Fix #963: foreach-over-array mishandles captured variables

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

@@ -16,6 +16,9 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 			TestCase4("TestCase4");
 			OutsideLoop();
 			InsideLoop();
+			OutsideLoopOverArray();
+			OutsideLoopOverArray2();
+			InsideLoopOverArray2();
 		}
 
 		static void TestCase1()
@@ -121,5 +124,55 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 				Console.WriteLine(func());
 			}
 		}
+
+		static void OutsideLoopOverArray()
+		{
+			Console.WriteLine("OutsideLoopOverArray:");
+			var functions = new List<Func<int>>();
+			var array = new int[] { 1, 2, 3 };
+			int val; // declared outside loop
+					 // The decompiler cannot convert this to a foreach-loop without
+					 // changing the lambda capture semantics.
+			for (int i = 0; i < array.Length; ++i) {
+				val = array[i];
+				functions.Add(() => val);
+			}
+			foreach (var func in functions) {
+				Console.WriteLine(func());
+			}
+		}
+
+		static void OutsideLoopOverArray2()
+		{
+			Console.WriteLine("OutsideLoopOverArray2:");
+			var functions = new List<Func<int>>();
+			var array = new int[] { 1, 2, 3 };
+			int val; // declared outside loop
+					 // The decompiler can convert this to a foreach-loop, but the 'val'
+					 // variable must be declared outside.
+			for (int i = 0; i < array.Length; ++i) {
+				int element = array[i];
+				val = element * 2;
+				functions.Add(() => val);
+			}
+			foreach (var func in functions) {
+				Console.WriteLine(func());
+			}
+		}
+
+		static void InsideLoopOverArray2()
+		{
+			Console.WriteLine("InsideLoopOverArray2:");
+			var functions = new List<Func<int>>();
+			var array = new int[] { 1, 2, 3 };
+			for (int i = 0; i < array.Length; ++i) {
+				int element = array[i];
+				int val = element * 2;
+				functions.Add(() => val);
+			}
+			foreach (var func in functions) {
+				Console.WriteLine(func());
+			}
+		}
 	}
 }

ICSharpCode.Decompiler/CSharp/Transforms/PatternStatementTransform.cs

@@ -251,7 +251,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 			var itemVariable = m.Get<IdentifierExpression>("itemVariable").Single().GetILVariable();
 			var indexVariable = m.Get<IdentifierExpression>("indexVariable").Single().GetILVariable();
 			var arrayVariable = m.Get<IdentifierExpression>("arrayVariable").Single().GetILVariable();
-			if (!itemVariable.IsSingleDefinition)
+			if (!itemVariable.IsSingleDefinition || itemVariable.CaptureScope != null)
 				return null;
 			if (indexVariable.StoreCount != 2 || indexVariable.LoadCount != 3 || indexVariable.AddressCount != 0)
 				return null;
@@ -264,6 +264,7 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 				InExpression = m.Get<IdentifierExpression>("arrayVariable").Single().Detach(),
 				EmbeddedStatement = body
 			};
+			foreachStmt.CopyAnnotationsFrom(forStatement);
 			itemVariable.Kind = IL.VariableKind.ForeachLocal;
 			// Add the variable annotation for highlighting (TokenTextWriter expects it directly on the ForeachStatement).
 			foreachStmt.AddAnnotation(new ILVariableResolveResult(itemVariable, itemVariable.Type));