |
6a06907d | 203 | ) -> &'tcx BTreeMap<DefId, Vec<LocalDefId>> { |
ba9703b0 XL |
204 | &tcx.hir_crate(krate).trait_impls |
205 | } | |
206 | ||
7cac9316 | 207 | // Query provider for `trait_impls_of`. |
f9f354fc | 208 | pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> TraitImpls { |
b7449926 | 209 | let mut impls = TraitImpls::default(); |
7cac9316 | 210 | |
3dfed10e XL |
211 | // Traits defined in the current crate can't have impls in upstream |
212 | // crates, so we don't bother querying the cstore. | |
213 | if !trait_id.is_local() { | |
214 | for &cnum in tcx.crates().iter() { | |
215 | for &(impl_def_id, simplified_self_ty) in | |
216 | tcx.implementations_of_trait((cnum, trait_id)).iter() | |
217 | { | |
218 | if let Some(simplified_self_ty) = simplified_self_ty { | |
219 | impls | |
220 | .non_blanket_impls | |
221 | .entry(simplified_self_ty) | |
222 | .or_default() | |
223 | .push(impl_def_id); | |
224 | } else { | |
225 | impls.blanket_impls.push(impl_def_id); | |
b7449926 XL |
226 | } |
227 | } | |
7cac9316 | 228 | } |
3dfed10e XL |
229 | } |
230 | ||
6a06907d XL |
231 | for &impl_def_id in tcx.hir().trait_impls(trait_id) { |
232 | let impl_def_id = impl_def_id.to_def_id(); | |
3dfed10e XL |
233 | |
234 | let impl_self_ty = tcx.type_of(impl_def_id); | |
235 | if impl_self_ty.references_error() { | |
236 | continue; | |
237 | } | |
7cac9316 | 238 | |
3dfed10e XL |
239 | if let Some(simplified_self_ty) = fast_reject::simplify_type(tcx, impl_self_ty, false) { |
240 | impls.non_blanket_impls.entry(simplified_self_ty).or_default().push(impl_def_id); | |
241 | } else { | |
242 | impls.blanket_impls.push(impl_def_id); | |
7cac9316 XL |
243 | } |
244 | } | |
245 | ||
f9f354fc | 246 | impls |
9cc50fc6 | 247 | } |
ea8adc8c | 248 | |
0531ce1d | 249 | impl<'a> HashStable<StableHashingContext<'a>> for TraitImpls { |
e74abb32 | 250 | fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { |
dfeec247 | 251 | let TraitImpls { ref blanket_impls, ref non_blanket_impls } = *self; |
ea8adc8c XL |
252 | |
253 | ich::hash_stable_trait_impls(hcx, hasher, blanket_impls, non_blanket_impls); | |
254 | } | |
255 | } |