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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; |
17df50a5 | 7 | use rustc_hir::def_id::DefId; |
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; |
8bb4bdeb | 14 | |
476ff2be | 15 | /// A trait's definition with type information. |
532ac7d7 | 16 | #[derive(HashStable)] |
476ff2be | 17 | pub struct TraitDef { |
532ac7d7 XL |
18 | // We already have the def_path_hash below, no need to hash it twice |
19 | #[stable_hasher(ignore)] | |
476ff2be | 20 | pub def_id: DefId, |
9cc50fc6 | 21 | |
9cc50fc6 SL |
22 | pub unsafety: hir::Unsafety, |
23 | ||
24 | /// If `true`, then this trait had the `#[rustc_paren_sugar]` | |
25 | /// attribute, indicating that it should be used with `Foo()` | |
32a655c1 | 26 | /// sugar. This is a temporary thing -- eventually any trait will |
9cc50fc6 SL |
27 | /// be usable with the sugar (or without it). |
28 | pub paren_sugar: bool, | |
29 | ||
abe05a73 | 30 | pub has_auto_impl: bool, |
8bb4bdeb | 31 | |
0bf4aa26 XL |
32 | /// If `true`, then this trait has the `#[marker]` attribute, indicating |
33 | /// that all its associated items have defaults that cannot be overridden, | |
34 | /// and thus `impl`s of it are allowed to overlap. | |
35 | pub is_marker: bool, | |
36 | ||
cdc7bbd5 XL |
37 | /// If `true`, then this trait has the `#[rustc_skip_array_during_method_dispatch]` |
38 | /// attribute, indicating that editions before 2021 should not consider this trait | |
39 | /// during method dispatch if the receiver is an array. | |
40 | pub skip_array_during_method_dispatch: bool, | |
41 | ||
ba9703b0 XL |
42 | /// Used to determine whether the standard library is allowed to specialize |
43 | /// on this trait. | |
44 | pub specialization_kind: TraitSpecializationKind, | |
45 | ||
9e0c209e SL |
46 | /// The ICH of this trait's DefPath, cached here so it doesn't have to be |
47 | /// recomputed all the time. | |
7cac9316 | 48 | pub def_path_hash: DefPathHash, |
9cc50fc6 SL |
49 | } |
50 | ||
ba9703b0 XL |
51 | /// Whether this trait is treated specially by the standard library |
52 | /// specialization lint. | |
3dfed10e | 53 | #[derive(HashStable, PartialEq, Clone, Copy, TyEncodable, TyDecodable)] |
ba9703b0 XL |
54 | pub enum TraitSpecializationKind { |
55 | /// The default. Specializing on this trait is not allowed. | |
56 | None, | |
57 | /// Specializing on this trait is allowed because it doesn't have any | |
58 | /// methods. For example `Sized` or `FusedIterator`. | |
59 | /// Applies to traits with the `rustc_unsafe_specialization_marker` | |
60 | /// attribute. | |
61 | Marker, | |
62 | /// Specializing on this trait is allowed because all of the impls of this | |
63 | /// trait are "always applicable". Always applicable means that if | |
64 | /// `X<'x>: T<'y>` for any lifetimes, then `for<'a, 'b> X<'a>: T<'b>`. | |
65 | /// Applies to traits with the `rustc_specialization_trait` attribute. | |
66 | AlwaysApplicable, | |
67 | } | |
68 | ||
5869c6ff | 69 | #[derive(Default, Debug)] |
7cac9316 | 70 | pub struct TraitImpls { |
041b39d2 | 71 | blanket_impls: Vec<DefId>, |
9fa01778 | 72 | /// Impls indexed by their simplified self type, for fast lookup. |
041b39d2 | 73 | non_blanket_impls: FxHashMap<fast_reject::SimplifiedType, Vec<DefId>>, |
7cac9316 | 74 | } |
9cc50fc6 | 75 | |
cdc7bbd5 XL |
76 | impl TraitImpls { |
77 | pub fn blanket_impls(&self) -> &[DefId] { | |
78 | self.blanket_impls.as_slice() | |
79 | } | |
80 | } | |
81 | ||
dc9dc135 | 82 | impl<'tcx> TraitDef { |
dfeec247 XL |
83 | pub fn new( |
84 | def_id: DefId, | |
