Using dotnet 9's save assembly api for debugging DI IL emit (#98234)

* using dotnet 9 save assembly api for debugging DI IL emit

* Update src/libraries/Microsoft.Extensions.DependencyInjection/src/Microsoft.Extensions.DependencyInjection.csproj

Co-authored-by: Austin Wise <AustinWise@gmail.com>

---------

Co-authored-by: Austin Wise <AustinWise@gmail.com>

Author: allantargino

src/libraries/Microsoft.Extensions.DependencyInjection/src/Microsoft.Extensions.DependencyInjection.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppPrevious);$(NetCoreAppMinimum);netstandard2.1;netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
@@ -14,8 +14,8 @@
   <PropertyGroup>
     <ILEmitBackend Condition="'$(TargetFramework)' != 'netstandard2.0'">true</ILEmitBackend>
     <DefineConstants Condition="'$(ILEmitBackend)' == 'true'">$(DefineConstants);IL_EMIT</DefineConstants>
-    <DefineConstants Condition="$([MSBuild]::GetTargetFrameworkIdentifier('$(TargetFramework)')) == '.NETFramework' and
-                                '$(ILEmitBackendSaveAssemblies)' == 'true'">$(DefineConstants);SAVE_ASSEMBLIES</DefineConstants>
+    <DefineConstants Condition="($([MSBuild]::GetTargetFrameworkIdentifier('$(TargetFramework)')) == '.NETFramework' or $([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net9.0'))) and
+                               '$(ILEmitBackendSaveAssemblies)' == 'true'">$(DefineConstants);SAVE_ASSEMBLIES</DefineConstants>
   </PropertyGroup>
 
   <ItemGroup>

src/libraries/Microsoft.Extensions.DependencyInjection/src/ServiceLookup/ILEmit/ILEmitResolverBuilder.cs

@@ -104,8 +104,13 @@ private GeneratedMethod BuildTypeNoCache(ServiceCallSite callSite)
             var assemblyName = "Test" + DateTime.Now.Ticks;
             var fileName = assemblyName + ".dll";
 
+#if NETFRAMEWORK
             var assembly = AssemblyBuilder.DefineDynamicAssembly(new AssemblyName(assemblyName), AssemblyBuilderAccess.RunAndSave);
             var module = assembly.DefineDynamicModule(assemblyName, fileName);
+#else
+            var assembly = AssemblyBuilder.DefinePersistedAssembly(new AssemblyName(assemblyName), typeof(object).Assembly);
+            var module = assembly.DefineDynamicModule(assemblyName);
+#endif
             var type = module.DefineType(callSite.ServiceType.Name + "Resolver");
 
             var method = type.DefineMethod(
@@ -114,7 +119,6 @@ private GeneratedMethod BuildTypeNoCache(ServiceCallSite callSite)
 
             GenerateMethodBody(callSite, method.GetILGenerator());
             type.CreateTypeInfo();
-            // Assembly.Save is only available in .NET Framework (https://github.com/dotnet/runtime/issues/15704)
             assembly.Save(fileName);
 #endif
             DependencyInjectionEventSource.Log.DynamicMethodBuilt(_rootScope.RootProvider, callSite.ServiceType, ilGenerator.ILOffset);
@@ -179,7 +183,7 @@ private GeneratedMethod BuildTypeNoCache(ServiceCallSite callSite)
             AddConstant(argument, generatedMethod.Lambda);
             // ProviderScope
             argument.Generator.Emit(OpCodes.Ldarg_1);
-            argument.Generator.Emit(OpCodes.Call, generatedMethod.Lambda.GetType().GetMethod("Invoke"));
+            argument.Generator.Emit(OpCodes.Call, generatedMethod.Lambda.GetType().GetMethod("Invoke")!);
 #else
             AddConstant(argument, generatedMethod.Context);
             // ProviderScope