Simplify equivalence comparers

src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/Utilities/SymbolEquivalenceComparer.EquivalenceVisitor.cs

@@ -13,37 +13,33 @@ namespace Microsoft.CodeAnalysis.Shared.Utilities;
 
 internal partial class SymbolEquivalenceComparer
 {
-    private class EquivalenceVisitor(
+    private sealed class EquivalenceVisitor(
         SymbolEquivalenceComparer symbolEquivalenceComparer,
-        bool compareMethodTypeParametersByIndex,
-        bool objectAndDynamicCompareEqually)
+        bool compareMethodTypeParametersByIndex)
     {
-
         public bool AreEquivalent(ISymbol? x, ISymbol? y, Dictionary<INamedTypeSymbol, INamedTypeSymbol>? equivalentTypesWithDifferingAssemblies)
         {
             if (ReferenceEquals(x, y))
-            {
                 return true;
-            }
 
             if (x == null || y == null)
-            {
                 return false;
-            }
 
             var xKind = GetKindAndUnwrapAlias(ref x);
             var yKind = GetKindAndUnwrapAlias(ref y);
 
             // Normally, if they're different types, then they're not the same.
             if (xKind != yKind)
             {
-                // Special case.  If we're comparing signatures then we want to compare 'object'
-                // and 'dynamic' as the same.  However, since they're different types, we don't
-                // want to bail out using the above check.
-                if (objectAndDynamicCompareEqually)
+                // Special case.  If we're comparing signatures then we want to compare 'object' and 'dynamic' as the
+                // same.  However, since they're different types, we don't want to bail out using the above check.
+                if (symbolEquivalenceComparer._objectAndDynamicCompareEqually)
                 {
-                    return (xKind == SymbolKind.DynamicType && IsObjectType(y)) ||
-                           (yKind == SymbolKind.DynamicType && IsObjectType(x));
+                    if ((xKind == SymbolKind.DynamicType && IsObjectType(y)) ||
+                        (yKind == SymbolKind.DynamicType && IsObjectType(x)))
+                    {
+                        return true;
+                    }
                 }
 
                 return false;

src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/Utilities/SymbolEquivalenceComparer.GetHashCodeVisitor.cs

@@ -13,22 +13,19 @@ namespace Microsoft.CodeAnalysis.Shared.Utilities;
 
 internal partial class SymbolEquivalenceComparer
 {
-    private class GetHashCodeVisitor
+    private sealed class GetHashCodeVisitor
     {
         private readonly SymbolEquivalenceComparer _symbolEquivalenceComparer;
         private readonly bool _compareMethodTypeParametersByIndex;
-        private readonly bool _objectAndDynamicCompareEqually;
         private readonly Func<int, IParameterSymbol, int> _parameterAggregator;
         private readonly Func<int, ISymbol, int> _symbolAggregator;
 
         public GetHashCodeVisitor(
             SymbolEquivalenceComparer symbolEquivalenceComparer,
-            bool compareMethodTypeParametersByIndex,
-            bool objectAndDynamicCompareEqually)
+            bool compareMethodTypeParametersByIndex)
         {
             _symbolEquivalenceComparer = symbolEquivalenceComparer;
             _compareMethodTypeParametersByIndex = compareMethodTypeParametersByIndex;
-            _objectAndDynamicCompareEqually = objectAndDynamicCompareEqually;
             _parameterAggregator = (acc, sym) => Hash.Combine(symbolEquivalenceComparer.ParameterEquivalenceComparer.GetHashCode(sym), acc);
             _symbolAggregator = (acc, sym) => GetHashCode(sym, acc);
         }
@@ -45,7 +42,7 @@ public int GetHashCode(ISymbol? x, int currentHash)
             // want to bail out using the above check.
 
             if (x.Kind == SymbolKind.DynamicType ||
-                (_objectAndDynamicCompareEqually && IsObjectType(x)))
+                (_symbolEquivalenceComparer._objectAndDynamicCompareEqually && IsObjectType(x)))
             {
                 return Hash.Combine(GetNullableAnnotationsHashCode((ITypeSymbol)x), Hash.Combine(typeof(IDynamicTypeSymbol), currentHash));
             }

src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/Utilities/SymbolEquivalenceComparer.SignatureTypeSymbolEquivalenceComparer.cs

@@ -8,15 +8,15 @@ namespace Microsoft.CodeAnalysis.Shared.Utilities;
 
 internal partial class SymbolEquivalenceComparer
 {
-    internal class SignatureTypeSymbolEquivalenceComparer(SymbolEquivalenceComparer symbolEquivalenceComparer) : IEqualityComparer<ITypeSymbol?>
+    internal sealed class SignatureTypeSymbolEquivalenceComparer(SymbolEquivalenceComparer symbolEquivalenceComparer) : IEqualityComparer<ITypeSymbol?>
     {
         public bool Equals(ITypeSymbol? x, ITypeSymbol? y)
             => this.Equals(x, y, null);
 
         public bool Equals(ITypeSymbol? x, ITypeSymbol? y, Dictionary<INamedTypeSymbol, INamedTypeSymbol>? equivalentTypesWithDifferingAssemblies)
-            => symbolEquivalenceComparer.GetEquivalenceVisitor(compareMethodTypeParametersByIndex: true, symbolEquivalenceComparer._objectAndDynamicCompareEqually).AreEquivalent(x, y, equivalentTypesWithDifferingAssemblies);
+            => symbolEquivalenceComparer.GetEquivalenceVisitor(compareMethodTypeParametersByIndex: true).AreEquivalent(x, y, equivalentTypesWithDifferingAssemblies);
 
         public int GetHashCode(ITypeSymbol? x)
-            => symbolEquivalenceComparer.GetGetHashCodeVisitor(compareMethodTypeParametersByIndex: true, symbolEquivalenceComparer._objectAndDynamicCompareEqually).GetHashCode(x, currentHash: 0);
+            => symbolEquivalenceComparer.GetGetHashCodeVisitor(compareMethodTypeParametersByIndex: true).GetHashCode(x, currentHash: 0);
     }
 }

src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/Utilities/SymbolEquivalenceComparer.cs