85 | unsafety: hir::Unsafety, | |
86 | paren_sugar: bool, | |
87 | has_auto_impl: bool, | |
88 | is_marker: bool, | |
cdc7bbd5 | 89 | skip_array_during_method_dispatch: bool, |
ba9703b0 | 90 | specialization_kind: TraitSpecializationKind, |
dfeec247 XL |
91 | def_path_hash: DefPathHash, |
92 | ) -> TraitDef { | |
ba9703b0 XL |
93 | TraitDef { |
94 | def_id, | |
95 | unsafety, | |
96 | paren_sugar, | |
97 | has_auto_impl, | |
98 | is_marker, | |
cdc7bbd5 | 99 | skip_array_during_method_dispatch, |
ba9703b0 XL |
100 | specialization_kind, |
101 | def_path_hash, | |
102 | } | |
54a0048b | 103 | } |
9cc50fc6 | 104 | |
dc9dc135 XL |
105 | pub fn ancestors( |
106 | &self, | |
107 | tcx: TyCtxt<'tcx>, | |
108 | of_impl: DefId, | |
ba9703b0 | 109 | ) -> Result<specialization_graph::Ancestors<'tcx>, ErrorReported> { |
7cac9316 | 110 | specialization_graph::ancestors(tcx, self.def_id, of_impl) |
8bb4bdeb | 111 | } |
041b39d2 | 112 | } |
8bb4bdeb | 113 | |
dc9dc135 | 114 | impl<'tcx> TyCtxt<'tcx> { |
041b39d2 XL |
115 | pub fn for_each_impl<F: FnMut(DefId)>(self, def_id: DefId, mut f: F) { |
116 | let impls = self.trait_impls_of(def_id); | |
117 | ||
118 | for &impl_def_id in impls.blanket_impls.iter() { | |
9cc50fc6 SL |
119 | f(impl_def_id); |
120 | } | |
041b39d2 XL |
121 | |
122 | for v in impls.non_blanket_impls.values() { | |
123 | for &impl_def_id in v { | |
124 | f(impl_def_id); | |
125 | } | |
126 | } | |
9cc50fc6 SL |
127 | } |
128 | ||
129 | /// Iterate over every impl that could possibly match the | |
9fa01778 | 130 | /// self type `self_ty`. |
dfeec247 XL |
131 | pub fn for_each_relevant_impl<F: FnMut(DefId)>( |
132 | self, | |
133 | def_id: DefId, | |
134 | self_ty: Ty<'tcx>, | |
135 | mut f: F, | |
136 | ) { | |
29967ef6 XL |
137 | let _: Option<()> = self.find_map_relevant_impl(def_id, self_ty, |did| { |
138 | f(did); | |
139 | None | |
140 | }); | |
141 | } | |
142 | ||
143 | /// Applies function to every impl that could possibly match the self type `self_ty` and returns | |
144 | /// the first non-none value. | |
145 | pub fn find_map_relevant_impl<T, F: FnMut(DefId) -> Option<T>>( | |
146 | self, | |
147 | def_id: DefId, | |
148 | self_ty: Ty<'tcx>, | |
149 | mut f: F, | |
150 | ) -> Option<T> { | |
041b39d2 XL |
151 | let impls = self.trait_impls_of(def_id); |
152 | ||
153 | for &impl_def_id in impls.blanket_impls.iter() { | |
29967ef6 XL |
154 | if let result @ Some(_) = f(impl_def_id) { |
155 | return result; | |
156 | } | |
041b39d2 XL |
157 | } |
158 | ||
9cc50fc6 SL |
159 | // simplify_type(.., false) basically replaces type parameters and |
160 | // projections with infer-variables. This is, of course, done on | |
161 | // the impl trait-ref when it is instantiated, but not on the | |
162 | // predicate trait-ref which is passed here. | |
163 | // | |
164 | // for example, if we match `S: Copy` against an impl like | |
165 | // `impl<T:Copy> Copy for Option<T>`, we replace the type variable | |
166 | // in `Option<T>` with an infer variable, to `Option<_>` (this | |
167 | // doesn't actually change fast_reject output), but we don't | |
168 | // replace `S` with anything - this impl of course can't be | |
169 | // selected, and as there are hundreds of similar impls, | |
170 | // considering them would significantly harm performance. | |
7cac9316 | 171 | |
041b39d2 XL |
172 | // This depends on the set of all impls for the trait. That is |
173 | // unfortunate. When we get red-green recompilation, we would like | |
174 | // to have a way of knowing whether the set of relevant impls | |
175 | // changed. The most naive | |
