Suppress linker warnings properly

src/libraries/System.Reflection.Emit/src/System/Reflection/Emit/MetadataHelper.cs

@@ -6,7 +6,7 @@
 
 namespace System.Reflection.Emit
 {
-    // This static helper class adds common entities to a Metadata Builder.
+    // This static helper class adds common entities to a MetadataBuilder.
     internal static class MetadataHelper
     {
         internal static AssemblyReferenceHandle AddAssemblyReference(Assembly assembly, MetadataBuilder metadata)
@@ -34,7 +34,7 @@ internal static TypeDefinitionHandle AddTypeDefinition(MetadataBuilder metadata,
             // Add type metadata
             return metadata.AddTypeDefinition(
                 attributes: typeBuilder.Attributes,
-                (typeBuilder.Namespace == null) ? default : metadata.GetOrAddString(typeBuilder.Namespace),
+                @namespace: (typeBuilder.Namespace == null) ? default : metadata.GetOrAddString(typeBuilder.Namespace),
                 name: metadata.GetOrAddString(typeBuilder.Name),
                 baseType: baseType,
                 fieldList: MetadataTokens.FieldDefinitionHandle(fieldToken),
@@ -49,28 +49,30 @@ internal static TypeReferenceHandle AddTypeReference(MetadataBuilder metadata, T
         internal static TypeReferenceHandle AddTypeReference(MetadataBuilder metadata, AssemblyReferenceHandle parent, string name, string? nameSpace)
         {
             return metadata.AddTypeReference(
-                parent,
-                (nameSpace == null) ? default : metadata.GetOrAddString(nameSpace),
-                metadata.GetOrAddString(name)
+                resolutionScope: parent,
+                @namespace: (nameSpace == null) ? default : metadata.GetOrAddString(nameSpace),
+                name: metadata.GetOrAddString(name)
                 );
         }
 
         internal static MethodDefinitionHandle AddMethodDefinition(MetadataBuilder metadata, MethodBuilderImpl methodBuilder, BlobBuilder methodSignatureBlob)
         {
             return metadata.AddMethodDefinition(
-                methodBuilder.Attributes,
-                MethodImplAttributes.IL,
-                metadata.GetOrAddString(methodBuilder.Name),
-                metadata.GetOrAddBlob(methodSignatureBlob),
-                -1, // No body supported yet
+                attributes: methodBuilder.Attributes,
+                implAttributes: MethodImplAttributes.IL,
+                name: metadata.GetOrAddString(methodBuilder.Name),
+                signature: metadata.GetOrAddBlob(methodSignatureBlob),
+                bodyOffset: -1, // No body supported yet
                 parameterList: MetadataTokens.ParameterHandle(1)
                 );
         }
 
-        internal static FieldDefinitionHandle AddFieldDefinition(MetadataBuilder metadata, FieldInfo field)
+        internal static FieldDefinitionHandle AddFieldDefinition(MetadataBuilder metadata, FieldInfo field, BlobBuilder fieldSignatureBlob)
         {
-            return metadata.AddFieldDefinition(field.Attributes, metadata.GetOrAddString(field.Name),
-                metadata.GetOrAddBlob(MetadataSignatureHelper.FieldSignatureEncoder(field.FieldType)));
+            return metadata.AddFieldDefinition(
+                attributes: field.Attributes,
+                name: metadata.GetOrAddString(field.Name),
+                signature: metadata.GetOrAddBlob(fieldSignatureBlob));
         }
     }
 }

src/libraries/System.Reflection.Emit/src/System/Reflection/Emit/MethodBuilderImpl.cs

