resolve: Refactor away the side table decl_parent_modules

Instead keep parent modules in `DeclData` itself

Author: petrochenkov

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -48,14 +48,12 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     /// and report an error in case of a collision.
     pub(crate) fn plant_decl_into_local_module(
         &mut self,
-        parent: Module<'ra>,
         ident: Ident,
         ns: Namespace,
         decl: Decl<'ra>,
     ) {
-        if let Err(old_decl) = self.try_plant_decl_into_local_module(parent, ident, ns, decl, false)
-        {
-            self.report_conflict(parent, ident, ns, old_decl, decl);
+        if let Err(old_decl) = self.try_plant_decl_into_local_module(ident, ns, decl, false) {
+            self.report_conflict(ident, ns, old_decl, decl);
         }
     }
 
@@ -70,8 +68,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         span: Span,
         expn_id: LocalExpnId,
     ) {
-        let decl = self.arenas.new_def_decl(res, vis.to_def_id(), span, expn_id);
-        self.plant_decl_into_local_module(parent, ident, ns, decl);
+        let decl = self.arenas.new_def_decl(res, vis.to_def_id(), span, expn_id, Some(parent));
+        self.plant_decl_into_local_module(ident, ns, decl);
     }
 
     /// Create a name definitinon from the given components, and put it into the extern module.
@@ -95,6 +93,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             vis: CmCell::new(vis),
             span,
             expansion,
+            parent_module: Some(parent),
         });
         // Even if underscore names cannot be looked up, we still need to add them to modules,
         // because they can be fetched by glob imports from those modules, and bring traits
@@ -287,7 +286,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             let ModChild { ident: _, res, vis, ref reexport_chain } = *ambig_child;
             let span = child_span(self, reexport_chain, res);
             let res = res.expect_non_local();
-            self.arenas.new_def_decl(res, vis, span, expansion)
+            self.arenas.new_def_decl(res, vis, span, expansion, Some(parent))
         });
 
         // Record primary definitions.
@@ -842,7 +841,6 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                     ident,
                     local_def_id,
                     vis,
-                    parent,
                 );
             }
 
@@ -974,10 +972,10 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
         ident: Ident,
         local_def_id: LocalDefId,
         vis: Visibility,
-        parent: Module<'ra>,
     ) {
         let sp = item.span;
         let parent_scope = self.parent_scope;
+        let parent = parent_scope.module;
         let expansion = parent_scope.expansion;
 
         let (used, module, decl) = if orig_name.is_none() && ident.name == kw::SelfLower {
@@ -1007,7 +1005,7 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
         let import = self.r.arenas.alloc_import(ImportData {
             kind: ImportKind::ExternCrate { source: orig_name, target: ident, id: item.id },
             root_id: item.id,
-            parent_scope: self.parent_scope,
+            parent_scope,
             imported_module: CmCell::new(module),
             has_attributes: !item.attrs.is_empty(),
             use_span_with_attributes: item.span_with_attributes(),
@@ -1055,7 +1053,7 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                 }),
             };
         }
-        self.r.plant_decl_into_local_module(parent, ident, TypeNS, import_decl);
+        self.r.plant_decl_into_local_module(ident, TypeNS, import_decl);
     }
 
     /// Constructs the reduced graph for one foreign item.
@@ -1298,14 +1296,19 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
             } else {
                 Visibility::Restricted(CRATE_DEF_ID)
             };
-            let decl = self.r.arenas.new_def_decl(res, vis.to_def_id(), span, expansion);
-            self.r.set_decl_parent_module(decl, parent_scope.module);
+            let decl = self.r.arenas.new_def_decl(
+                res,
+                vis.to_def_id(),
+                span,
+                expansion,
+                Some(parent_scope.module),
+            );
             self.r.all_macro_rules.insert(ident.name);
             if is_macro_export {
                 let import = self.r.arenas.alloc_import(ImportData {
                     kind: ImportKind::MacroExport,
                     root_id: item.id,
-                    parent_scope: self.parent_scope,
+                    parent_scope: ParentScope { module: self.r.graph_root, ..parent_scope },
                     imported_module: CmCell::new(None),
                     has_attributes: false,
                     use_span_with_attributes: span,
@@ -1318,7 +1321,7 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                 });
                 self.r.import_use_map.insert(import, Used::Other);
                 let import_decl = self.r.new_import_decl(decl, import);
-                self.r.plant_decl_into_local_module(self.r.graph_root, ident, MacroNS, import_decl);
+                self.r.plant_decl_into_local_module(ident, MacroNS, import_decl);
             } else {
                 self.r.check_reserved_macro_name(ident, res);
                 self.insert_unused_macro(ident, def_id, item.id);

compiler/rustc_resolve/src/diagnostics.rs

@@ -208,21 +208,20 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
     pub(crate) fn report_conflict(
         &mut self,
-        parent: Module<'_>,
         ident: Ident,
         ns: Namespace,
         new_binding: Decl<'ra>,
         old_binding: Decl<'ra>,
     ) {
         // Error on the second of two conflicting names
         if old_binding.span.lo() > new_binding.span.lo() {
-            return self.report_conflict(parent, ident, ns, old_binding, new_binding);
+            return self.report_conflict(ident, ns, old_binding, new_binding);
         }
 
