Auto merge of #155460 - cjgillot:unmut-resolver-ast, r=oli-obk

Do not modify resolver outputs during lowering



Split from #142830

I believe this achieves the same thing as #153656 but in a much simpler way. 

This PR forces AST->HIR lowering to stop mutating resolver outputs. Instead, it manages a few override maps that only live during lowering and are dropped afterwards.

r? @petrochenkov 
cc @aerooneqq

Author: bors

compiler/rustc_ast_lowering/src/asm.rs

@@ -18,11 +18,9 @@ use super::errors::{
     InvalidRegisterClass, RegisterClassOnlyClobber, RegisterClassOnlyClobberStable,
     RegisterConflict,
 };
-use crate::{
-    AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, ParamMode, ResolverAstLoweringExt,
-};
+use crate::{AllowReturnTypeNotation, ImplTraitContext, ImplTraitPosition, ParamMode};
 
-impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
+impl<'hir> LoweringContext<'_, 'hir> {
     pub(crate) fn lower_inline_asm(
         &mut self,
         sp: Span,
@@ -203,7 +201,6 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
                     },
                     InlineAsmOperand::Sym { sym } => {
                         let static_def_id = self
-                            .resolver
                             .get_partial_res(sym.id)
                             .and_then(|res| res.full_res())
                             .and_then(|res| match res {

compiler/rustc_ast_lowering/src/block.rs

@@ -4,9 +4,9 @@ use rustc_hir::Target;
 use rustc_span::sym;
 use smallvec::SmallVec;
 
-use crate::{ImplTraitContext, ImplTraitPosition, LoweringContext, ResolverAstLoweringExt};
+use crate::{ImplTraitContext, ImplTraitPosition, LoweringContext};
 
-impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
+impl<'hir> LoweringContext<'_, 'hir> {
     pub(super) fn lower_block(
         &mut self,
         b: &Block,

compiler/rustc_ast_lowering/src/contract.rs

@@ -2,9 +2,9 @@ use std::sync::Arc;
 
 use thin_vec::thin_vec;
 
-use crate::{LoweringContext, ResolverAstLoweringExt};
+use crate::LoweringContext;
 
-impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
+impl<'hir> LoweringContext<'_, 'hir> {
     /// Lowered contracts are guarded with the `contract_checks` compiler flag,
     /// i.e. the flag turns into a boolean guard in the lowered HIR. The reason
     /// for not eliminating the contract code entirely when the `contract_checks`

compiler/rustc_ast_lowering/src/delegation.rs

@@ -39,7 +39,7 @@
 use std::iter;
 
 use ast::visit::Visitor;
-use hir::def::{DefKind, PartialRes, Res};
+use hir::def::{DefKind, Res};
 use hir::{BodyId, HirId};
 use rustc_abi::ExternAbi;
 use rustc_ast as ast;
@@ -105,7 +105,7 @@ static ATTRS_ADDITIONS: &[AttrAdditionInfo] = &[
     },
 ];
 
-impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
+impl<'hir> LoweringContext<'_, 'hir> {
     fn is_method(&self, def_id: DefId, span: Span) -> bool {
         match self.tcx.def_kind(def_id) {
             DefKind::Fn => false,
@@ -266,7 +266,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
     }
 
     fn get_resolution_id(&self, node_id: NodeId) -> Option<DefId> {
-        self.resolver.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id())
+        self.get_partial_res(node_id).and_then(|r| r.expect_full_res().opt_def_id())
     }
 
     // Function parameter count, including C variadic `...` if present.
@@ -417,7 +417,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
                     && idx == 0
                 {
                     let mut self_resolver = SelfResolver {
-                        resolver: this.resolver,
+                        ctxt: this,
                         path_id: delegation.id,
                         self_param_id: pat_node_id,
                     };
@@ -665,25 +665,24 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
     }
 }
 
-struct SelfResolver<'a, R> {
-    resolver: &'a mut R,
+struct SelfResolver<'a, 'b, 'hir> {
+    ctxt: &'a mut LoweringContext<'b, 'hir>,
     path_id: NodeId,
     self_param_id: NodeId,
 }
 
-impl<'tcx, R: ResolverAstLoweringExt<'tcx>> SelfResolver<'_, R> {
+impl SelfResolver<'_, '_, '_> {
     fn try_replace_id(&mut self, id: NodeId) {
-        if let Some(res) = self.resolver.get_partial_res(id)
+        if let Some(res) = self.ctxt.get_partial_res(id)
             && let Some(Res::Local(sig_id)) = res.full_res()
             && sig_id == self.path_id
         {
-            let new_res = PartialRes::new(Res::Local(self.self_param_id));
-            self.resolver.insert_partial_res(id, new_res);
+            self.ctxt.partial_res_overrides.insert(id, self.self_param_id);
         }
     }
 }
 
