Fix assertion with async lambdas; fix async local functions.

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

@@ -137,6 +137,36 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 			}
 			return num;
 		}
+
+		public static Func<Task<int>> AsyncLambda()
+		{
+			return async () => await GetIntegerSumAsync(new int[3] {
+				1,
+				2,
+				3
+			});
+		}
+
+		public static Func<Task<int>> AsyncDelegate()
+		{
+			return async delegate {
+				await Task.Delay(10);
+				return 2;
+			};
+		}
+
+#if CS70
+		public static async Task<int> AsyncLocalFunctions()
+		{
+			return await Nested(1) + await Nested(2);
+
+			async Task<int> Nested(int i)
+			{
+				await Task.Delay(i);
+				return i;
+			}
+		}
+#endif
 	}
 
 	public struct HopToThreadPoolAwaitable : INotifyCompletion

ICSharpCode.Decompiler/CSharp/StatementBuilder.cs

@@ -968,6 +968,9 @@ namespace ICSharpCode.Decompiler.CSharp
 				stmt.Parameters.AddRange(exprBuilder.MakeParameters(function.Parameters, function));
 				stmt.ReturnType = exprBuilder.ConvertType(function.Method.ReturnType);
 				stmt.Body = nestedBuilder.ConvertAsBlock(function.Body);
+				if (function.IsAsync) {
+					stmt.Modifiers |= Modifiers.Async;
+				}
 				stmt.AddAnnotation(new MemberResolveResult(null, function.ReducedMethod));
 				return stmt;
 			}

ICSharpCode.Decompiler/IL/ControlFlow/YieldReturnDecompiler.cs

@@ -390,7 +390,7 @@ namespace ICSharpCode.Decompiler.IL.ControlFlow
 				methodTypeParameters: null);
 			var body = context.TypeSystem.MainModule.PEFile.Reader.GetMethodBody(methodDef.RelativeVirtualAddress);
 			var il = context.CreateILReader()
-				.ReadIL(method, body, genericContext, context.Function.Kind, context.CancellationToken);
+				.ReadIL(method, body, genericContext, ILFunctionKind.TopLevelFunction, context.CancellationToken);
 			il.RunTransforms(CSharpDecompiler.EarlyILTransforms(true),
 				new ILTransformContext(il, context.TypeSystem, context.DebugInfo, context.Settings) {
 					CancellationToken = context.CancellationToken,

ICSharpCode.Decompiler/IL/Instructions/ILFunction.cs

@@ -226,7 +226,7 @@ namespace ICSharpCode.Decompiler.IL
 					Debug.Assert(DelegateType?.FullName == "System.Linq.Expressions.Expression" && DelegateType.TypeParameterCount == 1);
 					break;
 				case ILFunctionKind.LocalFunction:
-					Debug.Assert(Parent is ILFunction);
+					Debug.Assert(Parent is ILFunction && SlotInfo == ILFunction.LocalFunctionsSlot);
 					Debug.Assert(DeclarationScope != null);
 					Debug.Assert(DelegateType == null);
 					Debug.Assert(Method != null);