Remove unnecessary lifetimes in borrowck structs.

Similar to the previous commit, this commit merges two lifetimes in
`Borrows`. This then lets lifetimes be removed from `BorrowckResults`
and `BorrowckFlowState`.

Author: nnethercote

compiler/rustc_borrowck/src/dataflow.rs

@@ -15,24 +15,24 @@ use tracing::debug;
 use crate::{places_conflict, BorrowSet, PlaceConflictBias, PlaceExt, RegionInferenceContext};
 
 /// The results of the dataflow analyses used by the borrow checker.
-pub(crate) struct BorrowckResults<'a, 'mir, 'tcx> {
-    pub(crate) borrows: Results<'tcx, Borrows<'a, 'mir, 'tcx>>,
+pub(crate) struct BorrowckResults<'mir, 'tcx> {
+    pub(crate) borrows: Results<'tcx, Borrows<'mir, 'tcx>>,
     pub(crate) uninits: Results<'tcx, MaybeUninitializedPlaces<'mir, 'tcx>>,
     pub(crate) ever_inits: Results<'tcx, EverInitializedPlaces<'mir, 'tcx>>,
 }
 
 /// The transient state of the dataflow analyses used by the borrow checker.
 #[derive(Debug)]
-pub(crate) struct BorrowckFlowState<'a, 'mir, 'tcx> {
-    pub(crate) borrows: <Borrows<'a, 'mir, 'tcx> as AnalysisDomain<'tcx>>::Domain,
+pub(crate) struct BorrowckFlowState<'mir, 'tcx> {
+    pub(crate) borrows: <Borrows<'mir, 'tcx> as AnalysisDomain<'tcx>>::Domain,
     pub(crate) uninits: <MaybeUninitializedPlaces<'mir, 'tcx> as AnalysisDomain<'tcx>>::Domain,
     pub(crate) ever_inits: <EverInitializedPlaces<'mir, 'tcx> as AnalysisDomain<'tcx>>::Domain,
 }
 
-impl<'a, 'mir, 'tcx> ResultsVisitable<'tcx> for BorrowckResults<'a, 'mir, 'tcx> {
+impl<'mir, 'tcx> ResultsVisitable<'tcx> for BorrowckResults<'mir, 'tcx> {
     // All three analyses are forward, but we have to use just one here.
-    type Direction = <Borrows<'a, 'mir, 'tcx> as AnalysisDomain<'tcx>>::Direction;
-    type FlowState = BorrowckFlowState<'a, 'mir, 'tcx>;
+    type Direction = <Borrows<'mir, 'tcx> as AnalysisDomain<'tcx>>::Direction;
+    type FlowState = BorrowckFlowState<'mir, 'tcx>;
 
     fn new_flow_state(&self, body: &mir::Body<'tcx>) -> Self::FlowState {
         BorrowckFlowState {
@@ -106,11 +106,11 @@ rustc_index::newtype_index! {
 /// `BorrowIndex`, and maps each such index to a `BorrowData`
 /// describing the borrow. These indexes are used for representing the
 /// borrows in compact bitvectors.
-pub struct Borrows<'a, 'mir, 'tcx> {
+pub struct Borrows<'mir, 'tcx> {
     tcx: TyCtxt<'tcx>,
     body: &'mir Body<'tcx>,
 
-    borrow_set: &'a BorrowSet<'tcx>,
+    borrow_set: &'mir BorrowSet<'tcx>,
     borrows_out_of_scope_at_location: FxIndexMap<Location, Vec<BorrowIndex>>,
 }
 
@@ -389,12 +389,12 @@ impl<'tcx> PoloniusOutOfScopePrecomputer<'_, 'tcx> {
     }
 }
 
-impl<'a, 'mir, 'tcx> Borrows<'a, 'mir, 'tcx> {
+impl<'mir, 'tcx> Borrows<'mir, 'tcx> {
     pub fn new(
         tcx: TyCtxt<'tcx>,
         body: &'mir Body<'tcx>,
         regioncx: &RegionInferenceContext<'tcx>,
-        borrow_set: &'a BorrowSet<'tcx>,
+        borrow_set: &'mir BorrowSet<'tcx>,
     ) -> Self {
         let mut borrows_out_of_scope_at_location =
             calculate_borrows_out_of_scope_at_location(body, regioncx, borrow_set);
@@ -494,7 +494,7 @@ impl<'a, 'mir, 'tcx> Borrows<'a, 'mir, 'tcx> {
     }
 }
 
-impl<'tcx> rustc_mir_dataflow::AnalysisDomain<'tcx> for Borrows<'_, '_, 'tcx> {
+impl<'tcx> rustc_mir_dataflow::AnalysisDomain<'tcx> for Borrows<'_, 'tcx> {
     type Domain = BitSet<BorrowIndex>;
 
     const NAME: &'static str = "borrows";
@@ -517,7 +517,7 @@ impl<'tcx> rustc_mir_dataflow::AnalysisDomain<'tcx> for Borrows<'_, '_, 'tcx> {
 ///   region stops containing the CFG points reachable from the issuing location.
 /// - we also kill loans of conflicting places when overwriting a shared path: e.g. borrows of
 ///   `a.b.c` when `a` is overwritten.
-impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, '_, 'tcx> {
+impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, 'tcx> {
     type Idx = BorrowIndex;
 
     fn domain_size(&self, _: &mir::Body<'tcx>) -> usize {
@@ -617,8 +617,8 @@ impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, '_, 'tcx> {
     }
 }
 
