Fix #1404: local variables with init flag are not declared in the correct scope

ICSharpCode.Decompiler.Tests/CorrectnessTestRunner.cs

@@ -166,6 +166,12 @@ namespace ICSharpCode.Decompiler.Tests
 			RunCS(options: options);
 		}
 
+		[Test]
+		public void Uninit([ValueSource("noMonoOptions")] CompilerOptions options)
+		{
+			RunVB(options: options);
+		}
+
 		[Test]
 		public void MemberLookup([ValueSource("defaultOptions")] CompilerOptions options)
 		{

ICSharpCode.Decompiler.Tests/Helpers/Tester.VB.cs

@@ -54,6 +54,7 @@ namespace ICSharpCode.Decompiler.Tests.Helpers
 				options.CompilerOptions = "/o" + (flags.HasFlag(CompilerOptions.Optimize) ? "+" : "-");
 				options.CompilerOptions += (flags.HasFlag(CompilerOptions.UseDebug) ? " /debug" : "");
 				options.CompilerOptions += (flags.HasFlag(CompilerOptions.Force32Bit) ? " /platform:anycpu32bitpreferred" : "");
+				options.CompilerOptions += "/optioninfer+ /optionexplicit+";
 				if (preprocessorSymbols.Count > 0) {
 					options.CompilerOptions += " /d:" + string.Join(",", preprocessorSymbols.Select(p => $"{p.Key}={p.Value}"));
 				}

ICSharpCode.Decompiler.Tests/ICSharpCode.Decompiler.Tests.csproj

@@ -52,6 +52,7 @@
   <ItemGroup>
     <None Include="TestCases\Correctness\Jmp.il" />
     <None Include="TestCases\Correctness\StackTypes.il" />
+    <None Include="TestCases\Correctness\Uninit.vb" />
     <None Include="TestCases\ILPretty\FSharpLoops.fs" />
     <None Include="TestCases\ILPretty\FSharpLoops_Debug.il" />
     <None Include="TestCases\ILPretty\FSharpLoops_Release.il" />

ICSharpCode.Decompiler.Tests/TestCases/Correctness/Uninit.vb

@@ -0,0 +1,21 @@
+Imports System
+
+Module UninitTest
+    Sub Main()
+        Dim i = 0
+        Dim result As Integer = -5
+        Dim num As Integer
+        Do
+            If num > result Then
+                num += 5
+                result += 5
+            End If
+            result += 1
+            i += 1
+            If i > 10 Then
+                Exit Do
+            End If
+        Loop
+        Console.WriteLine(result)
+    End Sub
+End Module

ICSharpCode.Decompiler/CSharp/Transforms/DeclareVariables.cs

@@ -187,10 +187,10 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 		private static bool IsValidInStatementExpression(Expression expr)
 		{
 			switch (expr) {
-				case InvocationExpression ie:
-				case ObjectCreateExpression oce:
-				case AssignmentExpression ae:
-				case ErrorExpression ee:
+				case InvocationExpression _:
+				case ObjectCreateExpression _:
+				case AssignmentExpression _:
+				case ErrorExpression _:
 					return true;
 				case UnaryOperatorExpression uoe:
 					switch (uoe.Operator) {
@@ -249,12 +249,27 @@ namespace ICSharpCode.Decompiler.CSharp.Transforms
 							newPoint = scopeTracking[startIndex + 1].InsertionPoint;
 						} else {
 							newPoint = new InsertionPoint { level = nodeLevel, nextNode = identExpr };
+							if (variable.HasInitialValue) {
+								// Uninitialized variables are logically initialized at the beginning of the functin
+								// Because it's possible that the variable has a loop-carried dependency,
+								// declare it outside of any loops.
+								while (startIndex >= 0) {
+									if (scopeTracking[startIndex].Scope.EntryPoint.IncomingEdgeCount > 1) {
+										// declare variable outside of loop
+										newPoint = scopeTracking[startIndex].InsertionPoint;
+									} else if (scopeTracking[startIndex].Scope.Parent is ILFunction) {
+										// stop at beginning of function
+										break;
+									}
+									startIndex--;
+								}
+							}
 						}
 						VariableToDeclare v;
-						if (variableDict.TryGetValue(rr.Variable, out v)) {
+						if (variableDict.TryGetValue(variable, out v)) {
 							v.InsertionPoint = FindCommonParent(v.InsertionPoint, newPoint);
 						} else {
-							v = new VariableToDeclare(rr.Variable, rr.Variable.HasInitialValue,
+							v = new VariableToDeclare(variable, variable.HasInitialValue,
 								newPoint, identExpr, sourceOrder: variableDict.Count);
 							variableDict.Add(rr.Variable, v);
 						}