Do not access HIR to check impl wf.

Author: cjgillot

compiler/rustc_typeck/src/impl_wf_check.rs

@@ -13,7 +13,6 @@ use min_specialization::check_min_specialization;
 
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_errors::struct_span_err;
-use rustc_hir as hir;
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalDefId;
 use rustc_middle::ty::query::Providers;
@@ -66,13 +65,10 @@ fn check_mod_impl_wf(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
     let module = tcx.hir_module_items(module_def_id);
     for id in module.items() {
         if matches!(tcx.def_kind(id.def_id), DefKind::Impl) {
-            let item = tcx.hir().item(id);
-            if let hir::ItemKind::Impl(ref impl_) = item.kind {
-                enforce_impl_params_are_constrained(tcx, item.def_id, impl_.items);
-                enforce_impl_items_are_distinct(tcx, impl_.items);
-                if min_specialization {
-                    check_min_specialization(tcx, item.def_id.to_def_id(), item.span);
-                }
+            enforce_impl_params_are_constrained(tcx, id.def_id);
+            enforce_impl_items_are_distinct(tcx, id.def_id);
+            if min_specialization {
+                check_min_specialization(tcx, id.def_id);
             }
         }
     }
@@ -82,11 +78,7 @@ pub fn provide(providers: &mut Providers) {
     *providers = Providers { check_mod_impl_wf, ..*providers };
 }
 
-fn enforce_impl_params_are_constrained(
-    tcx: TyCtxt<'_>,
-    impl_def_id: LocalDefId,
-    impl_item_refs: &[hir::ImplItemRef],
-) {
+fn enforce_impl_params_are_constrained(tcx: TyCtxt<'_>, impl_def_id: LocalDefId) {
     // Every lifetime used in an associated type must be constrained.
     let impl_self_ty = tcx.type_of(impl_def_id);
     if impl_self_ty.references_error() {
@@ -114,9 +106,9 @@ fn enforce_impl_params_are_constrained(
     );
 
     // Disallow unconstrained lifetimes, but only if they appear in assoc types.
-    let lifetimes_in_associated_types: FxHashSet<_> = impl_item_refs
+    let lifetimes_in_associated_types: FxHashSet<_> = tcx
+        .associated_item_def_ids(impl_def_id)
         .iter()
-        .map(|item_ref| item_ref.id.def_id)
         .flat_map(|def_id| {
             let item = tcx.associated_item(def_id);
             match item.kind {
@@ -216,33 +208,32 @@ fn report_unused_parameter(tcx: TyCtxt<'_>, span: Span, kind: &str, name: &str)
 }
 
 /// Enforce that we do not have two items in an impl with the same name.
-fn enforce_impl_items_are_distinct(tcx: TyCtxt<'_>, impl_item_refs: &[hir::ImplItemRef]) {
+fn enforce_impl_items_are_distinct(tcx: TyCtxt<'_>, impl_def_id: LocalDefId) {
     let mut seen_type_items = FxHashMap::default();
     let mut seen_value_items = FxHashMap::default();
-    for impl_item_ref in impl_item_refs {
-        let impl_item = tcx.hir().impl_item(impl_item_ref.id);
+    for &impl_item_ref in tcx.associated_item_def_ids(impl_def_id) {
+        let impl_item = tcx.associated_item(impl_item_ref);
         let seen_items = match impl_item.kind {
-            hir::ImplItemKind::TyAlias(_) => &mut seen_type_items,
+            ty::AssocKind::Type => &mut seen_type_items,
             _ => &mut seen_value_items,
         };
-        match seen_items.entry(impl_item.ident.normalize_to_macros_2_0()) {
+        let span = tcx.def_span(impl_item_ref);
+        let ident = impl_item.ident(tcx);
+        match seen_items.entry(ident.normalize_to_macros_2_0()) {
             Occupied(entry) => {
                 let mut err = struct_span_err!(
                     tcx.sess,
-                    impl_item.span,
+                    span,
                     E0201,
                     "duplicate definitions with name `{}`:",
-                    impl_item.ident
-                );
-                err.span_label(
-                    *entry.get(),
-                    format!("previous definition of `{}` here", impl_item.ident),
+                    ident
                 );
-                err.span_label(impl_item.span, "duplicate definition");
+                err.span_label(*entry.get(), format!("previous definition of `{}` here", ident));
+                err.span_label(span, "duplicate definition");
                 err.emit();
             }
             Vacant(entry) => {
-                entry.insert(impl_item.span);
+                entry.insert(span);
             }
         }
     }

compiler/rustc_typeck/src/impl_wf_check/min_specialization.rs

@@ -79,19 +79,19 @@ use rustc_middle::ty::{self, TyCtxt, TypeFoldable};
 use rustc_span::Span;
 use rustc_trait_selection::traits::{self, translate_substs, wf};
 
