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_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);
  50                     new_items.extend(impls.filter(|i| cx.inlined.insert(i.def_id)));
  51                 }
  52             });
  53         }
  54     }
  55
  56     let mut cleaner = BadImplStripper { prims, items: crate_items };
  57
  58     // scan through included items ahead of time to splice in Deref targets to the "valid" sets
  59     for it in &new_items {
  60         if let ImplItem(Impl { ref for_, ref trait_, ref items, .. }) = *it.kind {
  61             if cleaner.keep_impl(for_) && trait_.def_id() == cx.tcx.lang_items().deref_trait() {
  62                 let target = items
  63                     .iter()
  64                     .find_map(|item| match *item.kind {
  65                         TypedefItem(ref t, true) => Some(&t.type_),
  66                         _ => None,
  67                     })
  68                     .expect("Deref impl without Target type");
  69
  70                 if let Some(prim) = target.primitive_type() {
  71                     cleaner.prims.insert(prim);
  72                 } else if let Some(did) = target.def_id() {
  73                     cleaner.items.insert(did);
  74                 }
  75             }
  76         }
  77     }
  78
  79     new_items.retain(|it| {
  80         if let ImplItem(Impl { ref for_, ref trait_, ref blanket_impl, .. }) = *it.kind {
  81             cleaner.keep_impl(for_)
  82                 || trait_.as_ref().map_or(false, |t| cleaner.keep_impl(t))
  83                 || blanket_impl.is_some()
  84         } else {
  85             true
  86         }
  87     });
  88
  89     // `tcx.crates()` doesn't include the local crate, and `tcx.all_trait_implementations`
  90     // doesn't work with it anyway, so pull them from the HIR map instead
  91     let mut extra_attrs = Vec::new();
  92     for &trait_did in cx.tcx.all_traits(LOCAL_CRATE).iter() {
  93         for &impl_did in cx.tcx.hir().trait_impls(trait_did) {
  94             let impl_did = impl_did.to_def_id();
  95             cx.tcx.sess.prof.generic_activity("build_local_trait_impl").run(|| {
  96                 let mut parent = cx.tcx.parent(impl_did);
  97                 while let Some(did) = parent {
  98                     extra_attrs.extend(
  99                         cx.tcx
 100                             .get_attrs(did)
 101                             .iter()
 102                             .filter(|attr| attr.has_name(sym::doc))
 103                             .filter(|attr| {
 104                                 if let Some([attr]) = attr.meta_item_list().as_deref() {
 105                                     attr.has_name(sym::cfg)
 106                                 } else {
 107                                     false
 108                                 }
 109                             })
 110                             .cloned(),
 111                     );
 112                     parent = cx.tcx.parent(did);
 113                 }
 114                 inline::build_impl(cx, None, impl_did, Some(&extra_attrs), &mut new_items);
 115                 extra_attrs.clear();
 116             });
 117         }
 118     }
 119
 120     let items = if let Some(ref mut it) = krate.module {
 121         if let ModuleItem(Module { ref mut items, .. }) = *it.kind {
 122             items
 123         } else {
 124             panic!("collect-trait-impls can't run");
 125         }
 126     } else {
 127         panic!("collect-trait-impls can't run");
 128     };
 129
 130     items.extend(synth_impls);
 131     items.extend(new_items);
 132
 133     krate
 134 }
 135
 136 struct SyntheticImplCollector<'a, 'tcx> {
 137     cx: &'a mut DocContext<'tcx>,
 138     impls: Vec<Item>,
 139 }
 140
 141 impl<'a, 'tcx> DocFolder for SyntheticImplCollector<'a, 'tcx> {
 142     fn fold_item(&mut self, i: Item) -> Option<Item> {
 143         if i.is_struct() || i.is_enum() || i.is_union() {
 144             // FIXME(eddyb) is this `doc(hidden)` check needed?
 145             if !self.cx.tcx.get_attrs(i.def_id).lists(sym::doc).has_word(sym::hidden) {
 146                 self.impls.extend(get_auto_trait_and_blanket_impls(self.cx, i.def_id));
 147             }
 148         }
 149
 150         Some(self.fold_item_recur(i))
 151     }
 152 }
 153
 154 #[derive(Default)]
 155 struct ItemCollector {
 156     items: FxHashSet<DefId>,
 157 }
 158
 159 impl ItemCollector {
 160     fn new() -> Self {
 161         Self::default()
 162     }
 163 }
 164
 165 impl DocFolder for ItemCollector {
 166     fn fold_item(&mut self, i: Item) -> Option<Item> {
 167         self.items.insert(i.def_id);
 168
 169         Some(self.fold_item_recur(i))
 170     }
 171 }
 172
 173 struct BadImplStripper {
 174     prims: FxHashSet<PrimitiveType>,
 175     items: FxHashSet<DefId>,
 176 }
 177
 178 impl BadImplStripper {
 179     fn keep_impl(&self, ty: &Type) -> bool {
 180         if let Generic(_) = ty {
 181             // keep impls made on generics
 182             true
 183         } else if let Some(prim) = ty.primitive_type() {
 184             self.prims.contains(&prim)
 185         } else if let Some(did) = ty.def_id() {
 186             self.items.contains(&did)
 187         } else {
 188             false
 189         }
 190     }
 191 }