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.into());
  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_) && trait_.def_id() == cx.tcx.lang_items().deref_trait() {
  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() {
  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_.as_ref().map_or(false, |t| cleaner.keep_impl(t))
  82                 || blanket_impl.is_some()
  83         } else {
  84             true
  85         }
  86     });
  87
  88     // `tcx.crates(())` doesn't include the local crate, and `tcx.all_trait_implementations`
  89     // doesn't work with it anyway, so pull them from the HIR map instead
  90     let mut extra_attrs = Vec::new();
  91     for &trait_did in cx.tcx.all_traits(()).iter() {
  92         for &impl_did in cx.tcx.hir().trait_impls(trait_did) {
  93             let impl_did = impl_did.to_def_id();
  94             cx.tcx.sess.prof.generic_activity("build_local_trait_impl").run(|| {
  95                 let mut parent = cx.tcx.parent(impl_did);
  96                 while let Some(did) = parent {
  97                     extra_attrs.extend(
  98                         cx.tcx
  99                             .get_attrs(did)
 100                             .iter()
 101                             .filter(|attr| attr.has_name(sym::doc))
 102                             .filter(|attr| {
 103                                 if let Some([attr]) = attr.meta_item_list().as_deref() {
 104                                     attr.has_name(sym::cfg)
 105                                 } else {
 106                                     false
 107                                 }
 108                             })
 109                             .cloned(),
 110                     );
 111                     parent = cx.tcx.parent(did);
 112                 }
 113                 inline::build_impl(cx, None, impl_did, Some(&extra_attrs), &mut new_items);
 114                 extra_attrs.clear();
 115             });
 116         }
 117     }
 118
 119     let items = if let ModuleItem(Module { ref mut items, .. }) = *krate.module.kind {
 120         items
 121     } else {
 122         panic!("collect-trait-impls can't run");
 123     };
 124
 125     items.extend(synth_impls);
 126     items.extend(new_items);
 127     krate
 128 }
 129
 130 struct SyntheticImplCollector<'a, 'tcx> {
 131     cx: &'a mut DocContext<'tcx>,
 132     impls: Vec<Item>,
 133 }
 134
 135 impl<'a, 'tcx> DocFolder for SyntheticImplCollector<'a, 'tcx> {
 136     fn fold_item(&mut self, i: Item) -> Option<Item> {
 137         if i.is_struct() || i.is_enum() || i.is_union() {
 138             // FIXME(eddyb) is this `doc(hidden)` check needed?
 139             if !self.cx.tcx.get_attrs(i.def_id.expect_real()).lists(sym::doc).has_word(sym::hidden)
 140             {
 141                 self.impls
 142                     .extend(get_auto_trait_and_blanket_impls(self.cx, i.def_id.expect_real()));
 143             }
 144         }
 145
 146         Some(self.fold_item_recur(i))
 147     }
 148 }
 149
 150 #[derive(Default)]
 151 struct ItemCollector {
 152     items: FxHashSet<FakeDefId>,
 153 }
 154
 155 impl ItemCollector {
 156     fn new() -> Self {
 157         Self::default()
 158     }
 159 }
 160
 161 impl DocFolder for ItemCollector {
 162     fn fold_item(&mut self, i: Item) -> Option<Item> {
 163         self.items.insert(i.def_id);
 164
 165         Some(self.fold_item_recur(i))
 166     }
 167 }
 168
 169 struct BadImplStripper {
 170     prims: FxHashSet<PrimitiveType>,
 171     items: FxHashSet<FakeDefId>,
 172 }
 173
 174 impl BadImplStripper {
 175     fn keep_impl(&self, ty: &Type) -> bool {
 176         if let Generic(_) = ty {
 177             // keep impls made on generics
 178             true
 179         } else if let Some(prim) = ty.primitive_type() {
 180             self.prims.contains(&prim)
 181         } else if let Some(did) = ty.def_id() {
 182             self.keep_impl_with_def_id(did.into())
 183         } else {
 184             false
 185         }
 186     }
 187
 188     fn keep_impl_with_def_id(&self, did: FakeDefId) -> bool {
 189         self.items.contains(&did)
 190     }
 191 }