Add support for mcs 2.6.4 switch-on-string

ICSharpCode.Decompiler.Tests/CorrectnessTestRunner.cs

@@ -115,9 +115,6 @@ namespace ICSharpCode.Decompiler.Tests
 		[Test]
 		public void Switch([ValueSource("defaultOptions")] CompilerOptions options)
 		{
-			if (options.HasFlag(CompilerOptions.UseMcs)) {
-				Assert.Ignore("Decompiler bug with mono!");
-			}
 			RunCS(options: options);
 		}
 

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

@@ -25,7 +25,9 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 		public static void Main()
 		{
 			TestCase(SparseIntegerSwitch, -100, 1, 2, 3, 4);
+#if !MCS
 			TestCase(ShortSwitchOverString, "First case", "Else");
+#endif
 			TestCase(ShortSwitchOverString2, "First case", "Second case", "Third case", "Else");
 			TestCase(ShortSwitchOverStringNoExplicitDefault, "First case", "Second case", "Third case", "Else");
 			TestCase(SwitchOverString1, "First case", "Second case", "2nd case", "Third case", "Fourth case", "Fifth case", "Sixth case", null, "default", "else");
@@ -65,6 +67,7 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 			}
 		}
 
+#if !MCS
 		public static string ShortSwitchOverString(string text)
 		{
 			Console.WriteLine("ShortSwitchOverString: " + text);
@@ -75,6 +78,7 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 					return "Default";
 			}
 		}
+#endif
 
 		public static string ShortSwitchOverString2(string text)
 		{

ICSharpCode.Decompiler/CSharp/StatementBuilder.cs

@@ -83,7 +83,7 @@ namespace ICSharpCode.Decompiler.CSharp
 			return new IfElseStatement(condition, trueStatement, falseStatement);
 		}
 
-		ConstantResolveResult CreateTypedCaseLabel(long i, IType type, string[] map = null)
+		IEnumerable<ConstantResolveResult> CreateTypedCaseLabel(long i, IType type, List<(string Key, int Value)> map = null)
 		{
 			object value;
 			// unpack nullable type, if necessary:
@@ -92,14 +92,17 @@ namespace ICSharpCode.Decompiler.CSharp
 			if (type.IsKnownType(KnownTypeCode.Boolean)) {
 				value = i != 0;
 			} else if (type.IsKnownType(KnownTypeCode.String) && map != null) {
-				value = map[i];
+				var keys = map.Where(entry => entry.Value == i).Select(entry => entry.Key);
+				foreach (var key in keys)
+					yield return new ConstantResolveResult(type, key);
+				yield break;
 			} else if (type.Kind == TypeKind.Enum) {
 				var enumType = type.GetDefinition().EnumUnderlyingType;
 				value = CSharpPrimitiveCast.Cast(ReflectionHelper.GetTypeCode(enumType), i, false);
 			} else {
 				value = CSharpPrimitiveCast.Cast(ReflectionHelper.GetTypeCode(type), i, false);
 			}
-			return new ConstantResolveResult(type, value);
+			yield return new ConstantResolveResult(type, value);
 		}
 
 		protected internal override Statement VisitSwitchInstruction(SwitchInstruction inst)
@@ -143,7 +146,7 @@ namespace ICSharpCode.Decompiler.CSharp
 					astSection.CaseLabels.Add(new CaseLabel());
 					firstValueResolveResult = null;
 				} else {
-					var values = section.Labels.Values.Select(i => CreateTypedCaseLabel(i, value.Type, strToInt?.Map)).ToArray();
+					var values = section.Labels.Values.SelectMany(i => CreateTypedCaseLabel(i, value.Type, strToInt?.Map)).ToArray();
 					if (section.HasNullLabel) {
 						astSection.CaseLabels.Add(new CaseLabel(new NullReferenceExpression()));
 						firstValueResolveResult = new ConstantResolveResult(SpecialType.NullType, null);

ICSharpCode.Decompiler/IL/Instructions/StringToInt.cs

@@ -17,28 +17,46 @@
 // DEALINGS IN THE SOFTWARE.
 
 
+using System.Collections.Generic;
+
 namespace ICSharpCode.Decompiler.IL
 {
 	partial class StringToInt
 	{
-		public string[] Map { get; }
+		public List<(string Key, int Value)> Map { get; }
 
-		public StringToInt(ILInstruction argument, string[] map)
+		public StringToInt(ILInstruction argument, List<(string Key, int Value)> map)
 			: base(OpCode.StringToInt)
 		{
 			this.Argument = argument;
 			this.Map = map;
 		}
 
+		public StringToInt(ILInstruction argument, string[] map)
+			: this(argument, ArrayToDictionary(map))
+		{
+		}
+
+		static List<(string Key, int Value)> ArrayToDictionary(string[] map)
+		{
+			var dict = new List<(string Key, int Value)>();
+			for (int i = 0; i < map.Length; i++) {
+				dict.Add((map[i], i));
+			}
+			return dict;
+		}
+
 		public override void WriteTo(ITextOutput output, ILAstWritingOptions options)
 		{
 			ILRange.WriteTo(output, options);
 			output.Write("string.to.int (");
 			Argument.WriteTo(output, options);
 			output.Write(", { ");
-			for (int i = 0; i < Map.Length; i++) {
+			int i = 0;
+			foreach (var entry in Map) {
 				if (i > 0) output.Write(", ");
-				output.Write($"[{i}] = \"{Map[i]}\"");
+				output.Write($"[\"{entry.Key}\"] = {entry.Value}");
+				i++;
 			}
 			output.Write(" })");
 		}

