Refactor out MarshallingInfoParser creation from SignatureContext.

src/libraries/System.Runtime.InteropServices/gen/LibraryImportGenerator/Analyzers/ConvertToLibraryImportAnalyzer.cs

@@ -88,7 +88,7 @@ private static void AnalyzeSymbol(SymbolAnalysisContext context, INamedTypeSymbo
             AnyDiagnosticsSink diagnostics = new();
             StubEnvironment env = context.Compilation.CreateStubEnvironment();
             AttributeData dllImportAttribute = method.GetAttributes().First(attr => attr.AttributeClass.ToDisplayString() == TypeNames.DllImportAttribute);
-            SignatureContext targetSignatureContext = SignatureContext.Create(method, CreateInteropAttributeDataFromDllImport(dllImportData), env, diagnostics, dllImportAttribute, typeof(ConvertToLibraryImportAnalyzer).Assembly);
+            SignatureContext targetSignatureContext = SignatureContext.Create(method, DefaultMarshallingInfoParser.Create(env, diagnostics, method, CreateInteropAttributeDataFromDllImport(dllImportData), dllImportAttribute), env, typeof(ConvertToLibraryImportAnalyzer).Assembly);
 
             var generatorFactoryKey = LibraryImportGeneratorHelpers.CreateGeneratorFactory(env, new LibraryImportGeneratorOptions(context.Options.AnalyzerConfigOptionsProvider.GlobalOptions));
 

src/libraries/System.Runtime.InteropServices/gen/LibraryImportGenerator/DefaultMarshallingInfoParser.cs

@@ -0,0 +1,57 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Text;
+using Microsoft.CodeAnalysis;
+
+namespace Microsoft.Interop
+{
+    internal static class DefaultMarshallingInfoParser
+    {
+        public static MarshallingInfoParser Create(StubEnvironment env, IGeneratorDiagnostics diagnostics, IMethodSymbol method, InteropAttributeData interopAttributeData, AttributeData unparsedAttributeData)
+        {
+
+            // Compute the current default string encoding value.
+            CharEncoding defaultEncoding = CharEncoding.Undefined;
+            if (interopAttributeData.IsUserDefined.HasFlag(InteropAttributeMember.StringMarshalling))
+            {
+                defaultEncoding = interopAttributeData.StringMarshalling switch
+                {
+                    StringMarshalling.Utf16 => CharEncoding.Utf16,
+                    StringMarshalling.Utf8 => CharEncoding.Utf8,
+                    StringMarshalling.Custom => CharEncoding.Custom,
+                    _ => CharEncoding.Undefined, // [Compat] Do not assume a specific value
+                };
+            }
+            else if (interopAttributeData.IsUserDefined.HasFlag(InteropAttributeMember.StringMarshallingCustomType))
+            {
+                defaultEncoding = CharEncoding.Custom;
+            }
+
+            var defaultInfo = new DefaultMarshallingInfo(defaultEncoding, interopAttributeData.StringMarshallingCustomType);
+
+            var useSiteAttributeParsers = ImmutableArray.Create<IUseSiteAttributeParser>(
+                    new MarshalAsAttributeParser(env.Compilation, diagnostics, defaultInfo),
+                    new MarshalUsingAttributeParser(env.Compilation, diagnostics));
+
+            return new MarshallingInfoParser(
+                diagnostics,
+                new MethodSignatureElementInfoProvider(env.Compilation, diagnostics, method, useSiteAttributeParsers),
+                useSiteAttributeParsers,
+            ImmutableArray.Create<IMarshallingInfoAttributeParser>(
+                    new MarshalAsAttributeParser(env.Compilation, diagnostics, defaultInfo),
+                    new MarshalUsingAttributeParser(env.Compilation, diagnostics),
+                    new NativeMarshallingAttributeParser(env.Compilation, diagnostics)),
+                ImmutableArray.Create<ITypeBasedMarshallingInfoProvider>(
+                    new SafeHandleMarshallingInfoProvider(env.Compilation, method.ContainingType),
+                    new ArrayMarshallingInfoProvider(env.Compilation),
+            new CharMarshallingInfoProvider(defaultInfo),
+                    new StringMarshallingInfoProvider(env.Compilation, diagnostics, unparsedAttributeData, defaultInfo),
+                    new BooleanMarshallingInfoProvider(),
+                    new BlittableTypeMarshallingInfoProvider(env.Compilation)));
+        }
+    }
+}

src/libraries/System.Runtime.InteropServices/gen/LibraryImportGenerator/LibraryImportGenerator.cs

@@ -312,7 +312,7 @@ private static IncrementalStubGenerationContext CalculateStubInformation(
             }
 
