Annotate and adjust more of CoreLib for trimming

src/libraries/System.Private.CoreLib/src/System/Reflection/SignatureTypeExtensions.cs

@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Diagnostics.CodeAnalysis;
+
 namespace System.Reflection
 {
 #if CORERT
@@ -109,6 +111,8 @@ internal static bool MatchesExactly(this SignatureType pattern, Type actual)
             return signatureType.TryResolve(genericMethod.GetGenericArguments());
         }
 
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2006:UnrecognizedReflectionPattern",
+            Justification = "Used to find matching method overloads. Only used for assignability checks.")]
         private static Type? TryResolve(this SignatureType signatureType, Type[] genericMethodParameters)
         {
             if (signatureType.IsSZArray)

src/libraries/System.Private.CoreLib/src/System/Reflection/TypeInfo.cs

@@ -34,11 +34,16 @@ protected TypeInfo() { }
         [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicMethods | DynamicallyAccessedMemberTypes.NonPublicMethods)]
         public virtual IEnumerable<MethodInfo> GetDeclaredMethods(string name)
         {
-            foreach (MethodInfo method in GetMethods(TypeInfo.DeclaredOnlyLookup))
+            foreach (MethodInfo method in GetDeclaredOnlyMethods(this))
             {
                 if (method.Name == name)
                     yield return method;
             }
+
+            [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2006:UnrecognizedReflectionPattern",
+                Justification = "The yield return state machine doesn't propagate annotations")]
+            static MethodInfo[] GetDeclaredOnlyMethods(
+                Type type) => type.GetMethods(TypeInfo.DeclaredOnlyLookup);
         }
 
         public virtual IEnumerable<ConstructorInfo> DeclaredConstructors
@@ -76,10 +81,15 @@ public virtual IEnumerable<System.Reflection.TypeInfo> DeclaredNestedTypes
             [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicNestedTypes | DynamicallyAccessedMemberTypes.NonPublicNestedTypes)]
             get
             {
-                foreach (Type t in GetNestedTypes(TypeInfo.DeclaredOnlyLookup))
+                foreach (Type t in GetDeclaredOnlyNestedTypes(this))
                 {
                     yield return t.GetTypeInfo();
                 }
+
+                [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2006:UnrecognizedReflectionPattern",
+                    Justification = "The yield return state machine doesn't propagate annotations")]
+                static Type[] GetDeclaredOnlyNestedTypes(
+                    Type type) => type.GetNestedTypes(TypeInfo.DeclaredOnlyLookup);
             }
         }
 

src/libraries/System.Private.CoreLib/src/System/Resources/ResourceManager.cs

@@ -307,7 +307,9 @@ public virtual void ReleaseAllResources()
             }
         }
 
-        public static ResourceManager CreateFileBasedResourceManager(string baseName, string resourceDir, Type? usingResourceSet)
+        public static ResourceManager CreateFileBasedResourceManager(string baseName, string resourceDir,
+            [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors)]
+            Type? usingResourceSet)
         {
             return new ResourceManager(baseName, resourceDir, usingResourceSet);
         }

src/libraries/System.Private.CoreLib/src/System/Resources/ResourceSet.cs

@@ -15,6 +15,7 @@
 
 using System.Collections;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using System.Reflection;
 
@@ -115,10 +116,11 @@ public virtual Type GetDefaultReader()
         // Returns the preferred IResourceWriter class for this kind of ResourceSet.
         // Subclasses of ResourceSet using their own Readers &; should override
         // GetDefaultReader and GetDefaultWriter.
+        // TODO: https://github.com/mono/linker/issues/943
+        [DynamicDependency(DynamicallyAccessedMemberTypes.PublicConstructors, "System.Resources.ResourceWriter", "System.Resources.Writer")]
         public virtual Type GetDefaultWriter()
         {
-            Assembly resourceWriterAssembly = Assembly.Load("System.Resources.Writer, Version=4.0.1.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a");
-            return resourceWriterAssembly.GetType("System.Resources.ResourceWriter", throwOnError: true)!;
+            return Type.GetType("System.Resources.ResourceWriter, System.Resources.Writer", throwOnError: true)!;
         }
 
         public virtual IDictionaryEnumerator GetEnumerator()

src/mono/netcore/System.Private.CoreLib/src/System/Reflection/CustomAttribute.cs

@@ -591,6 +591,8 @@ internal static bool IsDefined(ICustomAttributeProvider obj, Type attributeType,
         [MethodImplAttribute(MethodImplOptions.InternalCall)]
         private static extern bool IsDefinedInternal(ICustomAttributeProvider obj, Type AttributeType);
 
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2006:UnrecognizedReflectionPattern",
+            Justification = "Linker analyzes base properties and marks them")]
         private static PropertyInfo? GetBasePropertyDefinition(RuntimePropertyInfo property)
         {
             MethodInfo? method = property.GetGetMethod(true);
@@ -620,6 +622,8 @@ internal static bool IsDefined(ICustomAttributeProvider obj, Type attributeType,
 
         }
 
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2006:UnrecognizedReflectionPattern",
+            Justification = "Linker analyzes base events and marks them")]
         private static EventInfo? GetBaseEventDefinition(RuntimeEventInfo evt)
         {
             MethodInfo? method = evt.GetAddMethod(true);

src/mono/netcore/System.Private.CoreLib/src/System/Reflection/Emit/TypeBuilder.Mono.cs

@@ -792,6 +792,8 @@ private bool has_ctor_method()
 
         // We require emitted types to have all members on their bases to be accessible.
         // This is basically an identity function for `this`.
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2006:UnrecognizedReflectionPattern",
+            Justification = "Reflection emitted types have all of their members")]
         [return: DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)]
         public
         TypeInfo? CreateTypeInfo()
@@ -1819,6 +1821,8 @@ public GenericTypeParameterBuilder[] DefineGenericParameters(params string[] nam
             return generic_params;
         }
 
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2006:UnrecognizedReflectionPattern",
+            Justification = "Linker thinks Type.GetConstructor(ConstructorInfo) is one of the public APIs because it doesn't analyze method signatures. We already have ConstructorInfo.")]
         public static ConstructorInfo GetConstructor(Type type, ConstructorInfo constructor)
         {
             /*FIXME I would expect the same checks of GetMethod here*/

src/mono/netcore/System.Private.CoreLib/src/System/Reflection/Emit/TypeBuilderInstantiation.cs

@@ -120,6 +120,8 @@ internal bool IsCreated
             return InflateType(type, type_arguments, method_args);
         }
 
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2006:UnrecognizedReflectionPattern",
+            Justification = "Reflection emitted types have all of their members")]
         internal static Type? InflateType(Type? type, Type[]? type_args, Type[]? method_args)
         {
             if (type == null)