Fix #878: InvalidCastException in StatementBuilder.TransformToForeach

ICSharpCode.Decompiler.Tests/TestCases/Correctness/Loops.cs

@@ -32,6 +32,9 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 			ForWithMultipleVariables();
 			DoubleForEachWithSameVariable(new[] { "a", "b", "c" });
 			ForeachExceptForNameCollision(new[] { 42, 43, 44, 45 });
+			NonGenericForeachWithReturnFallbackTest(new object[] { "a", 42, "b", 43 });
+			NonGenericForeachWithReturn(new object[] { "a", 42, "b", 43 });
+			ForeachWithReturn(new[] { 42, 43, 44, 45 });
 		}
 
 		public static void ForWithMultipleVariables()
@@ -90,5 +93,29 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 			}
 			Console.WriteLine("After finally!");
 		}
+
+		public static object NonGenericForeachWithReturn(IEnumerable enumerable)
+		{
+			Console.WriteLine("NonGenericForeachWithReturn:");
+			foreach (var obj in enumerable) {
+				Console.WriteLine("return: " + obj);
+				return obj;
+			}
+
+			Console.WriteLine("return: null");
+			return null;
+		}
+
+		public static int? ForeachWithReturn(IEnumerable<int> enumerable)
+		{
+			Console.WriteLine("ForeachWithReturn:");
+			foreach (var obj in enumerable) {
+				Console.WriteLine("return: " + obj);
+				return obj;
+			}
+
+			Console.WriteLine("return: null");
+			return null;
+		}
 	}
 }

ICSharpCode.Decompiler/CSharp/StatementBuilder.cs

@@ -510,7 +510,6 @@ namespace ICSharpCode.Decompiler.CSharp
 						forStmt.Iterators.Add(iterator.Detach());
 					}
 					return forStmt;
-				default:
 				case LoopKind.While:
 					if (loop.Body == null) {
 						blockStatement = ConvertBlockContainer(container, true);
@@ -534,6 +533,8 @@ namespace ICSharpCode.Decompiler.CSharp
 					if (blockStatement.LastOrDefault() is ContinueStatement stmt)
 						stmt.Remove();
 					return new WhileStatement(conditionExpr, blockStatement);
+				default:
+					throw new ArgumentOutOfRangeException();
 			}
 		}
 

ICSharpCode.Decompiler/IL/DetectedLoop.cs

@@ -23,7 +23,7 @@ using ICSharpCode.Decompiler.Util;
 
 namespace ICSharpCode.Decompiler.IL
 {
-	public enum LoopKind { While, DoWhile, For }
+	public enum LoopKind { None, While, DoWhile, For }
 
 	public class DetectedLoop
 	{
@@ -86,6 +86,10 @@ namespace ICSharpCode.Decompiler.IL
 
 		private DetectedLoop DetectLoopInternal()
 		{
+			if (Container.EntryPoint.IncomingEdgeCount <= 1) {
+				Kind = LoopKind.None;
+				return this;
+			}
 			Kind = LoopKind.While;
 			ContinueJumpTarget = Container.EntryPoint;
 			if (Container.EntryPoint.Instructions.Count == 2