From 6ba013d9dd0d3042f03074b5862ec9a8875505e0 Mon Sep 17 00:00:00 2001
From: Daniel Grunwald <daniel@danielgrunwald.de>
Date: Tue, 14 May 2013 14:54:06 +0200
Subject: [PATCH] Fix bugs in async/await decompiler.

---
 .../Ast/AstMethodBodyBuilder.cs                  | 16 +++++++++++-----
 ICSharpCode.Decompiler/ILAst/AsyncDecompiler.cs  |  3 ++-
 ICSharpCode.Decompiler/ILAst/ILInlining.cs       |  1 +
 ICSharpCode.Decompiler/Tests/Async.cs            | 11 +++++++++++
 4 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/ICSharpCode.Decompiler/Ast/AstMethodBodyBuilder.cs b/ICSharpCode.Decompiler/Ast/AstMethodBodyBuilder.cs
index 3437af546..078fd4fa7 100644
--- a/ICSharpCode.Decompiler/Ast/AstMethodBodyBuilder.cs
+++ b/ICSharpCode.Decompiler/Ast/AstMethodBodyBuilder.cs
@@ -849,7 +849,7 @@ namespace ICSharpCode.Decompiler.Ast
 					args[args.Count - 1].AddAnnotation(new ParameterDeclarationAnnotation(byteCode));
 					return args[args.Count - 1];
 				case ILCode.Await:
-					return new UnaryOperatorExpression(UnaryOperatorType.Await, arg1);
+					return new UnaryOperatorExpression(UnaryOperatorType.Await, UnpackDirectionExpression(arg1));
 				case ILCode.NullableOf:
 				case ILCode.ValueOf: 
 					return arg1;
@@ -975,10 +975,7 @@ namespace ICSharpCode.Decompiler.Ast
 				
 				// Unpack any DirectionExpression that is used as target for the call
 				// (calling methods on value types implicitly passes the first argument by reference)
-				if (target is DirectionExpression) {
-					target = ((DirectionExpression)target).Expression;
-					target.Remove(); // detach from DirectionExpression
-				}
+				target = UnpackDirectionExpression(target);
 				
 				if (cecilMethodDef != null) {
 					// convert null.ToLower() to ((string)null).ToLower()
@@ -1078,6 +1075,15 @@ namespace ICSharpCode.Decompiler.Ast
 			return target.Invoke(cecilMethod.Name, ConvertTypeArguments(cecilMethod), methodArgs).WithAnnotation(cecilMethod);
 		}
 		
+		static Expression UnpackDirectionExpression(Expression target)
+		{
+			if (target is DirectionExpression) {
+				return ((DirectionExpression)target).Expression.Detach();
+			} else {
+				return target;
+			}
+		}
+		
 		static void AdjustArgumentsForMethodCall(MethodReference cecilMethod, List<Expression> methodArgs)
 		{
 			// Convert 'ref' into 'out' where necessary
diff --git a/ICSharpCode.Decompiler/ILAst/AsyncDecompiler.cs b/ICSharpCode.Decompiler/ILAst/AsyncDecompiler.cs
index 4535c0f82..deed15a8b 100644
--- a/ICSharpCode.Decompiler/ILAst/AsyncDecompiler.cs
+++ b/ICSharpCode.Decompiler/ILAst/AsyncDecompiler.cs
@@ -475,7 +475,8 @@ namespace ICSharpCode.Decompiler.ILAst
 			newBody.RemoveAt(newBody.Count - 1); // remove AwaitUnsafeOnCompleted call
 			if (callAwaitUnsafeOnCompleted == null || callAwaitUnsafeOnCompleted.Code != ILCode.Call)
 				throw new SymbolicAnalysisFailedException();
-			if (((MethodReference)callAwaitUnsafeOnCompleted.Operand).Name != "AwaitUnsafeOnCompleted")
+			string methodName = ((MethodReference)callAwaitUnsafeOnCompleted.Operand).Name;
+			if (methodName != "AwaitUnsafeOnCompleted" && methodName != "AwaitOnCompleted")
 				throw new SymbolicAnalysisFailedException();
 			if (callAwaitUnsafeOnCompleted.Arguments.Count != 3)
 				throw new SymbolicAnalysisFailedException();
diff --git a/ICSharpCode.Decompiler/ILAst/ILInlining.cs b/ICSharpCode.Decompiler/ILAst/ILInlining.cs
index 880592b10..2951cfd53 100644
--- a/ICSharpCode.Decompiler/ILAst/ILInlining.cs
+++ b/ICSharpCode.Decompiler/ILAst/ILInlining.cs
@@ -334,6 +334,7 @@ namespace ICSharpCode.Decompiler.ILAst
 					case ILCode.Stfld:
 					case ILCode.Ldfld:
 					case ILCode.Ldflda:
+					case ILCode.Await:
 						return true;
 				}
 			}
diff --git a/ICSharpCode.Decompiler/Tests/Async.cs b/ICSharpCode.Decompiler/Tests/Async.cs
index ccd122255..7629dd5e6 100644
--- a/ICSharpCode.Decompiler/Tests/Async.cs
+++ b/ICSharpCode.Decompiler/Tests/Async.cs
@@ -20,6 +20,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
 
 public class Async
@@ -36,6 +37,16 @@ public class Async
 		Console.WriteLine("No Await");
 	}
 	
+	public async void AwaitYield()
+	{
+		await Task.Yield();
+	}
+	
+	public async void AwaitDefaultYieldAwaitable()
+	{
+		await default(YieldAwaitable);
+	}
+	
 	public async Task SimpleVoidTaskMethod()
 	{
 		Console.WriteLine("Before");