Enhance the bound generator concept to remove duplicate parameters and make it more pervasive throughout the system

src/libraries/System.Runtime.InteropServices.JavaScript/gen/JSImportGenerator/JSExportCodeGenerator.cs

@@ -16,7 +16,8 @@ internal sealed class JSExportCodeGenerator : JSCodeGenerator
     {
         private readonly BoundGenerators _marshallers;
 
-        private readonly JSExportCodeContext _context;
+        private readonly StubCodeContext _context;
+        private readonly JSExportData _jsExportData;
         private readonly JSSignatureContext _signatureContext;
 
         public JSExportCodeGenerator(
@@ -27,30 +28,29 @@ public JSExportCodeGenerator(
             IMarshallingGeneratorResolver generatorResolver)
         {
             _signatureContext = signatureContext;
-            NativeToManagedStubCodeContext innerContext = new NativeToManagedStubCodeContext(ReturnIdentifier, ReturnIdentifier)
+            _jsExportData = attributeData;
+            _context = new NativeToManagedStubCodeContext(ReturnIdentifier, ReturnIdentifier)
             {
                 CodeEmitOptions = new(SkipInit: true)
             };
-            _context = new JSExportCodeContext(attributeData, innerContext);
 
             _marshallers = BoundGenerators.Create(argTypes, generatorResolver, _context, new EmptyJSGenerator(), out var bindingFailures);
 
             diagnosticsBag.ReportGeneratorDiagnostics(bindingFailures);
 
-            if (_marshallers.ManagedReturnMarshaller.Generator.UsesNativeIdentifier(_marshallers.ManagedReturnMarshaller.TypeInfo, null))
+            if (_marshallers.ManagedReturnMarshaller.UsesNativeIdentifier(_context))
             {
                 // If we need a different native return identifier, then recreate the context with the correct identifier before we generate any code.
-                innerContext = new NativeToManagedStubCodeContext(ReturnIdentifier, ReturnNativeIdentifier)
+                _context = new NativeToManagedStubCodeContext(ReturnIdentifier, ReturnNativeIdentifier)
                 {
                     CodeEmitOptions = new(SkipInit: true)
                 };
-                _context = new JSExportCodeContext(attributeData, innerContext);
             }
 
             // validate task + span mix
             if (_marshallers.ManagedReturnMarshaller.TypeInfo.MarshallingAttributeInfo is JSMarshallingInfo(_, JSTaskTypeInfo))
             {
-                BoundGenerator spanArg = _marshallers.SignatureMarshallers.FirstOrDefault(m => m.TypeInfo.MarshallingAttributeInfo is JSMarshallingInfo(_, JSSpanTypeInfo));
+                IBoundMarshallingGenerator spanArg = _marshallers.SignatureMarshallers.FirstOrDefault(m => m.TypeInfo.MarshallingAttributeInfo is JSMarshallingInfo(_, JSSpanTypeInfo));
                 if (spanArg != default)
                 {
                     diagnosticsBag.ReportGeneratorDiagnostic(new GeneratorDiagnostic.NotSupported(spanArg.TypeInfo, _context)
@@ -160,8 +160,9 @@ public StatementSyntax GenerateJSExportRegistration()
 
         private ArgumentSyntax CreateSignaturesSyntax()
         {
-            var types = ((IJSMarshallingGenerator)_marshallers.ManagedReturnMarshaller.Generator).GenerateBind(_marshallers.ManagedReturnMarshaller.TypeInfo, _context)
-                .Concat(_marshallers.NativeParameterMarshallers.SelectMany(p => ((IJSMarshallingGenerator)p.Generator).GenerateBind(p.TypeInfo, _context)));
+            IEnumerable<ExpressionSyntax> types = _marshallers.ManagedReturnMarshaller is IJSMarshallingGenerator jsGen ? jsGen.GenerateBind(_context) : [];
+            types = types
+                .Concat(_marshallers.NativeParameterMarshallers.OfType<IJSMarshallingGenerator>().SelectMany(p => p.GenerateBind(_context)));
 
             return Argument(ArrayCreationExpression(ArrayType(IdentifierName(Constants.JSMarshalerTypeGlobal))
                 .WithRankSpecifiers(SingletonList(ArrayRankSpecifier(SingletonSeparatedList<ExpressionSyntax>(OmittedArraySizeExpression())))))
@@ -170,7 +171,7 @@ private ArgumentSyntax CreateSignaturesSyntax()
 
         private void SetupSyntax(List<StatementSyntax> statementsToUpdate)
         {
-            foreach (BoundGenerator marshaller in _marshallers.NativeParameterMarshallers)
+            foreach (IBoundMarshallingGenerator marshaller in _marshallers.NativeParameterMarshallers)
             {
                 statementsToUpdate.Add(LocalDeclarationStatement(VariableDeclaration(marshaller.TypeInfo.ManagedType.Syntax)
                     .WithVariables(SingletonSeparatedList(VariableDeclarator(marshaller.TypeInfo.InstanceIdentifier)))));
@@ -195,10 +196,10 @@ private List<StatementSyntax> InvokeSyntax()
             var arguments = new List<ArgumentSyntax>();
 
             // Generate code for each parameter for the current stage
-            foreach (BoundGenerator marshaller in _marshallers.NativeParameterMarshallers)
+            foreach (IBoundMarshallingGenerator marshaller in _marshallers.NativeParameterMarshallers)
             {
                 // convert arguments for invocation
-                statements.AddRange(marshaller.Generator.Generate(marshaller.TypeInfo, _context));
+                statements.AddRange(marshaller.Generate(_context));
                 arguments.Add(Argument(IdentifierName(marshaller.TypeInfo.InstanceIdentifier)));
             }
 

src/libraries/System.Runtime.InteropServices.JavaScript/gen/JSImportGenerator/JSExportGenerator.cs

@@ -119,13 +119,15 @@ public void Initialize(IncrementalGeneratorInitializationContext context)
 
                     StringBuilder source = new();
                     // Mark in source that the file is auto-generated.
-                    source.AppendLine("// <auto-generated/>");
+                    source.Append("// <auto-generated/>\r\n");
                     // this is the assembly level registration
-                    source.AppendLine(generatedSources[0].Item2);
+                    source.Append(generatedSources[0].Item2);
+                    source.Append("\r\n");
                     // this is the method wrappers to be called from JS
                     foreach (var generated in generatedSources)
                     {
-                        source.AppendLine(generated.Item1);
+                        source.Append(generated.Item1);
+                        source.Append("\r\n");
                     }
 
                     // Once https://github.com/dotnet/roslyn/issues/61326 is resolved, we can avoid the ToString() here.