Remove global next_disambiguator state and handle it with a DisambiguatorState type

compiler/rustc_ast_lowering/src/expr.rs

@@ -492,9 +492,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
         let mut generic_args = ThinVec::new();
         for (idx, arg) in args.iter().cloned().enumerate() {
             if legacy_args_idx.contains(&idx) {
-                let parent_def_id = self.current_hir_id_owner.def_id;
                 let node_id = self.next_node_id();
-                self.create_def(parent_def_id, node_id, None, DefKind::AnonConst, f.span);
+                self.create_def(node_id, None, DefKind::AnonConst, f.span);
                 let mut visitor = WillCreateDefIdsVisitor {};
                 let const_value = if let ControlFlow::Break(span) = visitor.visit_expr(&arg) {
                     AstP(Expr {

compiler/rustc_ast_lowering/src/lib.rs

@@ -494,12 +494,12 @@ enum GenericArgsMode {
 impl<'a, 'hir> LoweringContext<'a, 'hir> {
     fn create_def(
         &mut self,
-        parent: LocalDefId,
         node_id: ast::NodeId,
         name: Option<Symbol>,
         def_kind: DefKind,
         span: Span,
     ) -> LocalDefId {
+        let parent = self.current_hir_id_owner.def_id;
         debug_assert_ne!(node_id, ast::DUMMY_NODE_ID);
         assert!(
             self.opt_local_def_id(node_id).is_none(),
@@ -509,7 +509,11 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             self.tcx.hir_def_key(self.local_def_id(node_id)),
         );
 
-        let def_id = self.tcx.at(span).create_def(parent, name, def_kind).def_id();
+        let def_id = self
+            .tcx
+            .at(span)
+            .create_def(parent, name, def_kind, None, &mut self.resolver.disambiguator)
+            .def_id();
 
         debug!("create_def: def_id_to_node_id[{:?}] <-> {:?}", def_id, node_id);
         self.resolver.node_id_to_def_id.insert(node_id, def_id);
@@ -781,7 +785,6 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             LifetimeRes::Fresh { param, kind, .. } => {
                 // Late resolution delegates to us the creation of the `LocalDefId`.
                 let _def_id = self.create_def(
-                    self.current_hir_id_owner.def_id,
                     param,
                     Some(kw::UnderscoreLifetime),
                     DefKind::LifetimeParam,
@@ -2107,16 +2110,14 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             hir::ConstArgKind::Path(qpath)
         } else {
             // Construct an AnonConst where the expr is the "ty"'s path.
-
-            let parent_def_id = self.current_hir_id_owner.def_id;
             let node_id = self.next_node_id();
             let span = self.lower_span(span);
 
             // Add a definition for the in-band const def.
             // We're lowering a const argument that was originally thought to be a type argument,
             // so the def collector didn't create the def ahead of time. That's why we have to do
             // it here.
-            let def_id = self.create_def(parent_def_id, node_id, None, DefKind::AnonConst, span);
+            let def_id = self.create_def(node_id, None, DefKind::AnonConst, span);
             let hir_id = self.lower_node_id(node_id);
 
             let path_expr = Expr {

compiler/rustc_ast_lowering/src/pat.rs

@@ -517,14 +517,13 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         span: Span,
         base_type: Span,
     ) -> &'hir hir::ConstArg<'hir> {
-        let parent_def_id = self.current_hir_id_owner.def_id;
         let node_id = self.next_node_id();
 
         // Add a definition for the in-band const def.
         // We're generating a range end that didn't exist in the AST,
         // so the def collector didn't create the def ahead of time. That's why we have to do
         // it here.
-        let def_id = self.create_def(parent_def_id, node_id, None, DefKind::AnonConst, span);
+        let def_id = self.create_def(node_id, None, DefKind::AnonConst, span);
         let hir_id = self.lower_node_id(node_id);
 
         let unstable_span = self.mark_span_with_reason(

compiler/rustc_const_eval/src/const_eval/dummy_machine.rs

@@ -1,3 +1,5 @@
+use rustc_hir::def_id::LocalDefId;
+use rustc_hir::definitions::DisambiguatorState;
 use rustc_middle::mir::interpret::{AllocId, ConstAllocation, InterpResult};
 use rustc_middle::mir::*;
 use rustc_middle::query::TyCtxtAt;
@@ -42,7 +44,7 @@ pub macro throw_machine_stop_str($($tt:tt)*) {{
 pub struct DummyMachine;
 
 impl HasStaticRootDefId for DummyMachine {
-    fn static_def_id(&self) -> Option<rustc_hir::def_id::LocalDefId> {
+    fn static_parent_and_disambiguator(&mut self) -> Option<(LocalDefId, &mut DisambiguatorState)> {
         None
     }
 }

