support local variable usage

Author: DeagleGross

src/Framework/AspNetCoreAnalyzers/src/Analyzers/Kestrel/ListenOnIPv6AnyAnalyzer.cs

@@ -52,6 +52,10 @@ private void KestrelServerOptionsListenInvocation(SyntaxNodeAnalysisContext cont
 
         var args = kestrelOptionsListenExpressionSyntax.ArgumentList;
         var ipAddressArgumentSyntax = args.Arguments.FirstOrDefault();
+        if (ipAddressArgumentSyntax is null)
+        {
+            return;
+        }
 
         // explicit usage like `options.Listen(IPAddress.Any, ...)`
         if (ipAddressArgumentSyntax is ArgumentSyntax
@@ -64,6 +68,32 @@ private void KestrelServerOptionsListenInvocation(SyntaxNodeAnalysisContext cont
         {
             context.ReportDiagnostic(Diagnostic.Create(DiagnosticDescriptors.KestrelShouldListenOnIPv6AnyInsteadOfIpAny, ipAddressArgumentSyntax.GetLocation()));
         }
+
+        // usage via local variable like
+        // ```
+        // var myIp = IPAddress.Any;
+        // options.Listen(myIp, ...);
+        // ```
+        if (addressArgument!.Value is ILocalReferenceOperation localReferenceOperation)
+        {
+            var localVariableDeclaration = localReferenceOperation.Local.DeclaringSyntaxReferences.FirstOrDefault();
+            if (localVariableDeclaration is null)
+            {
+                return;
+            }
+
+            var localVarSyntax = localVariableDeclaration.GetSyntax(context.CancellationToken);
+            if (localVarSyntax is VariableDeclaratorSyntax
+            {
+                Initializer.Value: MemberAccessExpressionSyntax
+                {
+                    Name.Identifier.ValueText: "Any"
+                }
+            })
+            {
+                context.ReportDiagnostic(Diagnostic.Create(DiagnosticDescriptors.KestrelShouldListenOnIPv6AnyInsteadOfIpAny, ipAddressArgumentSyntax.GetLocation()));
+            }
+        }
     }
 
     private static bool IsIPAddressType(IParameterSymbol? parameter) => parameter is 

src/Framework/AspNetCoreAnalyzers/src/CodeFixes/Kestrel/ListenOnIPv6AnyFixer.cs

@@ -43,7 +43,31 @@ public override Task RegisterCodeFixesAsync(CodeFixContext context)
                             return context.Document;
                         }
 
-                        editor.ReplaceNode(argumentSyntax, argumentSyntax.WithExpression(SyntaxFactory.ParseExpression("IPAddress.IPv6Any")));
+                        // get to the `Listen(IPAddress.Any, ...)` invocation
+                        if (argumentSyntax.Parent?.Parent is not InvocationExpressionSyntax { ArgumentList.Arguments.Count: > 1 } invocationExpressionSyntax)
+                        {
+                            return context.Document;
+                        }
+                        if (invocationExpressionSyntax.Expression is not MemberAccessExpressionSyntax memberAccessExpressionSyntax)
+                        {
+                            return context.Document;
+                        }
+
+                        var instanceVariableInvoked = memberAccessExpressionSyntax.Expression;
+                        var adjustedArgumentList = invocationExpressionSyntax.ArgumentList.RemoveNode(invocationExpressionSyntax.ArgumentList.Arguments.First(), SyntaxRemoveOptions.KeepLeadingTrivia);
+                        if (adjustedArgumentList is null || adjustedArgumentList.Arguments.Count == 0)
+                        {
+                            return context.Document;
+                        }
+
+                        // changing invocation from `<variable>.Listen(IPAddress.Any, ...)` to `<variable>.ListenAnyIP(...)`
+                        editor.ReplaceNode(
+                            invocationExpressionSyntax,
+                            invocationExpressionSyntax
+                                .WithExpression(SyntaxFactory.ParseExpression($"{instanceVariableInvoked.ToString()}.ListenAnyIP"))
+                                .WithArgumentList(adjustedArgumentList!)
+                                .WithLeadingTrivia(invocationExpressionSyntax.GetLeadingTrivia())
+                        );
                         return editor.GetChangedDocument();
                     },
                     equivalenceKey: DiagnosticDescriptors.KestrelShouldListenOnIPv6AnyInsteadOfIpAny.Id),

src/Framework/AspNetCoreAnalyzers/test/Kestrel/ListenOnIPv6AnyAnalyzerAndFixerTests.cs