-impl<'ast, 'tcx, R: ResolverAstLoweringExt<'tcx>> Visitor<'ast> for SelfResolver<'_, R> {
+impl<'ast> Visitor<'ast> for SelfResolver<'_, '_, '_> {
     fn visit_id(&mut self, id: NodeId) {
         self.try_replace_id(id);
     }

compiler/rustc_ast_lowering/src/delegation/generics.rs

@@ -8,7 +8,7 @@ use rustc_middle::{bug, ty};
 use rustc_span::symbol::kw;
 use rustc_span::{Ident, Span, sym};
 
-use crate::{LoweringContext, ResolverAstLoweringExt};
+use crate::LoweringContext;
 
 #[derive(Clone, Copy)]
 pub(super) enum DelegationGenericsKind {
@@ -114,7 +114,7 @@ impl DelegationGenericsKind {
 impl<'hir> HirOrTyGenerics<'hir> {
     pub(super) fn into_hir_generics(
         &mut self,
-        ctx: &mut LoweringContext<'_, 'hir, impl ResolverAstLoweringExt<'hir>>,
+        ctx: &mut LoweringContext<'_, 'hir>,
         span: Span,
     ) -> &mut HirOrTyGenerics<'hir> {
         if let HirOrTyGenerics::Ty(ty) = self {
@@ -140,7 +140,7 @@ impl<'hir> HirOrTyGenerics<'hir> {
 
     pub(super) fn into_generic_args(
         &self,
-        ctx: &mut LoweringContext<'_, 'hir, impl ResolverAstLoweringExt<'hir>>,
+        ctx: &mut LoweringContext<'_, 'hir>,
         span: Span,
     ) -> &'hir hir::GenericArgs<'hir> {
         match self {
@@ -174,7 +174,7 @@ impl<'hir> GenericsGenerationResults<'hir> {
     pub(super) fn all_params(
         &mut self,
         span: Span,
-        ctx: &mut LoweringContext<'_, 'hir, impl ResolverAstLoweringExt<'hir>>,
+        ctx: &mut LoweringContext<'_, 'hir>,
     ) -> impl Iterator<Item = hir::GenericParam<'hir>> {
         // Now we always call `into_hir_generics` both on child and parent,
         // however in future we would not do that, when scenarios like
@@ -208,7 +208,7 @@ impl<'hir> GenericsGenerationResults<'hir> {
     pub(super) fn all_predicates(
         &mut self,
         span: Span,
-        ctx: &mut LoweringContext<'_, 'hir, impl ResolverAstLoweringExt<'hir>>,
+        ctx: &mut LoweringContext<'_, 'hir>,
     ) -> impl Iterator<Item = hir::WherePredicate<'hir>> {
         // Now we always call `into_hir_generics` both on child and parent,
         // however in future we would not do that, when scenarios like
@@ -226,7 +226,7 @@ impl<'hir> GenericsGenerationResults<'hir> {
     }
 }
 
-impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
+impl<'hir> LoweringContext<'_, 'hir> {
     pub(super) fn uplift_delegation_generics(
         &mut self,
         delegation: &Delegation,

compiler/rustc_ast_lowering/src/expr.rs

@@ -51,7 +51,7 @@ impl<'v> rustc_ast::visit::Visitor<'v> for WillCreateDefIdsVisitor {
     }
 }
 
-impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
+impl<'hir> LoweringContext<'_, 'hir> {
     fn lower_exprs(&mut self, exprs: &[Box<Expr>]) -> &'hir [hir::Expr<'hir>] {
         self.arena.alloc_from_iter(exprs.iter().map(|x| self.lower_expr_mut(x)))
     }
@@ -1235,10 +1235,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
         whole_span: Span,
     ) -> hir::ExprKind<'hir> {
         // Return early in case of an ordinary assignment.
-        fn is_ordinary<'hir>(
-            lower_ctx: &mut LoweringContext<'_, 'hir, impl ResolverAstLoweringExt<'hir>>,
-            lhs: &Expr,
-        ) -> bool {
+        fn is_ordinary(lower_ctx: &mut LoweringContext<'_, '_>, lhs: &Expr) -> bool {
             match &lhs.kind {
                 ExprKind::Array(..)
                 | ExprKind::Struct(..)
@@ -1293,7 +1290,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
     ) -> Option<(&'a Option<Box<QSelf>>, &'a Path)> {
         if let ExprKind::Path(qself, path) = &expr.kind {
             // Does the path resolve to something disallowed in a tuple struct/variant pattern?
-            if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
+            if let Some(partial_res) = self.get_partial_res(expr.id) {
                 if let Some(res) = partial_res.full_res()
                     && !res.expected_in_tuple_struct_pat()
                 {
@@ -1315,7 +1312,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
     ) -> Option<(&'a Option<Box<QSelf>>, &'a Path)> {
         if let ExprKind::Path(qself, path) = &expr.kind {
             // Does the path resolve to something disallowed in a unit struct/variant pattern?
-            if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
+            if let Some(partial_res) = self.get_partial_res(expr.id) {
                 if let Some(res) = partial_res.full_res()
                     && !res.expected_in_unit_struct_pat()
                 {

