Minor changes per code review.

src/Compilers/CSharp/Portable/Binder/DecisionDagBuilder.cs

@@ -386,7 +386,7 @@ out ImmutableArray<(BoundExpression, BoundDagTemp)> bindings)
         /// when an assertion fails (it is unaffected by exception filters on enclosing frames).
         /// </summary>
         [Conditional("DEBUG")]
-        private void Assert(bool condition, string message = null)
+        private static void Assert(bool condition, string message = null)
         {
             if (!condition)
             {
@@ -573,7 +573,7 @@ DagState uniqifyState(DagState state)
             workList.Free();
 
             // Now process the states in topological order, leaves first, and assign a BoundDecisionDag to each DagState.
-            ImmutableArray<DagState> sortedStates = initialState.TopologicallySortedReachableStates;
+            ImmutableArray<DagState> sortedStates = initialState.TopologicallySortedReachableStates();
             Debug.Assert(_defaultLabel != null);
             var finalStates = PooledDictionary<LabelSymbol, BoundDecisionDag>.GetInstance();
             finalStates.Add(_defaultLabel, defaultDecision);
@@ -935,27 +935,24 @@ public DagState(ImmutableArray<PartialCaseDecision> cases)
             public BoundDagDecision SelectedDecision;
             public DagState TrueBranch, FalseBranch;
 
-            public ImmutableArray<DagState> TopologicallySortedReachableStates
+            public ImmutableArray<DagState> TopologicallySortedReachableStates()
             {
-                get
+                // A successor function used to topologically sort the DagState set.
+                IEnumerable<DagState> succ(DagState state)
                 {
-                    // A successor function used to topologically sort the DagState set.
-                    IEnumerable<DagState> succ(DagState state)
+                    if (state.TrueBranch != null)
                     {
-                        if (state.TrueBranch != null)
-                        {
-                            yield return state.TrueBranch;
-                        }
-
-                        if (state.FalseBranch != null)
-                        {
-                            yield return state.FalseBranch;
-                        }
+                        yield return state.TrueBranch;
                     }
 
-                    // Now process the states in topological order, leaves first, and assign a BoundDecisionDag to each DagState.
-                    return TopologicalSort.IterativeSort<DagState>(SpecializedCollections.SingletonEnumerable<DagState>(this), succ);
+                    if (state.FalseBranch != null)
+                    {
+                        yield return state.FalseBranch;
+                    }
                 }
+
+                // Now process the states in topological order, leaves first, and assign a BoundDecisionDag to each DagState.
+                return TopologicalSort.IterativeSort<DagState>(SpecializedCollections.SingletonEnumerable<DagState>(this), succ);
             }
 
             // After the entire graph of DagState objects is complete, we translate each into its Dag.
@@ -987,7 +984,7 @@ internal BoundDagDecision ComputeSelectedDecision()
             /// </summary>
             internal string Dump()
             {
-                var allStates = this.TopologicallySortedReachableStates;
+                var allStates = this.TopologicallySortedReachableStates();
                 var stateIdentifierMap = PooledDictionary<DagState, int>.GetInstance();
                 for (int i = 0; i < allStates.Length; i++)
                 {

src/Compilers/CSharp/Portable/Binder/PatternSwitchBinder.cs

@@ -4,7 +4,7 @@
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
-using System.Threading;
+using System.Linq;
 using Microsoft.CodeAnalysis.CSharp.Symbols;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
 using Microsoft.CodeAnalysis.PooledObjects;
@@ -84,7 +84,7 @@ bool isSubsumed(BoundPatternSwitchLabel switchLabel)
             }
 
             // If no switch sections are subsumed, just return
-            if (switchSections.Count(s => s.SwitchLabels.Count(l => isSubsumed(l)) != 0) == 0)
+            if (!switchSections.Any(s => s.SwitchLabels.Any(l => isSubsumed(l))))
             {
                 return;
             }

src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_BasePatternSwitchLocalRewriter.cs

@@ -65,7 +65,7 @@ private void ComputeLabelSet(ImmutableArray<BoundDecisionDag> sortedNodes)
             {
                 // Nodes with more than one predecessor are assigned a label
                 var hasPredecessor = PooledHashSet<BoundDecisionDag>.GetInstance();
-                void notePreedecesssor(BoundDecisionDag successor)
+                void notePredecessor(BoundDecisionDag successor)
                 {
                     if (successor != null && !hasPredecessor.Add(successor))
                     {
@@ -92,11 +92,11 @@ void notePreedecesssor(BoundDecisionDag successor)
                             _dagNodeLabels[node] = d.Label;
                             break;
                         case BoundEvaluationPoint e:
-                            notePreedecesssor(e.Next);
+                            notePredecessor(e.Next);
                             break;
                         case BoundDecisionPoint p:
-                            notePreedecesssor(p.WhenTrue);
-                            notePreedecesssor(p.WhenFalse);
+                            notePredecessor(p.WhenTrue);
+                            notePredecessor(p.WhenFalse);
                             break;
                         default:
                             throw ExceptionUtilities.UnexpectedValue(node.Kind);