Auto merge of #132761 - nnethercote:resolve-tweaks, r=petrochenkov

Resolve tweaks

A couple of small perf improvements, and some minor refactorings, all in `rustc_resolve`.

r? `@petrochenkov`

5 files changed, 53 insertions, 93 deletions

diff --git a/compiler/rustc_parse/src/parser/mod.rs b/compiler/rustc_parse/src/parser/mod.rs
index 50a8b6542df..042ee96bbe8 100644
--- a/compiler/rustc_parse/src/parser/mod.rs
+++ b/compiler/rustc_parse/src/parser/mod.rs
@@ -641,9 +641,10 @@ impl<'a> Parser<'a> {
             return true;
         }
 
+        // Do an ASCII case-insensitive match, because all keywords are ASCII.
         if case == Case::Insensitive
             && let Some((ident, IdentIsRaw::No)) = self.token.ident()
-            && ident.as_str().to_lowercase() == kw.as_str().to_lowercase()
+            && ident.as_str().eq_ignore_ascii_case(kw.as_str())
         {
             true
         } else {
diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index 5437ca65935..5b78acd904a 100644
--- a/compiler/rustc_resolve/src/diagnostics.rs
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -535,14 +535,12 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         filter_fn: &impl Fn(Res) -> bool,
         ctxt: Option<SyntaxContext>,
     ) {
-        for (key, resolution) in self.resolutions(module).borrow().iter() {
-            if let Some(binding) = resolution.borrow().binding {
-                let res = binding.res();
-                if filter_fn(res) && ctxt.map_or(true, |ctxt| ctxt == key.ident.span.ctxt()) {
-                    names.push(TypoSuggestion::typo_from_ident(key.ident, res));
-                }
+        module.for_each_child(self, |_this, ident, _ns, binding| {
+            let res = binding.res();
+            if filter_fn(res) && ctxt.map_or(true, |ctxt| ctxt == ident.span.ctxt()) {
+                names.push(TypoSuggestion::typo_from_ident(ident, res));
             }
-        }
+        });
     }
 
     /// Combines an error with provided span and emits it.
diff --git a/compiler/rustc_resolve/src/ident.rs b/compiler/rustc_resolve/src/ident.rs
index b80e0e196ca..ad825d7813d 100644
--- a/compiler/rustc_resolve/src/ident.rs
+++ b/compiler/rustc_resolve/src/ident.rs
@@ -38,6 +38,12 @@ impl From<UsePrelude> for bool {
     }
 }
 
+#[derive(Debug, PartialEq)]
+enum Shadowing {
+    Restricted,
+    Unrestricted,
+}
+
 impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     /// A generic scope visitor.
     /// Visits scopes in order to resolve some identifier in them or perform other actions.
@@ -311,13 +317,12 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
         // Walk backwards up the ribs in scope.
         let mut module = self.graph_root;
-        for i in (0..ribs.len()).rev() {
-            debug!("walk rib\n{:?}", ribs[i].bindings);
+        for (i, rib) in ribs.iter().enumerate().rev() {
+            debug!("walk rib\n{:?}", rib.bindings);
             // Use the rib kind to determine whether we are resolving parameters
             // (macro 2.0 hygiene) or local variables (`macro_rules` hygiene).
-            let rib_ident = if ribs[i].kind.contains_params() { normalized_ident } else { ident };
-            if let Some((original_rib_ident_def, res)) = ribs[i].bindings.get_key_value(&rib_ident)
-            {
+            let rib_ident = if rib.kind.contains_params() { normalized_ident } else { ident };
+            if let Some((original_rib_ident_def, res)) = rib.bindings.get_key_value(&rib_ident) {
                 // The ident resolves to a type parameter or local variable.
                 return Some(LexicalScopeBinding::Res(self.validate_res_from_ribs(
                     i,
@@ -329,7 +334,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 )));
             }
 