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -6,6 +6,7 @@ use rustc_abi::{Align, Size};
 use rustc_ast::Mutability;
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap, IndexEntry};
 use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::definitions::DisambiguatorState;
 use rustc_hir::{self as hir, CRATE_HIR_ID, LangItem};
 use rustc_middle::mir::AssertMessage;
 use rustc_middle::mir::interpret::ReportedErrorInfo;
@@ -63,7 +64,7 @@ pub struct CompileTimeMachine<'tcx> {
     /// If `Some`, we are evaluating the initializer of the static with the given `LocalDefId`,
     /// storing the result in the given `AllocId`.
     /// Used to prevent reads from a static's base allocation, as that may allow for self-initialization loops.
-    pub(crate) static_root_ids: Option<(AllocId, LocalDefId)>,
+    pub(crate) static_root_ids: Option<(AllocId, LocalDefId, DisambiguatorState)>,
 
     /// A cache of "data range" computations for unions (i.e., the offsets of non-padding bytes).
     union_data_ranges: FxHashMap<Ty<'tcx>, RangeSet>,
@@ -706,7 +707,7 @@ impl<'tcx> interpret::Machine<'tcx> for CompileTimeMachine<'tcx> {
 
     fn before_alloc_read(ecx: &InterpCx<'tcx, Self>, alloc_id: AllocId) -> InterpResult<'tcx> {
         // Check if this is the currently evaluated static.
-        if Some(alloc_id) == ecx.machine.static_root_ids.map(|(id, _)| id) {
+        if Some(alloc_id) == ecx.machine.static_root_ids.as_ref().map(|(id, ..)| *id) {
             return Err(ConstEvalErrKind::RecursiveStatic).into();
         }
         // If this is another static, make sure we fire off the query to detect cycles.

compiler/rustc_const_eval/src/interpret/intern.rs

@@ -17,6 +17,7 @@ use hir::def::DefKind;
 use rustc_ast::Mutability;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_hir as hir;
+use rustc_hir::definitions::DisambiguatorState;
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
 use rustc_middle::mir::interpret::{ConstAllocation, CtfeProvenance, InterpResult};
 use rustc_middle::query::TyCtxtAt;
@@ -46,12 +47,13 @@ pub trait CompileTimeMachine<'tcx, T> = Machine<
 pub trait HasStaticRootDefId {
     /// Returns the `DefId` of the static item that is currently being evaluated.
     /// Used for interning to be able to handle nested allocations.
-    fn static_def_id(&self) -> Option<LocalDefId>;
+    fn static_parent_and_disambiguator(&mut self) -> Option<(LocalDefId, &mut DisambiguatorState)>;
 }
 
 impl HasStaticRootDefId for const_eval::CompileTimeMachine<'_> {
-    fn static_def_id(&self) -> Option<LocalDefId> {
-        Some(self.static_root_ids?.1)
+    fn static_parent_and_disambiguator(&mut self) -> Option<(LocalDefId, &mut DisambiguatorState)> {
+        let (_, static_id, d) = self.static_root_ids.as_mut()?;
+        Some((*static_id, d))
     }
 }
 