@@ -4,7 +4,6 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
 using System.Reflection.Metadata;
-using System.Reflection.Metadata.Ecma335;
 
 namespace System.Reflection.Emit
 {
@@ -22,7 +21,7 @@ internal MethodBuilderImpl(string name, MethodAttributes attributes, CallingConv
             Type[]? parameterTypes, ModuleBuilderImpl module, TypeBuilderImpl declaringType)
         {
             _module = module;
-            _returnType = returnType ?? _module.GetTypeFromCoreAssembly("System.Void"); ;
+            _returnType = returnType ?? _module.GetTypeFromCoreAssembly(CoreTypeId.Void)!;
             _name = name;
             _attributes = attributes;
             _callingConventions = callingConventions;

src/libraries/System.Reflection.Emit/src/System/Reflection/Emit/ModuleBuilderImpl.cs

@@ -13,33 +13,29 @@ internal sealed class ModuleBuilderImpl : ModuleBuilder
     {
         private readonly Assembly _coreAssembly;
         private readonly string _name;
-        private readonly Dictionary<string, Type> _coreTypes = new();
+        private Type?[]? _coreTypes;
         private readonly Dictionary<Assembly, AssemblyReferenceHandle> _assemblyRefStore = new();
         private readonly Dictionary<Type, TypeReferenceHandle> _typeRefStore = new();
         private readonly List<TypeBuilderImpl> _typeDefStore = new();
         private int _nextMethodDefRowId = 1;
         private int _nextFieldDefRowId = 1;
-
+        private static readonly Type[] s_coreTypes = { typeof(void), typeof(object), typeof(bool), typeof(char), typeof(sbyte), typeof(byte), typeof(short),
+                                                        typeof(ushort), typeof(int), typeof(uint), typeof(long), typeof(ulong), typeof(float), typeof(double),
+                                                        typeof(decimal), typeof(DateTime), typeof(string), typeof(nint), typeof(nuint) };
         internal ModuleBuilderImpl(string name, Assembly coreAssembly)
         {
             _coreAssembly = coreAssembly;
             _name = name;
         }
 
-        internal Type GetTypeFromCoreAssembly(string name)
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode", Justification = "Types are preserved via s_coreTypes")]
+        internal Type? GetTypeFromCoreAssembly(CoreTypeId typeId)
         {
-            Type? type;
-
-            // TODO: Use Enum as the key for perf
-            if (!_coreTypes.TryGetValue(name, out type))
-            {
-#pragma warning disable IL2026 // Members annotated with 'RequiresUnreferencedCodeAttribute' require dynamic access otherwise can break functionality when trimming application code
-                type = _coreAssembly.GetType(name, throwOnError: true)!;
-#pragma warning restore IL2026
-                _coreTypes.Add(name, type);
-            }
+            int index = (int)typeId;
+            // Use s_coreTypes directly for runtime reflection
+            _coreTypes ??= (_coreAssembly == typeof(object).Assembly) ? s_coreTypes : new Type[s_coreTypes.Length];
 
-            return type;
+            return _coreTypes[index] ?? (_coreTypes[index] = _coreAssembly.GetType(s_coreTypes[index].FullName!, throwOnError: true));
         }
 
         internal void AppendMetadata(MetadataBuilder metadata)
@@ -82,7 +78,7 @@ internal void AppendMetadata(MetadataBuilder metadata)
 
                 foreach (FieldBuilderImpl field in typeBuilder._fieldDefStore)
                 {
-                    MetadataHelper.AddFieldDefinition(metadata, field);
+                    MetadataHelper.AddFieldDefinition(metadata, field, MetadataSignatureHelper.FieldSignatureEncoder(field.FieldType, this));
                     _nextFieldDefRowId++;
                 }
             }

src/libraries/System.Reflection.Emit/src/System/Reflection/Emit/SignatureHelper.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Diagnostics.CodeAnalysis;
 using System.Reflection.Metadata;
 using System.Reflection.Metadata.Ecma335;
 
@@ -9,16 +10,16 @@ namespace System.Reflection.Emit
     // TODO: Only support simple signatures. More complex signatures will be added.
     internal static class MetadataSignatureHelper
     {
-        internal static BlobBuilder FieldSignatureEncoder(Type fieldType)
+        internal static BlobBuilder FieldSignatureEncoder(Type fieldType, ModuleBuilderImpl module)
         {
             BlobBuilder fieldSignature = new();
 