-        let container = match parent.kind {
+        let container = match old_binding.parent_module.unwrap().kind {
             // Avoid using TyCtxt::def_kind_descr in the resolver, because it
             // indirectly *calls* the resolver, and would cause a query cycle.
-            ModuleKind::Def(kind, _, _) => kind.descr(parent.def_id()),
+            ModuleKind::Def(kind, def_id, _) => kind.descr(def_id),
             ModuleKind::Block => "block",
         };
 
@@ -2032,15 +2031,17 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 help_msgs.push(format!("use `::{ident}` to refer to this {thing} unambiguously"))
             }
 
-            if let Scope::ModuleNonGlobs(module, _) | Scope::ModuleGlobs(module, _) = scope {
-                if module == self.graph_root {
-                    help_msgs.push(format!(
-                        "use `crate::{ident}` to refer to this {thing} unambiguously"
-                    ));
-                } else if module != self.empty_module && module.is_normal() {
-                    help_msgs.push(format!(
-                        "use `self::{ident}` to refer to this {thing} unambiguously"
-                    ));
+            if kind != AmbiguityKind::GlobVsGlob {
+                if let Scope::ModuleNonGlobs(module, _) | Scope::ModuleGlobs(module, _) = scope {
+                    if module == self.graph_root {
+                        help_msgs.push(format!(
+                            "use `crate::{ident}` to refer to this {thing} unambiguously"
+                        ));
+                    } else if module.is_normal() {
+                        help_msgs.push(format!(
+                            "use `self::{ident}` to refer to this {thing} unambiguously"
+                        ));
+                    }
                 }
             }
 

compiler/rustc_resolve/src/imports.rs

@@ -340,6 +340,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             span: import.span,
             vis: CmCell::new(vis),
             expansion: import.parent_scope.expansion,
+            parent_module: Some(import.parent_scope.module),
         })
     }
 
@@ -409,15 +410,14 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     /// and return existing declaration if there is a collision.
     pub(crate) fn try_plant_decl_into_local_module(
         &mut self,
-        module: Module<'ra>,
         ident: Ident,
         ns: Namespace,
         decl: Decl<'ra>,
         warn_ambiguity: bool,
     ) -> Result<(), Decl<'ra>> {
+        let module = decl.parent_module.unwrap();
         let res = decl.res();
         self.check_reserved_macro_name(ident, res);
-        self.set_decl_parent_module(decl, module);
         // Even if underscore names cannot be looked up, we still need to add them to modules,
         // because they can be fetched by glob imports from those modules, and bring traits
         // into scope both directly and through glob imports.
@@ -511,7 +511,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             if self.is_accessible_from(binding.vis(), scope) {
                 let import_decl = self.new_import_decl(binding, *import);
                 let _ = self.try_plant_decl_into_local_module(
-                    import.parent_scope.module,
                     ident.0,
                     key.ns,
                     import_decl,
@@ -534,8 +533,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             let dummy_decl = self.new_import_decl(dummy_decl, import);
             self.per_ns(|this, ns| {
                 let module = import.parent_scope.module;
-                let _ =
-                    this.try_plant_decl_into_local_module(module, target, ns, dummy_decl, false);
+                let _ = this.try_plant_decl_into_local_module(target, ns, dummy_decl, false);
                 // Don't remove underscores from `single_imports`, they were never added.
                 if target.name != kw::Underscore {
                     let key = BindingKey::new(target, ns);
@@ -916,7 +914,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         // We need the `target`, `source` can be extracted.
                         let import_decl = this.new_import_decl(binding, import);
                         this.get_mut_unchecked().plant_decl_into_local_module(
-                            parent,
                             target,
                             ns,
                             import_decl,
@@ -1541,7 +1538,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     .and_then(|r| r.binding())
                     .is_some_and(|binding| binding.warn_ambiguity_recursive());
                 let _ = self.try_plant_decl_into_local_module(
-                    import.parent_scope.module,
                     key.ident.0,
                     key.ns,
                     import_decl,

compiler/rustc_resolve/src/lib.rs

@@ -67,7 +67,6 @@ use rustc_metadata::creader::CStore;
 use rustc_middle::metadata::{AmbigModChild, ModChild, Reexport};
 use rustc_middle::middle::privacy::EffectiveVisibilities;
 use rustc_middle::query::Providers;
-use rustc_middle::span_bug;
 use rustc_middle::ty::{
     self, DelegationFnSig, DelegationInfo, Feed, MainDefinition, RegisteredTools,
     ResolverAstLowering, ResolverGlobalCtxt, TyCtxt, TyCtxtFeed, Visibility,
@@ -812,6 +811,7 @@ struct DeclData<'ra> {
     expansion: LocalExpnId,
     span: Span,
     vis: CmCell<Visibility<DefId>>,
+    parent_module: Option<Module<'ra>>,
 }
 