176 | // way would be to compute the Vec of relevant impls and see whether | |
177 | // it differs between compilations. That shouldn't be too slow by | |
178 | // itself - we do quite a bit of work for each relevant impl anyway. | |
179 | // | |
180 | // If we want to be faster, we could have separate queries for | |
181 | // blanket and non-blanket impls, and compare them separately. | |
182 | // | |
183 | // I think we'll cross that bridge when we get to it. | |
184 | if let Some(simp) = fast_reject::simplify_type(self, self_ty, true) { | |
185 | if let Some(impls) = impls.non_blanket_impls.get(&simp) { | |
186 | for &impl_def_id in impls { | |
29967ef6 XL |
187 | if let result @ Some(_) = f(impl_def_id) { |
188 | return result; | |
189 | } | |
041b39d2 XL |
190 | } |
191 | } | |
192 | } else { | |
0bf4aa26 | 193 | for &impl_def_id in impls.non_blanket_impls.values().flatten() { |
29967ef6 XL |
194 | if let result @ Some(_) = f(impl_def_id) { |
195 | return result; | |
196 | } | |
041b39d2 | 197 | } |
9cc50fc6 | 198 | } |
29967ef6 XL |
199 | |
200 | None | |
9cc50fc6 | 201 | } |
0bf4aa26 | 202 | |
1b1a35ee | 203 | /// Returns an iterator containing all impls |
ba9703b0 XL |
204 | pub fn all_impls(self, def_id: DefId) -> impl Iterator<Item = DefId> + 'tcx { |
205 | let TraitImpls { blanket_impls, non_blanket_impls } = self.trait_impls_of(def_id); | |
0bf4aa26 | 206 | |
f9f354fc | 207 | blanket_impls.iter().chain(non_blanket_impls.iter().map(|(_, v)| v).flatten()).cloned() |
0bf4aa26 | 208 | } |
9cc50fc6 SL |
209 | } |
210 | ||
7cac9316 | 211 | // Query provider for `trait_impls_of`. |
f9f354fc | 212 | pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> TraitImpls { |
b7449926 | 213 | let mut impls = TraitImpls::default(); |
7cac9316 | 214 | |
3dfed10e XL |
215 | // Traits defined in the current crate can't have impls in upstream |
216 | // crates, so we don't bother querying the cstore. | |
217 | if !trait_id.is_local() { | |
136023e0 | 218 | for &cnum in tcx.crates(()).iter() { |
3dfed10e XL |
219 | for &(impl_def_id, simplified_self_ty) in |
220 | tcx.implementations_of_trait((cnum, trait_id)).iter() | |
221 | { | |
222 | if let Some(simplified_self_ty) = simplified_self_ty { | |
223 | impls | |
224 | .non_blanket_impls | |
225 | .entry(simplified_self_ty) | |
226 | .or_default() | |
227 | .push(impl_def_id); | |
228 | } else { | |
229 | impls.blanket_impls.push(impl_def_id); | |
b7449926 XL |
230 | } |
231 | } | |
7cac9316 | 232 | } |
3dfed10e XL |
233 | } |
234 | ||
6a06907d XL |
235 | for &impl_def_id in tcx.hir().trait_impls(trait_id) { |
236 | let impl_def_id = impl_def_id.to_def_id(); | |
3dfed10e XL |
237 | |
238 | let impl_self_ty = tcx.type_of(impl_def_id); | |
239 | if impl_self_ty.references_error() { | |
240 | continue; | |
241 | } | |
7cac9316 | 242 | |
3dfed10e XL |
243 | if let Some(simplified_self_ty) = fast_reject::simplify_type(tcx, impl_self_ty, false) { |
244 | impls.non_blanket_impls.entry(simplified_self_ty).or_default().push(impl_def_id); | |
245 | } else { | |
246 | impls.blanket_impls.push(impl_def_id); | |
7cac9316 XL |
247 | } |
248 | } | |
249 | ||
f9f354fc | 250 | impls |
9cc50fc6 | 251 | } |
ea8adc8c | 252 | |
0531ce1d | 253 | impl<'a> HashStable<StableHashingContext<'a>> for TraitImpls { |
e74abb32 | 254 | fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { |
dfeec247 | 255 | let TraitImpls { ref blanket_impls, ref non_blanket_impls } = *self; |
ea8adc8c XL |
256 | |
257 | ich::hash_stable_trait_impls(hcx, hasher, blanket_impls, non_blanket_impls); | |
258 | } | |
259 | } |