Rollup merge of #97913 - dingxiangfei2009:wrap-into-local-var-id, r=nikomatsakis

Wrap `HirId`s of locals into `LocalVarId`s for THIR nodes

This is the first effort to decouple `HirId`s from THIR. `HirId` is not very relevant in building THIR and MIR.

Based on the changeset, I think there are a few other pending refactoring that we could perform after this, in case we want to eliminate use of `HirId` in THIR.
- `TypeckResults::closure_min_captures` could be remapped from the variable `HirId`s to `LocalVarId` while the THIR is getting built.
- Use of `ScopeTree::var_scope` could be eliminated as well, since we will consider deprecating `ScopeTree` in the future.

Author: Dylan-DPC

compiler/rustc_middle/src/thir.rs

@@ -191,6 +191,20 @@ pub enum StmtKind<'tcx> {
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
 rustc_data_structures::static_assert_size!(Expr<'_>, 104);
 
+#[derive(
+    Clone,
+    Debug,
+    Copy,
+    PartialEq,
+    Eq,
+    Hash,
+    HashStable,
+    TyEncodable,
+    TyDecodable,
+    TypeFoldable
+)]
+pub struct LocalVarId(pub hir::HirId);
+
 /// A THIR expression.
 #[derive(Clone, Debug, HashStable)]
 pub struct Expr<'tcx> {
@@ -332,15 +346,15 @@ pub enum ExprKind<'tcx> {
     },
     /// A local variable.
     VarRef {
-        id: hir::HirId,
+        id: LocalVarId,
     },
     /// Used to represent upvars mentioned in a closure/generator
     UpvarRef {
         /// DefId of the closure/generator
         closure_def_id: DefId,
 
         /// HirId of the root variable
-        var_hir_id: hir::HirId,
+        var_hir_id: LocalVarId,
     },
     /// A borrow, e.g. `&arg`.
     Borrow {
@@ -596,7 +610,7 @@ pub enum PatKind<'tcx> {
         mutability: Mutability,
         name: Symbol,
         mode: BindingMode,
-        var: hir::HirId,
+        var: LocalVarId,
         ty: Ty<'tcx>,
         subpattern: Option<Pat<'tcx>>,
         /// Is this the leftmost occurrence of the binding, i.e., is `var` the

compiler/rustc_mir_build/src/build/expr/as_place.rs

@@ -3,8 +3,7 @@
 use crate::build::expr::category::Category;
 use crate::build::ForGuard::{OutsideGuard, RefWithinGuard};
 use crate::build::{BlockAnd, BlockAndExtension, Builder};
-use rustc_hir::def_id::DefId;
-use rustc_hir::HirId;
+use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::hir::place::Projection as HirProjection;
 use rustc_middle::hir::place::ProjectionKind as HirProjectionKind;
 use rustc_middle::middle::region;
@@ -57,7 +56,7 @@ pub(crate) enum PlaceBase {
     /// figure out that it is captured until all the `Field` projections are applied.
     Upvar {
         /// HirId of the upvar
-        var_hir_id: HirId,
+        var_hir_id: LocalVarId,
         /// DefId of the closure
         closure_def_id: DefId,
         /// The trait closure implements, `Fn`, `FnMut`, `FnOnce`
@@ -151,12 +150,12 @@ fn is_ancestor_or_same_capture(
 /// `ty::MinCaptureList` of the root variable `var_hir_id`.
 fn compute_capture_idx<'tcx>(
     closure_min_captures: &ty::RootVariableMinCaptureList<'tcx>,
-    var_hir_id: HirId,
+    var_hir_id: LocalVarId,
     root_var_idx: usize,
 ) -> usize {
     let mut res = 0;
     for (var_id, capture_list) in closure_min_captures {
-        if *var_id == var_hir_id {
+        if *var_id == var_hir_id.0 {
             res += root_var_idx;
             break;
         } else {
@@ -176,12 +175,12 @@ fn compute_capture_idx<'tcx>(
 /// Returns None, when the ancestor is not found.
 fn find_capture_matching_projections<'a, 'tcx>(
     typeck_results: &'a ty::TypeckResults<'tcx>,
-    var_hir_id: HirId,
+    var_hir_id: LocalVarId,
     closure_def_id: DefId,
     projections: &[PlaceElem<'tcx>],
 ) -> Option<(usize, &'a ty::CapturedPlace<'tcx>)> {
     let closure_min_captures = typeck_results.closure_min_captures.get(&closure_def_id)?;
-    let root_variable_min_captures = closure_min_captures.get(&var_hir_id)?;
+    let root_variable_min_captures = closure_min_captures.get(&var_hir_id.0)?;
 
     let hir_projections = convert_to_hir_projections_and_truncate_for_capture(projections);
 