-pub(super) fn check_min_specialization(tcx: TyCtxt<'_>, impl_def_id: DefId, span: Span) {
+pub(super) fn check_min_specialization(tcx: TyCtxt<'_>, impl_def_id: LocalDefId) {
     if let Some(node) = parent_specialization_node(tcx, impl_def_id) {
         tcx.infer_ctxt().enter(|infcx| {
-            check_always_applicable(&infcx, impl_def_id, node, span);
+            check_always_applicable(&infcx, impl_def_id, node);
         });
     }
 }
 
-fn parent_specialization_node(tcx: TyCtxt<'_>, impl1_def_id: DefId) -> Option<Node> {
+fn parent_specialization_node(tcx: TyCtxt<'_>, impl1_def_id: LocalDefId) -> Option<Node> {
     let trait_ref = tcx.impl_trait_ref(impl1_def_id)?;
     let trait_def = tcx.trait_def(trait_ref.def_id);
 
-    let impl2_node = trait_def.ancestors(tcx, impl1_def_id).ok()?.nth(1)?;
+    let impl2_node = trait_def.ancestors(tcx, impl1_def_id.to_def_id()).ok()?.nth(1)?;
 
     let always_applicable_trait =
         matches!(trait_def.specialization_kind, TraitSpecializationKind::AlwaysApplicable);
@@ -103,15 +103,8 @@ fn parent_specialization_node(tcx: TyCtxt<'_>, impl1_def_id: DefId) -> Option<No
 }
 
 /// Check that `impl1` is a sound specialization
-fn check_always_applicable(
-    infcx: &InferCtxt<'_, '_>,
-    impl1_def_id: DefId,
-    impl2_node: Node,
-    span: Span,
-) {
-    if let Some((impl1_substs, impl2_substs)) =
-        get_impl_substs(infcx, impl1_def_id, impl2_node, span)
-    {
+fn check_always_applicable(infcx: &InferCtxt<'_, '_>, impl1_def_id: LocalDefId, impl2_node: Node) {
+    if let Some((impl1_substs, impl2_substs)) = get_impl_substs(infcx, impl1_def_id, impl2_node) {
         let impl2_def_id = impl2_node.def_id();
         debug!(
             "check_always_applicable(\nimpl1_def_id={:?},\nimpl2_def_id={:?},\nimpl2_substs={:?}\n)",
@@ -126,17 +119,10 @@ fn check_always_applicable(
             unconstrained_parent_impl_substs(tcx, impl2_def_id, impl2_substs)
         };
 
+        let span = tcx.def_span(impl1_def_id);
         check_static_lifetimes(tcx, &parent_substs, span);
         check_duplicate_params(tcx, impl1_substs, &parent_substs, span);
-
-        check_predicates(
-            infcx,
-            impl1_def_id.expect_local(),
-            impl1_substs,
-            impl2_node,
-            impl2_substs,
-            span,
-        );
+        check_predicates(infcx, impl1_def_id, impl1_substs, impl2_node, impl2_substs, span);
     }
 }
 
@@ -152,20 +138,21 @@ fn check_always_applicable(
 /// Would return `S1 = [C]` and `S2 = [Vec<C>, C]`.
 fn get_impl_substs<'tcx>(
     infcx: &InferCtxt<'_, 'tcx>,
-    impl1_def_id: DefId,
+    impl1_def_id: LocalDefId,
     impl2_node: Node,
-    span: Span,
 ) -> Option<(SubstsRef<'tcx>, SubstsRef<'tcx>)> {
     let tcx = infcx.tcx;
     let param_env = tcx.param_env(impl1_def_id);
 
-    let impl1_substs = InternalSubsts::identity_for_item(tcx, impl1_def_id);
-    let impl2_substs = translate_substs(infcx, param_env, impl1_def_id, impl1_substs, impl2_node);
+    let impl1_substs = InternalSubsts::identity_for_item(tcx, impl1_def_id.to_def_id());
+    let impl2_substs =
+        translate_substs(infcx, param_env, impl1_def_id.to_def_id(), impl1_substs, impl2_node);
 
     // Conservatively use an empty `ParamEnv`.
     let outlives_env = OutlivesEnvironment::new(ty::ParamEnv::empty());
-    infcx.resolve_regions_and_report_errors(impl1_def_id, &outlives_env);
+    infcx.resolve_regions_and_report_errors(impl1_def_id.to_def_id(), &outlives_env);
     let Ok(impl2_substs) = infcx.fully_resolve(impl2_substs) else {
+        let span = tcx.def_span(impl1_def_id);
         tcx.sess.emit_err(SubstsOnOverriddenImpl { span });
         return None;
     };