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 use crate::formats::cache::Cache;
   6
   7 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
   8 use rustc_hir::def_id::{DefId, LOCAL_CRATE};
   9 use rustc_middle::ty::DefIdTree;
  10 use rustc_span::symbol::sym;
  11
  12 crate const COLLECT_TRAIT_IMPLS: Pass = Pass {
  13     name: "collect-trait-impls",
  14     run: collect_trait_impls,
  15     description: "retrieves trait impls for items in the crate",
  16 };
  17
  18 crate fn collect_trait_impls(krate: Crate, cx: &DocContext<'_>) -> Crate {
  19     let mut synth = SyntheticImplCollector::new(cx);
  20     let mut krate = cx.sess().time("collect_synthetic_impls", || synth.fold_crate(krate));
  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.time("build_extern_trait_impl", || {
  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.sess().time("build_primitive_trait_impl", || {
  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 self_ty = cx.tcx.type_of(def_id);
  49                     let impls = get_auto_trait_and_blanket_impls(cx, self_ty, def_id);
  50                     let mut renderinfo = cx.renderinfo.borrow_mut();
  51
  52                     new_items.extend(impls.filter(|i| renderinfo.inlined.insert(i.def_id)));
  53                 }
  54             })
  55         }
  56     }
  57
  58     // `tcx.crates()` doesn't include the local crate, and `tcx.all_trait_implementations`
  59     // doesn't work with it anyway, so pull them from the HIR map instead
  60     for &trait_did in cx.tcx.all_traits(LOCAL_CRATE).iter() {
  61         for &impl_node in cx.tcx.hir().trait_impls(trait_did) {
  62             let impl_did = cx.tcx.hir().local_def_id(impl_node);
  63             cx.tcx.sess.time("build_local_trait_impl", || {
  64                 let mut extra_attrs = Vec::new();
  65                 let mut parent = cx.tcx.parent(impl_did.to_def_id());
  66                 while let Some(did) = parent {
  67                     extra_attrs.extend(
  68                         cx.tcx
  69                             .get_attrs(did)
  70                             .iter()
  71                             .filter(|attr| attr.has_name(sym::doc))
  72                             .filter(|attr| {
  73                                 if let Some([attr]) = attr.meta_item_list().as_deref() {
  74                                     attr.has_name(sym::cfg)
  75                                 } else {
  76                                     false
  77                                 }
  78                             })
  79                             .cloned(),
  80                     );
  81                     parent = cx.tcx.parent(did);
  82                 }
  83                 inline::build_impl(
  84                     cx,
  85                     None,
  86                     impl_did.to_def_id(),
  87                     Some(&extra_attrs),
  88                     &mut new_items,
  89                 );
  90             });
  91         }
  92     }
  93
  94     let mut cleaner = BadImplStripper { prims, items: crate_items };
  95
  96     let mut type_did_to_deref_target: FxHashMap<DefId, &Type> = FxHashMap::default();
  97     // Gather all type to `Deref` target edges.
  98     for it in &new_items {
  99         if let ImplItem(Impl { ref for_, ref trait_, ref items, .. }) = *it.kind {
 100             if trait_.def_id(&cx.cache) == cx.tcx.lang_items().deref_trait() {
 101                 let target = items.iter().find_map(|item| match *item.kind {
 102                     TypedefItem(ref t, true) => Some(&t.type_),
 103                     _ => None,
 104                 });
 105                 if let (Some(for_did), Some(target)) = (for_.def_id(&cx.cache), target) {
 106                     type_did_to_deref_target.insert(for_did, target);
 107                 }
 108             }
 109         }
 110     }
 111     // Follow all `Deref` targets of included items and recursively add them as valid
 112     fn add_deref_target(
 113         map: &FxHashMap<DefId, &Type>,
 114         cleaner: &mut BadImplStripper,
 115         type_did: &DefId,
 116         cache: &Cache,
 117     ) {
 118         if let Some(target) = map.get(type_did) {
 119             debug!("add_deref_target: type {:?}, target {:?}", type_did, target);
 120             if let Some(target_prim) = target.primitive_type() {
 121                 cleaner.prims.insert(target_prim);
 122             } else if let Some(target_did) = target.def_id(cache) {
 123                 // `impl Deref<Target = S> for S`
 124                 if target_did == *type_did {
 125                     // Avoid infinite cycles
 126                     return;
 127                 }
 128                 cleaner.items.insert(target_did);
 129                 add_deref_target(map, cleaner, &target_did, cache);
 130             }
 131         }
 132     }
 133     for type_did in type_did_to_deref_target.keys() {
 134         // Since only the `DefId` portion of the `Type` instances is known to be same for both the
 135         // `Deref` target type and the impl for type positions, this map of types is keyed by
 136         // `DefId` and for convenience uses a special cleaner that accepts `DefId`s directly.