-            module = match ribs[i].kind {
+            module = match rib.kind {
                 RibKind::Module(module) => module,
                 RibKind::MacroDefinition(def) if def == self.macro_def(ident.span.ctxt()) => {
                     // If an invocation of this macro created `ident`, give up on `ident`
@@ -350,6 +355,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 ident,
                 ns,
                 parent_scope,
+                Shadowing::Unrestricted,
                 finalize.map(|finalize| Finalize { used: Used::Scope, ..finalize }),
                 ignore_binding,
                 None,
@@ -494,7 +500,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     Scope::CrateRoot => {
                         let root_ident = Ident::new(kw::PathRoot, ident.span);
                         let root_module = this.resolve_crate_root(root_ident);
-                        let binding = this.resolve_ident_in_module_ext(
+                        let binding = this.resolve_ident_in_module(
                             ModuleOrUniformRoot::Module(root_module),
                             ident,
                             ns,
@@ -516,12 +522,16 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     }
                     Scope::Module(module, derive_fallback_lint_id) => {
                         let adjusted_parent_scope = &ParentScope { module, ..*parent_scope };
-                        let binding = this.resolve_ident_in_module_unadjusted_ext(
+                        let binding = this.resolve_ident_in_module_unadjusted(
                             ModuleOrUniformRoot::Module(module),
                             ident,
                             ns,
                             adjusted_parent_scope,
-                            !matches!(scope_set, ScopeSet::Late(..)),
+                            if matches!(scope_set, ScopeSet::Late(..)) {
+                                Shadowing::Unrestricted
+                            } else {
+                                Shadowing::Restricted
+                            },
                             finalize.map(|finalize| Finalize { used: Used::Scope, ..finalize }),
                             ignore_binding,
                             ignore_import,
@@ -590,6 +600,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                                 ident,
                                 ns,
                                 parent_scope,
+                                Shadowing::Unrestricted,
                                 None,
                                 ignore_binding,
                                 ignore_import,
@@ -748,7 +759,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         parent_scope: &ParentScope<'ra>,
         ignore_import: Option<Import<'ra>>,
     ) -> Result<NameBinding<'ra>, Determinacy> {
-        self.resolve_ident_in_module_ext(module, ident, ns, parent_scope, None, None, ignore_import)
+        self.resolve_ident_in_module(module, ident, ns, parent_scope, None, None, ignore_import)
             .map_err(|(determinacy, _)| determinacy)
     }
 
@@ -756,29 +767,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     pub(crate) fn resolve_ident_in_module(
         &mut self,
         module: ModuleOrUniformRoot<'ra>,
-        ident: Ident,
-        ns: Namespace,
-        parent_scope: &ParentScope<'ra>,
-        finalize: Option<Finalize>,
-        ignore_binding: Option<NameBinding<'ra>>,
-        ignore_import: Option<Import<'ra>>,
-    ) -> Result<NameBinding<'ra>, Determinacy> {
-        self.resolve_ident_in_module_ext(
-            module,
-            ident,
-            ns,
-            parent_scope,
-            finalize,
-            ignore_binding,
-            ignore_import,
-        )
-        .map_err(|(determinacy, _)| determinacy)
-    }
-
-    #[instrument(level = "debug", skip(self))]
-    fn resolve_ident_in_module_ext(
-        &mut self,
-        module: ModuleOrUniformRoot<'ra>,
         mut ident: Ident,
         ns: Namespace,
         parent_scope: &ParentScope<'ra>,
@@ -803,52 +791,28 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 // No adjustments
             }
         }
-        self.resolve_ident_in_module_unadjusted_ext(
+        self.resolve_ident_in_module_unadjusted(
             module,
             ident,
             ns,
             adjusted_parent_scope,
-            false,
+            Shadowing::Unrestricted,
             finalize,
             ignore_binding,
             ignore_import,
         )
     }
 
