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