Rollup merge of #118638 - nnethercote:rustc_mir_dataflow-more, r=cjgillot

More `rustc_mir_dataflow` cleanups

r? `@cjgillot`

9 files changed, 102 insertions, 138 deletions

diff --git a/compiler/rustc_borrowck/src/dataflow.rs b/compiler/rustc_borrowck/src/dataflow.rs
index 54f161ea9b4..1b544b53012 100644
--- a/compiler/rustc_borrowck/src/dataflow.rs
+++ b/compiler/rustc_borrowck/src/dataflow.rs
@@ -11,101 +11,88 @@ use rustc_middle::ty::TyCtxt;
 use rustc_mir_dataflow::impls::{EverInitializedPlaces, MaybeUninitializedPlaces};
 use rustc_mir_dataflow::ResultsVisitable;
 use rustc_mir_dataflow::{self, fmt::DebugWithContext, GenKill};
-use rustc_mir_dataflow::{Analysis, Direction, Results};
+use rustc_mir_dataflow::{Analysis, AnalysisDomain, Results};
 use std::fmt;
 
 use crate::{places_conflict, BorrowSet, PlaceConflictBias, PlaceExt, RegionInferenceContext};
 
-/// A tuple with named fields that can hold either the results or the transient state of the
-/// dataflow analyses used by the borrow checker.
-#[derive(Debug)]
-pub struct BorrowckAnalyses<B, U, E> {
-    pub borrows: B,
-    pub uninits: U,
-    pub ever_inits: E,
-}
-
 /// The results of the dataflow analyses used by the borrow checker.
-pub type BorrowckResults<'mir, 'tcx> = BorrowckAnalyses<
-    Results<'tcx, Borrows<'mir, 'tcx>>,
-    Results<'tcx, MaybeUninitializedPlaces<'mir, 'tcx>>,
-    Results<'tcx, EverInitializedPlaces<'mir, 'tcx>>,
->;
+pub 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.
-pub type BorrowckFlowState<'mir, 'tcx> =
-    <BorrowckResults<'mir, 'tcx> as ResultsVisitable<'tcx>>::FlowState;
-
-macro_rules! impl_visitable {
-    ( $(
-        $T:ident { $( $field:ident : $A:ident ),* $(,)? }
-    )* ) => { $(
-        impl<'tcx, $($A),*, D: Direction> ResultsVisitable<'tcx> for $T<$( Results<'tcx, $A> ),*>
-        where
-            $( $A: Analysis<'tcx, Direction = D>, )*
-        {
-            type Direction = D;
-            type FlowState = $T<$( $A::Domain ),*>;
+#[derive(Debug)]
+pub 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,
+}
 
-            fn new_flow_state(&self, body: &mir::Body<'tcx>) -> Self::FlowState {
-                $T {
-                    $( $field: self.$field.analysis.bottom_value(body) ),*
-                }
-            }
+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<'mir, 'tcx> as AnalysisDomain<'tcx>>::Direction;
+    type FlowState = BorrowckFlowState<'mir, 'tcx>;
 
-            fn reset_to_block_entry(
-                &self,
-                state: &mut Self::FlowState,
-                block: BasicBlock,
-            ) {
-                $( state.$field.clone_from(&self.$field.entry_set_for_block(block)); )*
-            }
+    fn new_flow_state(&self, body: &mir::Body<'tcx>) -> Self::FlowState {
+        BorrowckFlowState {
+            borrows: self.borrows.analysis.bottom_value(body),
+            uninits: self.uninits.analysis.bottom_value(body),
+            ever_inits: self.ever_inits.analysis.bottom_value(body),
+        }
+    }
 
-            fn reconstruct_before_statement_effect(
-                &mut self,
-                state: &mut Self::FlowState,
-                stmt: &mir::Statement<'tcx>,
-                loc: Location,
-            ) {
-                $( self.$field.analysis
-                    .apply_before_statement_effect(&mut state.$field, stmt, loc); )*
-            }
+    fn reset_to_block_entry(&self, state: &mut Self::FlowState, block: BasicBlock) {
+        state.borrows.clone_from(&self.borrows.entry_set_for_block(block));
+        state.uninits.clone_from(&self.uninits.entry_set_for_block(block));
+        state.ever_inits.clone_from(&self.ever_inits.entry_set_for_block(block));
+    }
 
