Add pseudo custom attribute lowering to managed ilasm

src/tools/ilasm/src/ILAssembler/Actions/GrammarActions.BuildImage.cs

@@ -54,6 +54,7 @@ internal sealed partial class GrammarActions
                 ValidateDataLabelFixups();
             ImmutableArray<ValidatedExport> validatedExports =
                 ValidateExports(validatedVTableAssociations, machine);
+            PseudoCustomAttributes.Lower(_entityRegistry, _diagnostics);
 
             // Return early if there are structural errors that prevent building valid metadata.
             // However, allow errors in method bodies (ILA0016-0019) to pass through so we can

src/tools/ilasm/src/ILAssembler/Actions/GrammarActions.CustomAttributes.Actions.cs

@@ -164,12 +164,14 @@ private void WriteCustomBlobNamedArguments(
     }
 
     private EntityRegistry.CustomAttributeEntity MaterializeCustomAttribute(
-        CustomAttributeDescriptorValue descriptor)
+        CustomAttributeDescriptorValue descriptor,
+        IToken location)
     {
         EntityRegistry.EntityBase constructor = MaterializeMethodReference(descriptor.Constructor);
         BlobBuilder value = MaterializeCustomAttributeBlob(descriptor.Value);
         EntityRegistry.CustomAttributeEntity attribute =
             _entityRegistry.CreateCustomAttribute(constructor, value);
+        attribute.Location = Location.From(location, _documents);
         if (descriptor.Owner is { } owner)
         {
             attribute.Owner = MaterializeOwnerType(owner);
@@ -196,6 +198,7 @@ private EntityRegistry.CustomAttributeEntity MaterializeCustomAttribute(
             EntityRegistry.CustomAttributeEntity typedefAttribute =
                 _entityRegistry.CreateCustomAttribute(resolved.Constructor, resolved.Value);
             typedefAttribute.Owner = resolved.Owner;
+            typedefAttribute.Location = Location.From(location, _documents);
             return typedefAttribute;
         }
 
@@ -204,7 +207,7 @@ private EntityRegistry.CustomAttributeEntity MaterializeCustomAttribute(
             return null;
         }
 
-        EntityRegistry.CustomAttributeEntity attribute = MaterializeCustomAttribute(descriptor);
+        EntityRegistry.CustomAttributeEntity attribute = MaterializeCustomAttribute(descriptor, location);
         return descriptor.Owner is null ? attribute : null;
     }
 
@@ -214,7 +217,7 @@ private EntityRegistry.CustomAttributeEntity MaterializeCustomAttribute(
 
     internal EntityRegistry.CustomAttributeEntity MaterializeCustomAttributeDescriptor(
         CILParser.CustomDescrContext context)
-        => MaterializeCustomAttribute(context.Value);
+        => MaterializeCustomAttribute(context.Value, context.Start);
 
     internal EntityRegistry.CustomAttributeEntity? MaterializeMethodBodyCustomAttributeDeclaration(
         CILParser.CustomDescrInMethodBodyContext context)

src/tools/ilasm/src/ILAssembler/Actions/GrammarActions.Manifest.Typedefs.cs

@@ -55,7 +55,7 @@ private void MaterializeTypedef(TypedefDeclarationValue declaration)
                 break;
             case CustomAttributeTypedefDeclarationValue customAttribute:
                 EntityRegistry.CustomAttributeEntity attribute =
-                    MaterializeCustomAttribute(customAttribute.Attribute);
+                    MaterializeCustomAttribute(customAttribute.Attribute, customAttribute.Location);
                 EntityRegistry.EntityBase? owner = attribute.Owner;
                 attribute.Owner = null;
                 _typedefs[customAttribute.Alias] =

src/tools/ilasm/src/ILAssembler/Actions/GrammarActions.Members.Class.cs

@@ -79,6 +79,7 @@ internal void SetClassSize(IToken token)
             _currentTypeDefinition.PeekOrDefault() is { } currentType)
         {
             currentType.ClassSize = ParseInt32(token);
+            currentType.HasExplicitClassSize = true;
         }
     }
 
@@ -88,6 +89,7 @@ internal void SetClassPackingSize(IToken token)
             _currentTypeDefinition.PeekOrDefault() is { } currentType)
         {
             currentType.PackingSize = ParseInt32(token);
+            currentType.HasExplicitPackingSize = true;
         }
     }
 

src/tools/ilasm/src/ILAssembler/Diagnostic.cs

@@ -64,6 +64,12 @@ public static class DiagnosticIds
     public const string DuplicateExportOrdinal = "ILA0044";
     public const string UnsupportedVTableDeclaration = "ILA0045";
     public const string InvalidOctalLiteral = "ILA0046";
+    public const string PseudoCustomAttributeInvalidTarget = "ILA0047";
+    public const string PseudoCustomAttributeInvalidValue = "ILA0048";
+    public const string PseudoCustomAttributeInvalidBlob = "ILA0049";
+    public const string PseudoCustomAttributeInvalidGuid = "ILA0050";
+    public const string PseudoCustomAttributeUnknownArgument = "ILA0051";
+    public const string PseudoCustomAttributeRepeatedArgument = "ILA0052";
 }
 