compiler/rustc_ast_lowering/src/format.rs

@@ -7,9 +7,8 @@ use rustc_session::config::FmtDebug;
 use rustc_span::{ByteSymbol, DesugaringKind, Ident, Span, Symbol, sym};
 
 use super::LoweringContext;
-use crate::ResolverAstLoweringExt;
 
-impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
+impl<'hir> LoweringContext<'_, 'hir> {
     pub(crate) fn lower_format_args(&mut self, sp: Span, fmt: &FormatArgs) -> hir::ExprKind<'hir> {
         // Never call the const constructor of `fmt::Arguments` if the
         // format_args!() had any arguments _before_ flattening/inlining.
@@ -231,7 +230,7 @@ enum ArgumentType {
 ///     <core::fmt::Argument>::new_…(arg)
 /// ```
 fn make_argument<'hir>(
-    ctx: &mut LoweringContext<'_, 'hir, impl ResolverAstLoweringExt<'hir>>,
+    ctx: &mut LoweringContext<'_, 'hir>,
     sp: Span,
     arg: &'hir hir::Expr<'hir>,
     ty: ArgumentType,
@@ -278,7 +277,7 @@ fn make_count(
 }
 
 fn expand_format_args<'hir>(
-    ctx: &mut LoweringContext<'_, 'hir, impl ResolverAstLoweringExt<'hir>>,
+    ctx: &mut LoweringContext<'_, 'hir>,
     macsp: Span,
     fmt: &FormatArgs,
     allow_const: bool,

compiler/rustc_ast_lowering/src/item.rs

@@ -1,22 +1,19 @@
 use std::mem;
-use std::sync::Arc;
 
 use rustc_abi::ExternAbi;
 use rustc_ast::visit::AssocCtxt;
 use rustc_ast::*;
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_data_structures::steal::Steal;
 use rustc_errors::{E0570, ErrorGuaranteed, struct_span_code_err};
 use rustc_hir::attrs::{AttributeKind, EiiImplResolution};
 use rustc_hir::def::{DefKind, PerNS, Res};
-use rustc_hir::def_id::{CRATE_DEF_ID, LocalDefId, LocalDefIdMap};
-use rustc_hir::definitions::PerParentDisambiguatorState;
+use rustc_hir::def_id::{CRATE_DEF_ID, LocalDefId};
 use rustc_hir::{
     self as hir, HirId, ImplItemImplKind, LifetimeSource, PredicateOrigin, Target, find_attr,
 };
 use rustc_index::{IndexSlice, IndexVec};
 use rustc_middle::span_bug;
-use rustc_middle::ty::TyCtxt;
+use rustc_middle::ty::{ResolverAstLowering, TyCtxt};
 use rustc_span::def_id::DefId;
 use rustc_span::edit_distance::find_best_match_for_name;
 use rustc_span::{DUMMY_SP, DesugaringKind, Ident, Span, Symbol, kw, sym};
@@ -51,21 +48,11 @@ impl<'hir> Owners<'_, 'hir> {
     }
 }
 
-/// Default disambiguators are used during default lowering, when we lower
-/// AST owners in a loop we can use the whole map, in contrast delayed lowering
-/// lowers each AST owner separately, so we use readonly disambiguators map
-/// with `Steal`s to get disambiguators.
-pub(super) enum Disambiguators {
-    Default(LocalDefIdMap<PerParentDisambiguatorState>),
-    Delayed(Arc<LocalDefIdMap<Steal<PerParentDisambiguatorState>>>),
-}
-
-pub(super) struct ItemLowerer<'a, 'hir, R> {
+pub(super) struct ItemLowerer<'a, 'hir> {
     pub(super) tcx: TyCtxt<'hir>,
-    pub(super) resolver: &'a mut R,
+    pub(super) resolver: &'a ResolverAstLowering<'hir>,
     pub(super) ast_index: &'a IndexSlice<LocalDefId, AstOwner<'a>>,
     pub(super) owners: Owners<'a, 'hir>,
-    pub(super) disambiguators: &'a mut Disambiguators,
 }
 