 137         if cleaner.keep_impl_with_def_id(type_did) {
 138             add_deref_target(&type_did_to_deref_target, &mut cleaner, type_did, &cx.cache);
 139         }
 140     }
 141
 142     new_items.retain(|it| {
 143         if let ImplItem(Impl { ref for_, ref trait_, ref blanket_impl, .. }) = *it.kind {
 144             cleaner.keep_impl(for_, &cx.cache)
 145                 || trait_.as_ref().map_or(false, |t| cleaner.keep_impl(t, &cx.cache))
 146                 || blanket_impl.is_some()
 147         } else {
 148             true
 149         }
 150     });
 151
 152     if let Some(ref mut it) = krate.module {
 153         if let ModuleItem(Module { ref mut items, .. }) = *it.kind {
 154             items.extend(synth.impls);
 155             items.extend(new_items);
 156         } else {
 157             panic!("collect-trait-impls can't run");
 158         }
 159     } else {
 160         panic!("collect-trait-impls can't run");
 161     }
 162
 163     krate
 164 }
 165
 166 struct SyntheticImplCollector<'a, 'tcx> {
 167     cx: &'a DocContext<'tcx>,
 168     impls: Vec<Item>,
 169 }
 170
 171 impl<'a, 'tcx> SyntheticImplCollector<'a, 'tcx> {
 172     fn new(cx: &'a DocContext<'tcx>) -> Self {
 173         SyntheticImplCollector { cx, impls: Vec::new() }
 174     }
 175 }
 176
 177 impl<'a, 'tcx> DocFolder for SyntheticImplCollector<'a, 'tcx> {
 178     fn fold_item(&mut self, i: Item) -> Option<Item> {
 179         if i.is_struct() || i.is_enum() || i.is_union() {
 180             // FIXME(eddyb) is this `doc(hidden)` check needed?
 181             if !self.cx.tcx.get_attrs(i.def_id).lists(sym::doc).has_word(sym::hidden) {
 182                 self.cx.sess().time("get_auto_trait_and_blanket_synthetic_impls", || {
 183                     self.impls.extend(get_auto_trait_and_blanket_impls(
 184                         self.cx,
 185                         self.cx.tcx.type_of(i.def_id),
 186                         i.def_id,
 187                     ));
 188                 });
 189             }
 190         }
 191
 192         Some(self.fold_item_recur(i))
 193     }
 194 }
 195
 196 #[derive(Default)]
 197 struct ItemCollector {
 198     items: FxHashSet<DefId>,
 199 }
 200
 201 impl ItemCollector {
 202     fn new() -> Self {
 203         Self::default()
 204     }
 205 }
 206
 207 impl DocFolder for ItemCollector {
 208     fn fold_item(&mut self, i: Item) -> Option<Item> {
 209         self.items.insert(i.def_id);
 210
 211         Some(self.fold_item_recur(i))
 212     }
 213 }
 214
 215 struct BadImplStripper {
 216     prims: FxHashSet<PrimitiveType>,
 217     items: FxHashSet<DefId>,
 218 }
 219
 220 impl BadImplStripper {
 221     fn keep_impl(&self, ty: &Type, cache: &Cache) -> bool {
 222         if let Generic(_) = ty {
 223             // keep impls made on generics
 224             true
 225         } else if let Some(prim) = ty.primitive_type() {
 226             self.prims.contains(&prim)
 227         } else if let Some(did) = ty.def_id(cache) {
 228             self.keep_impl_with_def_id(&did)
 229         } else {
 230             false
 231         }
 232     }
 233
 234     fn keep_impl_with_def_id(&self, did: &DefId) -> bool {
 235         self.items.contains(did)
 236     }
 237 }