src/librustdoc/passes/collect_trait_impls.rs

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