-            fn reconstruct_statement_effect(
-                &mut self,
-                state: &mut Self::FlowState,
-                stmt: &mir::Statement<'tcx>,
-                loc: Location,
-            ) {
-                $( self.$field.analysis
-                    .apply_statement_effect(&mut state.$field, stmt, loc); )*
-            }
+    fn reconstruct_before_statement_effect(
+        &mut self,
+        state: &mut Self::FlowState,
+        stmt: &mir::Statement<'tcx>,
+        loc: Location,
+    ) {
+        self.borrows.analysis.apply_before_statement_effect(&mut state.borrows, stmt, loc);
+        self.uninits.analysis.apply_before_statement_effect(&mut state.uninits, stmt, loc);
+        self.ever_inits.analysis.apply_before_statement_effect(&mut state.ever_inits, stmt, loc);
+    }
 
-            fn reconstruct_before_terminator_effect(
-                &mut self,
-                state: &mut Self::FlowState,
-                term: &mir::Terminator<'tcx>,
-                loc: Location,
-            ) {
-                $( self.$field.analysis
-                    .apply_before_terminator_effect(&mut state.$field, term, loc); )*
-            }
+    fn reconstruct_statement_effect(
+        &mut self,
+        state: &mut Self::FlowState,
+        stmt: &mir::Statement<'tcx>,
+        loc: Location,
+    ) {
+        self.borrows.analysis.apply_statement_effect(&mut state.borrows, stmt, loc);
+        self.uninits.analysis.apply_statement_effect(&mut state.uninits, stmt, loc);
+        self.ever_inits.analysis.apply_statement_effect(&mut state.ever_inits, stmt, loc);
+    }
 
-            fn reconstruct_terminator_effect(
-                &mut self,
-                state: &mut Self::FlowState,
-                term: &mir::Terminator<'tcx>,
-                loc: Location,
-            ) {
-                $( self.$field.analysis
-                    .apply_terminator_effect(&mut state.$field, term, loc); )*
-            }
-        }
-    )* }
-}
+    fn reconstruct_before_terminator_effect(
+        &mut self,
+        state: &mut Self::FlowState,
+        term: &mir::Terminator<'tcx>,
+        loc: Location,
+    ) {
+        self.borrows.analysis.apply_before_terminator_effect(&mut state.borrows, term, loc);
+        self.uninits.analysis.apply_before_terminator_effect(&mut state.uninits, term, loc);
+        self.ever_inits.analysis.apply_before_terminator_effect(&mut state.ever_inits, term, loc);
+    }
 
-impl_visitable! {
-    BorrowckAnalyses { borrows: B, uninits: U, ever_inits: E }
+    fn reconstruct_terminator_effect(
+        &mut self,
+        state: &mut Self::FlowState,
+        term: &mir::Terminator<'tcx>,
+        loc: Location,
+    ) {
+        self.borrows.analysis.apply_terminator_effect(&mut state.borrows, term, loc);
+        self.uninits.analysis.apply_terminator_effect(&mut state.uninits, term, loc);
+        self.ever_inits.analysis.apply_terminator_effect(&mut state.ever_inits, term, loc);
+    }
 }
 
 rustc_index::newtype_index! {
@@ -598,7 +585,7 @@ impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, 'tcx> {
 
     fn before_terminator_effect(
         &mut self,
-        trans: &mut impl GenKill<Self::Idx>,
+        trans: &mut Self::Domain,
         _terminator: &mir::Terminator<'tcx>,
         location: Location,
     ) {
@@ -625,7 +612,7 @@ impl<'tcx> rustc_mir_dataflow::GenKillAnalysis<'tcx> for Borrows<'_, 'tcx> {
 
     fn call_return_effect(
         &mut self,
-        _trans: &mut impl GenKill<Self::Idx>,
+        _trans: &mut Self::Domain,
         _block: mir::BasicBlock,
         _return_places: CallReturnPlaces<'_, 'tcx>,
     ) {
diff --git a/compiler/rustc_mir_dataflow/src/framework/direction.rs b/compiler/rustc_mir_dataflow/src/framework/direction.rs
index 08b7b1a2619..4c3fadf487b 100644
--- a/compiler/rustc_mir_dataflow/src/framework/direction.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/direction.rs
@@ -196,7 +196,7 @@ impl Direction for Backward {
     {
         results.reset_to_block_entry(state, block);
 