 /// All name declarations are unique and allocated on a same arena,
@@ -916,7 +916,6 @@ struct AmbiguityError<'ra> {
     ident: Ident,
     b1: Decl<'ra>,
     b2: Decl<'ra>,
-    // `empty_module` in module scope serves as an unknown module here.
     scope1: Scope<'ra>,
     scope2: Scope<'ra>,
     warning: bool,
@@ -1180,7 +1179,6 @@ pub struct Resolver<'ra, 'tcx> {
     local_module_map: FxIndexMap<LocalDefId, Module<'ra>>,
     /// Lazily populated cache of modules loaded from external crates.
     extern_module_map: CacheRefCell<FxIndexMap<DefId, Module<'ra>>>,
-    decl_parent_modules: FxHashMap<Decl<'ra>, Module<'ra>>,
 
     /// Maps glob imports to the names of items actually imported.
     glob_map: FxIndexMap<LocalDefId, FxIndexSet<Symbol>>,
@@ -1343,6 +1341,7 @@ impl<'ra> ResolverArenas<'ra> {
         vis: Visibility<DefId>,
         span: Span,
         expansion: LocalExpnId,
+        parent_module: Option<Module<'ra>>,
     ) -> Decl<'ra> {
         self.alloc_decl(DeclData {
             kind: DeclKind::Def(res),
@@ -1351,11 +1350,12 @@ impl<'ra> ResolverArenas<'ra> {
             vis: CmCell::new(vis),
             span,
             expansion,
+            parent_module,
         })
     }
 
     fn new_pub_def_decl(&'ra self, res: Res, span: Span, expn_id: LocalExpnId) -> Decl<'ra> {
-        self.new_def_decl(res, Visibility::Public, span, expn_id)
+        self.new_def_decl(res, Visibility::Public, span, expn_id, None)
     }
 
     fn new_module(
@@ -1610,7 +1610,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             local_module_map,
             extern_module_map: Default::default(),
             block_map: Default::default(),
-            decl_parent_modules: FxHashMap::default(),
             ast_transform_scopes: FxHashMap::default(),
 
             glob_map: Default::default(),
@@ -2061,8 +2060,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 ident,
                 b1: used_decl,
                 b2,
-                scope1: Scope::ModuleGlobs(self.empty_module, None),
-                scope2: Scope::ModuleGlobs(self.empty_module, None),
+                scope1: Scope::ModuleGlobs(used_decl.parent_module.unwrap(), None),
+                scope2: Scope::ModuleGlobs(b2.parent_module.unwrap(), None),
                 warning: warn_ambiguity,
             };
             if !self.matches_previous_ambiguity_error(&ambiguity_error) {
@@ -2227,14 +2226,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         vis.is_accessible_from(module.nearest_parent_mod(), self.tcx)
     }
 
-    fn set_decl_parent_module(&mut self, decl: Decl<'ra>, module: Module<'ra>) {
-        if let Some(old_module) = self.decl_parent_modules.insert(decl, module) {
-            if module != old_module {
-                span_bug!(decl.span, "parent module is reset for a name declaration");
-            }
-        }
-    }
-
     fn disambiguate_macro_rules_vs_modularized(
         &self,
         macro_rules: Decl<'ra>,
@@ -2244,13 +2235,13 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // is disambiguated to mitigate regressions from macro modularization.
         // Scoping for `macro_rules` behaves like scoping for `let` at module level, in general.
         //
-        // panic on index should be impossible, the only name_bindings passed in should be from
+        // Panic on unwrap should be impossible, the only name_bindings passed in should be from
         // `resolve_ident_in_scope_set` which will always refer to a local binding from an
-        // import or macro definition
-        let macro_rules = &self.decl_parent_modules[&macro_rules];
-        let modularized = &self.decl_parent_modules[&modularized];
+        // import or macro definition.
+        let macro_rules = macro_rules.parent_module.unwrap();
+        let modularized = modularized.parent_module.unwrap();
         macro_rules.nearest_parent_mod() == modularized.nearest_parent_mod()
-            && modularized.is_ancestor_of(*macro_rules)
+            && modularized.is_ancestor_of(macro_rules)
     }
 
     fn extern_prelude_get_item<'r>(