Auto merge of #153494 - aerooneqq:boxed-trait-candidates-to-hir-arena, r=petrochenkov

Replace Box<[TraitCandidate]> with &'hir [TraitCandidate<'hir>]

This PR allocates trait candidates on HIR arena and replaces `remove` with `get` in `ResolverAstLowering`. First step for #153489.

r? @petrochenkov

Author: bors

compiler/rustc_ast_lowering/src/delegation.rs

@@ -815,13 +815,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
     }
 }
 
-struct SelfResolver<'a> {
-    resolver: &'a mut ResolverAstLowering,
+struct SelfResolver<'a, 'tcx> {
+    resolver: &'a mut ResolverAstLowering<'tcx>,
     path_id: NodeId,
     self_param_id: NodeId,
 }
 
-impl<'a> SelfResolver<'a> {
+impl SelfResolver<'_, '_> {
     fn try_replace_id(&mut self, id: NodeId) {
         if let Some(res) = self.resolver.partial_res_map.get(&id)
             && let Some(Res::Local(sig_id)) = res.full_res()
@@ -833,7 +833,7 @@ impl<'a> SelfResolver<'a> {
     }
 }
 
-impl<'ast, 'a> Visitor<'ast> for SelfResolver<'a> {
+impl<'ast, 'a> Visitor<'ast> for SelfResolver<'a, '_> {
     fn visit_id(&mut self, id: NodeId) {
         self.try_replace_id(id);
     }

compiler/rustc_ast_lowering/src/item.rs

@@ -27,7 +27,7 @@ use super::{
 
 pub(super) struct ItemLowerer<'a, 'hir> {
     pub(super) tcx: TyCtxt<'hir>,
-    pub(super) resolver: &'a mut ResolverAstLowering,
+    pub(super) resolver: &'a mut ResolverAstLowering<'hir>,
     pub(super) ast_index: &'a IndexSlice<LocalDefId, AstOwner<'a>>,
     pub(super) owners: &'a mut IndexVec<LocalDefId, hir::MaybeOwner<'hir>>,
 }

compiler/rustc_ast_lowering/src/lib.rs

@@ -99,7 +99,7 @@ struct LoweringContext<'a, 'hir> {
     // will be in AST index.
     ast_index: &'a IndexSlice<LocalDefId, AstOwner<'a>>,
 
-    resolver: &'a mut ResolverAstLowering,
+    resolver: &'a mut ResolverAstLowering<'hir>,
     disambiguator: DisambiguatorState,
 
     /// Used to allocate HIR nodes.
@@ -133,7 +133,7 @@ struct LoweringContext<'a, 'hir> {
 
     current_hir_id_owner: hir::OwnerId,
     item_local_id_counter: hir::ItemLocalId,
-    trait_map: ItemLocalMap<Box<[TraitCandidate]>>,
+    trait_map: ItemLocalMap<&'hir [TraitCandidate<'hir>]>,
 
     impl_trait_defs: Vec<hir::GenericParam<'hir>>,
     impl_trait_bounds: Vec<hir::WherePredicate<'hir>>,
@@ -162,7 +162,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn new(
         tcx: TyCtxt<'hir>,
         ast_index: &'a IndexSlice<LocalDefId, AstOwner<'a>>,
-        resolver: &'a mut ResolverAstLowering,
+        resolver: &'a mut ResolverAstLowering<'hir>,
     ) -> Self {
         let registered_tools = tcx.registered_tools(()).iter().map(|x| x.name).collect();
         Self {
@@ -248,7 +248,7 @@ impl SpanLowerer {
 }
 
 #[extension(trait ResolverAstLoweringExt)]
-impl ResolverAstLowering {
+impl ResolverAstLowering<'_> {
     fn legacy_const_generic_args(&self, expr: &Expr, tcx: TyCtxt<'_>) -> Option<Vec<usize>> {
         let ExprKind::Path(None, path) = &expr.kind else {
             return None;
@@ -748,8 +748,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             self.children.push((def_id, hir::MaybeOwner::NonOwner(hir_id)));
         }
 
-        if let Some(traits) = self.resolver.trait_map.remove(&ast_node_id) {
-            self.trait_map.insert(hir_id.local_id, traits.into_boxed_slice());
+        if let Some(&traits) = self.resolver.trait_map.get(&ast_node_id) {
+            self.trait_map.insert(hir_id.local_id, traits);
         }
 
         // Check whether the same `NodeId` is lowered more than once.

compiler/rustc_hir/src/hir.rs

@@ -1633,7 +1633,7 @@ pub struct OwnerInfo<'hir> {
     pub attrs: AttributeMap<'hir>,
     /// Map indicating what traits are in scope for places where this
     /// is relevant; generated by resolve.
-    pub trait_map: ItemLocalMap<Box<[TraitCandidate]>>,
+    pub trait_map: ItemLocalMap<&'hir [TraitCandidate<'hir>]>,
 
