Avoid caching compilation data and use value equality for SyntaxNodes (#79051)

Fixes #78242

Creates separate types for InteropAttributeData: one that holds compilation data (InteropAttributeCompilationData), and one that holds only the data necessary for the model to create the generated code (InteropAttributeModelData).

This uncovered some issues with record equality in records that use SyntaxNode. For those, we need to override Equals or wrap the SyntaxNode in a type that overrides Equals to use IsEquivalentTo on the SyntaxNode.

There are probably more places where we use SyntaxNode that aren't caught in the current tests.

To make sure every record has the right equality, I wasn't sure if it would be better to override Equals for each of the records, or create a wrapper record struct for each SyntaxNode that implements the equality we want (and implicit casts to and from the SyntaxNode). Then we wouldn't have to explicitly override the equality in each record that has a SyntaxNode. I also overrode both Equals and GetHashCode, but I'm not confident in my GetHashCode implementation. It could also be done with IEquatable.Equals without needing GetHashCode, but that would require implementing the TypeSyntax equality for every type that inherits from ManagedTypeInfo.

Author: jtschuster

src/libraries/System.Runtime.InteropServices/gen/ComInterfaceGenerator/VirtualMethodIndexData.cs

@@ -8,7 +8,7 @@ namespace Microsoft.Interop
     /// <summary>
     /// VirtualMethodIndexAttribute data
     /// </summary>
-    internal sealed record VirtualMethodIndexData(int Index) : InteropAttributeData
+    internal sealed record VirtualMethodIndexData(int Index) : InteropAttributeCompilationData
     {
         public bool ImplicitThisParameter { get; init; }
 

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

@@ -8,7 +8,7 @@ namespace Microsoft.Interop
 {
     internal static class DefaultMarshallingInfoParser
     {
-        public static MarshallingInfoParser Create(StubEnvironment env, IGeneratorDiagnostics diagnostics, IMethodSymbol method, InteropAttributeData interopAttributeData, AttributeData unparsedAttributeData)
+        public static MarshallingInfoParser Create(StubEnvironment env, IGeneratorDiagnostics diagnostics, IMethodSymbol method, InteropAttributeCompilationData interopAttributeData, AttributeData unparsedAttributeData)
         {
 
             // Compute the current default string encoding value.

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

@@ -146,9 +146,9 @@ private static bool HasUnsupportedMarshalAsInfo(TypePositionInfo info)
                 || unmanagedType == UnmanagedType.SafeArray;
         }
 
-        private static InteropAttributeData CreateInteropAttributeDataFromDllImport(DllImportData dllImportData)
+        private static InteropAttributeCompilationData CreateInteropAttributeDataFromDllImport(DllImportData dllImportData)
         {
-            InteropAttributeData interopData = new();
+            InteropAttributeCompilationData interopData = new();
             if (dllImportData.SetLastError)
             {
                 interopData = interopData with { IsUserDefined = interopData.IsUserDefined | InteropAttributeMember.SetLastError, SetLastError = true };

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

@@ -1,16 +1,31 @@
 // 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.Runtime.InteropServices;
-using Microsoft.CodeAnalysis;
-
 namespace Microsoft.Interop
 {
     /// <summary>
-    /// LibraryImportAttribute data
+    /// Contains the data related to a LibraryImportAttribute, without references to Roslyn symbols.
+    /// See <seealso cref="LibraryImportCompilationData"/> for a type with a reference to the StringMarshallingCustomType
     /// </summary>
     internal sealed record LibraryImportData(string ModuleName) : InteropAttributeData
+    {
+        public string EntryPoint { get; init; }
+
+        public static LibraryImportData From(LibraryImportCompilationData libraryImport)
+            => new LibraryImportData(libraryImport.ModuleName) with
+            {
+                EntryPoint = libraryImport.EntryPoint,
+                IsUserDefined = libraryImport.IsUserDefined,
+                SetLastError = libraryImport.SetLastError,
+                StringMarshalling = libraryImport.StringMarshalling
+            };
+    }
+
+    /// <summary>
+    /// Contains the data related to a LibraryImportAttribute, with references to Roslyn symbols.
+    /// Use <seealso cref="LibraryImportData"/> instead when using for incremental compilation state to avoid keeping a compilation alive
+    /// </summary>
+    internal sealed record LibraryImportCompilationData(string ModuleName) : InteropAttributeCompilationData
     {
         public string EntryPoint { get; init; }
     }

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

@@ -7,7 +7,6 @@
 using System.Diagnostics;
 using System.Linq;
 using System.Runtime.InteropServices;
-using System.Text;
 using System.Threading;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
@@ -181,7 +180,7 @@ private static MemberDeclarationSyntax PrintGeneratedSource(
                 .WithBody(stubCode);
         }
 
