1 use crate::traits::specialization_graph;
2 use crate::ty::fast_reject::{self, SimplifiedType, SimplifyParams, StripReferences};
3 use crate::ty::fold::TypeFoldable;
4 use crate::ty::{Ty, TyCtxt};
6 use rustc_hir::def_id::DefId;
7 use rustc_hir::definitions::DefPathHash;
9 use rustc_data_structures::fx::FxIndexMap;
10 use rustc_errors::ErrorReported;
11 use rustc_macros::HashStable;
13 /// A trait's definition with type information.
16 // We already have the def_path_hash below, no need to hash it twice
17 #[stable_hasher(ignore)]
20 pub unsafety: hir::Unsafety,
22 /// If `true`, then this trait had the `#[rustc_paren_sugar]`
23 /// attribute, indicating that it should be used with `Foo()`
24 /// sugar. This is a temporary thing -- eventually any trait will
25 /// be usable with the sugar (or without it).
26 pub paren_sugar: bool,
28 pub has_auto_impl: bool,
30 /// If `true`, then this trait has the `#[marker]` attribute, indicating
31 /// that all its associated items have defaults that cannot be overridden,
32 /// and thus `impl`s of it are allowed to overlap.
35 /// If `true`, then this trait has the `#[rustc_skip_array_during_method_dispatch]`
36 /// attribute, indicating that editions before 2021 should not consider this trait
37 /// during method dispatch if the receiver is an array.
38 pub skip_array_during_method_dispatch: bool,
40 /// Used to determine whether the standard library is allowed to specialize
42 pub specialization_kind: TraitSpecializationKind,
44 /// The ICH of this trait's DefPath, cached here so it doesn't have to be
45 /// recomputed all the time.
46 pub def_path_hash: DefPathHash,
49 /// Whether this trait is treated specially by the standard library
50 /// specialization lint.
51 #[derive(HashStable, PartialEq, Clone, Copy, TyEncodable, TyDecodable)]
52 pub enum TraitSpecializationKind {
53 /// The default. Specializing on this trait is not allowed.
55 /// Specializing on this trait is allowed because it doesn't have any
56 /// methods. For example `Sized` or `FusedIterator`.
57 /// Applies to traits with the `rustc_unsafe_specialization_marker`
60 /// Specializing on this trait is allowed because all of the impls of this
61 /// trait are "always applicable". Always applicable means that if
62 /// `X<'x>: T<'y>` for any lifetimes, then `for<'a, 'b> X<'a>: T<'b>`.
63 /// Applies to traits with the `rustc_specialization_trait` attribute.
67 #[derive(Default, Debug, HashStable)]
68 pub struct TraitImpls {
69 blanket_impls: Vec<DefId>,
70 /// Impls indexed by their simplified self type, for fast lookup.
71 non_blanket_impls: FxIndexMap<SimplifiedType, Vec<DefId>>,
75 pub fn blanket_impls(&self) -> &[DefId] {
76 self.blanket_impls.as_slice()
83 unsafety: hir::Unsafety,
87 skip_array_during_method_dispatch: bool,
88 specialization_kind: TraitSpecializationKind,
89 def_path_hash: DefPathHash,
97 skip_array_during_method_dispatch,
107 ) -> Result<specialization_graph::Ancestors<'tcx>, ErrorReported> {
108 specialization_graph::ancestors(tcx, self.def_id, of_impl)
112 impl<'tcx> TyCtxt<'tcx> {
113 pub fn for_each_impl<F: FnMut(DefId)>(self, def_id: DefId, mut f: F) {
114 let impls = self.trait_impls_of(def_id);
116 for &impl_def_id in impls.blanket_impls.iter() {
120 for v in impls.non_blanket_impls.values() {
121 for &impl_def_id in v {
127 /// Iterate over every impl that could possibly match the
128 /// self type `self_ty`.
129 pub fn for_each_relevant_impl<F: FnMut(DefId)>(
135 let _: Option<()> = self.find_map_relevant_impl(def_id, self_ty, |did| {
141 /// Applies function to every impl that could possibly match the self type `self_ty` and returns
142 /// the first non-none value.
143 pub fn find_map_relevant_impl<T, F: FnMut(DefId) -> Option<T>>(
149 // FIXME: This depends on the set of all impls for the trait. That is
150 // unfortunate wrt. incremental compilation.
152 // If we want to be faster, we could have separate queries for
153 // blanket and non-blanket impls, and compare them separately.
154 let impls = self.trait_impls_of(def_id);
156 for &impl_def_id in impls.blanket_impls.iter() {
157 if let result @ Some(_) = f(impl_def_id) {
162 // Note that we're using `SimplifyParams::Yes` to query `non_blanket_impls` while using
163 // `SimplifyParams::No` while actually adding them.
165 // This way, when searching for some impl for `T: Trait`, we do not look at any impls
166 // whose outer level is not a parameter or projection. Especially for things like
167 // `T: Clone` this is incredibly useful as we would otherwise look at all the impls
168 // of `Clone` for `Option<T>`, `Vec<T>`, `ConcreteType` and so on.
170 fast_reject::simplify_type(self, self_ty, SimplifyParams::Yes, StripReferences::No)
172 if let Some(impls) = impls.non_blanket_impls.get(&simp) {
173 for &impl_def_id in impls {
174 if let result @ Some(_) = f(impl_def_id) {
180 for &impl_def_id in impls.non_blanket_impls.values().flatten() {
181 if let result @ Some(_) = f(impl_def_id) {
190 /// Returns an iterator containing all impls
191 pub fn all_impls(self, def_id: DefId) -> impl Iterator<Item = DefId> + 'tcx {
192 let TraitImpls { blanket_impls, non_blanket_impls } = self.trait_impls_of(def_id);
194 blanket_impls.iter().chain(non_blanket_impls.iter().map(|(_, v)| v).flatten()).cloned()
198 // Query provider for `trait_impls_of`.
199 pub(super) fn trait_impls_of_provider(tcx: TyCtxt<'_>, trait_id: DefId) -> TraitImpls {
200 let mut impls = TraitImpls::default();
202 // Traits defined in the current crate can't have impls in upstream
203 // crates, so we don't bother querying the cstore.
204 if !trait_id.is_local() {
205 for &cnum in tcx.crates(()).iter() {
206 for &(impl_def_id, simplified_self_ty) in
207 tcx.implementations_of_trait((cnum, trait_id)).iter()
209 if let Some(simplified_self_ty) = simplified_self_ty {
212 .entry(simplified_self_ty)
216 impls.blanket_impls.push(impl_def_id);
222 for &impl_def_id in tcx.hir().trait_impls(trait_id) {
223 let impl_def_id = impl_def_id.to_def_id();
225 let impl_self_ty = tcx.type_of(impl_def_id);
226 if impl_self_ty.references_error() {
230 if let Some(simplified_self_ty) =
231 fast_reject::simplify_type(tcx, impl_self_ty, SimplifyParams::No, StripReferences::No)
233 impls.non_blanket_impls.entry(simplified_self_ty).or_default().push(impl_def_id);
235 impls.blanket_impls.push(impl_def_id);