     /// Lints delayed during ast lowering to be emitted
     /// after hir has completely built
@@ -4683,10 +4683,10 @@ pub struct Upvar {
 // The TraitCandidate's import_ids is empty if the trait is defined in the same module, and
 // has length > 0 if the trait is found through an chain of imports, starting with the
 // import/use statement in the scope where the trait is used.
-#[derive(Debug, Clone, HashStable_Generic)]
-pub struct TraitCandidate {
+#[derive(Debug, Clone, Copy, HashStable_Generic)]
+pub struct TraitCandidate<'hir> {
     pub def_id: DefId,
-    pub import_ids: SmallVec<[LocalDefId; 1]>,
+    pub import_ids: &'hir [LocalDefId],
     // Indicates whether this trait candidate is ambiguously glob imported
     // in it's scope. Related to the AMBIGUOUS_GLOB_IMPORTED_TRAITS lint.
     // If this is set to true and the trait is used as a result of method lookup, this

compiler/rustc_hir_typeck/src/demand.rs

@@ -1008,7 +1008,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         );
         let container_id = pick.item.container_id(self.tcx);
         let container = with_no_trimmed_paths!(self.tcx.def_path_str(container_id));
-        for def_id in pick.import_ids {
+        for &def_id in pick.import_ids {
             let hir_id = self.tcx.local_def_id_to_hir_id(def_id);
             path_span
                 .push_span_label(self.tcx.hir_span(hir_id), format!("`{container}` imported here"));

compiler/rustc_hir_typeck/src/method/mod.rs

@@ -196,7 +196,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         // NOTE: on the failure path, we also record the possibly-used trait methods
         // since an unused import warning is kinda distracting from the method error.
-        for &import_id in &pick.import_ids {
+        for &import_id in pick.import_ids {
             debug!("used_trait_import: {:?}", import_id);
             self.typeck_results.borrow_mut().used_trait_imports.insert(import_id);
         }
@@ -554,7 +554,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         debug!(?pick);
         {
             let mut typeck_results = self.typeck_results.borrow_mut();
-            for import_id in pick.import_ids {
+            for &import_id in pick.import_ids {
                 debug!(used_trait_import=?import_id);
                 typeck_results.used_trait_imports.insert(import_id);
             }

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -36,7 +36,7 @@ use rustc_trait_selection::traits::query::method_autoderef::{
     CandidateStep, MethodAutoderefBadTy, MethodAutoderefStepsResult,
 };
 use rustc_trait_selection::traits::{self, ObligationCause, ObligationCtxt};
-use smallvec::{SmallVec, smallvec};
+use smallvec::SmallVec;
 use tracing::{debug, instrument};
 
 use self::CandidateKind::*;
@@ -99,7 +99,7 @@ impl<'a, 'tcx> Deref for ProbeContext<'a, 'tcx> {
 pub(crate) struct Candidate<'tcx> {
     pub(crate) item: ty::AssocItem,
     pub(crate) kind: CandidateKind<'tcx>,
-    pub(crate) import_ids: SmallVec<[LocalDefId; 1]>,
+    pub(crate) import_ids: &'tcx [LocalDefId],
 }
 
 #[derive(Debug, Clone)]
@@ -206,7 +206,7 @@ impl PickConstraintsForShadowed {
 pub(crate) struct Pick<'tcx> {
     pub item: ty::AssocItem,
     pub kind: PickKind<'tcx>,
-    pub import_ids: SmallVec<[LocalDefId; 1]>,
+    pub import_ids: &'tcx [LocalDefId],
 
     /// Indicates that the source expression should be autoderef'd N times
     /// ```ignore (not-rust)
@@ -574,7 +574,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 ty::Binder::dummy(trait_ref),
                                 false,
                             ),
-                            import_ids: smallvec![],
+                            import_ids: &[],
                         },
                         false,
                     );
@@ -946,7 +946,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 Candidate {
                     item,
                     kind: InherentImplCandidate { impl_def_id, receiver_steps },
-                    import_ids: smallvec![],
+                    import_ids: &[],
                 },
                 true,
             );
@@ -979,11 +979,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             traits::supertraits(self.tcx, trait_ref),
             |this, new_trait_ref, item| {
                 this.push_candidate(
-                    Candidate {
-                        item,
-                        kind: ObjectCandidate(new_trait_ref),
-                        import_ids: smallvec![],
-                    },
+                    Candidate { item, kind: ObjectCandidate(new_trait_ref), import_ids: &[] },
                     true,
                 );
             },
@@ -1018,11 +1014,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
 