-impl DebugWithContext<Borrows<'_, '_, '_>> for BorrowIndex {
-    fn fmt_with(&self, ctxt: &Borrows<'_, '_, '_>, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+impl DebugWithContext<Borrows<'_, '_>> for BorrowIndex {
+    fn fmt_with(&self, ctxt: &Borrows<'_, '_>, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(f, "{:?}", ctxt.location(*self))
     }
 }

compiler/rustc_borrowck/src/lib.rs

@@ -602,12 +602,12 @@ struct MirBorrowckCtxt<'a, 'mir, 'infcx, 'tcx> {
 impl<'a, 'mir, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'mir, 'tcx, R>
     for MirBorrowckCtxt<'a, 'mir, '_, 'tcx>
 {
-    type FlowState = Flows<'a, 'mir, 'tcx>;
+    type FlowState = Flows<'mir, 'tcx>;
 
     fn visit_statement_before_primary_effect(
         &mut self,
         _results: &mut R,
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
         stmt: &'mir Statement<'tcx>,
         location: Location,
     ) {
@@ -677,7 +677,7 @@ impl<'a, 'mir, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'mir, 'tcx, R>
     fn visit_terminator_before_primary_effect(
         &mut self,
         _results: &mut R,
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
         term: &'mir Terminator<'tcx>,
         loc: Location,
     ) {
@@ -794,7 +794,7 @@ impl<'a, 'mir, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'mir, 'tcx, R>
     fn visit_terminator_after_primary_effect(
         &mut self,
         _results: &mut R,
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
         term: &'mir Terminator<'tcx>,
         loc: Location,
     ) {
@@ -989,7 +989,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         place_span: (Place<'tcx>, Span),
         kind: (AccessDepth, ReadOrWrite),
         is_local_mutation_allowed: LocalMutationIsAllowed,
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
     ) {
         let (sd, rw) = kind;
 
@@ -1039,7 +1039,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         place_span: (Place<'tcx>, Span),
         sd: AccessDepth,
         rw: ReadOrWrite,
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
     ) -> bool {
         let mut error_reported = false;
         let borrow_set = Rc::clone(&self.borrow_set);
@@ -1180,7 +1180,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         location: Location,
         place_span: (Place<'tcx>, Span),
         kind: AccessDepth,
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
     ) {
         // Write of P[i] or *P requires P init'd.
         self.check_if_assigned_path_is_moved(location, place_span, flow_state);
@@ -1198,7 +1198,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         &mut self,
         location: Location,
         (rvalue, span): (&'mir Rvalue<'tcx>, Span),
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
     ) {
         match rvalue {
             &Rvalue::Ref(_ /*rgn*/, bk, place) => {
@@ -1456,7 +1456,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         &mut self,
         location: Location,
         (operand, span): (&'mir Operand<'tcx>, Span),
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
     ) {
         match *operand {
             Operand::Copy(place) => {
@@ -1580,7 +1580,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         &mut self,
         location: Location,
         span: Span,
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
     ) {
         // Two-phase borrow support: For each activation that is newly
         // generated at this statement, check if it interferes with
@@ -1744,7 +1744,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         location: Location,
         desired_action: InitializationRequiringAction,
         place_span: (PlaceRef<'tcx>, Span),
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
     ) {
         let maybe_uninits = &flow_state.uninits;
 
@@ -1849,7 +1849,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         location: Location,
         desired_action: InitializationRequiringAction,
         place_span: (PlaceRef<'tcx>, Span),
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
     ) {
         let maybe_uninits = &flow_state.uninits;
 
@@ -1948,7 +1948,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         &mut self,
         location: Location,
         (place, span): (Place<'tcx>, Span),
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
     ) {
         debug!("check_if_assigned_path_is_moved place: {:?}", place);
 
@@ -2014,7 +2014,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
             location: Location,
             base: PlaceRef<'tcx>,
             span: Span,
-            flow_state: &Flows<'_, 'mir, 'tcx>,
+            flow_state: &Flows<'mir, 'tcx>,
         ) {
             // rust-lang/rust#21232: Until Rust allows reads from the
             // initialized parts of partially initialized structs, we
@@ -2105,7 +2105,7 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
         (place, span): (Place<'tcx>, Span),
         kind: ReadOrWrite,
         is_local_mutation_allowed: LocalMutationIsAllowed,
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
         location: Location,
     ) -> bool {
         debug!(
@@ -2221,15 +2221,15 @@ impl<'mir, 'tcx> MirBorrowckCtxt<'_, 'mir, '_, 'tcx> {
     fn is_local_ever_initialized(
         &self,
         local: Local,
-        flow_state: &Flows<'_, 'mir, 'tcx>,
+        flow_state: &Flows<'mir, 'tcx>,
     ) -> Option<InitIndex> {
         let mpi = self.move_data.rev_lookup.find_local(local)?;
         let ii = &self.move_data.init_path_map[mpi];
         ii.into_iter().find(|&&index| flow_state.ever_inits.contains(index)).copied()
     }
 
     /// Adds the place into the used mutable variables set
-    fn add_used_mut(&mut self, root_place: RootPlace<'tcx>, flow_state: &Flows<'_, 'mir, 'tcx>) {
+    fn add_used_mut(&mut self, root_place: RootPlace<'tcx>, flow_state: &Flows<'mir, 'tcx>) {
         match root_place {
             RootPlace { place_local: local, place_projection: [], is_local_mutation_allowed } => {
                 // If the local may have been initialized, and it is now currently being