ICSharpCode.Decompiler/IL/Transforms/SwitchOnStringTransform.cs

@@ -245,7 +245,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				return false;
 			if (!defaultBlockJump.MatchBranch(out var defaultBlock))
 				return false;
-			if (!(condition.MatchLogicNot(out var arg) && arg is Call c && c.Method.Name == "TryGetValue" &&
+			if (!(condition.MatchLogicNot(out var arg) && arg is CallInstruction c && c.Method.Name == "TryGetValue" &&
 				MatchDictionaryFieldLoad(c.Arguments[0], IsStringToIntDictionary, out var dictField2, out _) && dictField2.Equals(dictField)))
 				return false;
 			if (!c.Arguments[1].MatchLdLoc(switchValueVar) || !c.Arguments[2].MatchLdLoca(out var switchIndexVar))
@@ -274,7 +274,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				switchValue = new LdLoc(switchValueVar);
 				keepAssignmentBefore = true;
 			}
-			var stringToInt = new StringToInt(switchValue, stringValues.ToArray());
+			var stringToInt = new StringToInt(switchValue, stringValues);
 			var inst = new SwitchInstruction(stringToInt);
 			inst.Sections.AddRange(sections);
 			instructions[i + 1].ReplaceWith(inst);
@@ -290,7 +290,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			return true;
 		}
 
-		private bool AddNullSection(List<SwitchSection> sections, List<string> stringValues, Block nullValueCaseBlock)
+		bool AddNullSection(List<SwitchSection> sections, List<(string, int)> stringValues, Block nullValueCaseBlock)
 		{
 			var label = new LongSet(sections.Count);
 			var possibleConflicts = sections.Where(sec => sec.Labels.Overlaps(label)).ToArray();
@@ -301,7 +301,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 					return false; // cannot remove only label
 				possibleConflicts[0].Labels = possibleConflicts[0].Labels.ExceptWith(label);
 			}
-			stringValues.Add(null);
+			stringValues.Add((null, (int)label.Values.First()));
 			sections.Add(new SwitchSection() { Labels = label, Body = new Branch(nullValueCaseBlock) });
 			return true;
 		}
@@ -322,7 +322,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 		/// <summary>
 		/// Matches and extracts values from Add-call sequences.
 		/// </summary>
-		bool ExtractStringValuesFromInitBlock(Block block, out List<string> values, Block targetBlock, IType dictionaryType, IField dictionaryField)
+		bool ExtractStringValuesFromInitBlock(Block block, out List<(string, int)> values, Block targetBlock, IType dictionaryType, IField dictionaryField)
 		{
 			values = null;
 			// stloc dictVar(newobj Dictionary..ctor(ldc.i4 valuesLength))
@@ -342,10 +342,10 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				if (!newObj.Arguments[0].MatchLdcI4(out valuesLength))
 					return false;
 			}
-			values = new List<string>(valuesLength);
+			values = new List<(string, int)>(valuesLength);
 			int i = 0;
-			while (MatchAddCall(dictionaryType, block.Instructions[i + 1], dictVar, i, out var value)) {
+			while (MatchAddCall(dictionaryType, block.Instructions[i + 1], dictVar, out var index, out var value)) {
-				values.Add(value);
+				values.Add((value, index));
 				i++;
 			}
 			// final store to compiler-generated variable:
@@ -362,16 +362,17 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 		/// -or-
 		/// call Add(ldloc dictVar, ldstr value, box System.Int32(ldc.i4 index))
 		/// </summary>
-		bool MatchAddCall(IType dictionaryType, ILInstruction inst, ILVariable dictVar, int index, out string value)
+		bool MatchAddCall(IType dictionaryType, ILInstruction inst, ILVariable dictVar, out int index, out string value)
 		{
 			value = null;
-			if (!(inst is Call c && c.Method.Name == "Add" && c.Arguments.Count == 3))
+			index = -1;
+			if (!(inst is CallInstruction c && c.Method.Name == "Add" && c.Arguments.Count == 3))
 				return false;
 			if (!(c.Arguments[0].MatchLdLoc(dictVar) && c.Arguments[1].MatchLdStr(out value)))
 				return false;
 			if (!(c.Method.DeclaringType.Equals(dictionaryType) && !c.Method.IsStatic))
 				return false;
-			return (c.Arguments[2].MatchLdcI4(index) || (c.Arguments[2].MatchBox(out var arg, out _) && arg.MatchLdcI4(index)));
+			return (c.Arguments[2].MatchLdcI4(out index) || (c.Arguments[2].MatchBox(out var arg, out _) && arg.MatchLdcI4(out index)));
 		}
 
 		bool IsStringToIntDictionary(IType dictionaryType)
@@ -474,7 +475,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 					return false;
 				}
 			}
-			var stringToInt = new StringToInt(switchValue, stringValues.ToArray());
+			var stringToInt = new StringToInt(switchValue, stringValues);
 			var inst = new SwitchInstruction(stringToInt);
 			inst.Sections.AddRange(sections);
 			instructions[i + 1].ReplaceWith(inst);