Rollup merge of rust-lang#163082 - nnethercote:rm-TypeChecker-root_cx, r=chenyukang

Remove `TypeChecker::root_cx`

It's only used for `self.root_cx.root_def_id()`, but `self.infcx.root_def_id` is also available.

r? @lqd

Author: Zalathar

compiler/rustc_borrowck/src/lib.rs

@@ -361,7 +361,6 @@ fn borrowck_collect_region_constraints<'tcx>(
         deferred_closure_requirements,
         polonius_context,
     } = type_check::type_check(
-        root_cx,
         &infcx,
         body,
         &promoted,

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -47,7 +47,7 @@ use crate::region_infer::values::{LivenessValues, PlaceholderIndex, PlaceholderI
 use crate::session_diagnostics::{MoveUnsized, SimdIntrinsicArgConst};
 use crate::type_check::free_region_relations::{CreateResult, UniversalRegionRelations};
 use crate::universal_regions::{DefiningTy, UniversalRegions};
-use crate::{BorrowCheckRootCtxt, BorrowckInferCtxt, DeferredClosureRequirements, path_utils};
+use crate::{BorrowckInferCtxt, DeferredClosureRequirements, path_utils};
 
 macro_rules! span_mirbug {
     ($context:expr, $elem:expr, $($message:tt)*) => ({
@@ -94,7 +94,6 @@ mod relate_tys;
 /// - `move_data` -- move-data constructed when performing the maybe-init dataflow analysis
 /// - `location_map` -- map between MIR `Location` and `PointIndex`
 pub(crate) fn type_check<'tcx>(
-    root_cx: &BorrowCheckRootCtxt<'_, 'tcx>,
     infcx: &BorrowckInferCtxt<'tcx>,
     body: &Body<'tcx>,
     promoted: &IndexSlice<Promoted, Body<'tcx>>,
@@ -145,7 +144,6 @@ pub(crate) fn type_check<'tcx>(
 
     let mut deferred_closure_requirements = Default::default();
     let mut typeck = TypeChecker {
-        root_cx,
         infcx,
         last_span: body.span,
         body,
@@ -227,7 +225,6 @@ enum FieldAccessError {
 /// way, it accrues region constraints -- these can later be used by
 /// NLL region checking.
 struct TypeChecker<'a, 'tcx> {
-    root_cx: &'a BorrowCheckRootCtxt<'a, 'tcx>,
     infcx: &'a BorrowckInferCtxt<'tcx>,
     last_span: Span,
     body: &'a Body<'tcx>,
@@ -2715,7 +2712,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         args: GenericArgsRef<'tcx>,
         location: Location,
     ) -> ty::InstantiatedClauses<'tcx> {
-        let root_def_id = self.root_cx.root_def_id();
+        let root_def_id = self.infcx.root_def_id;
         // We will have to handle propagated closure requirements for this closure,
         // but need to defer this until the nested body has been fully borrow checked.
         self.deferred_closure_requirements.push((def_id, args, location.to_locations()));