-        vis.visit_block_end(results, state, block_data, block);
+        vis.visit_block_end(state);
 
         // Terminator
         let loc = Location { block, statement_index: block_data.statements.len() };
@@ -214,7 +214,7 @@ impl Direction for Backward {
             vis.visit_statement_after_primary_effect(results, state, stmt, loc);
         }
 
-        vis.visit_block_start(results, state, block_data, block);
+        vis.visit_block_start(state);
     }
 
     fn join_state_into_successors_of<'tcx, A>(
@@ -449,7 +449,7 @@ impl Direction for Forward {
     {
         results.reset_to_block_entry(state, block);
 
-        vis.visit_block_start(results, state, block_data, block);
+        vis.visit_block_start(state);
 
         for (statement_index, stmt) in block_data.statements.iter().enumerate() {
             let loc = Location { block, statement_index };
@@ -466,7 +466,7 @@ impl Direction for Forward {
         results.reconstruct_terminator_effect(state, term, loc);
         vis.visit_terminator_after_primary_effect(results, state, term, loc);
 
-        vis.visit_block_end(results, state, block_data, block);
+        vis.visit_block_end(state);
     }
 
     fn join_state_into_successors_of<'tcx, A>(
diff --git a/compiler/rustc_mir_dataflow/src/framework/graphviz.rs b/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
index fa16cac3168..0270e059a58 100644
--- a/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/graphviz.rs
@@ -545,25 +545,13 @@ where
 {
     type FlowState = A::Domain;
 
-    fn visit_block_start(
-        &mut self,
-        _results: &mut Results<'tcx, A>,
-        state: &Self::FlowState,
-        _block_data: &mir::BasicBlockData<'tcx>,
-        _block: BasicBlock,
-    ) {
+    fn visit_block_start(&mut self, state: &Self::FlowState) {
         if A::Direction::IS_FORWARD {
             self.prev_state.clone_from(state);
         }
     }
 
-    fn visit_block_end(
-        &mut self,
-        _results: &mut Results<'tcx, A>,
-        state: &Self::FlowState,
-        _block_data: &mir::BasicBlockData<'tcx>,
-        _block: BasicBlock,
-    ) {
+    fn visit_block_end(&mut self, state: &Self::FlowState) {
         if A::Direction::IS_BACKWARD {
             self.prev_state.clone_from(state);
         }
diff --git a/compiler/rustc_mir_dataflow/src/framework/mod.rs b/compiler/rustc_mir_dataflow/src/framework/mod.rs
index b7dfbe0710d..09cdb055a3e 100644
--- a/compiler/rustc_mir_dataflow/src/framework/mod.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/mod.rs
@@ -248,18 +248,19 @@ pub trait Analysis<'tcx>: AnalysisDomain<'tcx> {
 
 /// A gen/kill dataflow problem.
 ///
-/// Each method in this trait has a corresponding one in `Analysis`. However, these methods only
-/// allow modification of the dataflow state via "gen" and "kill" operations. By defining transfer
-/// functions for each statement in this way, the transfer function for an entire basic block can
-/// be computed efficiently.
+/// Each method in this trait has a corresponding one in `Analysis`. However, the first two methods
+/// here only allow modification of the dataflow state via "gen" and "kill" operations. By defining
+/// transfer functions for each statement in this way, the transfer function for an entire basic
+/// block can be computed efficiently. The remaining methods match up with `Analysis` exactly.
 ///
-/// `Analysis` is automatically implemented for all implementers of `GenKillAnalysis`.
+/// `Analysis` is automatically implemented for all implementers of `GenKillAnalysis` via a blanket
+/// impl below.
 pub trait GenKillAnalysis<'tcx>: Analysis<'tcx> {
     type Idx: Idx;
 
     fn domain_size(&self, body: &mir::Body<'tcx>) -> usize;
 
