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             cx.tcx.sess.prof.generic_activity("build_extern_trait_impl").run(|| {
  35                 inline::build_impl(cx, None, did, None, &mut new_items);
  36             });
  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
  57     // scan through included items ahead of time to splice in Deref targets to the "valid" sets
  58     for it in &new_items {
  59         if let ImplItem(Impl { ref for_, ref trait_, ref items, .. }) = *it.kind {
  60             if cleaner.keep_impl(for_)
  61                 && trait_.as_ref().map(|t| t.def_id()) == cx.tcx.lang_items().deref_trait()
  62             {
  63                 let target = items
  64                     .iter()
  65                     .find_map(|item| match *item.kind {
  66                         TypedefItem(ref t, true) => Some(&t.type_),
  67                         _ => None,
  68                     })
  69                     .expect("Deref impl without Target type");
  70
  71                 if let Some(prim) = target.primitive_type() {
  72                     cleaner.prims.insert(prim);
  73                 } else if let Some(did) = target.def_id() {
  74                     cleaner.items.insert(did.into());
  75                 }
  76             }
  77         }
  78     }
  79
  80     new_items.retain(|it| {
  81         if let ImplItem(Impl { ref for_, ref trait_, ref blanket_impl, .. }) = *it.kind {
  82             cleaner.keep_impl(for_)
  83                 || trait_
  84                     .as_ref()
  85                     .map_or(false, |t| cleaner.keep_impl_with_def_id(t.def_id().into()))
  86                 || blanket_impl.is_some()
  87         } else {
  88             true
  89         }
  90     });
  91
  92     // `tcx.crates(())` doesn't include the local crate, and `tcx.all_trait_implementations`
  93     // doesn't work with it anyway, so pull them from the HIR map instead
  94     let mut extra_attrs = Vec::new();
  95     for &trait_did in cx.tcx.all_traits(()).iter() {
  96         for &impl_did in cx.tcx.hir().trait_impls(trait_did) {
  97             let impl_did = impl_did.to_def_id();
  98             cx.tcx.sess.prof.generic_activity("build_local_trait_impl").run(|| {
  99                 let mut parent = cx.tcx.parent(impl_did);
 100                 while let Some(did) = parent {
 101                     extra_attrs.extend(
 102                         cx.tcx
 103                             .get_attrs(did)
 104                             .iter()
 105                             .filter(|attr| attr.has_name(sym::doc))
 106                             .filter(|attr| {
 107                                 if let Some([attr]) = attr.meta_item_list().as_deref() {
 108                                     attr.has_name(sym::cfg)
 109                                 } else {
 110                                     false
 111                                 }
 112                             })
 113                             .cloned(),
 114                     );
 115                     parent = cx.tcx.parent(did);
 116                 }
 117                 inline::build_impl(cx, None, impl_did, Some(&extra_attrs), &mut new_items);
 118                 extra_attrs.clear();
 119             });
 120         }
 121     }
 122
 123     let items = if let ModuleItem(Module { ref mut items, .. }) = *krate.module.kind {
 124         items
 125     } else {
 126         panic!("collect-trait-impls can't run");
 127     };
 128
 129     items.extend(synth_impls);
 130     items.extend(new_items);
 131     krate
 132 }
 133
 134 struct SyntheticImplCollector<'a, 'tcx> {
 135     cx: &'a mut DocContext<'tcx>,
 136     impls: Vec<Item>,
 137 }
 138
 139 impl<'a, 'tcx> DocFolder for SyntheticImplCollector<'a, 'tcx> {
 140     fn fold_item(&mut self, i: Item) -> Option<Item> {
 141         if i.is_struct() || i.is_enum() || i.is_union() {
 142             // FIXME(eddyb) is this `doc(hidden)` check needed?
 143             if !self
 144                 .cx
 145                 .tcx
 146                 .get_attrs(i.def_id.expect_def_id())
 147                 .lists(sym::doc)
 148                 .has_word(sym::hidden)
 149             {
 150                 self.impls
 151                     .extend(get_auto_trait_and_blanket_impls(self.cx, i.def_id.expect_def_id()));
 152             }
 153         }
 154
 155         Some(self.fold_item_recur(i))
 156     }
 157 }
 158
 159 #[derive(Default)]
 160 struct ItemCollector {
 161     items: FxHashSet<ItemId>,
 162 }
 163
 164 impl ItemCollector {
 165     fn new() -> Self {
 166         Self::default()
 167     }
 168 }
 169
 170 impl DocFolder for ItemCollector {
 171     fn fold_item(&mut self, i: Item) -> Option<Item> {
 172         self.items.insert(i.def_id);
 173
 174         Some(self.fold_item_recur(i))
 175     }
 176 }
 177
 178 struct BadImplStripper {
 179     prims: FxHashSet<PrimitiveType>,
 180     items: FxHashSet<ItemId>,
 181 }
 182
 183 impl BadImplStripper {
 184     fn keep_impl(&self, ty: &Type) -> bool {
 185         if let Generic(_) = ty {
 186             // keep impls made on generics
 187             true
 188         } else if let Some(prim) = ty.primitive_type() {
 189             self.prims.contains(&prim)
 190         } else if let Some(did) = ty.def_id() {
 191             self.keep_impl_with_def_id(did.into())
 192         } else {
 193             false
 194         }
 195     }
 196
 197     fn keep_impl_with_def_id(&self, did: ItemId) -> bool {
 198         self.items.contains(&did)
 199     }
 200 }