Auto merge of #110493 - bvanjoi:new_disambiguated_key, r=petrochenkov

fix(resolve): only disambiguate binding key during define

- close https://github.com/rust-lang/rust/issues/110164
- discussion: https://github.com/rust-lang/rust/pull/110264#discussion_r1168895468

r? `@petrochenkov`

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -9,12 +9,9 @@
 use crate::imports::{Import, ImportKind};
 use crate::macros::{MacroRulesBinding, MacroRulesScope, MacroRulesScopeRef};
 use crate::Namespace::{self, MacroNS, TypeNS, ValueNS};
-use crate::{
-    errors, Determinacy, ExternPreludeEntry, Finalize, Module, ModuleKind, ModuleOrUniformRoot,
-};
-use crate::{
-    MacroData, NameBinding, NameBindingKind, ParentScope, PathResult, PerNS, ResolutionError,
-};
+use crate::{errors, BindingKey, MacroData};
+use crate::{Determinacy, ExternPreludeEntry, Finalize, Module, ModuleKind, ModuleOrUniformRoot};
+use crate::{NameBinding, NameBindingKind, ParentScope, PathResult, PerNS, ResolutionError};
 use crate::{Resolver, ResolverArenas, Segment, ToNameBinding, VisResolutionError};
 
 use rustc_ast::visit::{self, AssocCtxt, Visitor};
@@ -72,7 +69,7 @@ pub(crate) fn define<T>(&mut self, parent: Module<'a>, ident: Ident, ns: Namespa
         T: ToNameBinding<'a>,
     {
         let binding = def.to_name_binding(self.arenas);
-        let key = self.new_key(ident, ns);
+        let key = self.new_disambiguated_key(ident, ns);
         if let Err(old_binding) = self.try_define(parent, key, binding) {
             self.report_conflict(parent, ident, ns, old_binding, &binding);
         }
@@ -379,7 +376,7 @@ fn add_import(
             ImportKind::Single { target, type_ns_only, .. } => {
                 self.r.per_ns(|this, ns| {
                     if !type_ns_only || ns == TypeNS {
-                        let key = this.new_key(target, ns);
+                        let key = BindingKey::new(target, ns);
                         let mut resolution = this.resolution(current_module, key).borrow_mut();
                         resolution.add_single_import(import);
                     }

compiler/rustc_resolve/src/diagnostics.rs

@@ -28,10 +28,10 @@
 use rustc_span::{BytePos, Span, SyntaxContext};
 use thin_vec::ThinVec;
 
-use crate::errors as errs;
 use crate::imports::{Import, ImportKind};
 use crate::late::{PatternSource, Rib};
 use crate::path_names_to_string;
+use crate::{errors as errs, BindingKey};
 use crate::{AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, BindingError, Finalize};
 use crate::{HasGenericParams, MacroRulesScope, Module, ModuleKind, ModuleOrUniformRoot};
 use crate::{LexicalScopeBinding, NameBinding, NameBindingKind, PrivacyError, VisResolutionError};
@@ -2081,7 +2081,8 @@ pub(crate) fn check_for_module_export_macro(
         }
 
         let resolutions = self.resolutions(crate_module).borrow();
-        let resolution = resolutions.get(&self.new_key(ident, MacroNS))?;
+        let binding_key = BindingKey::new(ident, MacroNS);
+        let resolution = resolutions.get(&binding_key)?;
         let binding = resolution.borrow().binding()?;
         if let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() {
             let module_name = crate_module.kind.name().unwrap();

compiler/rustc_resolve/src/ident.rs

@@ -18,6 +18,7 @@
     ConstantHasGenerics, HasGenericParams, NoConstantGenericsReason, PathSource, Rib, RibKind,
 };
 use crate::macros::{sub_namespace_match, MacroRulesScope};
+use crate::BindingKey;
 use crate::{errors, AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, Determinacy, Finalize};
 use crate::{Import, ImportKind, LexicalScopeBinding, Module, ModuleKind, ModuleOrUniformRoot};
 use crate::{NameBinding, NameBindingKind, ParentScope, PathResult, PrivacyError, Res};
@@ -865,7 +866,7 @@ fn resolve_ident_in_module_unadjusted_ext(
             }
         };
 
-        let key = self.new_key(ident, ns);
+        let key = BindingKey::new(ident, ns);
         let resolution =
             self.resolution(module, key).try_borrow_mut().map_err(|_| (Determined, Weak::No))?; // This happens when there is a cycle of imports.
 

compiler/rustc_resolve/src/imports.rs

@@ -415,7 +415,7 @@ fn import_dummy_binding(&mut self, import: &'a Import<'a>) {
             let dummy_binding = self.dummy_binding;
             let dummy_binding = self.import(dummy_binding, import);
             self.per_ns(|this, ns| {
-                let key = this.new_key(target, ns);
+                let key = BindingKey::new(target, ns);
                 let _ = this.try_define(import.parent_scope.module, key, dummy_binding);
             });
             self.record_use(target, dummy_binding, false);
@@ -712,7 +712,7 @@ fn resolve_import(&mut self, import: &'a Import<'a>) -> usize {
                                 .span_label(import.span, "cannot be imported directly")
                                 .emit();
                         }
-                        let key = this.new_key(target, ns);
+                        let key = BindingKey::new(target, ns);
                         this.update_resolution(parent, key, |_, resolution| {
                             resolution.single_imports.remove(&Interned::new_unchecked(import));
                         });

compiler/rustc_resolve/src/late.rs

@@ -6,6 +6,7 @@
 //! If you wonder why there's no `early.rs`, that's because it's split into three files -
 //! `build_reduced_graph.rs`, `macros.rs` and `imports.rs`.
 
