diff options
Diffstat (limited to 'src/librustdoc/passes/collect_trait_impls.rs')
-rw-r--r-- | src/librustdoc/passes/collect_trait_impls.rs | 273 |
1 files changed, 273 insertions, 0 deletions
diff --git a/src/librustdoc/passes/collect_trait_impls.rs b/src/librustdoc/passes/collect_trait_impls.rs new file mode 100644 index 000000000..6b699c790 --- /dev/null +++ b/src/librustdoc/passes/collect_trait_impls.rs @@ -0,0 +1,273 @@ +//! Collects trait impls for each item in the crate. For example, if a crate +//! defines a struct that implements a trait, this pass will note that the +//! struct implements that trait. +use super::Pass; +use crate::clean::*; +use crate::core::DocContext; +use crate::formats::cache::Cache; +use crate::visit::DocVisitor; + +use rustc_data_structures::fx::{FxHashMap, FxHashSet}; +use rustc_hir::def_id::DefId; +use rustc_middle::ty::{self, DefIdTree}; +use rustc_span::symbol::sym; + +pub(crate) const COLLECT_TRAIT_IMPLS: Pass = Pass { + name: "collect-trait-impls", + run: collect_trait_impls, + description: "retrieves trait impls for items in the crate", +}; + +pub(crate) fn collect_trait_impls(mut krate: Crate, cx: &mut DocContext<'_>) -> Crate { + let synth_impls = cx.sess().time("collect_synthetic_impls", || { + let mut synth = SyntheticImplCollector { cx, impls: Vec::new() }; + synth.visit_crate(&krate); + synth.impls + }); + + let prims: FxHashSet<PrimitiveType> = krate.primitives.iter().map(|p| p.1).collect(); + + let crate_items = { + let mut coll = ItemCollector::new(); + cx.sess().time("collect_items_for_trait_impls", || coll.visit_crate(&krate)); + coll.items + }; + + let mut new_items_external = Vec::new(); + let mut new_items_local = Vec::new(); + + // External trait impls. + cx.with_all_trait_impls(|cx, all_trait_impls| { + let _prof_timer = cx.tcx.sess.prof.generic_activity("build_extern_trait_impls"); + for &impl_def_id in all_trait_impls.iter().skip_while(|def_id| def_id.is_local()) { + inline::build_impl(cx, None, impl_def_id, None, &mut new_items_external); + } + }); + + // Local trait impls. + cx.with_all_trait_impls(|cx, all_trait_impls| { + let _prof_timer = cx.tcx.sess.prof.generic_activity("build_local_trait_impls"); + let mut attr_buf = Vec::new(); + for &impl_def_id in all_trait_impls.iter().take_while(|def_id| def_id.is_local()) { + let mut parent = Some(cx.tcx.parent(impl_def_id)); + while let Some(did) = parent { + attr_buf.extend( + cx.tcx + .get_attrs(did, sym::doc) + .filter(|attr| { + if let Some([attr]) = attr.meta_item_list().as_deref() { + attr.has_name(sym::cfg) + } else { + false + } + }) + .cloned(), + ); + parent = cx.tcx.opt_parent(did); + } + inline::build_impl(cx, None, impl_def_id, Some(&attr_buf), &mut new_items_local); + attr_buf.clear(); + } + }); + + cx.tcx.sess.prof.generic_activity("build_primitive_trait_impls").run(|| { + for def_id in PrimitiveType::all_impls(cx.tcx) { + // Try to inline primitive impls from other crates. + if !def_id.is_local() { + inline::build_impl(cx, None, def_id, None, &mut new_items_external); + } + } + for (prim, did) in PrimitiveType::primitive_locations(cx.tcx) { + // Do not calculate blanket impl list for docs that are not going to be rendered. + // While the `impl` blocks themselves are only in `libcore`, the module with `doc` + // attached is directly included in `libstd` as well. + let tcx = cx.tcx; + if did.is_local() { + for def_id in prim.impls(tcx).filter(|def_id| { + // Avoid including impl blocks with filled-in generics. + // https://github.com/rust-lang/rust/issues/94937 + // + // FIXME(notriddle): https://github.com/rust-lang/rust/issues/97129 + // + // This tactic of using inherent impl blocks for getting + // auto traits and blanket impls is a hack. What we really + // want is to check if `[T]` impls `Send`, which has + // nothing to do with the inherent impl. + // + // Rustdoc currently uses these `impl` block as a source of + // the `Ty`, as well as the `ParamEnv`, `SubstsRef`, and + // `Generics`. To avoid relying on the `impl` block, these + // things would need to be created from wholecloth, in a + // form that is valid for use in type inference. + let ty = tcx.type_of(def_id); + match ty.kind() { + ty::Slice(ty) + | ty::Ref(_, ty, _) + | ty::RawPtr(ty::TypeAndMut { ty, .. }) => { + matches!(ty.kind(), ty::Param(..)) + } + ty::Tuple(tys) => tys.iter().all(|ty| matches!