@@ -500,8 +499,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 source_info,
             ),
             ExprKind::UpvarRef { closure_def_id, var_hir_id } => {
-                let upvar_id = ty::UpvarId::new(var_hir_id, closure_def_id.expect_local());
-                this.lower_captured_upvar(block, upvar_id)
+                this.lower_captured_upvar(block, closure_def_id.expect_local(), var_hir_id)
             }
 
             ExprKind::VarRef { id } => {
@@ -627,11 +625,11 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     fn lower_captured_upvar(
         &mut self,
         block: BasicBlock,
-        upvar_id: ty::UpvarId,
+        closure_expr_id: LocalDefId,
+        var_hir_id: LocalVarId,
     ) -> BlockAnd<PlaceBuilder<'tcx>> {
-        let closure_ty = self
-            .typeck_results
-            .node_type(self.tcx.hir().local_def_id_to_hir_id(upvar_id.closure_expr_id));
+        let closure_ty =
+            self.typeck_results.node_type(self.tcx.hir().local_def_id_to_hir_id(closure_expr_id));
 
         let closure_kind = if let ty::Closure(_, closure_substs) = closure_ty.kind() {
             self.infcx.closure_kind(closure_substs).unwrap()
@@ -641,8 +639,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         };
 
         block.and(PlaceBuilder::from(PlaceBase::Upvar {
-            var_hir_id: upvar_id.var_path.hir_id,
-            closure_def_id: upvar_id.closure_expr_id.to_def_id(),
+            var_hir_id,
+            closure_def_id: closure_expr_id.to_def_id(),
             closure_kind,
         }))
     }

compiler/rustc_mir_build/src/build/matches/mod.rs

@@ -14,7 +14,6 @@ use rustc_data_structures::{
     fx::{FxHashSet, FxIndexMap, FxIndexSet},
     stack::ensure_sufficient_stack,
 };
-use rustc_hir::HirId;
 use rustc_index::bit_set::BitSet;
 use rustc_middle::middle::region;
 use rustc_middle::mir::*;
@@ -690,7 +689,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
     pub(crate) fn storage_live_binding(
         &mut self,
         block: BasicBlock,
-        var: HirId,
+        var: LocalVarId,
         span: Span,
         for_guard: ForGuard,
         schedule_drop: bool,
@@ -700,20 +699,20 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         self.cfg.push(block, Statement { source_info, kind: StatementKind::StorageLive(local_id) });
         // Altough there is almost always scope for given variable in corner cases
         // like #92893 we might get variable with no scope.
-        if let Some(region_scope) = self.region_scope_tree.var_scope(var.local_id) && schedule_drop{
+        if let Some(region_scope) = self.region_scope_tree.var_scope(var.0.local_id) && schedule_drop{
             self.schedule_drop(span, region_scope, local_id, DropKind::Storage);
         }
         Place::from(local_id)
     }
 
     pub(crate) fn schedule_drop_for_binding(
         &mut self,
-        var: HirId,
+        var: LocalVarId,
         span: Span,
         for_guard: ForGuard,
     ) {
         let local_id = self.var_local_id(var, for_guard);
-        if let Some(region_scope) = self.region_scope_tree.var_scope(var.local_id) {
+        if let Some(region_scope) = self.region_scope_tree.var_scope(var.0.local_id) {
             self.schedule_drop(span, region_scope, local_id, DropKind::Value);
         }
     }
@@ -730,7 +729,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             Mutability,
             Symbol,
             BindingMode,
-            HirId,
+            LocalVarId,
             Span,
             Ty<'tcx>,
             UserTypeProjections,
@@ -917,7 +916,7 @@ fn traverse_candidate<'pat, 'tcx: 'pat, C, T, I>(
 struct Binding<'tcx> {
     span: Span,
     source: Place<'tcx>,
-    var_id: HirId,
+    var_id: LocalVarId,
     binding_mode: BindingMode,
 }
 
@@ -2184,7 +2183,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         mutability: Mutability,
         name: Symbol,
         mode: BindingMode,
-        var_id: HirId,
+        var_id: LocalVarId,
         var_ty: Ty<'tcx>,
         user_ty: UserTypeProjections,
         has_guard: ArmHasGuard,