@@ -73,20 +73,18 @@ public SymbolEquivalenceComparer(
         using var equivalenceVisitors = TemporaryArray<EquivalenceVisitor>.Empty;
         using var getHashCodeVisitors = TemporaryArray<GetHashCodeVisitor>.Empty;
 
-        AddVisitors(compareMethodTypeParametersByIndex: true, objectAndDynamicCompareEqually: true);
-        AddVisitors(compareMethodTypeParametersByIndex: true, objectAndDynamicCompareEqually: false);
-        AddVisitors(compareMethodTypeParametersByIndex: false, objectAndDynamicCompareEqually: true);
-        AddVisitors(compareMethodTypeParametersByIndex: false, objectAndDynamicCompareEqually: false);
+        AddVisitors(compareMethodTypeParametersByIndex: true);
+        AddVisitors(compareMethodTypeParametersByIndex: false);
 
         _equivalenceVisitors = equivalenceVisitors.ToImmutableAndClear();
         _getHashCodeVisitors = getHashCodeVisitors.ToImmutableAndClear();
 
         return;
 
-        void AddVisitors(bool compareMethodTypeParametersByIndex, bool objectAndDynamicCompareEqually)
+        void AddVisitors(bool compareMethodTypeParametersByIndex)
         {
-            equivalenceVisitors.Add(new(this, compareMethodTypeParametersByIndex, objectAndDynamicCompareEqually));
-            getHashCodeVisitors.Add(new(this, compareMethodTypeParametersByIndex, objectAndDynamicCompareEqually));
+            equivalenceVisitors.Add(new(this, compareMethodTypeParametersByIndex));
+            getHashCodeVisitors.Add(new(this, compareMethodTypeParametersByIndex));
         }
     }
 
@@ -107,27 +105,21 @@ public static SymbolEquivalenceComparer Create(
     // here.  So, instead, when asking if parameters are equal, we pass an appropriate flag so
     // that method type parameters are just compared by index and nothing else.
     private EquivalenceVisitor GetEquivalenceVisitor(
-        bool compareMethodTypeParametersByIndex = false, bool objectAndDynamicCompareEqually = false)
+        bool compareMethodTypeParametersByIndex = false)
     {
-        var visitorIndex = GetVisitorIndex(compareMethodTypeParametersByIndex, objectAndDynamicCompareEqually);
+        var visitorIndex = GetVisitorIndex(compareMethodTypeParametersByIndex);
         return _equivalenceVisitors[visitorIndex];
     }
 
     private GetHashCodeVisitor GetGetHashCodeVisitor(
-        bool compareMethodTypeParametersByIndex, bool objectAndDynamicCompareEqually)
+        bool compareMethodTypeParametersByIndex)
     {
-        var visitorIndex = GetVisitorIndex(compareMethodTypeParametersByIndex, objectAndDynamicCompareEqually);
+        var visitorIndex = GetVisitorIndex(compareMethodTypeParametersByIndex);
         return _getHashCodeVisitors[visitorIndex];
     }
 
-    private static int GetVisitorIndex(bool compareMethodTypeParametersByIndex, bool objectAndDynamicCompareEqually)
-        => (compareMethodTypeParametersByIndex, objectAndDynamicCompareEqually) switch
-        {
-            (true, true) => 0,
-            (true, false) => 1,
-            (false, true) => 2,
-            (false, false) => 3,
-        };
+    private static int GetVisitorIndex(bool compareMethodTypeParametersByIndex)
+        => compareMethodTypeParametersByIndex ? 0 : 1;
 
     public bool ReturnTypeEquals(IMethodSymbol x, IMethodSymbol y, Dictionary<INamedTypeSymbol, INamedTypeSymbol>? equivalentTypesWithDifferingAssemblies = null)
         => GetEquivalenceVisitor().ReturnTypesAreEquivalent(x, y, equivalentTypesWithDifferingAssemblies);
@@ -154,7 +146,7 @@ private bool EqualsCore(ISymbol? x, ISymbol? y, Dictionary<INamedTypeSymbol, INa
         => GetEquivalenceVisitor().AreEquivalent(x, y, equivalentTypesWithDifferingAssemblies);
 
     public int GetHashCode(ISymbol? x)
-        => GetGetHashCodeVisitor(compareMethodTypeParametersByIndex: false, objectAndDynamicCompareEqually: false).GetHashCode(x, currentHash: 0);
+        => GetGetHashCodeVisitor(compareMethodTypeParametersByIndex: false).GetHashCode(x, currentHash: 0);
 
     private static ISymbol UnwrapAlias(ISymbol symbol)
         => symbol.IsKind(SymbolKind.Alias, out IAliasSymbol? alias) ? alias.Target : symbol;