src/librustdoc/passes/collect_trait_impls.rs

   1 use super::Pass;
   2 use crate::clean::*;
   3 use crate::core::DocContext;
   4 use crate::visit::DocVisitor;
   5
   6 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
   7 use rustc_hir::def_id::DefId;
   8 use rustc_middle::ty::DefIdTree;
   9 use rustc_span::symbol::sym;
  10
  11 crate const COLLECT_TRAIT_IMPLS: Pass = Pass {
  12     name: "collect-trait-impls",
  13     run: collect_trait_impls,
  14     description: "retrieves trait impls for items in the crate",
  15 };
  16
  17 crate fn collect_trait_impls(mut krate: Crate, cx: &mut DocContext<'_>) -> Crate {
  18     let synth_impls = cx.sess().time("collect_synthetic_impls", || {
  19         let mut synth = SyntheticImplCollector { cx, impls: Vec::new() };
  20         synth.visit_crate(&krate);
  21         synth.impls
  22     });
  23
  24     let prims: FxHashSet<PrimitiveType> = krate.primitives.iter().map(|p| p.1).collect();
  25
  26     let crate_items = {
  27         let mut coll = ItemCollector::new();
  28         cx.sess().time("collect_items_for_trait_impls", || coll.visit_crate(&krate));
  29         coll.items
  30     };
  31
  32     let mut new_items = Vec::new();
  33
  34     for &cnum in cx.tcx.crates(()).iter() {
  35         for &(did, _) in cx.tcx.all_trait_implementations(cnum).iter() {
  36             inline::build_impl(cx, None, did, None, &mut new_items);
  37         }
  38     }
  39
  40     // Also try to inline primitive impls from other crates.
  41     for &def_id in PrimitiveType::all_impls(cx.tcx).values().flatten() {
  42         if !def_id.is_local() {
  43             cx.tcx.sess.prof.generic_activity("build_primitive_trait_impls").run(|| {
  44                 inline::build_impl(cx, None, def_id, None, &mut new_items);
  45
  46                 // FIXME(eddyb) is this `doc(hidden)` check needed?
  47                 if !cx.tcx.get_attrs(def_id).lists(sym::doc).has_word(sym::hidden) {
  48                     let impls = get_auto_trait_and_blanket_impls(cx, def_id);
  49                     new_items.extend(impls.filter(|i| cx.inlined.insert(i.def_id)));
  50                 }
  51             });
  52         }
  53     }
  54
  55     let mut cleaner = BadImplStripper { prims, items: crate_items };
  56     let mut type_did_to_deref_target: FxHashMap<DefId, &Type> = FxHashMap::default();
  57
  58     // Follow all `Deref` targets of included items and recursively add them as valid
  59     fn add_deref_target(
  60         cx: &DocContext<'_>,
  61         map: &FxHashMap<DefId, &Type>,
  62         cleaner: &mut BadImplStripper,
  63         type_did: DefId,
  64     ) {
  65         if let Some(target) = map.get(&type_did) {
  66             debug!("add_deref_target: type {:?}, target {:?}", type_did, target);
  67             if let Some(target_prim) = target.primitive_type() {
  68                 cleaner.prims.insert(target_prim);
  69             } else if let Some(target_did) = target.def_id(&cx.cache) {
  70                 // `impl Deref<Target = S> for S`
  71                 if target_did == type_did {
  72                     // Avoid infinite cycles
  73                     return;
  74                 }
  75                 cleaner.items.insert(target_did.into());
  76                 add_deref_target(cx, map, cleaner, target_did);
  77             }
  78         }
  79     }
  80
  81     // scan through included items ahead of time to splice in Deref targets to the "valid" sets
  82     for it in &new_items {
  83         if let ImplItem(Impl { ref for_, ref trait_, ref items, .. }) = *it.kind {
  84             if trait_.as_ref().map(|t| t.def_id()) == cx.tcx.lang_items().deref_trait()
  85                 && cleaner.keep_impl(for_, true)
  86             {
  87                 let target = items
  88                     .iter()
  89                     .find_map(|item| match *item.kind {
  90                         TypedefItem(ref t, true) => Some(&t.type_),
  91                         _ => None,
  92                     })
  93                     .expect("Deref impl without Target type");
  94
  95                 if let Some(prim) = target.primitive_type() {
  96                     cleaner.prims.insert(prim);
  97                 } else if let Some(did) = target.def_id(&cx.cache) {
  98                     cleaner.items.insert(did.into());
  99                 }
 100                 if let Some(for_did) = for_.def_id_no_primitives() {
 101                     if type_did_to_deref_target.insert(for_did, target).is_none() {
 102                         // Since only the `DefId` portion of the `Type` instances is known to be same for both the
 103                         // `Deref` target type and the impl for type positions, this map of types is keyed by
 104                         // `DefId` and for convenience uses a special cleaner that accepts `DefId`s directly.