-            WriteSignatureTypeForReflectionType(new BlobEncoder(fieldSignature).FieldSignature(), fieldType);
+            WriteSignatureTypeForReflectionType(new BlobEncoder(fieldSignature).FieldSignature(), fieldType, module);
 
             return fieldSignature;
         }
 
-        internal static BlobBuilder MethodSignatureEncoder(ModuleBuilderImpl _module, Type[]? parameters, Type? returnType, bool isInstance)
+        internal static BlobBuilder MethodSignatureEncoder(ModuleBuilderImpl module, Type[]? parameters, Type? returnType, bool isInstance)
         {
             // Encoding return type and parameters.
             BlobBuilder methodSignature = new();
@@ -30,9 +31,9 @@ internal static BlobBuilder MethodSignatureEncoder(ModuleBuilderImpl _module, Ty
                 MethodSignature(isInstanceMethod: isInstance).
                 Parameters((parameters == null) ? 0 : parameters.Length, out retEncoder, out parEncoder);
 
-            if (returnType != null && returnType != _module.GetTypeFromCoreAssembly("System.Void"))
+            if (returnType != null && returnType != module.GetTypeFromCoreAssembly(CoreTypeId.Void))
             {
-                WriteSignatureTypeForReflectionType(retEncoder.Type(), returnType);
+                WriteSignatureTypeForReflectionType(retEncoder.Type(), returnType, module);
             }
             else // If null mark ReturnTypeEncoder as void
             {
@@ -43,46 +44,95 @@ internal static BlobBuilder MethodSignatureEncoder(ModuleBuilderImpl _module, Ty
             {
                 foreach (Type parameter in parameters)
                 {
-                    WriteSignatureTypeForReflectionType(parEncoder.AddParameter().Type(), parameter);
+                    WriteSignatureTypeForReflectionType(parEncoder.AddParameter().Type(), parameter, module);
                 }
             }
 
             return methodSignature;
         }
 
-        private static void WriteSignatureTypeForReflectionType(SignatureTypeEncoder signature, Type type)
+        private static void WriteSignatureTypeForReflectionType(SignatureTypeEncoder signature, Type type, ModuleBuilderImpl module)
         {
-            // We need to translate from Reflection.Type to SignatureTypeEncoder. Most common types for proof of concept. More types will be added.
-            // TODO: This switch should be done by comparing Type objects, without fetching FullName.
-            switch (type.FullName)
+            // We need to translate from Reflection.Type to SignatureTypeEncoder.
+            if (Enum.TryParse(type.Name, out CoreTypeId typeId) && type.Equals(module.GetTypeFromCoreAssembly(typeId)))
             {
-                case "System.Boolean":
-                    signature.Boolean();
-                    break;
-                case "System.Byte":
-                    signature.Byte();
-                    break;
-                case "System.Char":
-                    signature.Char();
-                    break;
-                case "System.Double":
-                    signature.Double();
-                    break;
-                case "System.Int32":
-                    signature.Int32();
-                    break;
-                case "System.Int64":
-                    signature.Int64();
-                    break;
-                case "System.Object":
-                    signature.Object();
-                    break;
-                case "System.String":
-                    signature.String();
-                    break;
-
-                default: throw new NotSupportedException(SR.Format(SR.NotSupported_Signature, type.FullName));
+                switch (typeId)
+                {
+                    case CoreTypeId.Boolean:
+                        signature.Boolean();
+                        return;
+                    case CoreTypeId.Byte:
+                        signature.Byte();
+                        return;
+                    case CoreTypeId.SByte:
+                        signature.SByte();
+                        return;
+                    case CoreTypeId.Char:
+                        signature.Char();
+                        return;
+                    case CoreTypeId.Int16:
+                        signature.Int16();
+                        break;
+                    case CoreTypeId.UInt16:
+                        signature.UInt16();
+                        return;
+                    case CoreTypeId.Int32:
+                        signature.Int32();
+                        return;
+                    case CoreTypeId.UInt32:
+                        signature.UInt32();
+                        return;
+                    case CoreTypeId.Int64:
+                        signature.Int64();
+                        return;
+                    case CoreTypeId.UInt64:
+                        signature.UInt64();
+                        return;
+                    case CoreTypeId.Single:
+                        signature.Single();
+                        return;
+                    case CoreTypeId.Double:
+                        signature.Double();
+                        return;
+                    case CoreTypeId.IntPtr:
+                        signature.IntPtr();
+                        return;
+                    case CoreTypeId.UIntPtr:
+                        signature.UIntPtr();
+                        return;
+                    case CoreTypeId.Object:
+                        signature.Object();
+                        return;
+                    case CoreTypeId.String:
+                        signature.String();
+                        return;
+                }
             }
+
+            throw new NotSupportedException(SR.Format(SR.NotSupported_Signature, type.FullName));
         }
     }
+
+    internal enum CoreTypeId
+    {
+        Void = 0,
+        Object = 1,
+        Boolean = 2,
+        Char = 3,
+        SByte = 4,
+        Byte = 5,
+        Int16 = 6,
+        UInt16 = 7,
+        Int32 = 8,
+        UInt32 = 9,
+        Int64 = 10,
+        UInt64 = 11,
+        Single = 12,
+        Double = 13,
+        Decimal = 14,
+        DateTime = 15,
+        String = 16,
+        IntPtr = 17,
+        UIntPtr = 18,
+    }
 }