@@ -13,10 +13,17 @@ namespace Microsoft.AspNetCore.Analyzers.Kestrel;
 
 public class ListenOnIPv6AnyAnalyzerAndFixerTests
 {
-    [Fact] // do we need any other scenarios except the direct usage one?
+    [Fact]
+    public async Task ReportsDiagnostic_IPAddressAsLocalVariable_OuterScope()
+    {
+        var source = GetKestrelSetupSource("myIp", extraOuterCode: "var myIp = IPAddress.Any;");
+        await VerifyCS.VerifyAnalyzerAsync(source, codeSampleDiagnosticResult);
+    }
+
+    [Fact]
     public async Task ReportsDiagnostic_IPAddressAsLocalVariable()
     {
-        var source = GetKestrelSetupSource("myIp", "var myIp = IPAddress.Any;");
+        var source = GetKestrelSetupSource("myIp", extraInlineCode: "var myIp = IPAddress.Any;");
         await VerifyCS.VerifyAnalyzerAsync(source, codeSampleDiagnosticResult);
     }
 
@@ -31,19 +38,35 @@ public async Task ReportsDiagnostic_ExplicitUsage()
     public async Task CodeFix_ExplicitUsage()
     {
         var source = GetKestrelSetupSource("IPAddress.Any");
-        var fixedSource = GetKestrelSetupSource("IPAddress.IPv6Any");
+        var fixedSource = GetCorrectedKestrelSetup();
+        await VerifyCS.VerifyCodeFixAsync(source, codeSampleDiagnosticResult, fixedSource);
+    }
+
+    [Fact]
+    public async Task CodeFix_IPAddressAsLocalVariable()
+    {
+        var source = GetKestrelSetupSource("IPAddress.Any", extraInlineCode: "var myIp = IPAddress.Any;");
+        var fixedSource = GetCorrectedKestrelSetup(extraInlineCode: "var myIp = IPAddress.Any;");
         await VerifyCS.VerifyCodeFixAsync(source, codeSampleDiagnosticResult, fixedSource);
     }
 
     private static DiagnosticResult codeSampleDiagnosticResult
         = new DiagnosticResult(DiagnosticDescriptors.KestrelShouldListenOnIPv6AnyInsteadOfIpAny).WithLocation(0);
 
-    static string GetKestrelSetupSource(string ipAddressArgument, string extraInlineCode = null) => $$"""
+    static string GetKestrelSetupSource(string ipAddressArgument, string extraInlineCode = null, string extraOuterCode = null)
+        => GetCodeSample($$"""Listen({|#0:{{ipAddressArgument}}|}, """, extraInlineCode, extraOuterCode);
+
+    static string GetCorrectedKestrelSetup(string extraInlineCode = null, string extraOuterCode = null)
+        => GetCodeSample("ListenAnyIP(", extraInlineCode, extraOuterCode);
+
+    static string GetCodeSample(string invocation, string extraInlineCode = null, string extraOuterCode = null) => $$"""
         using Microsoft.Extensions.Hosting;
         using Microsoft.AspNetCore.Hosting;
         using Microsoft.AspNetCore.Server.Kestrel.Core;
         using System.Net;
     
+        {{extraOuterCode}}
+    
         var hostBuilder = new HostBuilder()
             .ConfigureWebHost(webHost =>
             {
@@ -53,7 +76,7 @@ static string GetKestrelSetupSource(string ipAddressArgument, string extraInline
                     
                     options.ListenLocalhost(5000);
                     options.ListenAnyIP(5000);
-                    options.Listen({|#0:{{ipAddressArgument}}|}, 5000, listenOptions =>
+                    options.{{invocation}}5000, listenOptions =>
                     {
                         listenOptions.UseHttps();
                         listenOptions.Protocols = HttpProtocols.Http1AndHttp2AndHttp3;