 105                         if cleaner.keep_impl_with_def_id(for_did.into()) {
 106                             add_deref_target(cx, &type_did_to_deref_target, &mut cleaner, for_did);
 107                         }
 108                     }
 109                 }
 110             }
 111         }
 112     }
 113
 114     new_items.retain(|it| {
 115         if let ImplItem(Impl { ref for_, ref trait_, ref kind, .. }) = *it.kind {
 116             cleaner.keep_impl(
 117                 for_,
 118                 trait_.as_ref().map(|t| t.def_id()) == cx.tcx.lang_items().deref_trait(),
 119             ) || trait_.as_ref().map_or(false, |t| cleaner.keep_impl_with_def_id(t.def_id().into()))
 120                 || kind.is_blanket()
 121         } else {
 122             true
 123         }
 124     });
 125
 126     // `tcx.crates(())` doesn't include the local crate, and `tcx.all_trait_implementations`
 127     // doesn't work with it anyway, so pull them from the HIR map instead
 128     let mut extra_attrs = Vec::new();
 129     for &trait_did in cx.tcx.all_traits(()).iter() {
 130         for &impl_did in cx.tcx.hir().trait_impls(trait_did) {
 131             let impl_did = impl_did.to_def_id();
 132             cx.tcx.sess.prof.generic_activity("build_local_trait_impl").run(|| {
 133                 let mut parent = cx.tcx.parent(impl_did);
 134                 while let Some(did) = parent {
 135                     extra_attrs.extend(
 136                         cx.tcx
 137                             .get_attrs(did)
 138                             .iter()
 139                             .filter(|attr| attr.has_name(sym::doc))
 140                             .filter(|attr| {
 141                                 if let Some([attr]) = attr.meta_item_list().as_deref() {
 142                                     attr.has_name(sym::cfg)
 143                                 } else {
 144                                     false
 145                                 }
 146                             })
 147                             .cloned(),
 148                     );
 149                     parent = cx.tcx.parent(did);
 150                 }
 151                 inline::build_impl(cx, None, impl_did, Some(&extra_attrs), &mut new_items);
 152                 extra_attrs.clear();
 153             });
 154         }
 155     }
 156
 157     if let ModuleItem(Module { items, .. }) = &mut *krate.module.kind {
 158         items.extend(synth_impls);
 159         items.extend(new_items);
 160     } else {
 161         panic!("collect-trait-impls can't run");
 162     };
 163
 164     krate
 165 }
 166
 167 struct SyntheticImplCollector<'a, 'tcx> {
 168     cx: &'a mut DocContext<'tcx>,
 169     impls: Vec<Item>,
 170 }
 171
 172 impl<'a, 'tcx> DocVisitor for SyntheticImplCollector<'a, 'tcx> {
 173     fn visit_item(&mut self, i: &Item) {
 174         if i.is_struct() || i.is_enum() || i.is_union() {
 175             // FIXME(eddyb) is this `doc(hidden)` check needed?
 176             if !self
 177                 .cx
 178                 .tcx
 179                 .get_attrs(i.def_id.expect_def_id())
 180                 .lists(sym::doc)
 181                 .has_word(sym::hidden)
 182             {
 183                 self.impls
 184                     .extend(get_auto_trait_and_blanket_impls(self.cx, i.def_id.expect_def_id()));
 185             }
 186         }
 187
 188         self.visit_item_recur(i)
 189     }
 190 }
 191
 192 #[derive(Default)]
 193 struct ItemCollector {
 194     items: FxHashSet<ItemId>,
 195 }
 196
 197 impl ItemCollector {
 198     fn new() -> Self {
 199         Self::default()
 200     }
 201 }
 202
 203 impl DocVisitor for ItemCollector {
 204     fn visit_item(&mut self, i: &Item) {
 205         self.items.insert(i.def_id);
 206
 207         self.visit_item_recur(i)
 208     }
 209 }
 210
 211 struct BadImplStripper {
 212     prims: FxHashSet<PrimitiveType>,
 213     items: FxHashSet<ItemId>,
 214 }
 215
 216 impl BadImplStripper {
 217     fn keep_impl(&self, ty: &Type, is_deref: bool) -> bool {
 218         if let Generic(_) = ty {
 219             // keep impls made on generics
 220             true
 221         } else if let Some(prim) = ty.primitive_type() {
 222             self.prims.contains(&prim)
 223         } else if let Some(did) = ty.def_id_no_primitives() {
 224             is_deref || self.keep_impl_with_def_id(did.into())
 225         } else {
 226             false
 227         }
 228     }
 229
 230     fn keep_impl_with_def_id(&self, did: ItemId) -> bool {
 231         self.items.contains(&did)
 232     }
 233 }