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, LOCAL_CRATE};
   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             cx.tcx.sess.prof.generic_activity("build_extern_trait_impl").run(|| {
  36                 inline::build_impl(cx, None, did, None, &mut new_items);
  37             });
  38         }
  39     }
  40
  41     // Also try to inline primitive impls from other crates.
  42     for &def_id in PrimitiveType::all_impls(cx.tcx).values().flatten() {
  43         if !def_id.is_local() {
  44             cx.tcx.sess.prof.generic_activity("build_primitive_trait_impls").run(|| {
  45                 inline::build_impl(cx, None, def_id, None, &mut new_items);
  46
  47                 // FIXME(eddyb) is this `doc(hidden)` check needed?
  48                 if !cx.tcx.get_attrs(def_id).lists(sym::doc).has_word(sym::hidden) {
  49                     let impls = get_auto_trait_and_blanket_impls(cx, def_id.into());
  50                     new_items.extend(impls.filter(|i| cx.inlined.insert(i.def_id)));
  51                 }
  52             });
  53         }
  54     }
  55
  56     // `tcx.crates()` doesn't include the local crate, and `tcx.all_trait_implementations`
  57     // doesn't work with it anyway, so pull them from the HIR map instead
  58     let mut extra_attrs = Vec::new();
  59     for &trait_did in cx.tcx.all_traits(LOCAL_CRATE).iter() {
  60         for &impl_did in cx.tcx.hir().trait_impls(trait_did) {
  61             let impl_did = impl_did.to_def_id();
  62             cx.tcx.sess.prof.generic_activity("build_local_trait_impl").run(|| {
  63                 let mut parent = cx.tcx.parent(impl_did);
  64                 while let Some(did) = parent {
  65                     extra_attrs.extend(
  66                         cx.tcx
  67                             .get_attrs(did)
  68                             .iter()
  69                             .filter(|attr| attr.has_name(sym::doc))
  70                             .filter(|attr| {
  71                                 if let Some([attr]) = attr.meta_item_list().as_deref() {
  72                                     attr.has_name(sym::cfg)
  73                                 } else {
  74                                     false
  75                                 }
  76                             })
  77                             .cloned(),
  78                     );
  79                     parent = cx.tcx.parent(did);
  80                 }
  81                 inline::build_impl(cx, None, impl_did, Some(&extra_attrs), &mut new_items);
  82                 extra_attrs.clear();
  83             });
  84         }
  85     }
  86
  87     let mut cleaner = BadImplStripper { prims, items: crate_items };
  88
  89     let mut type_did_to_deref_target: FxHashMap<DefId, &Type> = FxHashMap::default();
  90     // Gather all type to `Deref` target edges.
  91     for it in &new_items {
  92         if let ImplItem(Impl { ref for_, ref trait_, ref items, .. }) = *it.kind {
  93             if trait_.def_id() == cx.tcx.lang_items().deref_trait() {
  94                 let target = items.iter().find_map(|item| match *item.kind {
  95                     TypedefItem(ref t, true) => Some(&t.type_),
  96                     _ => None,
  97                 });
  98                 if let (Some(for_did), Some(target)) = (for_.def_id(), target) {
  99                     type_did_to_deref_target.insert(for_did, target);
 100                 }
 101             }
 102         }
 103     }
 104     // Follow all `Deref` targets of included items and recursively add them as valid
 105     fn add_deref_target(
 106         map: &FxHashMap<DefId, &Type>,
 107         cleaner: &mut BadImplStripper,
 108         type_did: &DefId,
 109     ) {
 110         if let Some(target) = map.get(type_did) {
 111             debug!("add_deref_target: type {:?}, target {:?}", type_did, target);
 112             if let Some(target_prim) = target.primitive_type() {
 113                 cleaner.prims.insert(target_prim);
 114             } else if let Some(target_did) = target.def_id() {
 115                 // `impl Deref<Target = S> for S`
 116                 if target_did == *type_did {
 117                     // Avoid infinite cycles
 118                     return;
 119                 }
 120                 cleaner.items.insert(target_did.into());
 121                 add_deref_target(map, cleaner, &target_did.into());
 122             }
 123         }
 124     }
 125     for type_did in type_did_to_deref_target.keys() {
 126         // Since only the `DefId` portion of the `Type` instances is known to be same for both the
 127         // `Deref` target type and the impl for type positions, this map of types is keyed by
 128         // `DefId` and for convenience uses a special cleaner that accepts `DefId`s directly.
 129         if cleaner.keep_impl_with_def_id(&FakeDefId::new_real(*type_did)) {
 130             add_deref_target(&type_did_to_deref_target, &mut cleaner, type_did);
 131         }
 132     }
 133
 134     let items = if let ModuleItem(Module { ref mut items, .. }) = *krate.module.kind {
 135         items
 136     } else {
 137         panic!("collect-trait-impls can't run");
 138     };
 139
 140     items.extend(synth_impls);
 141     for it in new_items.drain(..) {
 142         if let ImplItem(Impl { ref for_, ref trait_, ref blanket_impl, .. }) = *it.kind {
 143             if !(cleaner.keep_impl(for_)
 144                 || trait_.as_ref().map_or(false, |t| cleaner.keep_impl(t))
 145                 || blanket_impl.is_some())
 146             {
 147                 continue;
 148             }
 149         }
 150
 151         items.push(it);
 152     }
 153
 154     krate
 155 }
 156
 157 struct SyntheticImplCollector<'a, 'tcx> {
 158     cx: &'a mut DocContext<'tcx>,
 159     impls: Vec<Item>,
 160 }
 161
 162 impl<'a, 'tcx> DocFolder for SyntheticImplCollector<'a, 'tcx> {
 163     fn fold_item(&mut self, i: Item) -> Option<Item> {
 164         if i.is_struct() || i.is_enum() || i.is_union() {
 165             // FIXME(eddyb) is this `doc(hidden)` check needed?
 166             if !self.cx.tcx.get_attrs(i.def_id.expect_real()).lists(sym::doc).has_word(sym::hidden)
 167             {
 168                 self.impls
 169                     .extend(get_auto_trait_and_blanket_impls(self.cx, i.def_id.expect_real()));
 170             }
 171         }
 172
 173         Some(self.fold_item_recur(i))
 174     }
 175 }
 176
 177 #[derive(Default)]
 178 struct ItemCollector {
 179     items: FxHashSet<FakeDefId>,
 180 }
 181
 182 impl ItemCollector {
 183     fn new() -> Self {
 184         Self::default()
 185     }
 186 }
 187
 188 impl DocFolder for ItemCollector {
 189     fn fold_item(&mut self, i: Item) -> Option<Item> {
 190         self.items.insert(i.def_id);
 191
 192         Some(self.fold_item_recur(i))
 193     }
 194 }
 195
 196 struct BadImplStripper {
 197     prims: FxHashSet<PrimitiveType>,
 198     items: FxHashSet<FakeDefId>,
 199 }
 200
 201 impl BadImplStripper {
 202     fn keep_impl(&self, ty: &Type) -> bool {
 203         if let Generic(_) = ty {
 204             // keep impls made on generics
 205             true
 206         } else if let Some(prim) = ty.primitive_type() {
 207             self.prims.contains(&prim)
 208         } else if let Some(did) = ty.def_id() {
 209             self.keep_impl_with_def_id(&did.into())
 210         } else {
 211             false
 212         }
 213     }
 214
 215     fn keep_impl_with_def_id(&self, did: &FakeDefId) -> bool {
 216         self.items.contains(did)
 217     }
 218 }