-    /// See `Analysis::apply_statement_effect`.
+    /// See `Analysis::apply_statement_effect`. Note how the second arg differs.
     fn statement_effect(
         &mut self,
         trans: &mut impl GenKill<Self::Idx>,
@@ -267,7 +268,8 @@ pub trait GenKillAnalysis<'tcx>: Analysis<'tcx> {
         location: Location,
     );
 
-    /// See `Analysis::apply_before_statement_effect`.
+    /// See `Analysis::apply_before_statement_effect`. Note how the second arg
+    /// differs.
     fn before_statement_effect(
         &mut self,
         _trans: &mut impl GenKill<Self::Idx>,
@@ -287,7 +289,7 @@ pub trait GenKillAnalysis<'tcx>: Analysis<'tcx> {
     /// See `Analysis::apply_before_terminator_effect`.
     fn before_terminator_effect(
         &mut self,
-        _trans: &mut impl GenKill<Self::Idx>,
+        _trans: &mut Self::Domain,
         _terminator: &mir::Terminator<'tcx>,
         _location: Location,
     ) {
@@ -298,7 +300,7 @@ pub trait GenKillAnalysis<'tcx>: Analysis<'tcx> {
     /// See `Analysis::apply_call_return_effect`.
     fn call_return_effect(
         &mut self,
-        trans: &mut impl GenKill<Self::Idx>,
+        trans: &mut Self::Domain,
         block: BasicBlock,
         return_places: CallReturnPlaces<'_, 'tcx>,
     );
@@ -313,6 +315,7 @@ pub trait GenKillAnalysis<'tcx>: Analysis<'tcx> {
     }
 }
 
+// Blanket impl: any impl of `GenKillAnalysis` automatically impls `Analysis`.
 impl<'tcx, A> Analysis<'tcx> for A
 where
     A: GenKillAnalysis<'tcx>,
diff --git a/compiler/rustc_mir_dataflow/src/framework/visitor.rs b/compiler/rustc_mir_dataflow/src/framework/visitor.rs
index e3648bb4076..8b8a16bda99 100644
--- a/compiler/rustc_mir_dataflow/src/framework/visitor.rs
+++ b/compiler/rustc_mir_dataflow/src/framework/visitor.rs
@@ -31,14 +31,7 @@ pub fn visit_results<'mir, 'tcx, F, R>(
 pub trait ResultsVisitor<'mir, 'tcx, R> {
     type FlowState;
 
-    fn visit_block_start(
-        &mut self,
-        _results: &mut R,
-        _state: &Self::FlowState,
-        _block_data: &'mir mir::BasicBlockData<'tcx>,
-        _block: BasicBlock,
-    ) {
-    }
+    fn visit_block_start(&mut self, _state: &Self::FlowState) {}
 
     /// Called with the `before_statement_effect` of the given statement applied to `state` but not
     /// its `statement_effect`.
@@ -86,20 +79,13 @@ pub trait ResultsVisitor<'mir, 'tcx, R> {
     ) {
     }
 
-    fn visit_block_end(
-        &mut self,
-        _results: &mut R,
-        _state: &Self::FlowState,
-        _block_data: &'mir mir::BasicBlockData<'tcx>,
-        _block: BasicBlock,
-    ) {
-    }
+    fn visit_block_end(&mut self, _state: &Self::FlowState) {}
 }
 
 /// Things that can be visited by a `ResultsVisitor`.
 ///
-/// This trait exists so that we can visit the results of multiple dataflow analyses simultaneously.
-/// DO NOT IMPLEMENT MANUALLY. Instead, use the `impl_visitable` macro below.
+/// This trait exists so that we can visit the results of one or more dataflow analyses
+/// simultaneously.
 pub trait ResultsVisitable<'tcx> {
     type Direction: Direction;
     type FlowState;
diff --git a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
index 01acc380fa3..693994b5da7 100644
--- a/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/borrowed_locals.rs
@@ -62,7 +62,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeBorrowedLocals {
 