-    #[instrument(level = "debug", skip(self))]
-    fn resolve_ident_in_module_unadjusted(
-        &mut self,
-        module: ModuleOrUniformRoot<'ra>,
-        ident: Ident,
-        ns: Namespace,
-        parent_scope: &ParentScope<'ra>,
-        finalize: Option<Finalize>,
-        ignore_binding: Option<NameBinding<'ra>>,
-        ignore_import: Option<Import<'ra>>,
-    ) -> Result<NameBinding<'ra>, Determinacy> {
-        self.resolve_ident_in_module_unadjusted_ext(
-            module,
-            ident,
-            ns,
-            parent_scope,
-            false,
-            finalize,
-            ignore_binding,
-            ignore_import,
-        )
-        .map_err(|(determinacy, _)| determinacy)
-    }
-
     /// Attempts to resolve `ident` in namespaces `ns` of `module`.
     /// Invariant: if `finalize` is `Some`, expansion and import resolution must be complete.
     #[instrument(level = "debug", skip(self))]
-    fn resolve_ident_in_module_unadjusted_ext(
+    fn resolve_ident_in_module_unadjusted(
         &mut self,
         module: ModuleOrUniformRoot<'ra>,
         ident: Ident,
         ns: Namespace,
         parent_scope: &ParentScope<'ra>,
-        restricted_shadowing: bool,
+        shadowing: Shadowing,
         finalize: Option<Finalize>,
         // This binding should be ignored during in-module resolution, so that we don't get
         // "self-confirming" import resolutions during import validation and checking.
@@ -858,7 +822,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         let module = match module {
             ModuleOrUniformRoot::Module(module) => module,
             ModuleOrUniformRoot::CrateRootAndExternPrelude => {
-                assert!(!restricted_shadowing);
+                assert_eq!(shadowing, Shadowing::Unrestricted);
                 let binding = self.early_resolve_ident_in_lexical_scope(
                     ident,
                     ScopeSet::AbsolutePath(ns),
@@ -871,7 +835,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 return binding.map_err(|determinacy| (determinacy, Weak::No));
             }
             ModuleOrUniformRoot::ExternPrelude => {
-                assert!(!restricted_shadowing);
+                assert_eq!(shadowing, Shadowing::Unrestricted);
                 return if ns != TypeNS {
                     Err((Determined, Weak::No))
                 } else if let Some(binding) = self.extern_prelude_get(ident, finalize.is_some()) {
@@ -884,7 +848,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 };
             }
             ModuleOrUniformRoot::CurrentScope => {
-                assert!(!restricted_shadowing);
+                assert_eq!(shadowing, Shadowing::Unrestricted);
                 if ns == TypeNS {
                     if ident.name == kw::Crate || ident.name == kw::DollarCrate {
                         let module = self.resolve_crate_root(ident);
@@ -943,7 +907,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
             // Forbid expanded shadowing to avoid time travel.
             if let Some(shadowed_glob) = resolution.shadowed_glob
-                && restricted_shadowing
+                && shadowing == Shadowing::Restricted
                 && binding.expansion != LocalExpnId::ROOT
                 && binding.res() != shadowed_glob.res()
             {
@@ -958,7 +922,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 });
             }
 
-            if !restricted_shadowing
+            if shadowing == Shadowing::Unrestricted
                 && binding.expansion != LocalExpnId::ROOT
                 && let NameBindingKind::Import { import, .. } = binding.kind
                 && matches!(import.kind, ImportKind::MacroExport)
@@ -1047,13 +1011,13 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 ignore_binding,
                 ignore_import,
             ) {
-                Err(Determined) => continue,
+                Err((Determined, _)) => continue,
                 Ok(binding)
                     if !self.is_accessible_from(binding.vis, single_import.parent_scope.module) =>
                 {
                     continue;
                 }
-                Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::No)),
+                Ok(_) | Err((Undetermined, _)) => return Err((Undetermined, Weak::No)),
             }
         }
 
