Add tests.

src/EditorFeatures/CSharpTest/GenerateFromMembers/GenerateEqualsAndGetHashCodeFromMembers/GenerateEqualsAndGetHashCodeFromMembersTests.cs

@@ -1575,5 +1575,50 @@ public override bool Equals(object obj)
     }
 }");
         }
+
+        [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsGenerateEqualsAndGetHashCode)]
+        public async Task TestEqualsBaseWithOverriddenEquals_Patterns()
+        {
+            await TestInRegularAndScript1Async(
+@"using System.Collections.Generic;
+
+class Base
+{
+    public override bool Equals(object o)
+    {
+    }
+}
+
+class Program : Base
+{
+    [|int i;
+
+    string S { get; }|]
+}",
+@"using System.Collections.Generic;
+
+class Base
+{
+    public override bool Equals(object o)
+    {
+    }
+}
+
+class Program : Base
+{
+    int i;
+
+    string S { get; }
+
+    public override bool Equals(object obj)
+    {
+        return obj is Program program &&
+               base.Equals(obj) &&
+               i == program.i &&
+               S == program.S;
+    }
+}",
+index: 0);
+        }
     }
 }

src/Workspaces/Core/Portable/Shared/Extensions/ICodeDefinitionFactoryExtensions_CreateEqualsMethod.cs

@@ -157,18 +157,19 @@ public static IMethodSymbol CreateEqualsMethod(this Compilation compilation, Imm
                 //
                 //      myType != null
                 expressions.Add(factory.ReferenceNotEqualsExpression(localNameExpression, factory.NullLiteralExpression()));
-                if (HasExistingBaseEqualsMethod(containingType, cancellationToken))
-                {
-                    // If we're overriding something that also provided an overridden 'Equals',
-                    // then ensure the base type thinks it is equals as well.
-                    //
-                    //      base.Equals(obj)
-                    expressions.Add(factory.InvocationExpression(
-                        factory.MemberAccessExpression(
-                            factory.BaseExpression(),
-                            factory.IdentifierName(EqualsName)),
-                        objNameExpression));
-                }
+            }
+
+            if (!containingType.IsValueType && HasExistingBaseEqualsMethod(containingType, cancellationToken))
+            {
+                // If we're overriding something that also provided an overridden 'Equals',
+                // then ensure the base type thinks it is equals as well.
+                //
+                //      base.Equals(obj)
+                expressions.Add(factory.InvocationExpression(
+                    factory.MemberAccessExpression(
+                        factory.BaseExpression(),
+                        factory.IdentifierName(EqualsName)),
+                    objNameExpression));
             }
 
             AddMemberChecks(factory, compilation, members, localNameExpression, expressions);