1 //! Collects trait impls for each item in the crate. For example, if a crate
2 //! defines a struct that implements a trait, this pass will note that the
3 //! struct implements that trait.
6 use crate::core::DocContext;
7 use crate::formats::cache::Cache;
8 use crate::visit::DocVisitor;
10 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
11 use rustc_hir::def_id::DefId;
12 use rustc_middle::ty::DefIdTree;
13 use rustc_span::symbol::sym;
15 crate const COLLECT_TRAIT_IMPLS: Pass = Pass {
16 name: "collect-trait-impls",
17 run: collect_trait_impls,
18 description: "retrieves trait impls for items in the crate",
21 crate fn collect_trait_impls(mut krate: Crate, cx: &mut DocContext<'_>) -> Crate {
22 let synth_impls = cx.sess().time("collect_synthetic_impls", || {
23 let mut synth = SyntheticImplCollector { cx, impls: Vec::new() };
24 synth.visit_crate(&krate);
28 let prims: FxHashSet<PrimitiveType> = krate.primitives.iter().map(|p| p.1).collect();
31 let mut coll = ItemCollector::new();
32 cx.sess().time("collect_items_for_trait_impls", || coll.visit_crate(&krate));
36 let mut new_items = Vec::new();
38 // External trait impls.
39 cx.with_all_trait_impls(|cx, all_trait_impls| {
40 let _prof_timer = cx.tcx.sess.prof.generic_activity("build_extern_trait_impls");
41 for &impl_def_id in all_trait_impls.iter().skip_while(|def_id| def_id.is_local()) {
42 inline::build_impl(cx, None, impl_def_id, None, &mut new_items);
46 // Also try to inline primitive impls from other crates.
47 cx.tcx.sess.prof.generic_activity("build_primitive_trait_impls").run(|| {
48 for def_id in PrimitiveType::all_impls(cx.tcx) {
49 if !def_id.is_local() {
50 inline::build_impl(cx, None, def_id, None, &mut new_items);
52 // FIXME(eddyb) is this `doc(hidden)` check needed?
53 if !cx.tcx.is_doc_hidden(def_id) {
54 let impls = get_auto_trait_and_blanket_impls(cx, def_id);
55 new_items.extend(impls.filter(|i| cx.inlined.insert(i.def_id)));
61 let mut cleaner = BadImplStripper { prims, items: crate_items, cache: &cx.cache };
62 let mut type_did_to_deref_target: FxHashMap<DefId, &Type> = FxHashMap::default();
64 // Follow all `Deref` targets of included items and recursively add them as valid
67 map: &FxHashMap<DefId, &Type>,
68 cleaner: &mut BadImplStripper<'_>,
71 if let Some(target) = map.get(&type_did) {
72 debug!("add_deref_target: type {:?}, target {:?}", type_did, target);
73 if let Some(target_prim) = target.primitive_type() {
74 cleaner.prims.insert(target_prim);
75 } else if let Some(target_did) = target.def_id(&cx.cache) {
76 // `impl Deref<Target = S> for S`
77 if target_did == type_did {
78 // Avoid infinite cycles
81 cleaner.items.insert(target_did.into());
82 add_deref_target(cx, map, cleaner, target_did);
87 // scan through included items ahead of time to splice in Deref targets to the "valid" sets
88 for it in &new_items {
89 if let ImplItem(Impl { ref for_, ref trait_, ref items, .. }) = *it.kind {
90 if trait_.as_ref().map(|t| t.def_id()) == cx.tcx.lang_items().deref_trait()
91 && cleaner.keep_impl(for_, true)
95 .find_map(|item| match *item.kind {
96 AssocTypeItem(ref t, _) => Some(&t.type_),
99 .expect("Deref impl without Target type");
101 if let Some(prim) = target.primitive_type() {
102 cleaner.prims.insert(prim);
103 } else if let Some(did) = target.def_id(&cx.cache) {
104 cleaner.items.insert(did.into());
106 if let Some(for_did) = for_.def_id(&cx.cache) {
107 if type_did_to_deref_target.insert(for_did, target).is_none() {
108 // Since only the `DefId` portion of the `Type` instances is known to be same for both the
109 // `Deref` target type and the impl for type positions, this map of types is keyed by
110 // `DefId` and for convenience uses a special cleaner that accepts `DefId`s directly.
111 if cleaner.keep_impl_with_def_id(for_did.into()) {
112 add_deref_target(cx, &type_did_to_deref_target, &mut cleaner, for_did);
120 new_items.retain(|it| {
121 if let ImplItem(Impl { ref for_, ref trait_, ref kind, .. }) = *it.kind {
124 trait_.as_ref().map(|t| t.def_id()) == cx.tcx.lang_items().deref_trait(),
125 ) || trait_.as_ref().map_or(false, |t| cleaner.keep_impl_with_def_id(t.def_id().into()))
132 // Local trait impls.
133 cx.with_all_trait_impls(|cx, all_trait_impls| {
134 let _prof_timer = cx.tcx.sess.prof.generic_activity("build_local_trait_impls");
135 let mut attr_buf = Vec::new();
136 for &impl_def_id in all_trait_impls.iter().take_while(|def_id| def_id.is_local()) {
137 let mut parent = cx.tcx.parent(impl_def_id);
138 while let Some(did) = parent {
143 .filter(|attr| attr.has_name(sym::doc))
145 if let Some([attr]) = attr.meta_item_list().as_deref() {
146 attr.has_name(sym::cfg)
153 parent = cx.tcx.parent(did);
155 inline::build_impl(cx, None, impl_def_id, Some(&attr_buf), &mut new_items);
160 if let ModuleItem(Module { items, .. }) = &mut *krate.module.kind {
161 items.extend(synth_impls);
162 items.extend(new_items);
164 panic!("collect-trait-impls can't run");
170 struct SyntheticImplCollector<'a, 'tcx> {
171 cx: &'a mut DocContext<'tcx>,
175 impl<'a, 'tcx> DocVisitor for SyntheticImplCollector<'a, 'tcx> {
176 fn visit_item(&mut self, i: &Item) {
177 if i.is_struct() || i.is_enum() || i.is_union() {
178 // FIXME(eddyb) is this `doc(hidden)` check needed?
179 if !self.cx.tcx.is_doc_hidden(i.def_id.expect_def_id()) {
181 .extend(get_auto_trait_and_blanket_impls(self.cx, i.def_id.expect_def_id()));
185 self.visit_item_recur(i)
190 struct ItemCollector {
191 items: FxHashSet<ItemId>,
200 impl DocVisitor for ItemCollector {
201 fn visit_item(&mut self, i: &Item) {
202 self.items.insert(i.def_id);
204 self.visit_item_recur(i)
208 struct BadImplStripper<'a> {
209 prims: FxHashSet<PrimitiveType>,
210 items: FxHashSet<ItemId>,
214 impl<'a> BadImplStripper<'a> {
215 fn keep_impl(&self, ty: &Type, is_deref: bool) -> bool {
216 if let Generic(_) = ty {
217 // keep impls made on generics
219 } else if let Some(prim) = ty.primitive_type() {
220 self.prims.contains(&prim)
221 } else if let Some(did) = ty.def_id(self.cache) {
222 is_deref || self.keep_impl_with_def_id(did.into())
228 fn keep_impl_with_def_id(&self, did: ItemId) -> bool {
229 self.items.contains(&did)