             // Create the stub.
-            var signatureContext = SignatureContext.Create(symbol, libraryImportData, environment, generatorDiagnostics, generatedDllImportAttr, typeof(LibraryImportGenerator).Assembly);
+            var signatureContext = SignatureContext.Create(symbol, DefaultMarshallingInfoParser.Create(environment, generatorDiagnostics, symbol, libraryImportData, generatedDllImportAttr), environment, typeof(LibraryImportGenerator).Assembly);
 
             var containingTypeContext = new ContainingSyntaxContext(originalSyntax);
 

src/libraries/System.Runtime.InteropServices/gen/Microsoft.Interop.SourceGeneration/SignatureContext.cs

@@ -53,13 +53,11 @@ public IEnumerable<ParameterSyntax> StubParameters
 
         public static SignatureContext Create(
             IMethodSymbol method,
-            InteropAttributeData interopAttributeData,
+            MarshallingInfoParser marshallingInfoParser,
             StubEnvironment env,
-            IGeneratorDiagnostics diagnostics,
-            AttributeData signatureWideMarshallingAttributeData,
             Assembly generatorInfoAssembly)
         {
-            ImmutableArray<TypePositionInfo> typeInfos = GenerateTypeInformation(method, interopAttributeData, diagnostics, env, signatureWideMarshallingAttributeData);
+            ImmutableArray<TypePositionInfo> typeInfos = GenerateTypeInformation(method, marshallingInfoParser, env);
 
             ImmutableArray<AttributeListSyntax>.Builder additionalAttrs = ImmutableArray.CreateBuilder<AttributeListSyntax>();
 
@@ -102,49 +100,9 @@ public static SignatureContext Create(
 
         private static ImmutableArray<TypePositionInfo> GenerateTypeInformation(
             IMethodSymbol method,
-            InteropAttributeData interopAttributeData,
-            IGeneratorDiagnostics diagnostics,
-            StubEnvironment env,
-            AttributeData signatureWideMarshallingAttributeData)
+            MarshallingInfoParser marshallingInfoParser,
+            StubEnvironment env)
         {
-            // Compute the current default string encoding value.
-            CharEncoding defaultEncoding = CharEncoding.Undefined;
-            if (interopAttributeData.IsUserDefined.HasFlag(InteropAttributeMember.StringMarshalling))
-            {
-                defaultEncoding = interopAttributeData.StringMarshalling switch
-                {
-                    StringMarshalling.Utf16 => CharEncoding.Utf16,
-                    StringMarshalling.Utf8 => CharEncoding.Utf8,
-                    StringMarshalling.Custom => CharEncoding.Custom,
-                    _ => CharEncoding.Undefined, // [Compat] Do not assume a specific value
-                };
-            }
-            else if (interopAttributeData.IsUserDefined.HasFlag(InteropAttributeMember.StringMarshallingCustomType))
-            {
-                defaultEncoding = CharEncoding.Custom;
-            }
-
-            var defaultInfo = new DefaultMarshallingInfo(defaultEncoding, interopAttributeData.StringMarshallingCustomType);
-
-            var useSiteAttributeParsers = ImmutableArray.Create<IUseSiteAttributeParser>(
-                    new MarshalAsAttributeParser(env.Compilation, diagnostics, defaultInfo),
-                    new MarshalUsingAttributeParser(env.Compilation, diagnostics));
-
-            var marshallingInfoParser = new MarshallingInfoParser(
-                diagnostics,
-                new MethodSignatureElementInfoProvider(env.Compilation, diagnostics, method, useSiteAttributeParsers),
-                useSiteAttributeParsers,
-                ImmutableArray.Create<IMarshallingInfoAttributeParser>(
-                    new MarshalAsAttributeParser(env.Compilation, diagnostics, defaultInfo),
-                    new MarshalUsingAttributeParser(env.Compilation, diagnostics),
-                    new NativeMarshallingAttributeParser(env.Compilation, diagnostics)),
-                ImmutableArray.Create<ITypeBasedMarshallingInfoProvider>(
-                    new SafeHandleMarshallingInfoProvider(env.Compilation, method.ContainingType),
-                    new ArrayMarshallingInfoProvider(env.Compilation),
-                    new CharMarshallingInfoProvider(defaultInfo),
-                    new StringMarshallingInfoProvider(env.Compilation, diagnostics, signatureWideMarshallingAttributeData, defaultInfo),
-                    new BooleanMarshallingInfoProvider(),
-                    new BlittableTypeMarshallingInfoProvider(env.Compilation)));
 
             // Determine parameter and return types
             ImmutableArray<TypePositionInfo>.Builder typeInfos = ImmutableArray.CreateBuilder<TypePositionInfo>();