AZC0004 ensure that method signatures match

src/dotnet/Azure.ClientSdk.Analyzers/Azure.ClientSdk.Analyzers.Tests/AZC0004Tests.cs

@@ -396,5 +396,60 @@ public virtual Response Get(CancellationToken cancellationToken)
             await Verifier.CreateAnalyzer(code)
                 .RunAsync();
         }
+
+        [Fact]
+        public async Task AZC0004ProducedForMethodsWithMismatchedReturnTypes()
+        {
+            const string code = @"
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace RandomNamespace
+{
+    public class SomeClient
+    {
+        public virtual Task<string> {|AZC0004:GetAsync|}(CancellationToken cancellationToken = default)
+        {
+            return null;
+        }
+
+        public virtual int Get(CancellationToken cancellationToken = default)
+        {
+            return 0;
+        }
+    }
+}";
+            await Verifier.CreateAnalyzer(code)
+                .WithDisabledDiagnostics("AZC0015")
+                .RunAsync();
+        }
+
+        [Fact]
+        public async Task AZC0004ProducedForMethotsWithMismatchedParameters()
+        {
+            const string code = @"
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace RandomNamespace
+{
+    public class SomeClient
+    {
+        public virtual Task<string> {|AZC0004:GetAsync|}(CancellationToken cancellationToken = default)
+        {
+            return null;
+        }
+
+        public virtual string Get(string foo, CancellationToken cancellationToken = default)
+        {
+            return null;
+        }
+    }
+}";
+            await Verifier.CreateAnalyzer(code)
+                .WithDisabledDiagnostics("AZC0015")
+                .RunAsync();
+        }
+
     }
 }

src/dotnet/Azure.ClientSdk.Analyzers/Azure.ClientSdk.Analyzers/ClientMethodsAnalyzer.cs

@@ -279,6 +279,92 @@ private static bool IsClientMethodReturnType(ISymbolAnalysisContext context, IMe
             return false;
         }
 
+        private static bool CompareReturnTypesRecursively(ITypeSymbol asyncType, ITypeSymbol syncType)
+        {
+            // Unwrap Task<T> for async methods
+            if (asyncType is INamedTypeSymbol asyncNamedType && asyncNamedType.Name == TaskTypeName)
+            {
+                if (asyncNamedType.IsGenericType)
+                {
+                    asyncType = asyncNamedType.TypeArguments.Single();
+                }
+                else
+                {
+                    // async returns Task, sync should return void or non-generic Task
+                    if (syncType.SpecialType == SpecialType.System_Void ||
+                        (syncType is INamedTypeSymbol syncNamedType && syncNamedType.Name == TaskTypeName && !syncNamedType.IsGenericType))
+                    {
+                        return true;
+                    }
+                    return false;
+                }
+            }
+
+            // Map AsyncPageable<T> to Pageable<T> for easy comparison since they are equivalent for these purposes
+            if (asyncType is INamedTypeSymbol asyncTypeSymbol && asyncTypeSymbol.Name == AsyncPageableTypeName && asyncTypeSymbol.IsGenericType)
+            {
+                asyncType = asyncTypeSymbol.ContainingNamespace.GetTypeMembers(PageableTypeName).FirstOrDefault()?.Construct(asyncTypeSymbol.TypeArguments.ToArray());
+            }
+
+            // Compare directly if sync method return type is not a named type symbol
+            if (syncType is not INamedTypeSymbol syncTypeSymbol)
+            {
+                return SymbolEqualityComparer.Default.Equals(asyncType, syncType);
+            }
+
+            // Compare type names and namespaces
+            if (asyncType is INamedTypeSymbol asyncNamedTypeSymbol && syncType is INamedTypeSymbol syncNamedTypeSymbol)
+            {
+                if (asyncNamedTypeSymbol.Name != syncNamedTypeSymbol.Name ||
+                    asyncNamedTypeSymbol.ContainingNamespace.ToDisplayString() != syncNamedTypeSymbol.ContainingNamespace.ToDisplayString())
+                {
+                    return false;
+                }
+
+                // Compare nested types recursively
+                if (asyncNamedTypeSymbol.IsGenericType && syncNamedTypeSymbol.IsGenericType)
+                {
+                    var asyncTypeArguments = asyncNamedTypeSymbol.TypeArguments;
+                    var syncTypeArguments = syncNamedTypeSymbol.TypeArguments;
+
+                    if (asyncTypeArguments.Length != syncTypeArguments.Length)
+                    {
+                        return false;
+                    }
+
+                    for (int i = 0; i < asyncTypeArguments.Length; i++)
+                    {
+                        if (!CompareReturnTypesRecursively(asyncTypeArguments[i], syncTypeArguments[i]))
+                        {
+                            return false;
+                        }
+                    }
+                    return true;
+                }
+                else if ((!asyncNamedTypeSymbol.IsGenericType) && (!syncNamedTypeSymbol.IsGenericType))
+                {
+                    return true;
+                }
+                else
+                {
+                    // One is a generic type and the other is not
+                    return false;
+                }
+            }
+
+            return SymbolEqualityComparer.Default.Equals(asyncType, syncType);
+        }
+
+        private static bool DoReturnTypesMatch(ITypeSymbol asyncReturnType, ITypeSymbol syncReturnType)
+        {
+            if (asyncReturnType == null || syncReturnType == null)
+            {
+                return false;
+            }
+
+            return CompareReturnTypesRecursively(asyncReturnType, syncReturnType);
+        }
+
         public override void AnalyzeCore(ISymbolAnalysisContext context)
         {
             INamedTypeSymbol type = (INamedTypeSymbol)context.Symbol;
@@ -304,6 +390,16 @@ public override void AnalyzeCore(ISymbolAnalysisContext context)
                     }
                     else
                     {
+                        if (!DoReturnTypesMatch(methodSymbol.ReturnType, syncMember.ReturnType))
+                        {
+                            context.ReportDiagnostic(Diagnostic.Create(Descriptors.AZC0004, member.Locations.First()), member);
+                        }
+
+                        if (!methodSymbol.Parameters.SequenceEqual(syncMember.Parameters, ParameterEquivalenceComparer.Default))
+                        {
+                            context.ReportDiagnostic(Diagnostic.Create(Descriptors.AZC0005, member.Locations.First()), member);
+                        }
+
                         CheckClientMethod(context, syncMember);
                     }
                 }