Don't emit SA1414 for interface implementations

Author: CollinAlpert

StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp7/MaintainabilityRules/SA1414CSharp7UnitTests.cs

@@ -117,5 +117,23 @@ public static explicit operator TestClass({typeExpression} p1)
 
             await VerifyCSharpDiagnosticAsync(testCode, expected, CancellationToken.None).ConfigureAwait(false);
         }
+
+        [Fact]
+        public Task ValidateTuplesFromInheritedTypeAsync()
+        {
+            const string testCode = @"
+using System.Collections.Generic;
+
+namespace Test {
+    class StringTupleComparer : IEqualityComparer<(string, string)>
+    {
+	    public bool Equals((string, string) x, (string, string) y) => throw null;
+
+	    public int GetHashCode((string, string) obj) => throw null;
+    }
+}
+";
+            return VerifyCSharpDiagnosticAsync(testCode, DiagnosticResult.EmptyDiagnosticResults, default);
+        }
     }
 }

StyleCop.Analyzers/StyleCop.Analyzers/MaintainabilityRules/SA1414TupleTypesInSignaturesShouldHaveElementNames.cs

@@ -7,6 +7,7 @@ namespace StyleCop.Analyzers.MaintainabilityRules
 {
     using System;
     using System.Collections.Immutable;
+    using System.Linq;
     using Microsoft.CodeAnalysis;
     using Microsoft.CodeAnalysis.CSharp;
     using Microsoft.CodeAnalysis.CSharp.Syntax;
@@ -62,6 +63,20 @@ private static void HandleMethodDeclaration(SyntaxNodeAnalysisContext context)
             }
 
             var methodDeclaration = (MethodDeclarationSyntax)context.Node;
+            var methodSymbol = context.SemanticModel.GetDeclaredSymbol(methodDeclaration);
+            var containingType = methodSymbol.ContainingType;
+            if (containingType == null)
+            {
+                return;
+            }
+
+            foreach (var member in containingType.AllInterfaces.SelectMany(i => i.GetMembers(methodSymbol.Name).OfType<IMethodSymbol>()))
+            {
+                if (methodSymbol.Equals(containingType.FindImplementationForInterfaceMember(member)))
+                {
+                    return;
+                }
+            }
 
             CheckType(context, methodDeclaration.ReturnType);
             CheckParameterList(context, methodDeclaration.ParameterList);