-        private static LibraryImportData? ProcessLibraryImportAttribute(AttributeData attrData)
+        private static LibraryImportCompilationData? ProcessLibraryImportAttribute(AttributeData attrData)
         {
             // Found the LibraryImport, but it has an error so report the error.
             // This is most likely an issue with targeting an incorrect TFM.
@@ -198,7 +197,7 @@ private static MemberDeclarationSyntax PrintGeneratedSource(
             ImmutableDictionary<string, TypedConstant> namedArguments = ImmutableDictionary.CreateRange(attrData.NamedArguments);
 
             string? entryPoint = null;
-            if (namedArguments.TryGetValue(nameof(LibraryImportData.EntryPoint), out TypedConstant entryPointValue))
+            if (namedArguments.TryGetValue(nameof(LibraryImportCompilationData.EntryPoint), out TypedConstant entryPointValue))
             {
                 if (entryPointValue.Value is not string)
                 {
@@ -207,7 +206,7 @@ private static MemberDeclarationSyntax PrintGeneratedSource(
                 entryPoint = (string)entryPointValue.Value!;
             }
 
-            return new LibraryImportData(attrData.ConstructorArguments[0].Value!.ToString())
+            return new LibraryImportCompilationData(attrData.ConstructorArguments[0].Value!.ToString())
             {
                 EntryPoint = entryPoint,
             }.WithValuesFromNamedArguments(namedArguments);
@@ -261,9 +260,9 @@ private static IncrementalStubGenerationContext CalculateStubInformation(
             var generatorDiagnostics = new GeneratorDiagnostics();
 
             // Process the LibraryImport attribute
-            LibraryImportData libraryImportData =
+            LibraryImportCompilationData libraryImportData =
                 ProcessLibraryImportAttribute(generatedDllImportAttr!) ??
-                new LibraryImportData("INVALID_CSHARP_SYNTAX");
+                new LibraryImportCompilationData("INVALID_CSHARP_SYNTAX");
 
             if (libraryImportData.IsUserDefined.HasFlag(InteropAttributeMember.StringMarshalling))
             {
@@ -302,7 +301,7 @@ private static IncrementalStubGenerationContext CalculateStubInformation(
                 methodSyntaxTemplate,
                 new MethodSignatureDiagnosticLocations(originalSyntax),
                 new SequenceEqualImmutableArray<AttributeSyntax>(additionalAttributes.ToImmutableArray(), SyntaxEquivalentComparer.Instance),
-                libraryImportData,
+                LibraryImportData.From(libraryImportData),
                 LibraryImportGeneratorHelpers.CreateGeneratorFactory(environment, options),
                 new SequenceEqualImmutableArray<Diagnostic>(generatorDiagnostics.Diagnostics.ToImmutableArray())
                 );

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

@@ -3,7 +3,6 @@
 
 using System;
 using System.Collections.Immutable;
-using System.Runtime.InteropServices;
 using Microsoft.CodeAnalysis;
 
 namespace Microsoft.Interop
@@ -22,9 +21,24 @@ public enum InteropAttributeMember
     }
 
     /// <summary>
-    /// Common data for all source-generated-interop trigger attributes
+    /// Common data for all source-generated-interop trigger attributes.
+    /// This type and derived types should not have any reference that would keep a compilation alive.
     /// </summary>
     public record InteropAttributeData
+    {
+        /// <summary>
+        /// Value set by the user on the original declaration.
+        /// </summary>
+        public InteropAttributeMember IsUserDefined { get; init; }
+        public bool SetLastError { get; init; }
+        public StringMarshalling StringMarshalling { get; init; }
+    }
+
+    /// <summary>
+    /// Common data for all source-generated-interop trigger attributes that also includes a reference to the Roslyn symbol for StringMarshallingCustomType.
+    /// See <seealso cref="InteropAttributeData"/> for a type that doesn't keep a compilation alive.
+    /// </summary>
+    public record InteropAttributeCompilationData
     {
         /// <summary>
         /// Value set by the user on the original declaration.
@@ -37,14 +51,14 @@ public record InteropAttributeData
 
     public static class InteropAttributeDataExtensions
     {
-        public static T WithValuesFromNamedArguments<T>(this T t, ImmutableDictionary<string, TypedConstant> namedArguments) where T : InteropAttributeData
+        public static T WithValuesFromNamedArguments<T>(this T t, ImmutableDictionary<string, TypedConstant> namedArguments) where T : InteropAttributeCompilationData
         {
             InteropAttributeMember userDefinedValues = InteropAttributeMember.None;
             bool setLastError = false;
             StringMarshalling stringMarshalling = StringMarshalling.Custom;
             INamedTypeSymbol? stringMarshallingCustomType = null;
 
