Auto merge of #140453 - Zoxc:next-disambiguator, r=oli-obk

Remove global `next_disambiguator` state and handle it with a `DisambiguatorState` type

This removes `Definitions.next_disambiguator` as it doesn't guarantee deterministic def paths when `create_def` is called in parallel. Instead a new `DisambiguatorState` type is passed as a mutable reference to `create_def` to help create unique def paths. `create_def` calls with distinct  `DisambiguatorState` instances must ensure that that the def paths are unique without its help.

Anon associated types did rely on this global state for uniqueness and are changed to use (method they're defined in + their position in the method return type) as the `DefPathData` to ensure uniqueness. This also means that the method they're defined in appears in error messages, which is nicer.

`DefPathData::NestedStatic` is added to use for nested data inside statics instead of reusing `DefPathData::AnonConst` to avoid conflicts with those.

cc `@oli-obk`

1 files changed, 27 insertions, 8 deletions

diff --git a/compiler/rustc_const_eval/src/interpret/intern.rs b/compiler/rustc_const_eval/src/interpret/intern.rs
index 8f0cb197c44..1dd96297d1f 100644
--- a/compiler/rustc_const_eval/src/interpret/intern.rs
+++ b/compiler/rustc_const_eval/src/interpret/intern.rs
@@ -17,13 +17,13 @@ use hir::def::DefKind;
 use rustc_ast::Mutability;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_hir as hir;
+use rustc_hir::definitions::{DefPathData, DisambiguatorState};
 use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
 use rustc_middle::mir::interpret::{ConstAllocation, CtfeProvenance, InterpResult};
 use rustc_middle::query::TyCtxtAt;
 use rustc_middle::span_bug;
 use rustc_middle::ty::layout::TyAndLayout;
 use rustc_span::def_id::LocalDefId;
-use rustc_span::sym;
 use tracing::{instrument, trace};
 
 use super::{
@@ -66,6 +66,7 @@ fn intern_shallow<'tcx, T, M: CompileTimeMachine<'tcx, T>>(
     ecx: &mut InterpCx<'tcx, M>,
     alloc_id: AllocId,
     mutability: Mutability,
+    disambiguator: Option<&mut DisambiguatorState>,
 ) -> Result<impl Iterator<Item = CtfeProvenance> + 'tcx, ()> {
     trace!("intern_shallow {:?}", alloc_id);
     // remove allocation
@@ -88,7 +89,13 @@ 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);
+        intern_as_new_static(
+            ecx.tcx,
+            static_id,
+            alloc_id,
+            alloc,
+            disambiguator.expect("disambiguator needed"),
+        );
     } else {
         ecx.tcx.set_alloc_id_memory(alloc_id, alloc);
     }
@@ -102,11 +109,18 @@ fn intern_as_new_static<'tcx>(
     static_id: LocalDefId,
     alloc_id: AllocId,
     alloc: ConstAllocation<'tcx>,
+    disambiguator: &mut DisambiguatorState,
 ) {
+    // `intern_const_alloc_recursive` is called once per static and it contains the `DisambiguatorState`.
+    //  The `<static_id>::{{nested}}` path is thus unique to `intern_const_alloc_recursive` and the
+    // `DisambiguatorState` ensures the generated path is unique for this call as we generate
+    // `<static_id>::{{nested#n}}` where `n` is the `n`th `intern_as_new_static` call.
     let feed = tcx.create_def(
         static_id,
-        Some(sym::nested),
+        None,
         DefKind::Static { safety: hir::Safety::Safe, mutability: alloc.0.mutability, nested: true },
+        Some(DefPathData::NestedStatic),
+        disambiguator,
     );
     tcx.set_nested_alloc_id_static(alloc_id, feed.def_id());
 
@@ -154,6 +168,8 @@ pub fn intern_const_alloc_recursive<'tcx, M: CompileTimeMachine<'tcx, const_eval
     intern_kind: InternKind,
     ret: &MPlaceTy<'tcx>,
 ) -> Result<(), InternResult> {
+    let mut disambiguator = DisambiguatorState::new();
+
     // We are interning recursively, and for mutability we are distinguishing the "root" allocation
     // that we are starting in, and all other allocations that we are encountering recursively.
     let (base_mutability, inner_mutability, is_static) = match intern_kind {
@@ -197,7 +213,9 @@ pub fn intern_const_alloc_recursive<'tcx, M: CompileTimeMachine<'tcx, const_eval
         alloc.1.mutability = base_mutability;
         alloc.1.provenance().ptrs().iter().map(|&(_, prov)| prov).collect()
     } else {
-        intern_shallow(ecx, base_alloc_id, base_mutability).unwrap().collect()
+        intern_shallow(ecx, base_alloc_id, base_mutability, Some(&mut disambiguator))
+            .unwrap()
+            .collect()
     };
     // We need to distinguish "has just been interned" from "was already in `tcx`",
     // so we track this in a separate set.
@@ -291,7 +309,7 @@ pub fn intern_const_alloc_recursive<'tcx, M: CompileTimeMachine<'tcx, const_eval
         // okay with losing some potential for immutability here. This can anyway only affect
         // `static mut`.
         just_interned.insert(alloc_id);
-        match intern_shallow(ecx, alloc_id, inner_mutability) {
+        match intern_shallow(ecx, alloc_id, inner_mutability, Some(&mut disambiguator)) {
             Ok(nested) => todo.extend(nested),
             Err(()) => {
                 ecx.tcx.dcx().delayed_bug("found dangling pointer during const interning");
@@ -313,8 +331,9 @@ pub fn intern_const_alloc_for_constprop<'tcx, T, M: CompileTimeMachine<'tcx, T>>
         return interp_ok(());
     }
     // Move allocation to `tcx`.
-    if let Some(_) =
-        (intern_shallow(ecx, alloc_id, Mutability::Not).map_err(|()| err_ub!(DeadLocal))?).next()
+    if let Some(_) = intern_shallow(ecx, alloc_id, Mutability::Not, None)
+        .map_err(|()| err_ub!(DeadLocal))?
+        .next()
     {
         // We are not doing recursive interning, so we don't currently support provenance.
         // (If this assertion ever triggers, we should just implement a
@@ -340,7 +359,7 @@ impl<'tcx> InterpCx<'tcx, DummyMachine> {
         let dest = self.allocate(layout, MemoryKind::Stack)?;
         f(self, &dest.clone().into())?;
         let alloc_id = dest.ptr().provenance.unwrap().alloc_id(); // this was just allocated, it must have provenance
-        for prov in intern_shallow(self, alloc_id, Mutability::Not).unwrap() {
+        for prov in intern_shallow(self, alloc_id, Mutability::Not, None).unwrap() {
             // We are not doing recursive interning, so we don't currently support provenance.
             // (If this assertion ever triggers, we should just implement a
             // proper recursive interning loop -- or just call `intern_const_alloc_recursive`.