Fix bug in Clone() impl for collection slots.

ICSharpCode.Decompiler/IL/Instructions.cs

@@ -414,7 +414,7 @@ namespace ICSharpCode.Decompiler.IL
 		public sealed override ILInstruction Clone()
 		{
 			var clone = (CallInstruction)ShallowClone();
-			clone.Arguments = new InstructionCollection<ILInstruction>(this, 0);
+			clone.Arguments = new InstructionCollection<ILInstruction>(clone, 0);
 			clone.Arguments.AddRange(this.Arguments.Select(arg => arg.Clone()));
 			return clone;
 		}
@@ -2631,7 +2631,7 @@ namespace ICSharpCode.Decompiler.IL
 		public sealed override ILInstruction Clone()
 		{
 			var clone = (NewArr)ShallowClone();
-			clone.Indices = new InstructionCollection<ILInstruction>(this, 0);
+			clone.Indices = new InstructionCollection<ILInstruction>(clone, 0);
 			clone.Indices.AddRange(this.Indices.Select(arg => arg.Clone()));
 			return clone;
 		}
@@ -2896,7 +2896,7 @@ namespace ICSharpCode.Decompiler.IL
 		{
 			var clone = (LdElema)ShallowClone();
 			clone.Array = this.array.Clone();
-			clone.Indices = new InstructionCollection<ILInstruction>(this, 1);
+			clone.Indices = new InstructionCollection<ILInstruction>(clone, 1);
 			clone.Indices.AddRange(this.Indices.Select(arg => arg.Clone()));
 			return clone;
 		}

ICSharpCode.Decompiler/IL/Instructions.tt

@@ -737,7 +737,7 @@ namespace ICSharpCode.Decompiler.IL
 			b.AppendLine("\tvar clone = (" + opCode.Name + ")ShallowClone();");
 			for (int i = 0; i < children.Length; i++) {
 				if (children[i].IsCollection) {
-					b.AppendLine("\tclone." + children[i].PropertyName + " = new InstructionCollection<ILInstruction>(this, " + i + ");");
+					b.AppendLine("\tclone." + children[i].PropertyName + " = new InstructionCollection<ILInstruction>(clone, " + i + ");");
 					b.AppendLine("\tclone." + children[i].PropertyName + ".AddRange(this." + children[i].PropertyName + ".Select(arg => arg.Clone()));");
 				} else
 					b.AppendLine("\tclone." + children[i].PropertyName + " = this." + children[i].Name + ".Clone();");

ICSharpCode.Decompiler/IL/Instructions/ILInstruction.cs

@@ -522,6 +522,11 @@ namespace ICSharpCode.Decompiler.IL
 		/// <summary>
 		/// Creates a deep clone of the ILInstruction.
 		/// </summary>
+		/// <remarks>
+		/// It is valid to clone nodes with stale positions (see remarks on <c>Parent</c>);
+		/// the result of such a clone will not contain any stale positions (nodes at
+		/// multiple positions will be cloned once per position).
+		/// </remarks>
 		public abstract ILInstruction Clone();
 		
 		/// <summary>