     fn call_return_effect(
         &mut self,
-        _trans: &mut impl GenKill<Self::Idx>,
+        _trans: &mut Self::Domain,
         _block: BasicBlock,
         _return_places: CallReturnPlaces<'_, 'tcx>,
     ) {
diff --git a/compiler/rustc_mir_dataflow/src/impls/initialized.rs b/compiler/rustc_mir_dataflow/src/impls/initialized.rs
index b050e963d8e..6653b99b3f5 100644
--- a/compiler/rustc_mir_dataflow/src/impls/initialized.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/initialized.rs
@@ -376,7 +376,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeInitializedPlaces<'_, 'tcx> {
 
     fn call_return_effect(
         &mut self,
-        trans: &mut impl GenKill<Self::Idx>,
+        trans: &mut Self::Domain,
         _block: mir::BasicBlock,
         return_places: CallReturnPlaces<'_, 'tcx>,
     ) {
@@ -499,7 +499,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeUninitializedPlaces<'_, 'tcx> {
 
     fn call_return_effect(
         &mut self,
-        trans: &mut impl GenKill<Self::Idx>,
+        trans: &mut Self::Domain,
         _block: mir::BasicBlock,
         return_places: CallReturnPlaces<'_, 'tcx>,
     ) {
@@ -617,7 +617,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for DefinitelyInitializedPlaces<'_, 'tcx> {
 
     fn call_return_effect(
         &mut self,
-        trans: &mut impl GenKill<Self::Idx>,
+        trans: &mut Self::Domain,
         _block: mir::BasicBlock,
         return_places: CallReturnPlaces<'_, 'tcx>,
     ) {
@@ -712,7 +712,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for EverInitializedPlaces<'_, 'tcx> {
 
     fn call_return_effect(
         &mut self,
-        trans: &mut impl GenKill<Self::Idx>,
+        trans: &mut Self::Domain,
         block: mir::BasicBlock,
         _return_places: CallReturnPlaces<'_, 'tcx>,
     ) {
diff --git a/compiler/rustc_mir_dataflow/src/impls/liveness.rs b/compiler/rustc_mir_dataflow/src/impls/liveness.rs
index c3fdca1641a..04bae6ae2fe 100644
--- a/compiler/rustc_mir_dataflow/src/impls/liveness.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/liveness.rs
@@ -69,7 +69,7 @@ impl<'tcx> GenKillAnalysis<'tcx> for MaybeLiveLocals {
 
     fn call_return_effect(
         &mut self,
-        trans: &mut impl GenKill<Self::Idx>,
+        trans: &mut Self::Domain,
         _block: mir::BasicBlock,
         return_places: CallReturnPlaces<'_, 'tcx>,
     ) {
diff --git a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
index 26fc903973f..646c70eb88f 100644
--- a/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
+++ b/compiler/rustc_mir_dataflow/src/impls/storage_liveness.rs
@@ -72,7 +72,7 @@ impl<'tcx, 'a> crate::GenKillAnalysis<'tcx> for MaybeStorageLive<'a> {
 
     fn call_return_effect(
         &mut self,
-        _trans: &mut impl GenKill<Self::Idx>,
+        _trans: &mut Self::Domain,
         _block: BasicBlock,
         _return_places: CallReturnPlaces<'_, 'tcx>,
     ) {
@@ -144,7 +144,7 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeStorageDead {
 
     fn call_return_effect(
         &mut self,
-        _trans: &mut impl GenKill<Self::Idx>,
+        _trans: &mut Self::Domain,
         _block: BasicBlock,
         _return_places: CallReturnPlaces<'_, 'tcx>,
     ) {
@@ -238,7 +238,7 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, 'tcx> {
 
     fn before_terminator_effect(
         &mut self,
-        trans: &mut impl GenKill<Self::Idx>,
+        trans: &mut Self::Domain,
         terminator: &Terminator<'tcx>,
         loc: Location,
     ) {
@@ -334,7 +334,7 @@ impl<'tcx> crate::GenKillAnalysis<'tcx> for MaybeRequiresStorage<'_, 'tcx> {
 
     fn call_return_effect(
         &mut self,
-        trans: &mut impl GenKill<Self::Idx>,
+        trans: &mut Self::Domain,
         _block: BasicBlock,
         return_places: CallReturnPlaces<'_, 'tcx>,
     ) {