-            if (namedArguments.TryGetValue(nameof(InteropAttributeData.SetLastError), out TypedConstant setLastErrorValue))
+            if (namedArguments.TryGetValue(nameof(InteropAttributeCompilationData.SetLastError), out TypedConstant setLastErrorValue))
             {
                 userDefinedValues |= InteropAttributeMember.SetLastError;
                 if (setLastErrorValue.Value is not bool)
@@ -53,7 +67,7 @@ public static T WithValuesFromNamedArguments<T>(this T t, ImmutableDictionary<st
                 }
                 setLastError = (bool)setLastErrorValue.Value!;
             }
-            if (namedArguments.TryGetValue(nameof(InteropAttributeData.StringMarshalling), out TypedConstant stringMarshallingValue))
+            if (namedArguments.TryGetValue(nameof(InteropAttributeCompilationData.StringMarshalling), out TypedConstant stringMarshallingValue))
             {
                 userDefinedValues |= InteropAttributeMember.StringMarshalling;
                 // TypedConstant's Value property only contains primitive values.
@@ -64,7 +78,7 @@ public static T WithValuesFromNamedArguments<T>(this T t, ImmutableDictionary<st
                 // A boxed primitive can be unboxed to an enum with the same underlying type.
                 stringMarshalling = (StringMarshalling)stringMarshallingValue.Value!;
             }
-            if (namedArguments.TryGetValue(nameof(InteropAttributeData.StringMarshallingCustomType), out TypedConstant stringMarshallingCustomTypeValue))
+            if (namedArguments.TryGetValue(nameof(InteropAttributeCompilationData.StringMarshallingCustomType), out TypedConstant stringMarshallingCustomTypeValue))
             {
                 userDefinedValues |= InteropAttributeMember.StringMarshallingCustomType;
                 if (stringMarshallingCustomTypeValue.Value is not INamedTypeSymbol)

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

@@ -4,9 +4,6 @@
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
-using System;
-using System.Collections.Generic;
-using System.Text;
 
 namespace Microsoft.Interop
 {
@@ -18,6 +15,19 @@ public abstract record ManagedTypeInfo(string FullTypeName, string DiagnosticFor
         private TypeSyntax? _syntax;
         public TypeSyntax Syntax => _syntax ??= SyntaxFactory.ParseTypeName(FullTypeName);
 
+        public virtual bool Equals(ManagedTypeInfo? other)
+        {
+            return other is not null
+                && Syntax.IsEquivalentTo(other.Syntax)
+                && FullTypeName == other.FullTypeName
+                && DiagnosticFormattedName == other.DiagnosticFormattedName;
+        }
+
+        public override int GetHashCode()
+        {
+            return FullTypeName.GetHashCode() ^ DiagnosticFormattedName.GetHashCode();
+        }
+
         protected ManagedTypeInfo(ManagedTypeInfo original)
         {
             FullTypeName = original.FullTypeName;

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

@@ -24,6 +24,24 @@ public readonly record struct CustomTypeMarshallerData(
     public readonly record struct CustomTypeMarshallers(
         ImmutableDictionary<MarshalMode, CustomTypeMarshallerData> Modes)
     {
+        public bool Equals(CustomTypeMarshallers other)
+        {
+            // Check for equal count, then check if any KeyValuePairs exist in one 'Modes'
+            // but not the other (i.e. set equality on the set of items in the dictionary)
+            return Modes.Count == other.Modes.Count
+                && !Modes.Except(other.Modes).Any();
+        }
+
+        public override int GetHashCode()
+        {
+            int hash = 0;
+            foreach (KeyValuePair<MarshalMode, CustomTypeMarshallerData> mode in Modes)
+            {
+                hash ^= mode.Key.GetHashCode() ^ mode.Value.GetHashCode();
+            }
+            return hash;
+        }
+
         public CustomTypeMarshallerData GetModeOrDefault(MarshalMode mode)
         {
             CustomTypeMarshallerData data;

src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/CodeSnippets.cs

@@ -964,7 +964,7 @@ public static partial void Method(
             + CustomCollectionMarshallingCodeSnippets<CodeSnippets>.Stateless.In
             + CustomCollectionMarshallingCodeSnippets<CodeSnippets>.CustomIntMarshaller;
 
-    public static string RecursiveCountElementNameOnReturnValue => $@"
+        public static string RecursiveCountElementNameOnReturnValue => $@"
 using System.Runtime.InteropServices;
 using System.Runtime.InteropServices.Marshalling;
 {DisableRuntimeMarshalling}

src/libraries/System.Runtime.InteropServices/tests/LibraryImportGenerator.UnitTests/IncrementalGenerationTests.cs

@@ -1,17 +1,15 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using Microsoft.CodeAnalysis;
-using Microsoft.CodeAnalysis.CSharp;
-using Microsoft.CodeAnalysis.Text;
-using Microsoft.Interop.UnitTests;
 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
-using System.Text;
 using System.Threading.Tasks;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.Interop.UnitTests;
 using Xunit;
 using static Microsoft.Interop.LibraryImportGenerator;
 
@@ -217,8 +215,7 @@ public static IEnumerable<object[]> CompilationObjectLivenessSources()
             // Basic stub
             yield return new[] { CodeSnippets.BasicParametersAndModifiers<int>() };
             // Stub with custom string marshaller
-            // TODO: Compilation is held alive by the CustomStringMarshallingType property in LibraryImportData
-            // yield return new[] { CodeSnippets.CustomStringMarshallingParametersAndModifiers<string>() }; 
+            yield return new[] { CodeSnippets.CustomStringMarshallingParametersAndModifiers<string>() };
         }
 
         // This test requires precise GC to ensure that we're accurately testing that we aren't