compiler/rustc_mir_build/src/build/mod.rs

@@ -4,19 +4,20 @@ use crate::build::scope::DropKind;
 use crate::thir::constant::parse_float;
 use crate::thir::pattern::pat_from_hir;
 use rustc_ast as ast;
+use rustc_data_structures::fx::FxHashMap;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::lang_items::LangItem;
-use rustc_hir::{GeneratorKind, HirIdMap, Node};
+use rustc_hir::{GeneratorKind, Node};
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_middle::hir::place::PlaceBase as HirPlaceBase;
 use rustc_middle::middle::region;
 use rustc_middle::mir::interpret::Allocation;
 use rustc_middle::mir::interpret::{ConstValue, LitToConstError, LitToConstInput, Scalar};
 use rustc_middle::mir::*;
-use rustc_middle::thir::{BindingMode, Expr, ExprId, LintLevel, PatKind, Thir};
+use rustc_middle::thir::{BindingMode, Expr, ExprId, LintLevel, LocalVarId, PatKind, Thir};
 use rustc_middle::ty::subst::Subst;
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeckResults};
 use rustc_span::symbol::sym;
@@ -445,7 +446,7 @@ struct Builder<'a, 'tcx> {
 
     /// Maps `HirId`s of variable bindings to the `Local`s created for them.
     /// (A match binding can have two locals; the 2nd is for the arm's guard.)
-    var_indices: HirIdMap<LocalsForNode>,
+    var_indices: FxHashMap<LocalVarId, LocalsForNode>,
     local_decls: IndexVec<Local, LocalDecl<'tcx>>,
     canonical_user_type_annotations: ty::CanonicalUserTypeAnnotations<'tcx>,
     upvar_mutbls: Vec<Mutability>,
@@ -455,11 +456,11 @@ struct Builder<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
-    fn is_bound_var_in_guard(&self, id: hir::HirId) -> bool {
+    fn is_bound_var_in_guard(&self, id: LocalVarId) -> bool {
         self.guard_context.iter().any(|frame| frame.locals.iter().any(|local| local.id == id))
     }
 
-    fn var_local_id(&self, id: hir::HirId, for_guard: ForGuard) -> Local {
+    fn var_local_id(&self, id: LocalVarId, for_guard: ForGuard) -> Local {
         self.var_indices[&id].local_id(for_guard)
     }
 }
@@ -543,11 +544,11 @@ enum LocalsForNode {
 
 #[derive(Debug)]
 struct GuardFrameLocal {
-    id: hir::HirId,
+    id: LocalVarId,
 }
 
 impl GuardFrameLocal {
-    fn new(id: hir::HirId, _binding_mode: BindingMode) -> Self {
+    fn new(id: LocalVarId, _binding_mode: BindingMode) -> Self {
         GuardFrameLocal { id }
     }
 }

compiler/rustc_mir_build/src/thir/cx/expr.rs

@@ -903,9 +903,12 @@ impl<'tcx> Cx<'tcx> {
         );
 
         if is_upvar {
-            ExprKind::UpvarRef { closure_def_id: self.body_owner, var_hir_id }
+            ExprKind::UpvarRef {
+                closure_def_id: self.body_owner,
+                var_hir_id: LocalVarId(var_hir_id),
+            }
         } else {
-            ExprKind::VarRef { id: var_hir_id }
+            ExprKind::VarRef { id: LocalVarId(var_hir_id) }
         }
     }
 

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -19,7 +19,7 @@ use rustc_middle::mir::interpret::{get_slice_bytes, ConstValue};
 use rustc_middle::mir::interpret::{ErrorHandled, LitToConstError, LitToConstInput};
 use rustc_middle::mir::{self, UserTypeProjection};
 use rustc_middle::mir::{BorrowKind, Field, Mutability};
-use rustc_middle::thir::{Ascription, BindingMode, FieldPat, Pat, PatKind, PatRange};
+use rustc_middle::thir::{Ascription, BindingMode, FieldPat, LocalVarId, Pat, PatKind, PatRange};
 use rustc_middle::ty::subst::{GenericArg, SubstsRef};
 use rustc_middle::ty::CanonicalUserTypeAnnotation;
 use rustc_middle::ty::{self, AdtDef, ConstKind, DefIdTree, Region, Ty, TyCtxt, UserType};
@@ -288,7 +288,7 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
                     mutability,
                     mode,
                     name: ident.name,
-                    var: id,
+                    var: LocalVarId(id),
                     ty: var_ty,
                     subpattern: self.lower_opt_pattern(sub),
                     is_primary: id == pat.hir_id,
@@ -664,7 +664,7 @@ macro_rules! ClonePatternFoldableImpls {
 }
 
 ClonePatternFoldableImpls! { <'tcx>
-    Span, Field, Mutability, Symbol, hir::HirId, usize, ty::Const<'tcx>,
+    Span, Field, Mutability, Symbol, LocalVarId, usize, ty::Const<'tcx>,
     Region<'tcx>, Ty<'tcx>, BindingMode, AdtDef<'tcx>,
     SubstsRef<'tcx>, &'tcx GenericArg<'tcx>, UserType<'tcx>,
     UserTypeProjection, CanonicalUserTypeAnnotation<'tcx>