 internal static class DiagnosticMessageTemplates
@@ -114,4 +120,10 @@ internal static class DiagnosticMessageTemplates
     public const string DuplicateExportOrdinal = "Export '{0}' uses ordinal {1}, which is already assigned to a different VTable target";
     public const string UnsupportedVTableDeclaration = "Raw .vtable declarations are not supported; use .vtfixup instead";
     public const string InvalidOctalLiteral = "The value '{0}' is not a valid octal literal";
+    public const string PseudoCustomAttributeInvalidTarget = "Custom attribute '{0}' cannot be applied to this target";
+    public const string PseudoCustomAttributeInvalidValue = "Custom attribute '{0}' has an invalid argument value";
+    public const string PseudoCustomAttributeInvalidBlob = "Custom attribute '{0}' has a malformed value blob";
+    public const string PseudoCustomAttributeInvalidGuid = "Custom attribute '{0}' does not specify a valid GUID";
+    public const string PseudoCustomAttributeUnknownArgument = "Custom attribute '{0}' does not have a field or property named '{1}'";
+    public const string PseudoCustomAttributeRepeatedArgument = "Custom attribute '{0}' specifies '{1}' more than once";
 }

src/tools/ilasm/src/ILAssembler/EntityRegistry.cs

@@ -870,6 +870,34 @@ public TypeDefinitionEntity GetOrCreateTypeDefinition(TypeDefinitionEntity? cont
             return null;
         }
 
+        /// <summary>
+        /// Finds the local type definition that a type reference refers to, without assigning or
+        /// reading any handles. Passes that run before <see cref="WriteContentTo"/> resolves
+        /// references need this, because handles are not assigned until emission.
+        /// </summary>
+        public TypeDefinitionEntity? FindLocalTypeDefinition(TypeReferenceEntity typeReference)
+        {
+            switch (typeReference.ResolutionScope)
+            {
+                case TypeReferenceEntity enclosing:
+                    return FindLocalTypeDefinition(enclosing) is { } enclosingTypeDef
+                        ? FindTypeDefinition(enclosingTypeDef, typeReference.Namespace, typeReference.Name)
+                        : null;
+
+                case AssemblyReferenceEntity assemblyReference:
+                    return Assembly is not null
+                        && string.Equals(assemblyReference.Name, Assembly.Name, StringComparison.OrdinalIgnoreCase)
+                        ? FindTypeDefinition(null, typeReference.Namespace, typeReference.Name)
+                        : null;
+
+                case ModuleEntity:
+                    return FindTypeDefinition(null, typeReference.Namespace, typeReference.Name);
+
+                default:
+                    return null;
+            }
+        }
+
         public AssemblyReferenceEntity GetOrCreateAssemblyReference(string name, Action<AssemblyReferenceEntity> onCreateAssemblyReference)
         {
             return GetOrCreateEntity(name, TableIndex.AssemblyRef, _seenAssemblyRefs, _ => new(name), onCreateAssemblyReference);
@@ -1678,6 +1706,31 @@ public CustomAttributeEntity CreateCustomAttribute(EntityBase constructor, BlobB
             return entity;
         }
 
+        /// <summary>
+        /// Removes custom attributes that were lowered to metadata bits or auxiliary table rows
+        /// by the pseudo custom attribute pass, and renumbers the handles of the survivors.
+        /// </summary>
+        /// <remarks>
+        /// Nothing in metadata refers to a CustomAttribute handle (a CustomAttribute can never be
+        /// the parent of another custom attribute), so removing rows is safe. Handles are still
+        /// reassigned so that they stay consistent with the emitted row numbers.
+        /// </remarks>
+        public void RemoveCustomAttributes(IReadOnlyCollection<CustomAttributeEntity> toRemove)
+        {
+            if (toRemove.Count == 0 || !_seenEntities.TryGetValue(TableIndex.CustomAttribute, out List<EntityBase>? entities))
+            {
+                return;
+            }
+
+            var removeSet = new HashSet<CustomAttributeEntity>(toRemove);
+            entities.RemoveAll(entity => entity is CustomAttributeEntity customAttribute && removeSet.Contains(customAttribute));
+
+            for (int i = 0; i < entities.Count; i++)
+            {
+                ((IHasHandle)entities[i]).SetHandle(MetadataTokens.EntityHandle(TableIndex.CustomAttribute, i + 1));
+            }
+        }
+
         public static MethodImplementationEntity CreateUnrecordedMethodImplementation(MethodDefinitionEntity methodBody, MemberReferenceEntity methodDeclaration)
         {
             return new MethodImplementationEntity(methodBody.ContainingType, methodBody, methodDeclaration);
@@ -1872,6 +1925,8 @@ static string CreateReflectionNotation(TypeDefinitionEntity typeDefinition)
             // ClassLayout table fields
             public int? PackingSize { get; set; }
             public int? ClassSize { get; set; }
+            public bool HasExplicitPackingSize { get; set; }
+            public bool HasExplicitClassSize { get; set; }
         }
 