         self.assemble_candidates_for_bounds(bounds, |this, poly_trait_ref, item| {
             this.push_candidate(
-                Candidate {
-                    item,
-                    kind: WhereClauseCandidate(poly_trait_ref),
-                    import_ids: smallvec![],
-                },
+                Candidate { item, kind: WhereClauseCandidate(poly_trait_ref), import_ids: &[] },
                 true,
             );
         });
@@ -1072,11 +1064,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         let mut duplicates = FxHashSet::default();
         for trait_info in suggest::all_traits(self.tcx) {
             if duplicates.insert(trait_info.def_id) {
-                self.assemble_extension_candidates_for_trait(
-                    &smallvec![],
-                    trait_info.def_id,
-                    false,
-                );
+                self.assemble_extension_candidates_for_trait(&[], trait_info.def_id, false);
             }
         }
     }
@@ -1100,7 +1088,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     #[instrument(level = "debug", skip(self))]
     fn assemble_extension_candidates_for_trait(
         &mut self,
-        import_ids: &SmallVec<[LocalDefId; 1]>,
+        import_ids: &'tcx [LocalDefId],
         trait_def_id: DefId,
         lint_ambiguous: bool,
     ) {
@@ -1123,7 +1111,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                         self.push_candidate(
                             Candidate {
                                 item,
-                                import_ids: import_ids.clone(),
+                                import_ids,
                                 kind: TraitCandidate(bound_trait_ref, lint_ambiguous),
                             },
                             false,
@@ -1146,7 +1134,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
                 self.push_candidate(
                     Candidate {
                         item,
-                        import_ids: import_ids.clone(),
+                        import_ids,
                         kind: TraitCandidate(ty::Binder::dummy(trait_ref), lint_ambiguous),
                     },
                     false,
@@ -2353,7 +2341,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         Some(Pick {
             item: probes[0].0.item,
             kind: TraitPick(lint_ambiguous),
-            import_ids: probes[0].0.import_ids.clone(),
+            import_ids: probes[0].0.import_ids,
             autoderefs: 0,
             autoref_or_ptr_adjustment: None,
             self_ty,
@@ -2430,7 +2418,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         Some(Pick {
             item: child_candidate.item,
             kind: TraitPick(lint_ambiguous),
-            import_ids: child_candidate.import_ids.clone(),
+            import_ids: child_candidate.import_ids,
             autoderefs: 0,
             autoref_or_ptr_adjustment: None,
             self_ty,
@@ -2707,7 +2695,7 @@ impl<'tcx> Candidate<'tcx> {
                     WhereClausePick(trait_ref)
                 }
             },
-            import_ids: self.import_ids.clone(),
+            import_ids: self.import_ids,
             autoderefs: 0,
             autoref_or_ptr_adjustment: None,
             self_ty,

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -199,7 +199,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         // NOTE: Reporting a method error should also suppress any unused trait errors,
         // since the method error is very possibly the reason why the trait wasn't used.
         for &import_id in
-            self.tcx.in_scope_traits(call_id).into_iter().flatten().flat_map(|c| &c.import_ids)
+            self.tcx.in_scope_traits(call_id).into_iter().flatten().flat_map(|c| c.import_ids)
         {
             self.typeck_results.borrow_mut().used_trait_imports.insert(import_id);
         }

compiler/rustc_interface/src/passes.rs

@@ -781,7 +781,7 @@ fn write_out_deps(tcx: TyCtxt<'_>, outputs: &OutputFilenames, out_filenames: &[P
 fn resolver_for_lowering_raw<'tcx>(
     tcx: TyCtxt<'tcx>,
     (): (),
-) -> (&'tcx Steal<(ty::ResolverAstLowering, Arc<ast::Crate>)>, &'tcx ty::ResolverGlobalCtxt) {
+) -> (&'tcx Steal<(ty::ResolverAstLowering<'tcx>, Arc<ast::Crate>)>, &'tcx ty::ResolverGlobalCtxt) {
     let arenas = Resolver::arenas();
     let _ = tcx.registered_tools(()); // Uses `crate_for_resolver`.
     let (krate, pre_configured_attrs) = tcx.crate_for_resolver(()).steal();

compiler/rustc_middle/src/arena.rs

@@ -32,7 +32,7 @@ macro_rules! arena_types {
                 rustc_middle::ty::DefinitionSiteHiddenType<'tcx>,
             >,
             [] resolver: rustc_data_structures::steal::Steal<(
-                rustc_middle::ty::ResolverAstLowering,
+                rustc_middle::ty::ResolverAstLowering<'tcx>,
                 std::sync::Arc<rustc_ast::Crate>,
             )>,
             [] crate_for_resolver: rustc_data_structures::steal::Steal<(rustc_ast::Crate, rustc_ast::AttrVec)>,