Fix #241: type analysis causes truncation of integer literals when calculating with types smaller than int32.

ICSharpCode.Decompiler/ILAst/InitializerPeepholeTransforms.cs

@@ -148,7 +148,6 @@ namespace ICSharpCode.Decompiler.ILAst
 		{
 			switch (elementType) {
 				case TypeCode.Boolean:
-				case TypeCode.SByte:
 				case TypeCode.Byte:
 					if (initialValue.Length == output.Length) {
 						for (int j = 0; j < output.Length; j++) {
@@ -157,9 +156,15 @@ namespace ICSharpCode.Decompiler.ILAst
 						return true;
 					}
 					return false;
-				case TypeCode.Char:
+				case TypeCode.SByte:
+					if (initialValue.Length == output.Length) {
+						for (int j = 0; j < output.Length; j++) {
+							output[j] = new ILExpression(ILCode.Ldc_I4, (int)unchecked((sbyte)initialValue[j]));
+						}
+						return true;
+					}
+					return false;
 				case TypeCode.Int16:
-				case TypeCode.UInt16:
 					if (initialValue.Length == output.Length * 2) {
 						for (int j = 0; j < output.Length; j++) {
 							output[j] = new ILExpression(ILCode.Ldc_I4, (int)BitConverter.ToInt16(initialValue, j * 2));
@@ -167,6 +172,15 @@ namespace ICSharpCode.Decompiler.ILAst
 						return true;
 					}
 					return false;
+				case TypeCode.Char:
+				case TypeCode.UInt16:
+					if (initialValue.Length == output.Length * 2) {
+						for (int j = 0; j < output.Length; j++) {
+							output[j] = new ILExpression(ILCode.Ldc_I4, (int)BitConverter.ToUInt16(initialValue, j * 2));
+						}
+						return true;
+					}
+					return false;
 				case TypeCode.Int32:
 				case TypeCode.UInt32:
 					if (initialValue.Length == output.Length * 4) {

ICSharpCode.Decompiler/ILAst/TypeAnalysis.cs

@@ -543,9 +543,19 @@ namespace ICSharpCode.Decompiler.ILAst
 				case ILCode.Ldc_I4:
 					if (IsBoolean(expectedType) && ((int)expr.Operand == 0 || (int)expr.Operand == 1))
 						return typeSystem.Boolean;
-					return (IsIntegerOrEnum(expectedType) || expectedType is PointerType) ? expectedType : typeSystem.Int32;
+					if (expectedType is PointerType && (int)expr.Operand == 0)
+						return expectedType;
+					if (IsIntegerOrEnum(expectedType) && OperandFitsInType(expectedType, (int)expr.Operand))
+						return expectedType;
+					else
+						return typeSystem.Int32;
 				case ILCode.Ldc_I8:
-					return (IsIntegerOrEnum(expectedType) || expectedType is PointerType) ? expectedType : typeSystem.Int64;
+					if (expectedType is PointerType && (long)expr.Operand == 0)
+						return expectedType;
+					if (IsIntegerOrEnum(expectedType) && GetInformationAmount(expectedType) >= NativeInt)
+						return expectedType;
+					else
+						return typeSystem.Int64;
 				case ILCode.Ldc_R4:
 					return typeSystem.Single;
 				case ILCode.Ldc_R8:
@@ -1043,6 +1053,29 @@ namespace ICSharpCode.Decompiler.ILAst
 			}
 		}
 		
+		static bool OperandFitsInType(TypeReference type, int num)
+		{
+			TypeDefinition typeDef = type.Resolve() as TypeDefinition;
+			if (typeDef != null && typeDef.IsEnum) {
+				type = typeDef.Fields.Single(f => f.IsRuntimeSpecialName && !f.IsStatic).FieldType;
+			}
+			switch (type.MetadataType) {
+				case MetadataType.SByte:
+					return sbyte.MinValue <= num && num <= sbyte.MaxValue;
+				case MetadataType.Int16:
+					return short.MinValue <= num && num <= short.MaxValue;
+				case MetadataType.Byte:
+					return byte.MinValue <= num && num <= byte.MaxValue;
+				case MetadataType.Char:
+					return char.MinValue <= num && num <= char.MaxValue;
+				case MetadataType.UInt16:
+					return ushort.MinValue <= num && num <= ushort.MaxValue;
+					break;
+				default:
+					return true;
+			}
+		}
+		
 		static bool IsArrayPointerOrReference(TypeReference type)
 		{
 			TypeSpecification typeSpec = type as TypeSpecification;

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

@@ -63,6 +63,7 @@
     <Compile Include="PInvoke.cs" />
     <Compile Include="QueryExpressions.cs" />
     <Compile Include="Switch.cs" />
+    <Compile Include="TypeAnalysisTests.cs" />
     <Compile Include="UndocumentedExpressions.cs" />
     <Compile Include="UnsafeCode.cs" />
     <Compile Include="Types\S_TypeDeclarations.cs" />

ICSharpCode.Decompiler/Tests/TestRunner.cs

@@ -142,6 +142,12 @@ namespace ICSharpCode.Decompiler.Tests
 			TestFile(@"..\..\Tests\YieldReturn.cs");
 		}
 		
+		[Test]
+		public void TypeAnalysis()
+		{
+			TestFile(@"..\..\Tests\TypeAnalysisTests.cs");
+		}
+		
 		static void TestFile(string fileName)
 		{
 			string code = File.ReadAllText(fileName);

ICSharpCode.Decompiler/Tests/TypeAnalysisTests.cs

@@ -0,0 +1,27 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+
+public class TypeAnalysisTests
+{
+	public byte SubtractFrom256(byte b)
+	{
+		return (byte)(256 - (int)b);
+	}
+}