Fix #1760: NRE in ILInlining, if nullable.rewrap is used with an expression that has a type parameter as its type.

ICSharpCode.Decompiler.Tests/TestCases/Pretty/Generics.cs

@@ -24,10 +24,17 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 	{
 		private class GenericClass<T>
 		{
+			private readonly T issue1760;
+
 			public void M(out GenericClass<T> self)
 			{
 				self = this;
 			}
+
+			public void Issue1760()
+			{
+				Console.WriteLine(", " + issue1760);
+			}
 		}
 
 		public class BaseClass

ICSharpCode.Decompiler/IL/Transforms/ILInlining.cs

@@ -269,6 +269,8 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 
 		internal static bool MethodRequiresCopyForReadonlyLValue(IMethod method)
 		{
+			if (method == null)
+				return true;
 			var type = method.DeclaringType;
 			if (type.IsReferenceType == true)
 				return false; // reference types are never implicitly copied
@@ -303,6 +305,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 					}
 					return !method.IsStatic;
 				case OpCode.Await:
+					method = ((Await)inst.Parent).GetAwaiterMethod;
 					return true;
 				case OpCode.NullableUnwrap:
 					return ((NullableUnwrap)inst.Parent).RefInput;