Merge from rustc

4 files changed, 22 insertions, 45 deletions

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;