@@ -1070,7 +1034,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         // and prohibit access to macro-expanded `macro_export` macros instead (unless restricted
         // shadowing is enabled, see `macro_expanded_macro_export_errors`).
         if let Some(binding) = binding {
-            if binding.determined() || ns == MacroNS || restricted_shadowing {
+            if binding.determined() || ns == MacroNS || shadowing == Shadowing::Restricted {
                 return check_usable(self, binding);
             } else {
                 return Err((Undetermined, Weak::No));
@@ -1122,19 +1086,20 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 ident,
                 ns,
                 adjusted_parent_scope,
+                Shadowing::Unrestricted,
                 None,
                 ignore_binding,
                 ignore_import,
             );
 
             match result {
-                Err(Determined) => continue,
+                Err((Determined, _)) => continue,
                 Ok(binding)
                     if !self.is_accessible_from(binding.vis, glob_import.parent_scope.module) =>
                 {
                     continue;
                 }
-                Ok(_) | Err(Undetermined) => return Err((Undetermined, Weak::Yes)),
+                Ok(_) | Err((Undetermined, _)) => return Err((Undetermined, Weak::Yes)),
             }
         }
 
@@ -1200,7 +1165,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                             // Still doesn't deal with upvars
                             if let Some(span) = finalize {
                                 let (span, resolution_error) = match item {
-                                    None if rib_ident.as_str() == "self" => (span, LowercaseSelf),
+                                    None if rib_ident.name == kw::SelfLower => {
+                                        (span, LowercaseSelf)
+                                    }
                                     None => {
                                         // If we have a `let name = expr;`, we have the span for
                                         // `name` and use that to see if it is followed by a type
@@ -1563,6 +1530,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     ignore_binding,
                     ignore_import,
                 )
+                .map_err(|(determinacy, _)| determinacy)
             } else if let Some(ribs) = ribs
                 && let Some(TypeNS | ValueNS) = opt_ns
             {
diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index f4a85c358e3..26b345f5941 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -1688,9 +1688,9 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
             }
         }
 
+        let normalized_ident = ident.normalize_to_macros_2_0();
         let mut outer_res = None;
         for rib in lifetime_rib_iter {
-            let normalized_ident = ident.normalize_to_macros_2_0();
             if let Some((&outer, _)) = rib.bindings.get_key_value(&normalized_ident) {
                 outer_res = Some(outer);
                 break;
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 9abb3180388..e382295b8f6 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -1082,8 +1082,6 @@ pub struct Resolver<'ra, 'tcx> {
     binding_parent_modules: FxHashMap<NameBinding<'ra>, Module<'ra>>,
 
     underscore_disambiguator: u32,
-    /// Disambiguator for anonymous adts.
-    empty_disambiguator: u32,
 
     /// Maps glob imports to the names of items actually imported.
     glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
@@ -1462,7 +1460,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             module_children: Default::default(),
             trait_map: NodeMap::default(),
             underscore_disambiguator: 0,
-            empty_disambiguator: 0,
             empty_module,
             module_map,
             block_map: Default::default(),
@@ -1809,12 +1806,11 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         assoc_item: Option<(Symbol, Namespace)>,
     ) -> bool {
         match (trait_module, assoc_item) {
-            (Some(trait_module), Some((name, ns))) => {
-                self.resolutions(trait_module).borrow().iter().any(|resolution| {
-                    let (&BindingKey { ident: assoc_ident, ns: assoc_ns, .. }, _) = resolution;
-                    assoc_ns == ns && assoc_ident.name == name
-                })
-            }
+            (Some(trait_module), Some((name, ns))) => self
+                .resolutions(trait_module)
+                .borrow()
+                .iter()
+                .any(|(key, _name_resolution)| key.ns == ns && key.ident.name == name),
             _ => true,
         }
     }
@@ -1842,9 +1838,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         let disambiguator = if ident.name == kw::Underscore {
             self.underscore_disambiguator += 1;
             self.underscore_disambiguator
-        } else if ident.name == kw::Empty {
-            self.empty_disambiguator += 1;
-            self.empty_disambiguator
         } else {
             0
         };