(ty.kind(), ty::Param(..))), + _ => true, + } + }) { + let impls = get_auto_trait_and_blanket_impls(cx, def_id); + new_items_external.extend(impls.filter(|i| cx.inlined.insert(i.item_id))); + } + } + } + }); + + let mut cleaner = BadImplStripper { prims, items: crate_items, cache: &cx.cache }; + let mut type_did_to_deref_target: FxHashMap<DefId, &Type> = FxHashMap::default(); + + // Follow all `Deref` targets of included items and recursively add them as valid + fn add_deref_target( + cx: &DocContext<'_>, + map: &FxHashMap<DefId, &Type>, + cleaner: &mut BadImplStripper<'_>, + targets: &mut FxHashSet<DefId>, + type_did: DefId, + ) { + if let Some(target) = map.get(&type_did) { + debug!("add_deref_target: type {:?}, target {:?}", type_did, target); + if let Some(target_prim) = target.primitive_type() { + cleaner.prims.insert(target_prim); + } else if let Some(target_did) = target.def_id(&cx.cache) { + // `impl Deref<Target = S> for S` + if !targets.insert(target_did) { + // Avoid infinite cycles + return; + } + cleaner.items.insert(target_did.into()); + add_deref_target(cx, map, cleaner, targets, target_did); + } + } + } + + // scan through included items ahead of time to splice in Deref targets to the "valid" sets + for it in new_items_external.iter().chain(new_items_local.iter()) { + if let ImplItem(box Impl { ref for_, ref trait_, ref items, .. }) = *it.kind { + if trait_.as_ref().map(|t| t.def_id()) == cx.tcx.lang_items().deref_trait() + && cleaner.keep_impl(for_, true) + { + let target = items + .iter() + .find_map(|item| match *item.kind { + AssocTypeItem(ref t, _) => Some(&t.type_), + _ => None, + }) + .expect("Deref impl without Target type"); + + if let Some(prim) = target.primitive_type() { + cleaner.prims.insert(prim); + } else if let Some(did) = target.def_id(&cx.cache) { + cleaner.items.insert(did.into()); + } + if let Some(for_did) = for_.def_id(&cx.cache) { + if type_did_to_deref_target.insert(for_did, target).is_none() { + // Since only the `DefId` portion of the `Type` instances is known to be same for both the + // `Deref` target type and the impl for type positions, this map of types is keyed by + // `DefId` and for convenience uses a special cleaner that accepts `DefId`s directly. + if cleaner.keep_impl_with_def_id(for_did.into()) { + let mut targets = FxHashSet::default(); + targets.insert(for_did); + add_deref_target( + cx, + &type_did_to_deref_target, + &mut cleaner, + &mut targets, + for_did, + ); + } + } + } + } + } + } + + // Filter out external items that are not needed + new_items_external.retain(|it| { + if let ImplItem(box Impl { ref for_, ref trait_, ref kind, .. }) = *it.kind { + cleaner.keep_impl( + for_, + trait_.as_ref().map(|t| t.def_id()) == cx.tcx.lang_items().deref_trait(), + ) || trait_.as_ref().map_or(false, |t| cleaner.keep_impl_with_def_id(t.def_id().into())) + || kind.is_blanket() + } else { + true + } + }); + + if let ModuleItem(Module { items, .. }) = &mut *krate.module.kind { + items.extend(synth_impls); + items.extend(new_items_external); + items.extend(new_items_local); + } else { + panic!("collect-trait-impls can't run"); + }; + + krate +} + +struct SyntheticImplCollector<'a, 'tcx> { + cx: &'a mut DocContext<'tcx>, + impls: Vec<Item>, +} + +impl<'a, 'tcx> DocVisitor for SyntheticImplCollector<'a, 'tcx> { + fn visit_item(&mut self, i: &Item) { + if i.is_struct() || i.is_enum() || i.is_union() { + // FIXME(eddyb) is this `doc(hidden)` check needed? + if !self.cx.tcx.is_doc_hidden(i.item_id.expect_def_id()) { + self.impls + .extend(get_auto_trait_and_blanket_impls(self.cx, i.item_id.expect_def_id())); + } + } + + self.visit_item_recur(i) + } +} + +#[derive(Default)] +struct ItemCollector { + items: FxHashSet<ItemId>, +} + +impl ItemCollector { + fn new() -> Self { + Self::default() + } +} + +impl DocVisitor for ItemCollector { + fn visit_item(&mut self, i: &Item) { + self.items.insert(i.item_id); + + self.visit_item_recur(i) + } +} + +struct BadImplStripper<'a> { + prims: FxHashSet<PrimitiveType>, + items: FxHashSet<ItemId>, + cache: &'a Cache, +} + +impl<'a> BadImplStripper<'a> { + fn keep_impl(&self, ty: &Type, is_deref: bool) -> bool { + if let Generic(_) = ty { + // keep impls made on generics + true + } else if let Some(prim) = ty.primitive_type() { + self.prims.contains(&prim) + } else if let Some(did) = ty.def_id(self.cache) { + is_deref || self.keep_impl_with_def_id(did.into()) + } else { + false + } + } + + fn keep_impl_with_def_id(&self, item_id: ItemId) -> bool { + self.items.contains(&item_id) + } +} |