Don't store all traits in DocContext

This is already a query so we're just needlessly copying the data
around.

Author: Mark-Simulacrum

src/librustdoc/clean/blanket_impl.rs

@@ -3,6 +3,7 @@ use rustc::traits;
 use rustc::ty::ToPredicate;
 use rustc::ty::subst::Subst;
 use rustc::infer::InferOk;
+use rustc::hir::def_id::LOCAL_CRATE;
 use syntax_pos::DUMMY_SP;
 
 use super::*;
@@ -27,7 +28,7 @@ impl<'a, 'tcx> BlanketImplFinder<'a, 'tcx> {
 
         debug!("get_blanket_impls({:?})", ty);
         let mut impls = Vec::new();
-        for &trait_def_id in self.cx.all_traits.iter() {
+        for &trait_def_id in self.cx.tcx.all_traits(LOCAL_CRATE).iter() {
             if !self.cx.renderinfo.borrow().access_levels.is_public(trait_def_id) ||
                self.cx.generated_synthetics
                       .borrow_mut()

src/librustdoc/core.rs

@@ -68,7 +68,6 @@ pub struct DocContext<'tcx> {
     /// Auto-trait or blanket impls processed so far, as `(self_ty, trait_def_id)`.
     // FIXME(eddyb) make this a `ty::TraitRef<'tcx>` set.
     pub generated_synthetics: RefCell<FxHashSet<(Ty<'tcx>, DefId)>>,
-    pub all_traits: Vec<DefId>,
     pub auto_traits: Vec<DefId>,
 }
 
@@ -364,7 +363,6 @@ pub fn run_core(options: RustdocOptions) -> (clean::Crate, RenderInfo, RenderOpt
             let mut renderinfo = RenderInfo::default();
             renderinfo.access_levels = access_levels;
 
-            let all_traits = tcx.all_traits(LOCAL_CRATE).to_vec();
             let ctxt = DocContext {
                 tcx,
                 resolver,
@@ -379,10 +377,9 @@ pub fn run_core(options: RustdocOptions) -> (clean::Crate, RenderInfo, RenderOpt
                 fake_def_ids: Default::default(),
                 all_fake_def_ids: Default::default(),
                 generated_synthetics: Default::default(),
-                auto_traits: all_traits.iter().cloned().filter(|trait_def_id| {
+                auto_traits: tcx.all_traits(LOCAL_CRATE).iter().cloned().filter(|trait_def_id| {
                     tcx.trait_is_auto(*trait_def_id)
                 }).collect(),
-                all_traits,
             };
             debug!("crate: {:?}", tcx.hir().krate());
 

src/librustdoc/passes/collect_trait_impls.rs

@@ -4,7 +4,7 @@ use crate::fold::DocFolder;
 use super::Pass;
 
 use rustc::util::nodemap::FxHashSet;
-use rustc::hir::def_id::DefId;
+use rustc::hir::def_id::{LOCAL_CRATE, DefId};
 use syntax::symbol::sym;
 
 pub const COLLECT_TRAIT_IMPLS: Pass = Pass {
@@ -116,7 +116,7 @@ pub fn collect_trait_impls(krate: Crate, cx: &DocContext<'_>) -> Crate {
 
     // `tcx.crates()` doesn't include the local crate, and `tcx.all_trait_implementations`
     // doesn't work with it anyway, so pull them from the HIR map instead
-    for &trait_did in cx.all_traits.iter() {
+    for &trait_did in cx.tcx.all_traits(LOCAL_CRATE).iter() {
         for &impl_node in cx.tcx.hir().trait_impls(trait_did) {
             let impl_did = cx.tcx.hir().local_def_id(impl_node);
             inline::build_impl(cx, impl_did, None, &mut new_items);