Auto merge of #111753 - cjgillot:simp-place-conflict, r=compiler-errors

Only consider places with the same local in each_borrow_involving_path.

This avoids having a busy loop that repeatedly checks for equality of locals.

compiler/rustc_borrowck/src/lib.rs

@@ -23,7 +23,7 @@ use rustc_errors::{Diagnostic, DiagnosticBuilder, DiagnosticMessage, Subdiagnost
 use rustc_fluent_macro::fluent_messages;
 use rustc_hir as hir;
 use rustc_hir::def_id::LocalDefId;
-use rustc_index::bit_set::ChunkedBitSet;
+use rustc_index::bit_set::{BitSet, ChunkedBitSet};
 use rustc_index::{IndexSlice, IndexVec};
 use rustc_infer::infer::{
     InferCtxt, NllRegionVariableOrigin, RegionVariableOrigin, TyCtxtInferExt,
@@ -42,7 +42,6 @@ use rustc_session::lint::builtin::UNUSED_MUT;
 use rustc_span::{Span, Symbol};
 use rustc_target::abi::FieldIdx;
 
-use either::Either;
 use smallvec::SmallVec;
 use std::cell::RefCell;
 use std::collections::BTreeMap;
@@ -1035,12 +1034,16 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         let borrow_set = self.borrow_set.clone();
 
         // Use polonius output if it has been enabled.
-        let polonius_output = self.polonius_output.clone();
-        let borrows_in_scope = if let Some(polonius) = &polonius_output {
+        let mut polonius_output;
+        let borrows_in_scope = if let Some(polonius) = &self.polonius_output {
             let location = self.location_table.start_index(location);
-            Either::Left(polonius.errors_at(location).iter().copied())
+            polonius_output = BitSet::new_empty(borrow_set.len());
+            for &idx in polonius.errors_at(location) {
+                polonius_output.insert(idx);
+            }
+            &polonius_output
         } else {
-            Either::Right(flow_state.borrows.iter())
+            &flow_state.borrows
         };
 
         each_borrow_involving_path(
@@ -1050,7 +1053,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             location,
             (sd, place_span.0),
             &borrow_set,
-            borrows_in_scope,
+            |borrow_index| borrows_in_scope.contains(borrow_index),
             |this, borrow_index, borrow| match (rw, borrow.kind) {
                 // Obviously an activation is compatible with its own
                 // reservation (or even prior activating uses of same