Use () for all_traits.

compiler/rustc_middle/src/query/mod.rs

@@ -1420,7 +1420,7 @@
     /// A vector of every trait accessible in the whole crate
     /// (i.e., including those from subcrates). This is used only for
     /// error reporting.
-    query all_traits(_: CrateNum) -> &'tcx [DefId] {
+    query all_traits(_: ()) -> &'tcx [DefId] {
         desc { "fetching all foreign and local traits" }
     }
 

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -14,7 +14,7 @@
 use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder, ErrorReported};
 use rustc_hir as hir;
-use rustc_hir::def_id::{DefId, LOCAL_CRATE};
+use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::Node;
 use rustc_middle::mir::abstract_const::NotConstEvaluatable;
@@ -1427,7 +1427,7 @@ fn note_version_mismatch(
             self.tcx.find_map_relevant_impl(trait_def_id, trait_ref.skip_binder().self_ty(), Some)
         };
         let required_trait_path = self.tcx.def_path_str(trait_ref.def_id());
-        let all_traits = self.tcx.all_traits(LOCAL_CRATE);
+        let all_traits = self.tcx.all_traits(());
         let traits_with_same_path: std::collections::BTreeSet<_> = all_traits
             .iter()
             .filter(|trait_def_id| **trait_def_id != trait_ref.def_id())

compiler/rustc_typeck/src/check/method/suggest.rs

@@ -6,7 +6,7 @@
 use rustc_errors::{pluralize, struct_span_err, Applicability, DiagnosticBuilder};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Namespace, Res};
-use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX, LOCAL_CRATE};
+use rustc_hir::def_id::{DefId, CRATE_DEF_INDEX};
 use rustc_hir::intravisit;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::{ExprKind, Node, QPath};
@@ -1440,11 +1440,11 @@ fn cmp(&self, other: &TraitInfo) -> Ordering {
 
 /// Retrieves all traits in this crate and any dependent crates.
 pub fn all_traits(tcx: TyCtxt<'_>) -> Vec<TraitInfo> {
-    tcx.all_traits(LOCAL_CRATE).iter().map(|&def_id| TraitInfo { def_id }).collect()
+    tcx.all_traits(()).iter().map(|&def_id| TraitInfo { def_id }).collect()
 }
 
 /// Computes all traits in this crate and any dependent crates.
-fn compute_all_traits(tcx: TyCtxt<'_>) -> Vec<DefId> {
+fn compute_all_traits(tcx: TyCtxt<'_>, (): ()) -> &[DefId] {
     use hir::itemlikevisit;
 
     let mut traits = vec![];
@@ -1503,14 +1503,11 @@ fn handle_external_res(
         handle_external_res(tcx, &mut traits, &mut external_mods, Res::Def(DefKind::Mod, def_id));
     }
 
-    traits
+    tcx.arena.alloc_from_iter(traits)
 }
 
 pub fn provide(providers: &mut ty::query::Providers) {
-    providers.all_traits = |tcx, cnum| {
-        assert_eq!(cnum, LOCAL_CRATE);
-        &tcx.arena.alloc(compute_all_traits(tcx))[..]
-    }
+    providers.all_traits = compute_all_traits;
 }
 
 struct UsePlacementFinder<'tcx> {

src/librustdoc/clean/blanket_impl.rs

@@ -1,6 +1,5 @@
 use crate::rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_hir as hir;
-use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_infer::infer::{InferOk, TyCtxtInferExt};
 use rustc_infer::traits;
 use rustc_middle::ty::subst::Subst;
@@ -20,7 +19,7 @@ impl<'a, 'tcx> BlanketImplFinder<'a, 'tcx> {
 
         debug!("get_blanket_impls({:?})", ty);
         let mut impls = Vec::new();
-        for &trait_def_id in self.cx.tcx.all_traits(LOCAL_CRATE).iter() {
+        for &trait_def_id in self.cx.tcx.all_traits(()).iter() {
             if !self.cx.cache.access_levels.is_public(trait_def_id)
                 || self.cx.generated_synthetics.get(&(ty, trait_def_id)).is_some()
             {

src/librustdoc/core.rs

@@ -6,7 +6,7 @@
 use rustc_errors::json::JsonEmitter;
 use rustc_feature::UnstableFeatures;
 use rustc_hir::def::Res;
-use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
+use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::HirId;
 use rustc_hir::{
     intravisit::{self, NestedVisitorMap, Visitor},
@@ -371,7 +371,7 @@ impl<'tcx> DocContext<'tcx> {
         impl_trait_bounds: Default::default(),
         generated_synthetics: Default::default(),
         auto_traits: tcx
-            .all_traits(LOCAL_CRATE)
+            .all_traits(())
             .iter()
             .cloned()
             .filter(|trait_def_id| tcx.trait_is_auto(*trait_def_id))

src/librustdoc/passes/collect_trait_impls.rs

@@ -4,7 +4,7 @@
 use crate::fold::DocFolder;
 
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-use rustc_hir::def_id::{DefId, LOCAL_CRATE};
+use rustc_hir::def_id::DefId;
 use rustc_middle::ty::DefIdTree;
 use rustc_span::symbol::sym;
 
@@ -56,7 +56,7 @@
     // `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
     let mut extra_attrs = Vec::new();
-    for &trait_did in cx.tcx.all_traits(LOCAL_CRATE).iter() {
+    for &trait_did in cx.tcx.all_traits(()).iter() {
         for &impl_did in cx.tcx.hir().trait_impls(trait_did) {
             let impl_did = impl_did.to_def_id();
             cx.tcx.sess.prof.generic_activity("build_local_trait_impl").run(|| {