         public sealed class TypeReferenceEntity(EntityBase resolutionScope, string @namespace, string name) : TypeEntity, IHasReflectionNotation
@@ -2023,7 +2078,7 @@ public sealed class MethodDefinitionEntity(TypeDefinitionEntity containingType,
 
         public sealed class ParameterEntity(ParameterAttributes attributes, string? name, BlobBuilder marshallingDescriptor, int sequence) : EntityBase
         {
-            public ParameterAttributes Attributes { get; } = attributes;
+            public ParameterAttributes Attributes { get; set; } = attributes;
             public string? Name { get; } = name;
             public BlobBuilder MarshallingDescriptor { get; set; } = marshallingDescriptor;
             public bool HasCustomAttributes { get; set; }
@@ -2088,6 +2143,12 @@ public sealed class CustomAttributeEntity(EntityBase constructor, BlobBuilder va
             public EntityBase? Owner { get; set; }
             public EntityBase Constructor { get; } = constructor;
             public BlobBuilder Value { get; } = value;
+
+            /// <summary>
+            /// Source location of the originating <c>.custom</c> directive, used to report
+            /// diagnostics from the pseudo custom attribute lowering pass, which runs after parsing.
+            /// </summary>
+            public Location? Location { get; set; }
         }
 
         public sealed class MethodImplementationEntity(TypeDefinitionEntity type, EntityBase methodBody, MemberReferenceEntity methodDeclaration) : EntityBase
@@ -2099,7 +2160,7 @@ public sealed class MethodImplementationEntity(TypeDefinitionEntity type, Entity
 
         public sealed class FieldDefinitionEntity(FieldAttributes attributes, TypeDefinitionEntity type, string name, BlobBuilder signature) : EntityBase
         {
-            public FieldAttributes Attributes { get; } = attributes;
+            public FieldAttributes Attributes { get; set; } = attributes;
             public TypeDefinitionEntity ContainingType { get; } = type;
             public string Name { get; } = name;
             public BlobBuilder Signature { get; } = signature;
@@ -2123,7 +2184,7 @@ public sealed class InterfaceImplementationEntity(TypeDefinitionEntity type, Typ
 
         public sealed class EventEntity(EventAttributes attributes, TypeEntity? type, string name) : EntityBase
         {
-            public EventAttributes Attributes { get; } = attributes;
+            public EventAttributes Attributes { get; set; } = attributes;
             public TypeEntity? Type { get; } = type;
             public string Name { get; } = name;
 

src/tools/ilasm/src/ILAssembler/MetadataExtensions.cs

@@ -3,17 +3,40 @@
 
 using System.Reflection;
 using System.Reflection.Metadata;
+using System.Runtime.InteropServices;
 
 namespace ILAssembler;
 
 internal static class MetadataExtensions
 {
+    extension(MethodImplAttributes)
+    {
+        public static MethodImplAttributes UserMask =>
+            MethodImplAttributes.ManagedMask |
+            MethodImplAttributes.ForwardRef |
+            MethodImplAttributes.PreserveSig |
+            MethodImplAttributes.InternalCall |
+            MethodImplAttributes.Synchronized |
+            MethodImplAttributes.NoInlining |
+            MethodImplAttributes.AggressiveInlining |
+            MethodImplAttributes.NoOptimization |
+            MethodImplAttributes.AggressiveOptimization |
+            MethodImplAttributes.Async;
+    }
+
     extension(TypeAttributes)
     {
         public static TypeAttributes ExtendedLayout => (TypeAttributes)0x18;
         public static TypeAttributes Forwarder => (TypeAttributes)0x00200000;
     }
 
+    extension(UnmanagedType)
+    {
+        public static int ArraySizeParamIndexSpecified => 0x0001;
+        public static UnmanagedType ByValStr => (UnmanagedType)0x22;
+        public static UnmanagedType Max => (UnmanagedType)0x50;
+    }
+
     extension(DeclarativeSecurityAction)
     {
         public static DeclarativeSecurityAction Request => (DeclarativeSecurityAction)1;
@@ -35,3 +58,19 @@ internal static class MetadataExtensions
         public static ILOpCode Unused => (ILOpCode)0xFE22;
     }
 }
+
+internal static class ClassInterfaceTypeExtensions
+{
+    extension(ClassInterfaceType)
+    {
+        public static ClassInterfaceType Last => (ClassInterfaceType)3;
+    }
+}
+
+internal static class ComInterfaceTypeExtensions
+{
+    extension(ComInterfaceType)
+    {
+        public static ComInterfaceType Last => (ComInterfaceType)4;
+    }
+}