@@ -87,8 +89,8 @@ fn intern_shallow<'tcx, T, M: CompileTimeMachine<'tcx, T>>(
     }
     // link the alloc id to the actual allocation
     let alloc = ecx.tcx.mk_const_alloc(alloc);
-    if let Some(static_id) = ecx.machine.static_def_id() {
-        intern_as_new_static(ecx.tcx, static_id, alloc_id, alloc);
+    if let Some((static_id, disambiguator)) = ecx.machine.static_parent_and_disambiguator() {
+        intern_as_new_static(ecx.tcx, static_id, alloc_id, alloc, disambiguator);
     } else {
         ecx.tcx.set_alloc_id_memory(alloc_id, alloc);
     }
@@ -102,11 +104,14 @@ fn intern_as_new_static<'tcx>(
     static_id: LocalDefId,
     alloc_id: AllocId,
     alloc: ConstAllocation<'tcx>,
+    disambiguator: &mut DisambiguatorState,
 ) {
     let feed = tcx.create_def(
         static_id,
         Some(sym::nested),
         DefKind::Static { safety: hir::Safety::Safe, mutability: alloc.0.mutability, nested: true },
+        None,
+        disambiguator,
     );
     tcx.set_nested_alloc_id_static(alloc_id, feed.def_id());
 

compiler/rustc_const_eval/src/interpret/util.rs

@@ -1,4 +1,5 @@
 use rustc_hir::def_id::LocalDefId;
+use rustc_hir::definitions::DisambiguatorState;
 use rustc_middle::mir;
 use rustc_middle::mir::interpret::{AllocInit, Allocation, InterpResult, Pointer};
 use rustc_middle::ty::layout::TyAndLayout;
@@ -40,8 +41,8 @@ pub(crate) fn create_static_alloc<'tcx>(
 ) -> InterpResult<'tcx, MPlaceTy<'tcx>> {
     let alloc = Allocation::try_new(layout.size, layout.align.abi, AllocInit::Uninit)?;
     let alloc_id = ecx.tcx.reserve_and_set_static_alloc(static_def_id.into());
-    assert_eq!(ecx.machine.static_root_ids, None);
-    ecx.machine.static_root_ids = Some((alloc_id, static_def_id));
+    assert!(ecx.machine.static_root_ids.is_none());
+    ecx.machine.static_root_ids = Some((alloc_id, static_def_id, DisambiguatorState::new()));
     assert!(ecx.memory.alloc_map.insert(alloc_id, (MemoryKind::Stack, alloc)).is_none());
     interp_ok(ecx.ptr_to_mplace(Pointer::from(alloc_id).into(), layout))
 }

compiler/rustc_hir/src/def.rs

@@ -269,14 +269,9 @@ impl DefKind {
             | DefKind::TyParam
             | DefKind::ExternCrate => DefPathData::TypeNs(name.unwrap()),
 
-            // An associated type name will be missing for an RPITIT.
-            DefKind::AssocTy => {
-                if let Some(name) = name {
-                    DefPathData::TypeNs(name)
-                } else {
-                    DefPathData::AnonAssocTy
-                }
-            }
+            // An associated type name will be missing for an RPITIT (DefPathData::AnonAssocTy),
+            // but those provide their own DefPathData.
+            DefKind::AssocTy => DefPathData::TypeNs(name.unwrap()),
 
             // It's not exactly an anon const, but wrt DefPathData, there
             // is no difference.

compiler/rustc_hir/src/definitions.rs

@@ -68,7 +68,7 @@ impl DefPathTable {
             //
             // See the documentation for DefPathHash for more information.
             panic!(
-                "found DefPathHash collision between {def_path1:?} and {def_path2:?}. \
+                "found DefPathHash collision between {def_path1:#?} and {def_path2:#?}. \
                     Compilation cannot continue."
             );
         }
@@ -97,13 +97,31 @@ impl DefPathTable {
     }
 }
 
+#[derive(Debug)]
+pub struct DisambiguatorState {
+    next: UnordMap<(LocalDefId, DefPathData), u32>,
+}
+
+impl DisambiguatorState {
+    pub fn new() -> Self {
+        Self { next: Default::default() }
+    }
+
+    /// Creates a `DisambiguatorState` where the next allocated `(LocalDefId, DefPathData)` pair
+    /// will have `index` as the disambiguator.
+    pub fn with(def_id: LocalDefId, data: DefPathData, index: u32) -> Self {
+        let mut this = Self::new();
+        this.next.insert((def_id, data), index);
+        this
+    }
+}
+
 /// The definition table containing node definitions.
 /// It holds the `DefPathTable` for `LocalDefId`s/`DefPath`s.
 /// It also stores mappings to convert `LocalDefId`s to/from `HirId`s.
 #[derive(Debug)]
 pub struct Definitions {
     table: DefPathTable,
-    next_disambiguator: UnordMap<(LocalDefId, DefPathData), u32>,
 }
 