src/libraries/System.Reflection.Emit/src/System/Reflection/Emit/TypeBuilderImpl.cs

@@ -71,7 +71,9 @@ protected override MethodBuilder DefineMethodCore(string name, MethodAttributes
         protected override void SetCustomAttributeCore(ConstructorInfo con, byte[] binaryAttribute) => throw new NotImplementedException();
         protected override void SetCustomAttributeCore(CustomAttributeBuilder customBuilder) => throw new NotImplementedException();
 
-        protected override void SetParentCore([DynamicallyAccessedMembers((DynamicallyAccessedMemberTypes)(-1))] Type? parent)
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2074:DynamicallyAccessedMembers",
+            Justification = "No need to propogate the attribute to the called method")]
+        protected override void SetParentCore([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] Type? parent)
         {
             if (parent != null)
             {
@@ -86,9 +88,7 @@ protected override void SetParentCore([DynamicallyAccessedMembers((DynamicallyAc
             {
                 if ((_attributes & TypeAttributes.Interface) != TypeAttributes.Interface)
                 {
-#pragma warning disable IL2074 // Value stored in field does not satisfy 'DynamicallyAccessedMembersAttribute' requirements. The return value of the source method does not have matching annotations.
-                    _typeParent = _module.GetTypeFromCoreAssembly("System.Object");
-#pragma warning restore IL2074
+                    _typeParent = _module.GetTypeFromCoreAssembly(CoreTypeId.Object);
                 }
                 else
                 {

src/libraries/System.Reflection.Emit/tests/PersistableAssemblyBuilder/AssemblySaveTestsWithVariousTypes.cs

@@ -63,7 +63,7 @@ public static IEnumerable<object[]> VariousInterfacesStructsTestData()
             yield return new object[] { new Type[] { typeof(EmptyStruct) } };
             yield return new object[] { new Type[] { typeof(StructWithField) } };
             yield return new object[] { new Type[] { typeof(StructWithField), typeof(EmptyStruct) } };
-            yield return new object[] { new Type[] { typeof(IMultipleMethod), typeof(EmptyStruct) , typeof(INoMethod2), typeof(StructWithField) } };
+            yield return new object[] { new Type[] { typeof(IMultipleMethod), typeof(EmptyStruct), typeof(INoMethod2), typeof(StructWithField) } };
         }
 
         [Theory]