+use crate::BindingKey;
 use crate::{path_names_to_string, rustdoc, BindingError, Finalize, LexicalScopeBinding};
 use crate::{Module, ModuleOrUniformRoot, NameBinding, ParentScope, PathResult};
 use crate::{ResolutionError, Resolver, Segment, UseError};
@@ -2967,7 +2968,7 @@ fn check_trait_item<F>(
         // If there is a TraitRef in scope for an impl, then the method must be in the trait.
         let Some((module, _)) = &self.current_trait_ref else { return; };
         ident.span.normalize_to_macros_2_0_and_adjust(module.expansion);
-        let key = self.r.new_key(ident, ns);
+        let key = BindingKey::new(ident, ns);
         let mut binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
         debug!(?binding);
         if binding.is_none() {
@@ -2978,7 +2979,7 @@ fn check_trait_item<F>(
                 TypeNS => ValueNS,
                 _ => ns,
             };
-            let key = self.r.new_key(ident, ns);
+            let key = BindingKey::new(ident, ns);
             binding = self.r.resolution(module, key).try_borrow().ok().and_then(|r| r.binding);
             debug!(?binding);
         }

compiler/rustc_resolve/src/lib.rs

@@ -469,6 +469,13 @@ struct BindingKey {
     disambiguator: u32,
 }
 
+impl BindingKey {
+    fn new(ident: Ident, ns: Namespace) -> Self {
+        let ident = ident.normalize_to_macros_2_0();
+        BindingKey { ident, ns, disambiguator: 0 }
+    }
+}
+
 type Resolutions<'a> = RefCell<FxIndexMap<BindingKey, &'a RefCell<NameResolution<'a>>>>;
 
 /// One node in the tree of modules.
@@ -943,6 +950,7 @@ pub struct Resolver<'a, 'tcx> {
     empty_module: Module<'a>,
     module_map: FxHashMap<DefId, Module<'a>>,
     binding_parent_modules: FxHashMap<Interned<'a, NameBinding<'a>>, Module<'a>>,
+
     underscore_disambiguator: u32,
 
     /// Maps glob imports to the names of items actually imported.
@@ -1595,7 +1603,7 @@ fn find_transitive_imports(
         import_ids
     }
 
-    fn new_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
+    fn new_disambiguated_key(&mut self, ident: Ident, ns: Namespace) -> BindingKey {
         let ident = ident.normalize_to_macros_2_0();
         let disambiguator = if ident.name == kw::Underscore {
             self.underscore_disambiguator += 1;

tests/ui/underscore-imports/issue-110164.rs

@@ -0,0 +1,19 @@
+use self::*;
+//~^ ERROR unresolved import `self::*`
+use crate::*;
+//~^ ERROR unresolved import `crate::*`
+use _::a;
+//~^ ERROR expected identifier, found reserved identifier `_`
+//~| ERROR unresolved import `_`
+use _::*;
+//~^ ERROR expected identifier, found reserved identifier `_`
+//~| ERROR unresolved import `_`
+
+fn main() {
+    use _::a;
+    //~^ ERROR expected identifier, found reserved identifier `_`
+    //~| ERROR unresolved import `_`
+    use _::*;
+    //~^ ERROR expected identifier, found reserved identifier `_`
+    //~| ERROR unresolved import `_`
+}

tests/ui/underscore-imports/issue-110164.stderr

@@ -0,0 +1,71 @@
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/issue-110164.rs:5:5
+   |
+LL | use _::a;
+   |     ^ expected identifier, found reserved identifier
+
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/issue-110164.rs:8:5
+   |
+LL | use _::*;
+   |     ^ expected identifier, found reserved identifier
+
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/issue-110164.rs:13:9
+   |
+LL |     use _::a;
+   |         ^ expected identifier, found reserved identifier
+
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/issue-110164.rs:16:9
+   |
+LL |     use _::*;
+   |         ^ expected identifier, found reserved identifier
+
+error[E0432]: unresolved import `self::*`
+  --> $DIR/issue-110164.rs:1:5
+   |
+LL | use self::*;
+   |     ^^^^^^^ cannot glob-import a module into itself
+
+error[E0432]: unresolved import `crate::*`
+  --> $DIR/issue-110164.rs:3:5
+   |
+LL | use crate::*;
+   |     ^^^^^^^^ cannot glob-import a module into itself
+
+error[E0432]: unresolved import `_`
+  --> $DIR/issue-110164.rs:8:5
+   |
+LL | use _::*;
+   |     ^ maybe a missing crate `_`?
+   |
+   = help: consider adding `extern crate _` to use the `_` crate
+
+error[E0432]: unresolved import `_`
+  --> $DIR/issue-110164.rs:5:5
+   |
+LL | use _::a;
+   |     ^ maybe a missing crate `_`?
+   |
+   = help: consider adding `extern crate _` to use the `_` crate
+
+error[E0432]: unresolved import `_`
+  --> $DIR/issue-110164.rs:13:9
+   |
+LL |     use _::a;
+   |         ^ maybe a missing crate `_`?
+   |
+   = help: consider adding `extern crate _` to use the `_` crate
+
+error[E0432]: unresolved import `_`
+  --> $DIR/issue-110164.rs:16:9
+   |
+LL |     use _::*;
+   |         ^ maybe a missing crate `_`?
+   |
+   = help: consider adding `extern crate _` to use the `_` crate
+
+error: aborting due to 10 previous errors
+
+For more information about this error, try `rustc --explain E0432`.