 /// A unique identifier that we can use to lookup a definition
@@ -173,7 +191,11 @@ impl DisambiguatedDefPathData {
                 }
             }
             DefPathDataName::Anon { namespace } => {
-                write!(writer, "{{{}#{}}}", namespace, self.disambiguator)
+                if let DefPathData::AnonAssocTy(method) = self.data {
+                    write!(writer, "{}::{{{}#{}}}", method, namespace, self.disambiguator)
+                } else {
+                    write!(writer, "{{{}#{}}}", namespace, self.disambiguator)
+                }
             }
         }
     }
@@ -288,7 +310,7 @@ pub enum DefPathData {
     /// Argument position `impl Trait` have a `TypeNs` with their pretty-printed name.
     OpaqueTy,
     /// An anonymous associated type from an RPITIT.
-    AnonAssocTy,
+    AnonAssocTy(Symbol),
     /// A synthetic body for a coroutine's by-move body.
     SyntheticCoroutineBody,
 }
@@ -342,24 +364,33 @@ impl Definitions {
         let root = LocalDefId { local_def_index: table.allocate(key, def_path_hash) };
         assert_eq!(root.local_def_index, CRATE_DEF_INDEX);
 
-        Definitions { table, next_disambiguator: Default::default() }
+        Definitions { table }
     }
 
-    /// Adds a definition with a parent definition.
-    pub fn create_def(&mut self, parent: LocalDefId, data: DefPathData) -> LocalDefId {
+    /// Creates a definition with a parent definition.
+    /// If there are multiple definitions with the same DefPathData and the same parent, use
+    /// `disambiguator` to differentiate them. Distinct `DisambiguatorState` instances are not
+    /// guaranteed to generate unique disambiguators and should instead ensure that the `parent`
+    /// and `data` pair is distinct from other instances.
+    pub fn create_def(
+        &mut self,
+        parent: LocalDefId,
+        data: DefPathData,
+        disambiguator: &mut DisambiguatorState,
+    ) -> LocalDefId {
         // We can't use `Debug` implementation for `LocalDefId` here, since it tries to acquire a
         // reference to `Definitions` and we're already holding a mutable reference.
         debug!(
             "create_def(parent={}, data={data:?})",
             self.def_path(parent).to_string_no_crate_verbose(),
         );
 
-        // The root node must be created with `create_root_def()`.
+        // The root node must be created in `new()`.
         assert!(data != DefPathData::CrateRoot);
 
         // Find the next free disambiguator for this key.
         let disambiguator = {
-            let next_disamb = self.next_disambiguator.entry((parent, data)).or_insert(0);
+            let next_disamb = disambiguator.next.entry((parent, data)).or_insert(0);
             let disambiguator = *next_disamb;
             *next_disamb = next_disamb.checked_add(1).expect("disambiguator overflow");
             disambiguator
@@ -411,7 +442,9 @@ impl DefPathData {
     pub fn get_opt_name(&self) -> Option<Symbol> {
         use self::DefPathData::*;
         match *self {
-            TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => Some(name),
+            TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) | AnonAssocTy(name) => {
+                Some(name)
+            }
 
             Impl
             | ForeignMod
@@ -422,7 +455,6 @@ impl DefPathData {
             | Ctor
             | AnonConst
             | OpaqueTy
-            | AnonAssocTy
             | SyntheticCoroutineBody => None,
         }
     }
@@ -443,7 +475,7 @@ impl DefPathData {
             Ctor => DefPathDataName::Anon { namespace: sym::constructor },
             AnonConst => DefPathDataName::Anon { namespace: sym::constant },
             OpaqueTy => DefPathDataName::Anon { namespace: sym::opaque },
-            AnonAssocTy => DefPathDataName::Anon { namespace: sym::anon_assoc },
+            AnonAssocTy(..) => DefPathDataName::Anon { namespace: sym::anon_assoc },
             SyntheticCoroutineBody => DefPathDataName::Anon { namespace: sym::synthetic },
         }
     }