 /// When we have a ty alias we *may* have two where clauses. To give the best diagnostics, we set the span
@@ -87,13 +74,13 @@ fn add_ty_alias_where_clause(
         if before.0 || !after.0 { before } else { after };
 }
 
-impl<'hir, R: ResolverAstLoweringExt<'hir>> ItemLowerer<'_, 'hir, R> {
+impl<'hir> ItemLowerer<'_, 'hir> {
     fn with_lctx(
         &mut self,
         owner: NodeId,
-        f: impl FnOnce(&mut LoweringContext<'_, 'hir, R>) -> hir::OwnerNode<'hir>,
+        f: impl for<'a> FnOnce(&mut LoweringContext<'a, 'hir>) -> hir::OwnerNode<'hir>,
     ) {
-        let mut lctx = LoweringContext::new(self.tcx, self.resolver, self.disambiguators);
+        let mut lctx = LoweringContext::new(self.tcx, self.resolver);
         lctx.with_hir_id_owner(owner, |lctx| f(lctx));
 
         for (def_id, info) in lctx.children {
@@ -135,7 +122,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> ItemLowerer<'_, 'hir, R> {
     }
 }
 
-impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
+impl<'hir> LoweringContext<'_, 'hir> {
     pub(super) fn lower_mod(
         &mut self,
         items: &[Box<Item>],
@@ -648,7 +635,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
     }
 
     fn lower_path_simple_eii(&mut self, id: NodeId, path: &Path) -> Option<DefId> {
-        let res = self.resolver.get_partial_res(id)?;
+        let res = self.get_partial_res(id)?;
         let Some(did) = res.expect_full_res().opt_def_id() else {
             self.dcx().span_delayed_bug(path.span, "should have errored in resolve");
             return None;
@@ -1349,7 +1336,6 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
                 ImplItemImplKind::Trait {
                     defaultness,
                     trait_item_def_id: self
-                        .resolver
                         .get_partial_res(i.id)
                         .and_then(|r| r.expect_full_res().opt_def_id())
                         .ok_or_else(|| {
@@ -1545,7 +1531,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
     pub(crate) fn lower_coroutine_body_with_moved_arguments(
         &mut self,
         decl: &FnDecl,
-        lower_body: impl FnOnce(&mut LoweringContext<'_, 'hir, R>) -> hir::Expr<'hir>,
+        lower_body: impl FnOnce(&mut LoweringContext<'_, 'hir>) -> hir::Expr<'hir>,
         fn_decl_span: Span,
         body_span: Span,
         coroutine_kind: CoroutineKind,
@@ -1682,7 +1668,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
             parameters.push(new_parameter);
         }
 
-        let mkbody = |this: &mut LoweringContext<'_, 'hir, R>| {
+        let mkbody = |this: &mut LoweringContext<'_, 'hir>| {
             // Create a block from the user's function body:
             let user_body = lower_body(this);
 
@@ -1867,7 +1853,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
         let kind = match &r.kind {
             RestrictionKind::Unrestricted => hir::RestrictionKind::Unrestricted,
             RestrictionKind::Restricted { path, id, shorthand: _ } => {
-                let res = self.resolver.get_partial_res(*id);
+                let res = self.get_partial_res(*id);
                 if let Some(did) = res.and_then(|res| res.expect_full_res().opt_def_id()) {
                     hir::RestrictionKind::Restricted(self.arena.alloc(hir::Path {
                         res: did,
@@ -1933,7 +1919,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
 
         // Introduce extra lifetimes if late resolution tells us to.
         let extra_lifetimes = self.resolver.extra_lifetime_params(parent_node_id);
-        params.extend(extra_lifetimes.into_iter().filter_map(|(ident, node_id, res)| {
+        params.extend(extra_lifetimes.into_iter().filter_map(|&(ident, node_id, res)| {
             self.lifetime_res_to_generic_param(
                 ident,
                 node_id,
@@ -1975,7 +1961,7 @@ impl<'hir, R: ResolverAstLoweringExt<'hir>> LoweringContext<'_, 'hir, R> {
             return;
         };
         let define_opaque = define_opaque.iter().filter_map(|(id, path)| {
-            let res = self.resolver.get_partial_res(*id);
+            let res = self.get_partial_res(*id);
             let Some(did) = res.and_then(|res| res.expect_full_res().opt_def_id()) else {
                 self.dcx().span_delayed_bug(path.span, "should have errored in resolve");
                 return None;