AccessTools.CreateInstance can now use non-public parameterless const…

…ructors, define internal CodeInstruction parameterless constructor

AccessTools.CreateInstance also now invokes the ConstructorInfo rather than using Activator.CreateInstance; the former should be faster.

Harmony/Public/CodeInstruction.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
@@ -11,21 +11,26 @@ namespace HarmonyLib
 	public class CodeInstruction
 	{
 		/// <summary>The opcode</summary>
-		/// 
+		///
 		public OpCode opcode;
 
 		/// <summary>The operand</summary>
 		///
 		public object operand;
 
 		/// <summary>All labels defined on this instruction</summary>
-		/// 
+		///
 		public List<Label> labels = new List<Label>();
 
 		/// <summary>All exception block boundaries defined on this instruction</summary>
-		/// 
+		///
 		public List<ExceptionBlock> blocks = new List<ExceptionBlock>();
 
+		// Internal parameterless constructor that AccessTools.CreateInstance can use, ensuring that labels/blocks are initialized.
+		internal CodeInstruction()
+		{
+		}
+
 		/// <summary>Creates a new CodeInstruction with a given opcode and optional operand</summary>
 		/// <param name="opcode">The opcode</param>
 		/// <param name="operand">The operand</param>

Harmony/Tools/AccessTools.cs

@@ -1692,9 +1692,10 @@ public static object CreateInstance(Type type)
 		{
 			if (type is null)
 				throw new ArgumentNullException(nameof(type));
-			var ctor = type.GetConstructor(BindingFlags.Public | BindingFlags.Instance, null, CallingConventions.Any, new Type[0], null);
+			var ctor = type.GetConstructor(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance, binder: null,
+				CallingConventions.Any, new Type[0], modifiers: null);
 			if (ctor is object)
-				return Activator.CreateInstance(type);
+				return ctor.Invoke(null);
 			return FormatterServices.GetUninitializedObject(type);
 		}
 

HarmonyTests/Tools/TestAccessTools.cs

@@ -365,10 +365,10 @@ public void Test_AccessTools_CreateInstance()
 			Assert.IsTrue(AccessTools.CreateInstance<AccessToolsCreateInstance.NoConstructor>().constructorCalled);
 			Assert.IsFalse(AccessTools.CreateInstance<AccessToolsCreateInstance.OnlyNonParameterlessConstructor>().constructorCalled);
 			Assert.IsTrue(AccessTools.CreateInstance<AccessToolsCreateInstance.PublicParameterlessConstructor>().constructorCalled);
-			Assert.IsFalse(AccessTools.CreateInstance<AccessToolsCreateInstance.InternalParameterlessConstructor>().constructorCalled);
+			Assert.IsTrue(AccessTools.CreateInstance<AccessToolsCreateInstance.InternalParameterlessConstructor>().constructorCalled);
 			var instruction = AccessTools.CreateInstance<CodeInstruction>();
-			Assert.Null(instruction.labels);
-			Assert.Null(instruction.blocks);
+			Assert.NotNull(instruction.labels);
+			Assert.NotNull(instruction.blocks);
 		}
 
 		[Test]